Dissertations / Theses: 'Invasive shrubs'

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Miranda, Courtney Elizabeth. "Facilitative Interactions Among Native Perennial Shrubs and Native and Exotic Annuals in Recovering Coastal Sage Scrub." Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/scripps_theses/280.

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Facilitative interactions can have a powerful influence on the structure of plant communities and must be accounted for in efforts to restore disturbed and invaded habitats, such as the now rare coastal sage scrub (CSS) of California. In this study, I tested for evidence of facilitative effects by the native shrubs Eriogonum fasciculatum var. foliolosum and Artemisia californica on germination and survival of the CSS native annual forb Phacelia distans. P. distans seeds were planted near patches of native shrubs, both under the shrub canopy where any facilitative effects should be strongest, and 0.5 m away in the more exposed grassland. To determine whether the shrub-forb relationship was affected by the presence of invasive annuals, E. fasciculatum sites were assigned either invasive annual removal or non-removal control treatment; no removal treatments were carried out for A. californica. P. distans had significantly higher germination but lower survivorship under the canopy of E. fasciculatum. The results showed no overall effect of invasive removal, but there was a weak interaction effect with location; in shrub-canopy plots, invasive species further lowered survivorship. A. californica showed neither facilitative nor negative effects of this shrub species on either germination or survivorship of P. distans, in contrast with the results for E. fasciculatum. Although E. fasciculatum appears to facilitate the germination of native forbs under its canopy, it also seems to have a negative effect on survival. The weak interaction between location and removal to further decrease survival under the canopy when invasives are present, and the abundance of grasses growing under the canopy, suggest that native shrubs may facilitate the growth of invasive annuals as well as the germination of natives. Consequently, controlling invasive grass abundance may be necessary to capture the benefits of shrub facilitation for the restoration of native CSS herbs.

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Lash, Kevin D. "Facilitative effects of dead Amur honeysuckle (Lonicera maackii) shrubs on native tree seedling growth and survival." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1540296714970484.

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Pieterson, Elisabeth Corrie. "Nature versus Nurture: The Influence of Phylogenetic Relatedness, Origin, and Environment on Native and Introduced Woody Shrubs in the Eastern United States." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534521742118989.

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Mottl, Erik Charles. "Oak forest decline and effects of two invasive shrubs in the Midwest Driftless Area current status and implications for the future /." [Ames, Iowa : Iowa State University], 2007.

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5

Hoven, Brian Michael. "The Effect of Emerald Ash Borer (Agrilus Planipennis)-Caused Ash Mortality and White-Tailed Deer Abundance on Understory Invasive Shrubs and Forest Regeneration." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1627656584529987.

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Gayek, Ann. "Effect of Habitat Variation on Rate and Success of Colonization of Two Invasive Shrubs, Lonicera Maackii and Ligustrum Vulgare, in a Forested Glen." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1391593413.

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Peterson, Thomas E. "FACTORS AFFECTING DENSITIES OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) IN EASTERN DECIDUOUS FOREST: THE ROLES OF AND SURROUNDING LAND USE, FOREST HABITAT EDGE, AND INVASIVE SHRUBS." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1526295117069628.

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8

Beniušis, Aurelijus. "Pavasarinio vikio būklė ir invazinių krūmų plitimas Palangos botanikos parke." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100621_113854-61774.

