Tesis: "Vegetation disturbance"

1

Thonicke, Kirsten. "Fire disturbance and vegetation dynamics analysis and models /". Phd thesis, [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968686885.

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2

Bahre, Conrad J. "Human Disturbance and Vegetation in Arizona's Chiricahua Mountains in 1902". University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/553077.

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3

Pryor, Philip J. "Disturbance studies on open Juncus trifidus heath and other Cairngorms vegetation". Thesis, University of Aberdeen, 1986. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU362517.

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The studies were set against a background of concern over the effects of high levels of recreation in the Gairn Gorm area on vegetation and fauna. The aims were to compare the effects of disturbance by trampling on different mountain vegetation types, to examine these effects in detail on one locally widespread vegetation type, Open Juncus trifidus heath, and to make detailed studies of the structure and dynamics of this vegetation type. Comparison of the effects of experimental trampling on six vegetation types showed Alpine Nardus grassland to be the least damaged, followed by Open Juncus trifidus heath. Dwarf-shrub heaths were more heavily damaged. Open Juncus trifidus heath also showed moderate recovery. Vegetation responses were largely determined by the responses of the most abundant species. Such responses supported groupings of species as showing high, moderate or low susceptibility to trampling. Density (4- 4-1 m-** excluding seedlings) and size-class structure were determined for a J.trifidus population at Cairn Lochan, and J.trifidus tussocks were found to be randomly dispersed. Numbers of seedlings seemed to vary from year to year and their spatial distribution was related to the type of surface. Most seedlings occurred on bare soil and on surfaces of fine and medium gravel. A reduction in seedling density from in June, 1980 to 1 . 5m22 in June, 1981 was recorded. The quantitative morphology of J.trifidus tussocks was documented. Tussock size was related to age, based on node counts and the annual production of tillers. The annual cycle of growth and the changes in tussock morphology with age were described. The annual rate of radial growth of tussocks was indicated to be 2 - 3mm per year. An age-state classification for J.trifidus was described. The effects of different surfaces on the germination and establishment of J.trifidus were examined experimentally using a range of gravel sizes and depths at four sites. The benefits of a gravel covering at high altitude were clear. Differences between treatments in numbers of seeds germinating, germination rate, survival, growth and development were sometimes difficult to interpret, but clear altitudinal trends existed. In general, the results supported observations on seedling occurrence in terms of differential effects of surfaces on germination and establishment of J.trifidus? Six Open Juncus trifidus heath sites were used to study the effects of disturbance level on the vegetation and the structure of the J.trifidus population. Significantly lower total plant and J.trifidus cover were only found where the level of disturbance was high. However, moderate disturbance was associated with an increase in smaller J.trifidus individuals, and the number of these and other sized individuals decreased with increasing disturbance. These results were supported by the findings of two studies of footpath disturbance. Wind tunnel experiments showed that surfaces modify microenvironmental conditions with consequent effects on the germination and early growth of J.trifidus. Changes in rates of water loss were important, and a thin layer of gravel benefited J.trifidus establishment. In general, disturbance was thought to influence the recruitment of individuals into the J.trifidus population and thereby modify population structure. The overall dynamics of Open Juncus trifidus heath were discussed and suggestions made for future work.

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4

Isaacs, Rachel E. "Spatial patterns of ice storm disturbance in the forested landscape of Ouachita Mountains, Arkansas and Oklahoma". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1515.

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5

Villegas, Juan Camilo, Darin J. Law, Scott C. Stark, David M. Minor, David D. Breshears, Scott R. Saleska, Abigail L. S. Swann et al. "Prototype campaign assessment of disturbance-induced tree loss effects on surface properties for atmospheric modeling". WILEY, 2017. http://hdl.handle.net/10150/623209.

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Changes in large-scale vegetation structure triggered by processes such as deforestation, wildfires, and tree die-off alter surface structure, energy balance, and associated albedo-all critical for land surface models. Characterizing these properties usually requires long-term data, precluding characterization of rapid vegetation changes such as those increasingly occurring in the Anthropocene. Consequently, the characterization of rapid events is limited and only possible in a few specific areas. We use a campaign approach to characterize surface properties associated with vegetation structure. In our approach, a profiling LiDAR and hemispherical image analyses quantify vegetation structure and a portable mast instrumented with a net radiometer, wind-humidity-temperature stations in a vertical profile, and soil temperature-heat flux characterize surface properties. We illustrate the application of our approach in two forest types (boreal and semiarid) with disturbance-induced tree loss. Our prototype characterizes major structural changes associated with tree loss, changes in vertical wind profiles, surface roughness energy balance partitioning, a proxy for NDVI (Normalized Differential Vegetation Index), and albedo. Multi-day albedo estimates, which differed between control and disturbed areas, were similar to tower-based multiyear characterizations, highlighting the utility and potential of the campaign approach. Our prototype provides general characterization of surface and boundary-layer properties relevant for land surface models, strategically enabling preliminary characterization of rapid vegetation disturbance events.

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6

Lister, Tonya Whitcomb. "Forest Harvesting Disturbance and Site Preparation Effects on Soil Processes and Vegetation in a Young Pine Plantation". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/10051.

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The favorable growth of young loblolly pines (Pinus taeda L.) in response to controlling non-crop vegetation is well documented. However, the beneficial effects of non-crop vegetation on soil quality, nutrient cycling, and biodiversity have not been thoroughly explored. A study was conducted to determine the effects of harvesting-induced soil disturbance, bedding and chemical vegetation control on soil processes and productivity, and to characterize the effects of silvicultural treatments on non-crop vegetation dynamics. Study plots were established on a wet pine flat on South Carolina's lower Coastal Plain. Treatments included a range of 5 disturbance classes (undisturbed, compression tracked, shallowly rutted, deeply rutted and churned), two site preparation treatments (flat planted and bedded) and a gradient of vegetation control (no vegetation control, operational-level weed control and complete weed control). Soil disturbances had relatively small effects on soil quality. Soil compaction reduced soil aeration, but this condition was fully ameliorated by bedding. Churning did not degrade the soil physical environment in any measureable way, largely because slash and litter were incorporated into the surface soil. Bedding and churning increase soil biological activity, which increased nitrogen mineralization in excess of pine demand. When non-crop vegetation was chemically controlled, mineralization rates increased due to increases in surface soil temperatures. With less vegetation on the site, the amount of nitrogen sequestered was less, furthering the potential for nitrogen loss by leaching or denitrification. Soil quality improved somewhat with increasing levels of non-crop vegetation biomass; however, these beneficial effects were marginal during two years of operational vegetation control. The majority of dominant species on undisturbed treatment areas were woody, and soil disturbance, including bedding, reduced the proportions of these species. Silvicultural treatments had little effect on the prevalence of hydrophytic species on these wetland study sites. From a forest management point of view, for this site type, it appears that much is gained by reducing competition from non-crop vegetation; the benefits of controlling the density of non-crop vegetation for encouraging early pine growth are clear. While non-crop vegetation slightly improved system function by sequestering available nitrogen, increasing diversity and increasing soil quality, these improvements do not appear to be critical to forest function on these inherently high-quality sites.
Master of Science

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7

Hough-Snee, Nathaniel. "Relationships between Riparian Vegetation, Hydrology, Climate and Disturbance across the Western United States". Thesis, Utah State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10154374.

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Flow regime, the magnitude, duration and timing of streamflow, controls the development of floodplain landforms on which riparian vegetation communities assemble. Streamflow scours and deposits sediment, structures floodplain soil moisture dynamics, and transports propagules. Flow regime interacts with environmental gradients like climate, land-use, and biomass-removing disturbance to shape riparian plant distributions across landscapes. These gradients select for groups of riparian plant species with traits that allow them to establish, grow, and reproduce on floodplains – riparian vegetation guilds. Here I ask, what governs the distributions of groups of similar riparian plant species across landscapes? To answer this question, I identify relationships between riparian vegetation guilds and communities and environmental gradients across the American West. In Chapter One, I discuss guild-based classification in the context of community ecology and streams. In Chapter Two, I identified five woody riparian vegetation guilds across the interior Columbia and upper Missouri River Basins, USA, based on species’ traits and morphological attributes. I modeled guild occurrence across environmental gradients, including climate, disturbance, channel form attributes that reflect hydrology, and relationships between guilds. I found guilds’ distributions were related to hydrology, disturbance, and competitive or complementary interactions (niche partitioning) between co-occurring guilds. In Chapter Three, I examine floodplain riparian vegetation across the American West, identifying how hydrology, climate, and floodplain alteration shape riparian vegetation communities and their guilds. I identified eight distinct plant communities ranging from high elevation mixed conifer forests to gallery cottonwood forests to Tamarisk-dominated novel shrublands. I aggregated woody species into four guilds based on their traits and morphological attributes: an evergreen tree guild, a mesoriparian shrub guild, a mesoriparian tree guild, and a drought and hydrologic disturbance tolerant shrub guild. Communities and guilds’ distributions were governed by climate directly, and indirectly as mediated through streamflow. In Chapter Four, I discuss the utility of guild-based assessments of riparian vegetation, current limitations to these approaches, and potential future applications of the riparian vegetation guild concept to floodplain conservation and management. The classification of vegetation into functional trait-based guilds provides a flexible, framework from which to understand riparian biogeography, complementing other models frameworks for riparian vegetation.

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8

McManus, Kay Barbara. "Airborne thermography and ground geophysical investigation for detecting shallow ground disturbance under vegetation". Thesis, Durham University, 2004. http://etheses.dur.ac.uk/3127/.

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This thesis discusses the potential of airborne thermal prospection for detecting shallow ground disturbance beneath vegetation based on images acquired by the NERC Airborne Thematic Mapper (ATM) at thermal infrared wavelengths. Shallow ground disturbance creates a differential heat flux due to a variation in the thermal properties between disturbed and undisturbed soils. When observed above a canopy, the effect of vegetation growth on the thermal regime of the underlying soils is poorly understood. The research extends current understanding by examining areas where ground disturbance is known to exist under variable vegetation cover at an archaeological site at Bosworth, Leicestershire and areas of abandoned mine activity on Baildon Moor, W. Yorkshire and in the N. Pennine Orefield, Weardale. The investigation focuses on qualitative image interpretation techniques, where anomalies on day and night thermal images are compared with those manifest on the multispectral images, and a more quantitative approach of Apparent Thermal Inertia (ATI) modelling. Physical thermal inertia is a parameter that is sensitive to volumetric variations in the soil, but cannot be measured directly using remote sensing techniques. However, an apparent thermal inertia is determined by examining the day and night temperature contrast of the surface, where spatial variations can signify potential features buried in the near-surface environment. Ground temperature profiling at the Bosworth site indicates that diurnal heat dissipates between 0.20-0.50m at an early stage in vegetation development with progressively lower diurnal amplitudes observed at 0.20m as the vegetation develops. Results also show that the time of diurnal maximum temperature occurs progressively later as vegetation develops, implying an importance for thermal image acquisition. The quantitative investigation concentrates on the Bosworth site where extensive ground geophysical prospection was performed and vertical soil samples extracted across features of variable multispectral, thermal and ATI response to enable comparison of the observed airborne thermal response with physical soil properties. Results suggest that there is a high correlation between ATI and soil moisture properties at 0.15-0.25m depth (R(^2)=0.99) at an early stage in cereal crop development but has a high correlation at a wider depth range (0.10-0.30m) at a later stage in development (R(^2)=0.98). The high correlation between physical ground disturbance and the thermal response is also corroborated qualitatively with the results of the resistivity surveys. The ATI modelling reveals similar features to those evident on day or night thermal images at an early stage in vegetation growth, suggesting that thermal imaging during the day at an early stage in vegetation growth may supply sufficient information on features buried in the near-surface environment. Airborne thermal imaging therefore provides a useful complementary prospection tool for archaeological and geological applications for surfaces covered by vegetation.

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9

Wilson, Barbara Anne y mikewood@deakin edu au. "The effects of vegetation, fire and other disturbance factors on small mammal, ecology and conservation". Deakin University. School of Science, 1990. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051111.135542.

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The relationship of vegetation and disturbance factors to the distribution, abundance and diversity of small mammals in the eastern Otway region, Victoria were investigated. Antechinus stuartii, Rattus fuscipes and Rattus lutreolus were widely distributed and occurred in the majority of the eleven floristic vegetation groups identified. Antechinus minimus, Antechinus swainsonnii and Pseudomys novaehollandiae had restricted distributions and were recorded in only two or three vegetation groups. New information on the distribution of the rare species P. novaehollandiae, was obtained and two floristically rich vegetation groups that it preferred were identified. Species-rich small mammal communities occurred in vegetation communities with high numbers of sclerophyll plant species and high structural diversity. Maximum food resources were considered to be provided in these communities. Local habitat diversity was also correlated with species-richness. Small mammal abundance was maximum in non-sclerophyllous canmunities, where high plant productivity was considered to be important. For the first time, the presence of the plant pathogen Phytophthora cinnamomi was shown to affect small mammals. It was associated with small mammal communities of low species richness and abundance, Recovery of small mammal populations after wildfire was slow until the fourth year. Mus musculus reached peak abundance from 2-3 years and then declined rapidly. P. novaehollandiae was the only native species that achieved maximum abundance early in the succession. A. stuartii, R. fuscipes and R. lutreolus approached maximum abundance in mid-succession, while Isoodon obesulus was a mid- to late-successional species. A. minimus survived the fire, but did not persist after one year. The pattern of succession was influenced by attributes of species, such as survival after fire, their ability to disperse and reproduce.

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10

Allen, Bruce Peter. "Vegetation dynamics and response to disturbance, in floodplain forest ecosystems with a focus on lianas". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1179427491.

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11

Alvarez, Barra Valentina [Verfasser]. "Holocene vegetation dynamics and disturbance regimes in north Patagonia Argentina (40°S) / Valentina Alvarez Barra". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1213974739/34.

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12

Wilson, Barbara Anne. "The effects of vegetation, fire and other disturbance factors on small mammal ecology and conservation". Click here to access, 1990. http://tux.lib.deakin.edu.au/adt-VDU/public/adt-VDU20051111.135542.

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Thesis (Ph.D.)--Deakin University, Victoria, 1990.
Submitted to the Dept. of Biological Sciences of the School of Sciences, Deakin University. Appendices are separately published papers. Bibliography: leaves 274-302.

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13

Karrick, Megan M. "Soil Disturbance Effects on Marsh Vegetation Along the Central Mississippi River Near St. Louis, MO". Thesis, Southern Illinois University at Edwardsville, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1551577.

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The Riverlands Migratory Bird Sanctuary (1500 ha) was established in 1988 on US Army Corps of Engineers (USACE) land along the Mississippi river in West Alton, Missouri (38.87° N, -90.17° W). It is now cooperatively operated by USACE and the National Audubon Society. About 485 ha consist of actively managed restored bottomland prairie and marshland. The Great Flood of 1993 caused prolonged inundation and destroyed vegetation beds and moist soil plants in the Sanctuary—an impact still visible today. The goal of this study was to improve plant species diversity and cover, as well as generate more natural vegetation. We employed differing degrees of soil disturbance (tilling and disking) as a means stimulate seed germination from the seed bank. We predicted that the more extreme soil disturbance, tilling, would achieve our goals best. Six replicate marshes within the Sanctuary were chosen for this study. Each marsh was divided into three similarly sized areas and which were randomly assigned one of three treatments: disking, tilling, and control. Vegetative cover and species presence were recorded in 0.25 m² sampling plots at random intervals along each transect in each treatment area. A pre-treatment sample was obtained for comparison. ANOVA of a randomized complete block design revealed strong interactions between marsh (block) and treatment for nearly every community measure. However, marsh effects for cover, species richness, and Shannon diversity were significant beyond this effect. Treatment effects were not significant. Community ordinations by NMDS revealed a strong tendency for plots to aggregate by marsh, not treatment. Preliminary management recommendations can be given based on this study. Restoration activities should focus on site specific characteristics such as the species pool and local hydrology and lean away from immediate additional disturbances.

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14

Allen, Bruce Peter. "Vegetation dynamics and response to disturbance of floodplain forest ecosystems with a focus on lianas". The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1179427491.

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15

Ban, Bibek. "MAPPING VEGETATION COVER AND DISTURBANCE BASED ON UNMANNED AIRCRAFT SYSTEMS (UASs) FOR A MILITARY INSTALLATION". OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2874.

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Unmanned Aerial Vehicles (UAVs) can be used as a cost-effective alternative to map military training induced vegetation disturbances and monitor their dynamics because of high spatial resolution images provided at acceptable cost, great accuracy and flexibility of time to collect the images. This study aims to develop a method to map vegetation cover change from different military training activities using UAV imagery acquired at two different dates (before and after the military training). Three flight boxes located in the Fort Riley (FR) were selected as the study area. Vegetation cover data was collected in the field using Daubenmire frame for 1m, 5m and 10m sample plots. The UAV imagery was resampled to the spatial resolutions that match the plot sizes. The UAV images were processed for their geometric and radiometric calibrations and quality control. Eight vegetation indices (VIs) were calculated from UAV imagery and step-wise regression was used to find the final model for each boxes. The results suggested that the UAV images can be used to map vegetation cover and disturbance caused by military training activities. Moreover, it was found that separately modelling the military training induced vegetation disturbances for the training boxes led to greater accuracy than modelling the vegetation disturbances by pooling the data together. The accuracy of modelling was also higher before the training than that after the training because the training activities led to higher spatial variation of vegetation cover. In addition, the 5 m by 5 m spatial resolution images were more capable in capturing spatial variation of the vegetation disturbances than those at 10 m by 10 m spatial resolution, which implied that the 5 m by 5 m plots should be utilized for field data collection. Finally, compared with the original UAV image bands, the VIs improved the correlation with vegetation cover, and the Red Edge Modified Simple Ratio (REMSR), Normalized Difference Vegetation Index (NDVI) and Green Normalized Difference Vegetation Index (GNDVI) were more frequently selected in the final models than other vegetation indices (VIs). Overall, this study enhanced the understanding of using UAV images to map vegetation cover change from different military training activities

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16

Scherrer, Pascal y n/a. "Monitoring Vegetation Change in the Kosciuszko Alpine Zone, Australia". Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040715.125310.