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Magistro darbe tiriama į Lietuvos Raudonąją knygą įrašyto pavasarinio vikio būklė, bei invazinių krūmų plitimo ypatumai. Darbo objektas – Palangos botanikos parke augantis pavasarinis vikis (Vicia lathyroides L.) ir aštuoni invaziniai krūmai: guobalapė lanksva (Spiraea chamaedryfolia L.), šermukšnialapė lanksvūnė (Sorbaria sorbifolia (L.) A. Braun), paprastasis ligustras (Ligustrum vulgare L.), baltoji sedula (Cornus alba L.), blizgantysis kaulenis (Cotoneaster lucidus Schltdl.), darželinis jazminas (Philadelphus coronarius L.), baltauogė meškytė (Symphoricarpos albus (L.) S. F. Blake), šluotinis sausakrūmis (Sarothamnus scoparius (L.) W. D. J. Koch). Darbo tikslas – nustatyti pavasarinio vikio būklę ir invazinių krūmų plitimo ypatumus. Darbo metodai. Pavasarinio vikio būklės nustatymui buvo vertinta žydinčių ir derančių vikių kiekis, vegetacijos trukmė, bendrijos įvairovė. Aprašant kiekvienos radavietės medyno sudėtį ir žolinę augaliją, buvo naudojama Braun – Blanquet skalė. Invazinių krūmų plitimo intensyvumo nustatymui buvo vertinta šakninių atžalų plitimo atstumas nuo motininio krūmo, nugenėtų ūglių rudeninis ir pavasarinis žėlimas. Statistinė analizė atlikta naudojant Microsoft Exel skaičiuoklę. Darbo rezultatai. Nustatytos trys pavasarinio vikio augavietės Palangos botanikos parke. Lyginant su senesniaisiais tyrimo duomenimis, pavasarinis vikis aptiktas 3 naujose vietose. Gausiausias pavasarinių vikių padengimas, žiedų ir anksčių skaičius rastas tokiose sąlygose, kur... [toliau žr. visą tekstą]
Master thesis examined the spring vetch condition and the spread of invasive shrub. The object of the study – spring vetch (Vicia lathyroides L.) and eight invasive shrubs: Spiraea chamaedryfolia L., Sorbaria sorbifolia (L.) A. Braun, Ligustrum vulgare L., Cornus alba L., Cotoneaster lucidus Schltdl., Philadelphus coronaries L., Symphoricarpos albus (L.) S. F. Blake, Sarothamnus scoparius (L.) W. D. J. Koch growing in Palanga Botanical Park, The aim of the study – to determine the Vicia lathyroides L. condition and the spread of invasive shrub features. The methods. Spring vetch condition determination was calculated by the density of flowering plants and established their growing time. Description of each finding local stand composition and herbs have been used by Braun – Blanquet scale. Spread of invasive shrubs were evaluated in determining the intensity of root suckers spread of the distance from the parent bush, intensity of shoots spreading after autumn cut. The statistical analysis was performed using Microsoft Excel spreadsheet. The results. There were we found the three habitats of Vicia lathyroides L. in Palanga Botanical Park. To the comparison of the old survey, spring vetch was detected in three new places. Abundant spring vetch cover, flowers and pods appeared in such conditions with adequate lighting, absence of walk trails. Root suckers most intensive spread of Sorbaria sorbifolia (L.) A. Braun, Sarothamnus scoparius (L.) W. D. J. Koch, Symphoricarpos albus (L... [to full text]

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Parker, Ingrid Marie. "Ecological factors affecting rates of spread in Cytisus scoparius, an invasive exotic shrub /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5218.

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Soley, Nathan. "Reproductive Biology of the invasive plant Elaeagnus umbellata: breeding system, pollinators, and implications for invasive spread." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1164.

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Reproductive studies in invasive plants are necessary for an understanding of their potential to establish and spread in foreign environments. Elaeagnus umbellata Thunb. (autumn olive) is an invasive woody shrub that flowers early in the spring and is often noted for its abundant fruit set. This study examined the reproductive biology of E. umbellata in Illinois, where it is highly invasive. Hand-pollination experiments were performed to determine the breeding system of E. umbellata, and floral visitors were collected to determine its pollinators. Experiments showed that E. umbellata is a predominantly outcrossing species with a self-incompatible breeding system. However, individual variation was detected in several reproductive characteristics. Pollen tube analyses revealed that a small percentage of individuals allow successful self-pollen tube growth, and self-fruit set resulting from automatic self-pollination (autogamy) was relatively high in a few plants. Automatic self-pollination is possible because the male and female parts of flowers mature sychronously, but the likelihood of autogamy may vary among individuals due to variability in the spatial separation of male and female parts (herkogamy). Variability in the incompatibility system and the level of herkogamy may impact the outcrossing rates and reproductive success of individuals. The majority of floral visitors to E. umbellata were generalist pollinators. Frequently visiting bees included small and large species such as native Andrena spp., Augochlorella aurata, Bombus spp., Ceratina calcarata, Xylocopa virginica, and the introduced Apis mellifera. Bombylius major (large bee fly) and the moth Mythimna unipuncta (armyworm) were also frequent visitors. Most of the above insect taxa are pollinators of E. umbellata based on analysis of pollen on insect bodies. E. umbellata is likely to achieve its abundant fruit set where these common pollinators and other E. umbellata are present. However, in my study sites, many individuals experienced low fruit set on branches that were open to pollinator visitation, suggesting pollen limitation may be common in some years and at certain sites. The discovery of autogamous individuals demonstrates that some E. umbellata individuals may be able to establish and spread even when mates or pollinators are limiting.