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This thesis examined vegetation change over the last 43 years in Australia's largest contiguous alpine area, the Kosciuszko alpine zone in south-eastern Australia. Using historical and current data about the state of the most common vegetation community, tall alpine herbfield, this thesis addressed the questions: (1) what were the patterns of change at the species/genera and life form levels during this time period; (2) what were the patterns of recovery, if recovery occurred, from anthropogenic disturbances such as livestock grazing or trampling by tourists; (3) what impacts did natural disturbances such as drought have on the vegetation and how does it compare to anthropogenic disturbances; and (4) What are the benefits, limitations and management considerations when using long-term data for assessing vegetation changes at the species/genera, life form and community levels? The Kosciuszko alpine zone has important economic, cultural and ecological values. It is of great scientific and biological importance, maintaining an assemblage of vegetation communities found nowhere else in the world. It is one of the few alpine regions in the world with deep loamy soils, and contains endemic flora and fauna and some of the few periglacial and glacial features in Australia. The area also forms the core of the Australian mainland's most important water catchment and is a popular tourist destination, offering a range of recreational opportunities. The vegetation of the Kosciuszko alpine zone is recovering from impacts of livestock grazing and is increasingly exposed to pressures from tourism and anthropogenic climate change. At the same time, natural disturbances such as drought and fire can influence the distribution, composition and diversity of plants. Thus, there is a need for detailed environmental data on this area in order to: (1) better understand ecological relationships; (2) understand existing and potential effects of recreational and management pressures on the region; (3) provide data against which future changes can be assessed; and (4) provide better information on many features of this area, including vegetation, for interpretation, education and management. The research in this thesis utilised three types of ecological information: (1) scientific long-term datasets; (2) photographic records; and (3) a comparison of disturbed and undisturbed vegetation. This research analysed data from one of the longest ongoing monitoring programs in the Australian Alps established by Alec Costin and Dane Wimbush in 1959. Permanent plots (6 transects and 30 photoquadrats) were established at two locations that differed in the time since grazing and have been repeatedly surveyed. Plots near Mt Kosciuszko had not been grazed for 15 years and had nearly complete vegetation cover in 1959, while plots near Mt Gungartan showed extensive impacts of grazing and associated activities which only ceased in 1958. Some transect data from 1959 to 1978 have been analysed by the original researchers. The research presented in this thesis extends this monitoring program with data from additional surveys in 1990, 1999 and 2002 and applies current methods of statistical evaluation, such as ordination techniques, to the whole data set for the first time. Results indicated that the recovery from livestock grazing and the effects of drought have been the main factors affecting vegetation. Recovery from livestock grazing at the three transects at Gungartan was slow and involved: (1) increasing genera diversity; (2) increasing vegetation cover; (3) decreasing amounts of bare ground; and (4) a directional change over time in species composition. Patterns of colonisation and species succession were also documented. In 2002, 44 years after the cessation of grazing, transects near Mt Gungartan had similar vegetation cover and genera diversity to the transects near Mt Kosciuszko, but cover by exposed rock remained higher. A drought in the 1960s resulted in a temporary increase of litter and a shift in the proportional cover of life forms, as grasses died and herb cover increased at both locations. Proportions of cover for life forms reverted to pre-drought levels within a few years. The results also highlighted the spatial variability of tall alpine herbfield. The photoquadrats were surveyed in the years 1959, 1964, 1968, 1978 and 2001 and are analysed for the first time in this thesis. After comparing a range of methods, visual assessment using a 130 point grid was found to be the most suitable technique to measure vegetation cover and genera diversity. At the 18 quadrats near Mt Gungartan, there was a pattern of increasing vegetation cover as bare areas were colonised by native cudweeds and the naturalized herb Acetosella vulgaris. Revegetation from within bare areas largely occurred by herb species, while graminoids and shrub species predominately colonised bare ground by lateral expansion from the edges, eventually replacing the colonising herbs. At the 12 quadrats near Mt Kosciuszko, vegetation cover was almost complete in all years surveyed except 1968, which was at the end of a six year drought. Similar to the results from the transect study, the drought caused an increase in litter at both locations as graminoid cover declined. Initially herb cover increased, potentially as a result of decreased competition from the graminoids and a nutrient spike from decaying litter, but as the drought became more severe, herb cover also declined. Graminoid cover rapidly recovered after the drought, reaching pre-drought levels by 1978, and was at similar levels in 2001. Herb cover continued to decline after peaking in 1964. The photoquadrat study also documented the longevity and growth rates of several species indicating that many taxa may persist for several decades. It further provided insights into replacement patterns amongst life forms. In addition to assessing vegetation change following livestock grazing and drought at the long-term plots, recovery from tourism impacts was examined by comparing vegetation and soils on a closed walking track, with that of adjacent undisturbed tall alpine herbfield at a series of 22 paired quadrats. Fifteen years after the track was closed there was limited success in restoration. Over a quarter of the closed track was still bare ground with non-native species the dominant vegetation. Plant species composition differed and vegetation height, soil nutrients and soil moisture were lower on the track which had a higher compaction level than adjacent natural vegetation. The results presented in this thesis highlight that tall alpine herbfield is characterised by nearly entire vegetation cover which is dominated by graminoids, followed by herbs and shrubs in the absence of disturbance by livestock grazing, trampling or drought. The studies also showed that under quot;average" conditions, the relative cover of herbs and graminoids remained fairly stable even though there can be considerable cycling between them. Spatial variability in terms of taxa composition was high. The only common introduced species in unrehabilitated sites was Acetosella vulgaris, which was effective at colonising bare ground but was eventually replaced by other native species. However, in areas actively rehabilitated, such as on the closed track, non-native species introduced during revegetation efforts still persist with high cover 15 years after their introduction. Monitoring of vegetation change is also important at the landscape scale. This thesis provides a review of the potential use, the limitations and the benefits of aerial photography to examine vegetation change in the Kosciuszko alpine zone. Numerous aerial photography runs have been flown over the area since the 1930s for government agencies, industry and the military. Some of these records have been used to map vegetation communities and eroding areas at a point in time. Other studies compared different types and scales of photographs, highlighting in particular the benefits and potential of large scale colour aerial photography to map alpine vegetation. However, despite their potential to assess vegetation change over time, a temporal comparison of vegetation in the Kosciuszko alpine zone from aerial photographs has not been completed to this date. Historical photographs may not be easy to locate or access and difficulties with vegetation classification may restrict the practicality of using historical aerial photographs to assess vegetation change. Despite these issues, aerial photography may provide a very useful and efficient tool to assess changes over time when applied appropriately, even in alpine environments. The development of digital classification techniques, the application of statistical measures of error to both methodology and data, and the application of geographic information systems are likely to further improve the practicality of historical aerial photographs for the detection of vegetation change and assist in overcoming some of the limitations. The results presented in this thesis highlight the need for limiting disturbance, for ongoing rehabilitation of disturbed areas and for long-term monitoring in the Kosciuszko alpine zone. The results contribute to our understanding of how vegetation may change in the future and may be affected by new land use activities and climate change. This type of information, which otherwise would require the establishment of long-term studies and years of monitoring, can assist land managers of this and other important protected areas. The study highlights how the use and expansion of already existing datasets to gather ecological information can save considerable money and time, providing valuable data for current and emerging issues.

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17

Lantz, Trevor Charles. "Relative influence of temperature and disturbance on vegetation dynamics in the Low Arctic : an investigation at multiple scales". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1240.

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Climate change will affect Arctic plant communities directly, by altering growth and recruitment, and indirectly, by increasing the frequency of natural disturbance. Since the structure of northern vegetation influences global climate, understanding both temperature and disturbance effects on vegetation is critical. Here, I investigate the influence of temperature and disturbance on Low Arctic vegetation at several spatio-temporal scales in the Mackenzie Delta Region, N.W.T. To disentangle the relative impact of temperature and disturbance on forest-tundra and tundra ecosystems, I sampled microenvironmental variability, plant community composition, and green alder abundance, growth, and reproduction on disturbed (burns and thaw slumps) and undisturbed sites across a regional temperature gradient. Disturbed areas showed increases in alder productivity, catkin production, and seed viability, as well as differences in plant community composition and microenvironment. The magnitude of plot-level responses to disturbance compared to variation across the temperature gradient suggests that in the short-term, increasing the frequency of disturbance may exert a stronger influence on tundra ecosystems than changes in temperature. At the plot level, increases in alder seed viability and recruitment at warmer sites point to the fine-scale mechanisms by which shrub abundance will change. To examine the relative influence of temperature and biophysical variables on landscape-level patterns of shrub dominance, I mapped Low Arctic vegetation using aerial photos. At this broader scale, correlations between temperature and the areal extent of shrub tundra suggest that warming will increase the dominance of shrub tundra. To assess the magnitude of changes in temperature and thaw slump activity, I analyzed climate records and mapped retrogressive thaw slumps using aerial photographs. An increase in thaw slump activity in recent decades, coincident with higher temperatures, suggests that continued warming will change the area affected by thermokarst disturbances like slumps. Taken together, my research indicates that the effects climate change will be magnified by shifts in the frequency of disturbance, initiating changes to Arctic vegetation with significant implications for global climate. My work also shows that to fully understand the influence of patch-landscape feedbacks on Arctic vegetation dynamics, the effects of disturbance must be examined across longer temporal and broader spatial scales.

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18

Privett, Sean David John. "Determinants of pattern in fynbos vegetation: physical site factors, disturbance regime, species attributes and temporal change". Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/17365.

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This study set out to explore the patterns and determinants of contemporary species distribution in a fynbos landscape based on information on 1) physical habitat characteristics, 2) past disturbance regime, 3) intrinsic properties of individual species and 4) temporal change in communities. The body of the thesis is divided into four parts covering each of these aspects individually. Each chapter has been written up as an individual paper and thus includes some repetition as well as cross-referencing. Each chapter includes a detailed rationale for the study in the introduction, as well as methods, results and a discussion of the findings. Chapter 2 describes the patterns of vegetation units in the Cape of Good Hope Nature Reserve and provides a quantitative assessment of the importance of physical site features as determinants of these units. These results are compared with the vegetation classifications of the area derived in earlier studies by Taylor (1984b) and Cowling et al. (1996a). Chapter 3 is the first study in fynbos to partition the variance in vegetation pattern into that explained by physical site factors and that explained by the recent disturbance regime. The study explores the role of 30 years of fire and alien plant infestations in influencing species distribution at the community and landscape scale. While a number of studies have explored spatial determinants of diversity and pattern in fynbos, temporal change within communities has been neglected. High levels of species turnover through time, as a result of colonisation and extinction, could be an important component of diversity at the landscape scale. Hence Chapters 4 and 5 both explore aspects of temporal dynamics in fynbos. The objectives of Chapter 4 are to determine the stability of populations at the landscape scale over a 30-year period and to establish the determinants of local extinction of species. Information on the stability of species over time and the attributes which enable species to persist or go extinct are important for understanding potential impacts of management practices as well as the importance of temporal dynamics in influencing spatial patterns. This is especially appropriate in the context of the results of Chapter 3, which suggest that a high proportion of the variance in species composition is unexplained despite the inclusion of physical factors, and past disturbance regime. The fifth chapter provides a descriptive account of the change in vegetation composition over a 30-year period. It is recommended that those readers not familiar with the fynbos system read it as it provides an overview of a variety of aspects of fynbos dynamics. Its objective is to show how the various components of the disturbance regime, as well as fluctuations in abundance of overstorey Proteaceae and their resultant competitive effects can influence community composition. The final chapter is a general discussion that summarises the major findings of the study.

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19

Carrozzino, Amy Leigh. "Evaluating wildlife response to vegetation restoration on reclaimed mine lands in southwestern Virginia". Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32190.

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Coal mining has had profound impacts in the Appalachian region, initiating a need to understand the implications of traditional and current reclamation practices on wildlife. I evaluated wildlife use of reclaimed sites of varying ages and cover types in southwestern Virginia. I compared reclaimed sites to another form of anthropogenic disturbance (clearcut) and relatively undisturbed mature forest. Birds were surveyed during early mornings throughout the breeding season in 2007 and 2008 using the point count method. Amphibians were surveyed using artificial cover, constrained-time night searches, and auditory pond surveys. Microhabitat data were collected at each sampling point and were combined with landscape-level GIS information to relate habitat characteristics and wildlife patterns.

I observed 80 bird species using reclaimed areas, clearcuts, and mature forest. Pre-regulation sites (prior to the Surface Mining Control and Reclamation Act of 1977) supported the highest number of species overall. Cluster analysis identified 4 bird associations based on habitat characteristics. I developed site-specific, landscape-level, and mixed-scale logistic regression models to identify habitat characteristics that best predicted the presence of 27 species. For 18 species, mixed-scale models performed best, suggesting the importance of a multi-scale approach to habitat analysis.

Salamanders were generally not detected on reclaimed areas, possibly due to the lack of soil moisture, leaf litter, and woody debris on young sites. Frogs were present in all water bodies surveyed, suggesting the importance of managing ponds and wetlands on reclaimed sites. Identifying and focusing on important habitat characteristics will help managers enhance post-mining land for wildlife.
Master of Science

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20

Nelson, John. "Fire history and vegetation response to tornado and salvage harvesting disturbance in a southern Illinois bottomland forest /". Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1328058021&sid=22&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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21

Matheny, Ashley Michelle. "Development of a Novel Plant-Hydrodynamic Approach for Modeling of Forest Transpiration during Drought and Disturbance". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468595149.

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22

Forbes, Bruce Cameron. "Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196.

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The literature of disturbance ecology reveals that, under present climatic conditions, non-native plants have little or no role in high arctic tundra revegetation. Rather, it has been suggested that indigenous flora, especially long-lived perennial graminoids, are crucial to recovery. However, few long-term data are available on past impacts within productive sedge-meadows in the High Arctic, and none which consider the non-vascular flora.
This thesis combines biogeographical and patch dynamics perspectives to focus on $ geq$21 yr of natural and assisted recovery of vegetation and soils from a wide range of dated anthropogenic surface disturbances at three Canadian Arctic sites. Empirical, experimental and archival investigations were made among climatically similar, but widely disjunct, coastal lowlands of contrasting geologies on Baffin, Devon, and Cornwallis Islands. These data encompass minerotrophic and oligotrophic wetlands in which the vascular floras show minimal differentiation yet the sampled bryofloras share only 31.8% of their total taxa. The occurrences chosen for study are representative of the most widespread, small-scale human impacts in the North, including vehicular, pedestrian, construction, and pollution disturbances.
It was determined that rutting from even a single passage of a tracked vehicle in summer resulted in significant reductions in species richness and biomass. On slopes $ geq$2$ sp circ$, these same small ruts have drained large areas of peatlands, a serious cumulative impact. Long-term effects of drainage include the local extinction of populations of Sphagnum spp. and rhizomatous vascular aquatics, and changes in the chemistry and thermal regime of drained mineral soils. Other effects include significant changes in biomass and the concentrations of macronutrients in the leaves of dominant species. These effects were magnified in peatlands drained where multi-pass vehicle movements occurred.
Species richness displayed an inverse relationship with trampling intensity and the soils of heavily trampled ground remained severely compacted after 21 years. These patches were dominated by dense swards of ruderal grasses. Nutrient concentrations in the leaves of the latter and other colonizing and surviving species tended to increase with trampling intensity. Trampled patches and archaeological sites appeared selectively grazed by several herbivores. Although humans initiated the disturbances within these patches, it is the animals which are responsible for many of the dynamics of patch change over the long-term.
Classification and ordination procedures revealed linkages between the floristic associations of trampled meadows on Baffin Island and archaeological sites on Devon and Cornwallis Islands. One critical implication is that even low levels of human impact may give rise to ruderal plant communities which are extremely persistent. These patches are poor in terms of species richness, but contribute to habitat heterogeneity at the landscape level and comprise preferred forage for local vertebrate herbivores.
Archaeological excavation and restoration revealed that at least some stores of viable seed exist in both mesic and wet tundra soils and point to the importance of initial floristic composition (sensu Egler 1954). From a long-term perspective, the data establish that mesic tundra vegetation and soils are easily disturbed and recover much more slowly than their low arctic counterparts under similar disturbance regimes.

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23

Birch, Stacy Jo. "Stand Dynamics and Spatio-temporal Patterns of Natural Disturbance in an Acadian Old-Growth Reserve". Fogler Library, University of Maine, 2010. http://www.library.umaine.edu/theses/pdf/BirchSJ2010.pdf.

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24

Moreno-González, Ricardo [Verfasser]. "Holocene Vegetation and Disturbance Dynamics in the Araucaria araucana Forest: a paleoecological contribution for conservation / Ricardo Moreno-González". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1213974631/34.

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25

DeRose, R. Justin. "Disturbance Ecology and Vegetation Dynamics at Varying Spatial and Temporal Scales in Southern Rocky Mountain Engelmann Spruce Forests". DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/516.

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High-severity disturbances are the primary drivers of Engelmann spruce-subalpine fir ecosystems in the southern Rocky Mountain. Recently, an unprecedented, landscape-wide (at least 250 km2) spruce beetle outbreak killed virtually all the Engelmann spruce on the Markagunt Plateau in southwestern Utah, USA. Results from dendroecological analyses suggested the combination of antecedent disturbance history and drought-driven stand development was responsible for creating suitable host conditions prior to the recent outbreak. Multiple and consistent lines of evidence suggested mixed- and high-severity fires shaped the development of the Markagunt Plateau. Subsequent stand development, influenced by species-specific differential tree-ring response to drought, resulted in the gradual increase of Engelmann spruce dominance across the landscape. Spatiotemporal outbreak dynamics included the early, independent and spatially synchronous building of beetle populations in moist sites with large Engelmann spruce across the landscape. As the outbreak evolved over time, it is likely temperature anomalies accelerated beetle population growth, leading to more rapid spruce mortality. In the wake of the spruce beetle outbreak, results from simulated potential fire behavior suggested there was a reduction in probability of active crown fire for one or two decades on near-pure Engelmann spruce sites after the outbreak. This counterintuitive result suggested extreme fire behavior is not an inevitable consequence of spruce beetle outbreaks. Regardless of the occurrence of fire, forest response is likely to be dominated by advance regeneration in the seedling bank. Furthermore, because spruce was virtually absent from the understory, forest reorganization is likely to be dominated by subalpine fir. In response to recent outbreaks such as the Markagunt Plateau, silviculturists are questioning what they can do to limit the loss from these likely inevitable spruce beetle outbreaks. Concepts of resistance and resilience can be used in planning vegetation management intended to indirectly control beetle populations by manipulating their habitat (vegetation). Resilient landscapes will ideally have spruce age class diversity and size class diversity in spatially discontinuous patches.