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Lawrence, Jessica. "Impact of the invasive shrub Lonicera maackii on shrub-dwelling arthropods in an eastern deciduous forest." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289234685.

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12

Blackstock, Philip. "Broad-leaved tree and shrub invasion of conifer plantations in Ireland." Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267812.

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13

Wilfong, Bryan N. "Detecting an invasive shrub in deciduous forest understories using remote sensing." Oxford, Ohio : Miami University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1217288997.

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14

Rowekamp, Erin Catherine. "Seeing the Forest and the Stream: Assessing the Influence of Riparian Invasion by the Exotic Shrub Amur Honeysuckle (Lonicera maackii) on Terrestrial-to-Aquatic Linkages." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1511907835465838.

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15

Barriball, Kelly. "Population structure and mating system of the invasive shrub Lonicera maackii in Ohio." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1342357868.

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16

Lillian, Sarah. "Associational Susceptibility of a Native Shrub, Atriplex canescens, Mediated by an Invasive Annual Forb, Brassica tournefortii, and Invasive Stinkbug, Bagrada hilaris." Thesis, University of California, Riverside, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10624437.

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Indirect interactions have increasingly been recognized as important forces influencing population dynamics and structuring communities. Associational susceptibility is a form of indirect effect in which a focal plant experiences greater herbivore damage due to neighboring plant identity or diversity. These interactions remain poorly understood in the context of invasion ecology, though they may be responsible for huge impacts of invasive species on native communities. This dissertation investigates the potential mechanisms and consequences of associational susceptibility of a native perennial shrub, Atriplex canescens, driven by an invasive annual forb, Brassica tournefortii, and an invasive herbivorous stinkbug, Bagrada hilaris. In Chapter 1, a potential associational effect is experimentally demonstrated and a phenologically-driven trait is identified as a potential mechanism for this interaction. In Chapter 2, relative host plant quality is explored for its role in mediating the numerical response of the shared herbivore, and the herbivore’s damage impact on A. canescens. In Chapter 3, neighbor density, herbivore presence and herbivore density were manipulated to identify their impacts on spillover timing, extent, and fitness consequences for A. canescens. Overall, potential mechanisms of A. canescens associational susceptibility to Br. tournefortii and Ba. hilaris identified include: Ba. hilaris accumulation on Br. tournefortii followed by Br. tournefortii senescence and depletion, triggering Ba. hilaris alternative host-seeking. Associational susceptibility of A. canescens could not be re-created under experimental conditions, but further study is required to ascertain whether this interaction is due to experimental limitations or ecological implausibility.

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Brzyski, Jessica R. "Population genetics and breeding ecology of the rare clonal shrub, Spiraea virginiana (Rosaceae)." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1306497965.

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Garrett, Daniel Roy. "The Role of Exotic Shrubs in Determining Nesting Success of Hooded Warblers." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1449082191.

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Chen, Hao Yuan. "Impact of changes in the light environment caused by an invasive honeysuckle (Lonicera maackii)”." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1468335505.

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Borgmann, Kathi L. "Invasion of riparian forests by exotic shrubs: effects of landscape matrix and implications for breeding birds." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1399558713.