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26

White, Lee J. T. "Vegetation history and logging disturbance : effects on rain forest in the Lope Reserve, Gabon (with special emphasis on elephants and apes)". Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/653.

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An investigation of the effects of commercial mechanised selective logging on rain forest vegetation and mammals, was undertaken in the Lope Reserve, central Gabon, between January 1989 to July 1991. Vegetation in Lope is mostly semi-evergreen lowland tropical rain forest, but there are some localised patches of savanna., which are thought to be natural in origin, but which are maintained today by regular fires started by humans. Study sites were established in areas of forest logged 20-25, 10-15, and 3-5 years previously, a fourth was logged during the study, and a fifth remained unexploited. None of the study sites had been subject to hunting in the recent past. A line-transect five kilometres in length was cut across the drainage in each site. Forest composition and structure was assessed along each transect, by identifying and measuring trees and lianes in botanical plots, counting stem density of herbaceous vegetation in the families Marantaceae and Zingiberaceae, and by measuring canopy cover at three heights. At total of 4885 trees and lianes of 327 species occurred in five 2.5 ha samples of plants greater than 10 cm dbh, whilst 1832 individuals of 137 species were found in five 25ha samples of trees greater than 70cm dbh. There were marked differences in structure and species composition both between and within sites. A model was developed to attempt to explain this variation, based upon the theory that much of Lope had been covered by savanna vegetation during a previous cool, dry climatic phase, and that forest structure and composition reflected recolonisation of the savanna by forest. Physical features such as swamps, rocky outcrops and altitude were also considered. Two types of multivariate analysis were applied to botanical data and supported the model. The effects of logging on forest vegetation were assessed by returning after logging to botanical plots established before exploitation. Damage levels were low, compared to other parts of the World, resulting in about a 10% reduction in canopy cover. Patterns of fruit production were studied by counting fallen ripe and unripe fruit on transects. Fruits encountered were classified on the basis of their morphology and dispersal mechanism. There was a period of low fruit production during the major dry season, when frugivores are likely to suffer dietary stress. A number of plant species which did produce fruit at this time were identified as species which might represent 'keystone' resources. Over 70% of fruit species were animal-dispersed, demonstrating the the important role animals play in the ecology of tropical rain forests. Forest elephant (Loxodonta africana cyclotis) diet, ecological role and group structure were analysed. The bulk of the diet consisted of the bark and leaves of trees, and some monocotyledons in the families Marantaceae and Zingiberaceae, but fruit was also important. Large-scale seasonal movements in response to fruit availability were detected. Elephants were important seed dispersers f o r many plant species, and were responsible for less than 1% of natural tree mortality. The social structure of these forest elephants differed from that of populations that have been studied i n east and southern Africa. Average group size was 2.8, and no groups of more than 10 individuals were encountered. Densi ties of primates, ungulates and squirrels were assessed using standard line-transect censuses. Resolution was poor, but statistical differences were detected between sites for some species. Chimpanzee, (Pan t. troglodytes) densities declined in logged forest, but no other species could be shown to decline after logging. Some other differences between sites were related to vegetation composition. Biomass was high, estimated a t up to 4692.6 kg km-2, but was dominated by elephants, which made up 25-82%. Conservation implications of this study are discussed, and recommendations made.

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27

Hiding, Camilla. "Diversity of birds in relation to area, vegetation structure and connectivity in urban green areas in La Paz, Bolivia". Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-79408.

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With a growing human population, cities keep growing worldwide altering ecosystem and thereby affecting the species living in these areas. Most studies of urbanization and its effect on ecosystem have been conducted in the western world and little is known about its effect in the neotropical part of the world. I examined effects of fragment size, vegetation structure and connectivity of urban green areas on bird species richness, mean abundance, diversity and biomass in La Paz, Bolivia. Additionally, the effects of different disturbance variables on bird community were evaluated. In total, 36 bird species were found in 24 fragment of varying size, connectivity and level of disturbance. Bird species richness decreased with increasing disturbance while connectivity and fragment size did not contribute significantly to explain the variation in species richness at count point scale (p>0.005, multiple linear regression). At fragment scale, however, species richness increased with fragment sizes, which has been shown in other studies from neotrophical regions. Variation in abundance, diversity or biomass could not be explained by connectivity, fragment size or disturbance. Furthermore, coverage of construction had a negative effect on species richness while coverage of bushes and coverage of herbs were negatively related to biomass and diversity, respectively. The composition of bird species differed with size and disturbance of the fragments, so that more omnivorous and granivorous species such as Zonotrichia capensis, Turdus chiguanco and Zenaida auriculata, were present in areas highly affected by human activities. Larger fragments, less affected by human presence held a larger proportion of insectivorous species.

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28

Nettleton, Benjamin. "The role of vegetation-topographic interactions in a barrier island system: island migration in a changing climate". VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5572.

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Islands have been characterized based on vegetation and topography as exhibiting different disturbance regimes - reinforcing or resisting. This study had two objectives: quantify barrier island upland migration and vegetation cover change over 32 years (1984-2016), and assess tolerance of two prevalent dune grass species, A. breviligulata, and S. patens to sand burial. Using Landsat imagery from the Virginia Coast Reserve, islands were categorized within the disturbance resistance/reinforcing framework based on dune elevation. Resistant areas were associated with woody cover and low marsh to upland migration while reinforcing areas had low vegetation cover and high rates of migration. System-wide, migration rates increased over time and large losses of upland and marsh, paired with expansions of woody cover occurred. In the field, each grass species was subject to repeated burials. S. patens was able to maintain biomass and height in high rates of burial, whereas A. breviligulata did not survive.

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29

ASANTE, MELDOMI ASABEA. "EFFECT OF URBAN RIPARIAN DEVELOPMENT ON BIODIVERSITY; USING BIRDS AND VEGETATION AS ECOLOGICAL INDICATORS IN COOPER CREEK LOCATED IN SOUTHWEST OHIO". Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1146157392.

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30

Villarreal, Miguel Luis. "Land Use and Disturbance Interactions in Dynamic Arid Systems: Multiscale Remote Sensing Approaches for Monitoring and Analyzing Riparian Vegetation Change". Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195061.

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Riparian systems are comprised of interacting aquatic and terrestrial elements that contribute distinctively to the natural capital of arid landscapes. Riparian vegetation is a major component of riparian systems, providing the ecosystem services required to support watershed health. The spatial and temporal distributions of riparian vegetation are influenced by hydrologic and disturbance processes operating at scales from local to regional. I believe both these processes are well suited to monitoring using synoptic and multitemporal approaches.The research in this dissertation is presented as 3 related studies. The first study focused on historical riparian dynamics related to natural disturbance and land use. Using current and historical riparian vegetation maps, we examined vegetation change within catchments of varying land use intensity. Results suggest that land use activities and wastewater subsidy affect the rate of development and diversity of riparian community typesThe second study used moderate resolution satellite imagery to monitor changes in riparian structure and pattern within a land cover change framework. We classified Landsat Thematic Mapper satellite imagery of the Upper Santa Cruz River watershed using Classification and Regression Tree (CART) models. We tested the ability of our models to capture change at landscape, floodplain, and catchment scales, centering our change detection efforts on a riparian tree die-off episode and found they can be used to describe both general landscape dynamics and disturbance-related riparian change.The third study examined historical and environmental factors contributing to spatial patterns of vegetation following two riparian tree die-offs. We used high resolution aerial imagery to map locations of individual live and dead trees and collected a suite of environmental variables and historical variables related directly and indirectly to land use and disturbance history. We tested for differences between groups of live and dead trees using Multi-response Permutation Procedures and found strong relationships between historical factors and mortality incidence.The results from these studies demonstrate the importance of examining historical information and spatial linkages across scales when monitoring riparian vegetation. From a land management perspective, the results identify the need for landscape-level, ecosystem-based management programs to maintain functioning and spatially connected riparian systems.

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31

Gradowski, Tomasz Aleksander. "The influences of geoclimatic site conditions, disturbance type and canopy composition on the composition of understorey vegetation of boreal mixedwoods". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58807.pdf.

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32

Ndam, Nouhou. "Tree regeneration, vegetation dynamics and the maintenance of biodiversity on Mount Cameroon : the relative impact of natural and human disturbance". Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285517.

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33

Kaltenrieder, Petra. "Long-term vegetation dynamics, fire disturbance and their driving factors in the boreal and temperate biomes: evidences from palaeoecological approaches /". Bern : [s.n.], 2008. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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34

Pfaff, Eric. "Patterns of grassland, shrubland, and woodland vegetation abundance in relation to landscape-scale environmental and disturbance variables, Applegate Watershed southwest, Oregon /". View full-text version online through Southern Oregon Digital Archives, 2007. http://soda.sou.edu/awdata/070406z1.pdf.

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Thesis (M.S.)--Southern Oregon University, 2007
Computer printout. Includes bibliographical references (leaves 49-53). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

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35

Little, Patrick James. "Hydrogeomorphic disturbance, landscape development and riparian vegetation dynamics of an alluvial, temperate rainforest in the Carmanah River valley, British Columbia, Canada". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39382.

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The alluvial forest of the Carmanah River valley on the west coast of Vancouver Island, British Columbia, was studied to examine the role of hydrogeomorphic disturbance in perpetuating the shifting-mosaic of habitats within this diverse ecosystem. Field-based research was complemented by a landscape-scale analysis that examined changes in the extent of specific forest types using a 70-year aerial photographic record. Thirty-eight plots containing 4509 trees were sampled for forest structure, composition, age, understory composition, and elevation above the contemporary channel. These field data, including a vegetation chronosequence spanning over 500 years, were used to examine vegetation dynamics. Over the past century, Carmanah River has eroded nearly 30% of the alluvial forest in this study area – 65% over the past 500 years. High magnitude floods result in diminished floodplain forest area by converting forests to channel. This results in a subsequent course of vegetation succession and geomorphic development. Fluvial deposits are colonized by a high density of Alnus rubra accompanied by a subcanopy of Picea sitchensis individuals. As Alnus die off after 60-100 years, Picea increasingly dominates the canopy while Tsuga heterophylla regenerate within the understory. The original cohort of Picea dies off after 300-500 years, which allows Tsuga to dominate old growth terrace forests. Picea or Alnus do not tend to regenerate under these dense canopies and without disturbance Tsuga may remain dominant indefinitely. Understory composition was related to landform age, however species distributions at low elevation floodplain sites were also driven by elevation above thalweg and flood frequency. Light availability was also a significant factor in driving community composition. It appears that understory dynamics were linked to overstory succession and geomorphic development processes, which alter environmental conditions at the understory level. That is, species distributions are driven by dynamic environmental filters, which change as a result of biogeomorphic succession. Mature forest patches tended to persist longer than young forests. The landscape composition reflects a balance between episodes of hydrogeomorphic disturbance and periods of successional development. Increased hydrogeomorphic disturbance rates due to climate change have the capacity to alter the landscape composition resulting in diminished mature forest area.

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36

Romo, Leon Jose Raul. "Examining Trends in Post-Disturbance Ecosystem Dynamics in the Southwestern United States and Northwestern Mexico Using Remote Sensing Time-Series Data and Land Cover Change Detection". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/205420.

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New forms of disturbance, and alteration of current disturbance regimes in arid and semiarid ecosystems, have resulted in the modification and degradation of large regions. This research explores vegetation response as a consequence of two different disturbance events in the southwestern US and northwestern Mexico. This topic was explored in this dissertation utilizing remotely sensed geospatial information in three separate studies.The first study explores the development of methods to assess the effectiveness of pre-fire restoration efforts, by evaluating vegetation response as a function of local environmental variables. Here I evaluated three fire locations at Bandelier National Monument (New Mexico). My models explain post-fire vegetation response as a function of environmental inputs and pre-fire site conditions (restored, unrestored and control areas). However, further analysis will be needed to better understand the effect of pre-fire restoration techniques on post-fire vegetation response.My second study explores the development of monitoring practices using remotely sensed data to assess land cover dynamics through time. The study area was the arid agro-ecosystem of La Costa de Hermosillo (LCH) in northwestern Mexico. My results show a continuous tendency towards a decrease in agriculture from 1988 until 2009. Detailed change detection demonstrates high rates of change from agriculture to other land cover classes in areas with dense agricultural developments. Implementation of these monitoring protocols would help with the application of restoration practices.The third study we used remote sensing time series data to assess phenological trends and variability among land cover types in relation to climatic variability within communities present in a heavily impacted agro-ecosystem (LCH). My analysis comprised three different agricultural land cover types including abandoned agricultural fields, and four additional natural land cover classes. I found that productivity has not increased in abandoned fields (since abandonment). Furthermore, I found that the models developed in this study significantly explain phenological variability as a function of climatic variability.These studies suggest that the use of remote sensing tools could effectively contribute to our ability to monitor vegetation dynamics in arid ecosystems. The implementation of methodologies generated in this work would significantly inform managers in decision making processes.

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37

Hacker, Molly. "ASSESSING SEED BANK CONTRIBUTION TO LANDWARD EXPANSION OF COASTAL WETLAND COMMUNITIES AND RESPONSES TO FIRE AND TRANSLOCATION ALONG COENOCLINE". OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2332.

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Land loss is a major threat to coastal wetlands of the northern Gulf of Mexico due to the impacts and interactions of sea level rise, regional subsidence, and anthropogenic changes to land cover and sediment supply. Here, coastlines are rapidly converting to open water due to an inability of coastal systems to keep pace with sea level rise via marsh migration due to barriers in the landscape, including dense shrub encroachment from fire suppression of inland communities. Fire may play an important role in promoting resiliency by in two ways, first by reducing or removing woody encroachment, allowing species to be released to migrate inland, second, by promoting primary productivity of herbaceous vegetation, which in turn, may promote vertical expansion. Where elimination of barriers is not possible (i.e., roads, industry and infrastructure), assisted migration of coastal communities landward (via translocation) may be also be a viable solution to bypass these barriers. This research is focused on the potential contribution of seed banks in landward migration of species, the role that fire plays in compositional change, and how seed banks compare to translocated communities when introduced into new environments. Here, seed bank dynamics were assessed and compared to aboveground vegetation of naturally regenerating and reciprocally transplanted (translocated) sods through time, with and without fire. The objectives of this study were to examine: 1) richness and abundance of species in the seed bank among vegetation zones of the coastal transition gradient; 2) effect of fire on expression of the soil seed bank; 3) emergence patterns and the degree of mixing/dispersion of dominant species within the seed bank among zones; 4) similarity of species composition of seed bank to that of the standing vegetation, pre- and post-fire; 5) similarity of species composition of the seed bank to that of the inter-zonally transplanted sods, with and without fire; and 6) fire behaviors through fuel loads and fire temperatures across zones. Results demonstrate the effect of zone on the composition, species richness and propagule density of the seed bank, and differences in similarity of the composition of the seed bank and standing vegetation. Fire did not appear to affect the composition of the seed bank. Ordinations indicate that seed bank communities are more widely distributed than standing vegetation assemblages. An overlap of communities was observed in each zone of the seed bank except salt marsh. Reciprocally transplanted sods that were burned prior to translocation were more similar to seed bank composition than no-fire transplants. Similarity, related to habitat preference, was most retained when sods were transplanted one zone away, and when transplanted upslope. A series of Procrustes analyses was conducted for combinations of seed bank treatments to standing vegetation of naturally regenerated and reciprocally transplanted plots of varying survey periods. Results showed that seed bank composition was most similar to the standing vegetation of the same survey period, and least similar for no-fire seed bank to transplanted plots surveyed 15 months after transplant. That the no-fire transplant plots were less similar to seed bank than burned transplant plot indicate that similarity between the seed bank and standing vegetation may be retained with fire. Comparisons of the Jaccard’s Similarity Coefficient of transplanted plot to seed bank with and without fire showed that overall, plots that had been burned were more similar to their source plots than those that had not been burned, across all zones. This study provides insight to zonation patterns of the seed bank across the coastal coenocline of the northern Gulf of Mexico, and compositional similarity of the seed bank to both naturally generated and reciprocally transplanted propagules, in order to understand the how these communities respond to sea level rise, how they may be managed with fire, and how plant species respond to conditions across zone, thereby the potential contribution of the seed bank to landward migration and the promotion of resiliency of coastal communities through facilitation of lateral migration in response sea level rise.

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38

Small, Christine Jodie. "Herb Layer Dynamics and Disturbance Response in the Mixed Mesophytic Forest Region of Southeastern Ohio". Ohio University / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou994780001.

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Althof, Arnhild Johanna. "Human impact on flora and vegetation of Kakamega Forest, Kenya structure, distribution and disturbance of plant communities in an East African rainforest /". [S.l.] : [s.n.], 2005. http://kola.opus.hbz-nrw.de/volltexte/2005/22.

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40

Pajunen, A. (Anu). "Willow-characterised shrub vegetation in tundra and its relation to abiotic, biotic and anthropogenic factors". Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514261138.