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Boersma, Nicholas Neal. "Natural weed controls potential of the invasive shrub Rhamnus cathartica and improvement of corn gluten meal /." [Ames, Iowa : Iowa State University], 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1481846.

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Hartman, Kurt M. "The Impacts, Invasibility, and Restoration Ecology of an Invasive Shrub, Amur Honeysuckle (Lonicera maackii)." Ohio : Ohio University, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1133734744.

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Davis, Benjamin. "The mechanisms used by the invasive shrub Rhododendron ponticum to inhibit the growth of surrounding vegetation." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/362597/.

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In the United Kingdom, Rhododendron ponticum is one of our most invasive plant species, and yet there have been few published scientific studies compared with many other invasive species. Changes in environmental conditions are often implicated as being responsible for its impact on the native vegetation, and this study demonstrated that light availability, temperature, water availability, organic matter and soil pH were all different beneath stands of R. ponticum, compared to areas of open grassland where growth of the native species was not limited. Studies in the New Forest highlighted that light availability and soil pH were the two environmental conditions most likely to explain the impact of R. ponticum. However, glasshouse experiments testing the effect of these changes on the germination and growth of two native species, Lolium perenne (perennial rye grass) and Trifolium repens (white clover), revealed that the low light conditions only reduced the root elongation and leaf appearance of T. repens, and the soil pH had no inhibitory effect on either species. R. ponticum was also shown to release allelopathic compounds into the soil. However, on their own these compounds had no inhibitory effect on the germination or growth of L. perenne, and germination and leaf appearance of T. repens were reduced by less than 60%, indicating that other factors are involved in the inhibition of growth. Light and nutrient stress were shown to increase the susceptibility of the test species to allelopathic compounds, and the light and pH conditions found in uninvaded woodland in the New Forest increased the synthesis and accumulation of allelopathic compounds in the soil beneath the rhododendron. These findings demonstrate the importance of pre-existing conditions and the presence of other species in the success of invasive species, and that the inhibition of growth of the native species is due to a complex combination of biotic and abiotic factors.

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Wright, Gabrielle A. Wright. "WHITE-TAILED DEER BROWSE PREFERENCE FOR AN INVASIVE SHRUB, AMUR HONEYSUCKLE, DEPENDS ON WOODY SPECIES COMPOSITION." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1510834316256772.

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Alverson, Sarah Elizabeth. "Assessing the Ecological Implications of Arbuscular Mycorrhizal Fungal Colonization of the Invasive Shrub Amur Honeysuckle (Lonicera maackii)." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1366847079.

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Poulette, Megan Marie. "ECOSYSTEM IMPACTS OF THE INVASIVE SHRUB LONICERA MAACKII ARE INFLUENCED BY ASSOCIATIONS WITH NATIVE TREE SPECIES." UKnowledge, 2012. http://uknowledge.uky.edu/biology_etds/6.

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Invasive species are significant drivers of global environmental change, altering the stability and functioning of numerous ecosystems. The exotic shrub Lonicera maackii is an aggressive invader throughout much of the eastern United States. While much is known about its population and community impacts, little is known about effects on ecosystem processes. This dissertation documents changes in ecosystem processes associated with L. maackii growing beneath three native tree species (Fraxinus quadrangulata, Quercus muehlenbergii, Carya ovata) in a savanna in Kentucky. Like many invasive plants, L. maackii litter decomposed and lost nitrogen (N) rapidly, especially in comparison with native tree litter. In comparison to the soils beneath the trees where the exotic shrub was absent, soils beneath L. maackii had a lower bulk density, elevated soil organic matter, C:N, and total soil N and a modified soil microbial community. Inorganic N deposition from spring throughfall was also altered by L. maackii, with higher NO3-N deposition beneath shrubs located beneath the tree canopy relative to canopy locations without L. maackii. While many exotic plant species have been shown to alter ecosystem processes, their impact is often not uniform. This variability is attributed to among-site differences (soil, climate, plant community): within site variability is often ignored. While many of L. maackii’s alterations to ecosystem processes were uniform across the site, several were dependent upon interactions between the exotic and the native tree species. Litter from L. maackii decomposed and lost N more rapidly under C. ovata than under the other native tree species. Soils beneath L. maackii shrubs located under C. ovata also had a greater fungal:bacterial ratio and a greater abundance of the saprophytic fungal lipid biomarker 18:1ω9c. These results demonstrate that L. maackii’s impact extends to ecosystem processes and suggests that invasive plants may have variable effects within a given environment depending on their interactions with the dominant native species. Identifying native species or communities that are more vulnerable to alterations of ecosystem function upon invasion may prove useful to land managers and foster a better understanding of the role that community dynamics play in moderating or enhancing invasive species impacts.