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Abstract Deciduous shrubs form the tallest type of vegetation in arctic-alpine areas and are important for ecosystem function. In the southern part of the Eurasian tundra zone, willows (Salix spp.) are the most common species in the shrub layer. In the alpine areas of Northern Fennoscandia, willow shrubs are characteristic to areas between tree line and treeless tundra heaths. Vertical structure and composition of willow-characterized tundra vegetation is affected by a variety of ecological factors including climate and herbivory. In turn, the abundance of the willow canopy affects understory species in several ways that still remain inadequately understood. In this PhD work I describe compositional differentiation of willow-characterized vegetation by using a large data set spanning from north-western Fennoscandia to the Yamal Peninsula in north-western Siberia. I studied environmental factors affecting willow-characterized vegetation and willow growth by using correlative analyses. The factors under investigation were latitude, distance from the sea, depth of thaw, position in the slope, industrial disturbance and reindeer grazing. In addition, I examined the relationships between the shrub biomass estimate and composition and species richness of understory vegetation. The effects of reindeer grazing on vegetation in an alpine forest-tundra ecotone were studied experimentally using reindeer-proof exclosures. I found that willow-characterized vegetation is floristically variable and comprises at least eight vegetation types. The most abundant willow thickets typically have a forb-rich understory. The growth of willow increased along with increasing summer temperatures. However the height of willow was more determined by distance from the sea, thaw depth and slope position. Reindeer grazing decreased the abundance of willow and changed the composition of understory vegetation. In addition, industrial activities were detected to have destructed shrub vegetation and turned it into graminoid-dominated vegetation. Shrub canopies facilitated forbs but decreased the cover of all the other groups including dwarf shrubs, bryophytes and lichens. The species richness of vegetation decreased along with increasing shrub abundance. My study shows that arctic-alpine willow vegetation is more diverse than previously thought. There is a predictable relationship between summer temperatures and willow growth. However, the results also show that there are many factors, both physical and anthropogenic, that are likely to complicate this pattern. Most important of these counteracting effects are industrial activities and reindeer grazing. In the areas where shrubs grow in abundance, the species richness of understory vegetation is likely to decrease and forbs are likely to replace other tundra species.

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41

Bo, Sann. "Functional Trait Based Community Assembly in a Secondary Tropical Dry Forest (熱帯乾燥地の二次林における機能形質に基づいた群集形成)". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225668.

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42

Clough, Elizabeth Anne y n/a. "Factors Influencing Ant Assemblages and Ant Community Composition in a Sub-Tropical Suburban Environment". Griffith University. School of Environmental and Applied Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040719.141317.

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The main objective of this study was to examine the abundance and diversity of ants in suburban sites following vegetation removal or modification for development. This research examines the capacity of suburban sites to support ant diversity, which is dependent on the site characteristics and their surrounding environment. The study focused on 29 suburban garden and 3 suburban reserve sites on the Gold Coast, Queensland, Australia. This region, through continuing land development, undergoes ongoing habitat disturbance and modification. Ground-dwelling ants were collected by pitfall trapping in study sites over three summers between 1997 and 1999. In total, 28,512 ants from 60 species in 31 genera were collected. Garden sites that maintain vegetation structural diversity were found to be most similar to reserve sites in terms of ant community composition. These sites were highest in ant richness and diversity and contained particularly high proportions of specialized ant species. Sites in close proximity to remnants of native vegetation contained higher species diversity and a greater proportion of specialized ant species. The introduced tramp ant, Pheidole megacephala was found in 28 of the 32 sites and was found to significantly reduce ant species richness and diversity and displace the dominant ant Iridomyrmex sp. 1 in suburban environments. This ant poses a serious threat to the recovery of a diverse ant fauna to suburban environments. Ant community composition was shown to vary significantly among suburban sites. The ant functional groups commonly found in disturbed sites were abundant in open sites with little canopy cover in this study. Sites that provided vegetation structural diversity and areas of closed canopy supported similar functional groups to natural vegetation remnants. These results indicate that ant communities in suburban environments respond to disturbance in a similar manner to ant communities in tropical forests and rainforests. The dominance by functional groups and presence of specialized species may therefore be used as an indicator of disturbance and the restoration of suitable habitat in suburban sites. The presence of specialized species of ants in suburban garden sites and their clear preference for particular site characteristics indicate that these species utilize resources available in the suburban matrix. These results indicate that residential suburban sites are of value in the enhancement of ant diversity in fragmented landscapes and that they may provide supportive habitat to, and act as corridors between, vegetation fragments. In order to preserve biodiversity within suburban environments, landowners should be advised to retain as much existing vegetation within a site as possible. Clearing should be limited to that necessary to allow construction of dwellings and for safety. In addition, landowners should be encouraged to establish or maintain structurally diverse vegetation layers within sites in order to provide diverse microenvironments for fauna habitat.

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43

Fox, Helen Elizabeth. "The role of anthropogenic disturbance in the creation of a socio-ecological landscape". Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1008061.

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The aim of this thesis is to examine the role of anthropogenic disturbance in the creation of a socio-ecological landscape. Three key questions were answered: what impact has past anthropogenic disturbance had on present vegetative characteristics; what value did this disturbed landscape have to local people; how did the local peoples' worldviews and eco-cosmologies influence how they perceived, valued and managed their landscape? Research was based in a rural, predominantly amaXhosa village in the Kat River valley, Eastern Cape, South Africa. Four major landscape components characterised the environment, namely dense forests, former grazing lands, abandoned fields and old settlements. A combination of qualitative and quantitative methods were adopted, consisting of a vegetation and soil survey and social science methods including semistructured interviews, focus groups, transect walks and participant observation. The key finding was that anthropogenic disturbance is necessary to enhance the potential of the area to support human habitation. However, anthropogenic disturbance can have positive or negative effects for both local people and the environment. An intermediate level of disturbance is a key factor leading to a resilient socio-ecological system. Various anthropogenic disturbances have had significant affects on vegetation characteristics in terms of species richness, and a change in vegetation composition and species heights. Of the three anthropogenic landscapes examined, former grazing lands were the least intensively disturbed. They were also more species rich and structurally diverse than areas that were under agricultural production or used as a settlement. Dense forests, although the least desirable landscape to local people were, together with sacred pools, sources of ecosystem renewal and played a critical role during times of disturbance. Anthropogenic disturbance has added value to local people's livelihoods; this disturbance has resulted in a patchy landscape that supplies a wide variety of resources to local people. Local people are dependent on their environment for their basic needs; this has encouraged sustainable management practices. The local AmaXhosa still retain many elements of their traditional worldview, which has many characteristics of Animism. The environment is an integral component of their belief system and certain sites and species have significant cultural value and are protected.

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44

Brown, Eleanor Clare. "Changes in vegetation composition and rates of erosion on Trotternish Ridge, Isle of Skye, in response to climatic variation and anthropogenic disturbance during the mid- to late- Holocene". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25969.

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45

Hekkala, A. M. (Anne-Maarit). "Restoration of the naturalness of boreal forests". Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526209104.

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Abstract Restoration is considered to be a crucial action in order to maintain and enhance ecosystem functioning and halt the decline of biodiversity. Within forested ecosystems, heavily exploited forests have lost a great part of their biodiversity values, and even nature conservation is insufficient to prevent the loss of habitats and the endangerment of species. The aim of this thesis was to provide new information on the impacts of forest restoration methods on boreal forest naturalness, including forest structure, forest-dwelling species and ecosystem processes and functions. This information is needed to develop the restoration methods and their cost-efficiency and to support decision-making concerning restoration and nature conservation. The restoration methods studied were felling with a chainsaw either without or with subsequent burning, and storm treatment, in which the trees were uprooted with an excavator. The variables measured were vegetation assemblages, deadwood dynamics, and deadwood-dependent insect assemblages. In addition to field measurements, a simulation approach was used so as to predict deadwood continuity after different restoration methods. The main finding of this thesis is that the aspects of naturalness studied were most enhanced by burning, whereas felling had the least effect. Restoration burning increased deadwood volume and diversity, enabled the establishment of pioneer plants, increased the relative cover of the forest keystone species Vaccinium myrtillus, enhanced the regeneration of the keystone tree Populus tremula, and provided habitat for red-listed, especially pyrophilous beetles (Coleoptera) and flat bugs (Heteroptera: Aradidae). Felling only increased the volume of deadwood. Storm treatment with tree uprooting was a more effective method than felling with a chainsaw, due to the additional disturbance it caused to ground, enhancing the regeneration of e.g. Pinus sylvestris. According to simulation models, compared to controls restored stands are predicted to have greater deadwood volumes at least for 40 years. The study shows that restoration can be used to accelerate the development of degraded forests towards a higher level of naturalness. The results can be used to choose appropriate restoration methods for forests, based on their initial stage and the goal set for the level of their naturalness
Tiivistelmä Ennallistamista pidetään tärkeänä keinona palauttaa ja ylläpitää luonnontilaisten ekosysteemien toimintaa. Metsien ennallistamista tarvitaan, koska tehokkaasti hoidettujen metsien monimuotoisuus on köyhtynyt niin pitkälle, ettei pelkkä suojelu enää riitä pysäyttämään elinympäristöjen häviämistä ja lajien uhanalaistumista. Väitöskirjan tavoitteena oli tuottaa uutta tietoa siitä, miten erilaiset metsien ennallistamiskeinot vaikuttavat metsän luonnontilaisuuden elementteihin, kuten rakennepiirteisiin, lajistoon ja toiminnallisuuteen. Tietoa tarvitaan ennallistamismenetelmien ja niiden kustannustehokkuuden parantamiseksi sekä tukemaan ennallistamista ja luonnonsuojelua koskevaa päätöksentekoa. Tutkitut ennallistamismenetelmät olivat: lahopuun lisäys sahaamalla joko ilman polttoa tai polton kanssa ja myrskytuhokäsittely, jossa puut kaadettiin juurineen. Metsän aluskasvillisuus, lahopuusto ja lahopuusta riippuvaisten hyönteisten lajiyhteisöt olivat mitattuja muuttujia. Maastoinventointien ohella tehtiin simulaatiomallinnuksia, joilla ennustettiin ennallistamisen jälkeistä lahopuujatkumoa. Väitöskirjatyön keskeisin havainto on, että ennallistamispoltot paransivat tutkittuja luonnontilaisuuden elementtejä eniten, kun taas lahopuun lisäyksellä oli vähäisimmät vaikutukset. Ennallistamispoltto lisäsi lahopuun tilavuutta ja monimuotoisuutta, mahdollisti sukkession varhaisvaiheen kasvillisuuden kehittymisen, lisäsi mustikan (Vaccinium myrtillus) suhteellista peittävyyttä, paransi monimuotoisuudelle tärkeän puulajin, haavan (Populus tremula), uudistumista sekä lisäsi lahopuuriippuvaisten, erityisesti palanutta puuta suosivien kovakuoriaisten (Coleoptera) ja latikoiden (Heteroptera:Aradidae), laji- ja yksilömääriä. Myrskytuhon jäljittely oli tehokkaampi ennallistamiskeino kuin lahopuun lisäys sahaamalla, sillä juurilaikku lisäsi maanpinnan häiriötä parantaen samalla mm. männyn (Pinus sylvestris) taimettumista. Simulaatiomallinnus osoitti, että verrattuna kontrollialueisiin ennallistetuilla alueilla lahopuuta on runsaammin vähintään 40 vuoden ajan. Väitöskirja osoittaa, että kaikkia työssä tutkittuja ennallistamismenetelmiä voidaan käyttää nopeuttamaan metsän kehittymistä kohti luonnontilaa, mutta menetelmät eroavat toisistaan vaikutuksiltaan. Saatuja tuloksia voidaan käyttää, kun valitaan metsiin niihin parhaiten soveltuvaa ennallistamismenetelmää

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46

Cole, Lydia Eve Spencer. "Disturbance, recovery and resilience in tropical forests : a focus on the coastal peat swamp forests of Malaysian Borneo". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:a135aff3-ea84-4766-8046-b3bb4ce31275.

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Tropical forests have existed for up to one hundred million years, and today provide many ecosystem services vital for human well-being. They also harbour great biodiversity, which, in addition to its intrinsic value, plays a key role in the functioning of these ecosystems. Despite their local to global significance, there are still many knowledge gaps concerning the dynamic processes that govern the functioning of tropical forests. Rapid rates of deforestation and landscape conversion, predominantly for logging and industrial agriculture, are limiting the time and opportunity available to collect the information needed to fill these gaps. This research aims to shed light on the long-term ecological functioning of tropical forests, specifically investigating the history of disturbance in these ecosystems and the response of forest vegetation to past perturbations. The carbon-rich tropical peat swamp forests found along the coast of Sarawak, Malaysian Borneo, are a central focus of this study. For these forests in particular, a large deficit of knowledge surrounding their history and unique ecological functioning is coupled with some of the highest conversion rates of all tropical forest ecosystems across the world. In this thesis, palaeoecological data has been used to reconstruct temporal variability in forest vegetation coincident with external perturbations in order to identify changes in the resilience of these ecosystems through time, via indicators such as slowing rates of recovery and reduced regeneration of forest vegetation. Results suggest that tropical forest ecosystems have, for the most part, shown resilience to natural disturbances in the past, ranging from instantaneous localised tree-fall to longer-term regional climatic change; but that recent anthropogenic disturbances, of novel forms and greater intensities, are jeopardizing the potential for forest recovery and thus compromising ecosystem resilience. These findings enhance our understanding of the ecology of tropical peat swamp forests, and tropical forests more broadly. They also provide a context for contemporary tropical forest management, allowing for predictions on future responses to disturbance and enabling more ecologically sustainable landscape planning.

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47

Stettner, Samuel [Verfasser], Hugues [Akademischer Betreuer] Lantuit, Hugues [Gutachter] Lantuit, Annett [Gutachter] Bartsch y Ralf [Gutachter] Ludwig. "Exploring the seasonality of rapid Arctic changes from space : monitoring of permafrost disturbance, snow cover and vegetation in tundra environments with TerraSAR-X / Samuel Stettner ; Gutachter: Hugues Lantuit, Annett Bartsch, Ralf Ludwig ; Betreuer: Hugues Lantuit". Potsdam : Universität Potsdam, 2018. http://d-nb.info/1218404485/34.

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48

Stettner, Samuel [Verfasser], Hugues [Akademischer Betreuer] Lantuit, Hugues Gutachter] Lantuit, Annett [Gutachter] [Bartsch y Ralf [Gutachter] Ludwig. "Exploring the seasonality of rapid Arctic changes from space : monitoring of permafrost disturbance, snow cover and vegetation in tundra environments with TerraSAR-X / Samuel Stettner ; Gutachter: Hugues Lantuit, Annett Bartsch, Ralf Ludwig ; Betreuer: Hugues Lantuit". Potsdam : Universität Potsdam, 2018. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-425783.

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49

Kangas, K. (Katja). "Recreation and tourism induced changes in northern boreal environments". Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514292798.

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Abstract The popularity of nature-based tourism has increased worldwide and peripheral areas with conservational value, like protected areas, are attractive destinations. The recreational use and construction of tourism facilities can cause environmental degradation and decrease the conservational and recreational value of areas if not well planned and managed. The aim of this thesis was to improve our knowledge of recreation and tourism induced changes in northern boreal environments. Direct and indirect impacts of recreation on vegetation and birds in protected areas were examined. Furthermore, the environmental impacts of ski resorts in terms of changes in vegetation and soil, threats from non-native species and water pollution were investigated. In protected areas, the size of the disturbed areas around campsites was found to be mainly determined by the distance between the main tourism facilities (wilderness hut and campfire-site), and the mountain biotopes were more sensitive to disturbance than forests. Recreational use had induced changes also in the bird community. The occurrence and the composition of birds were affected, and the open nesters nesting on the ground were found to be the most sensitive. The construction, revegetation and management practices of ski runs had increased the nutrient concentrations, pH and conductivity of the soil, and changed the original vegetation notably. Non-native seed mixture species, used in revegetating the ski runs, were found to be favoured by management practices (disturbance and peat addition) in an experimental study, but, eventually, were not able to be established themselves into study plots. Ski resorts’ construction and management have also affected the water quality. Concentrations of nutrients were higher in ski resort lakes in relation to reference lakes and were comparable to lakes polluted by agriculture and forestry. The results of this theses give new information on tourism and recreation induced changes and are applicable for planning and management. Nature-based tourism and recreation can cause long-term changes in terrestrial and aquatic environments, which should be considered at all levels of planning and management. For sustainable tourism development, it is essential that impacts are regularly monitored and preventative means are developed and used to minimize environmental degradation.

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50

Wendelberger, Kristie Susan. "Evaluating plant community response to sea level rise and anthropogenic drying: Can life stage and competitive ability be used as indicators in guiding conservation actions?" FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2558.

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Increasing sea levels and anthropogenic disturbances have caused the world’s coastal vegetation to decline 25-50% in the past 50 years. Future sea level rise (SLR) rates are expected to increase, further threatening coastal habitats. In combination with SLR, the Everglades ecosystem has undergone large-scale drainage and restoration changing Florida’s coastal vegetation. Everglades National Park (ENP) has 21 coastal plant species threatened by SLR. My dissertation focuses on three aspects of coastal plant community change related to SLR and dehydration. 1) I assessed the extent and direction coastal communities—three harboring rare plant species—shifted from 1978 to 2011. I created a classified vegetation map and compared it to a 1978 map. I hypothesized coastal communities transitioned from less salt- and inundation-tolerant to more salt- and inundation-tolerant communities. I found communities shifted as hypothesized, suggesting the site became saltier and wetter. Additionally, all three communities harboring rare plants shrunk in size. 2) I evaluated invading halophyte (salt-tolerant) plant influence on soil salinity via a replacement series greenhouse experiment. I used two halophytes and two glycophytes (non-salt-tolerant) to look at soil salinity over time under 26 and 38‰ groundwater. I hypothesized that halophytes increase soil salinity as compared to glycophytes through continued transpiration during dry, highly saline periods. My results supported halophytic influence on soil salinity; however, not from higher transpiration rates. Osmotic or ionic stress likely decreased glycophytic biomass resulting in less overall plant transpiration. 3) I assessed the best plant life-stage to use for on-the-ground plot-based community change monitoring. I tested the effects of increasing salinity (0, 5, 15, 30, and 45‰) on seed germination and seedling establishment of five coastal species, and compared my results to salinity effects on one-year olds and adults of the same species. I hypothesized that seedling establishment was the most vulnerable life-stage to salt stress. The results supported my hypothesis; seedling establishment is the life-stage best monitored for community change. Additionally, I determined the federally endangered plant Chromolaena frustrata’s salinity tolerance. The species was sensitive to salinity >5‰ at all developmental stages suggesting C. frustrata is highly threatened by SLR.

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Tesis sobre el tema "Vegetation disturbance"

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