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Barker, Rachel Elizabeth. "Invasive Shrub (Lonicera maackii) Effects on Terrestrial-Aquatic Linkages in Stream Ecosystems: Organic Matter Processing and Macroinvertebrate Community Colonization." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1310485004.

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Peebles-Spencer, Jessica Rene. "Interactions between invasive shrub, Lonicera maackii, and a generalist herbivore, White-tailed deer, in Southwestern Ohio forests." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1461269925.

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Martinod, Kylie. "Importance of an invasive shrub, Lonicera maackii, in the diet of white-tailed deer: nutritional quality and browse rates." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470059937.

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Lieurance, Deah M. "Leaf Phenology, Fecundity, and Biomass Allocation of the Invasive Shrub Lonicera maackii (Rupr.) Maxim in Contrasting Light Environments." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1108143238.

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Minnick, Michael John. "The roles of forest fragments and an invasive shrub in structuring native bee communities and pollination services in intensive agricultural landscapes." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1581000018403528.

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Kakembo, Vincent. "Factors affecting the invasion of Pteronia incana (Blue bush) onto hillslopes in Ngqushwa (formerly Peddie) District, Eastern Cape." Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1005508.

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The factors that influence the invasion of hillslopes by the shrub Pteronia incana in the communal rangelands of Ngqushwa (formerly Peddie) district were investigated. Mgwalana, one of the catchments in the district where encroachment by the species is widespread, was chosen. The study combined field observations with image analysis based on high resolution infrared imagery. The catchment was flown and high resolution infrared images (1mx1m) were taken using a Kodak DCS420 digital, colour-infrared camera. The images were analysed using Idrisi32 and Kilimanjaro GIS versions. The ability of different vegetation indices to separate P. incana from the other cover types was investigated. Field observations of the degree of P. incana invasion in relation to, inter alia, soil surface conditions, slope angle and visible forms of erosion were made. A Digital Elevation Model (DEM) of 20m spatial resolution was used to derive terrain parameters. The presence and absence of P. incana in relation to slope gradient and aspect were determined. The combined influence of the two terrain parameters and land use on the invasion was also investigated. The Topographic Wetness Index (WI), a component of the TOPMODEL was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. Soil moisture dependencies for P. incana and grass species as well as surrogates for runoff under the shrub and adjacent bare areas were determined in the field. A high level of classification accuracy confirmed the reliability of digital camera imagery for spatial analyses. Distinct spectral separability for the surface vegetation cover types was achieved by means of the Perpendicular Vegetation Index (PVI) as opposed to the ratio based vegetation indices (NDVI, SAVI and MSAVI). The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots. Blanket invasion of the former signified the high susceptibility of abandoned land to P. incana invasion. The combined influence of land use, slope gradient and aspect was also noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation. Local topographic variations were identified as having a strong bearing on P. incana spatial distribution. The topographically driven WI confirmed this relationship, such that P. incana was associated with the low WI values of convexities. Differences in the moisture dependencies between P. incana and grass species were demonstrated by the greater rooting depth of the former. During field surveys, soil surface crusting was noted as inherent to P. incana patchiness. The coupling between local topography and soil surface crusting underpins soil moisture variability at hillslope and patch scales respectively. This in turn determines the competition between P. incana and grass species and the eventual replacement of the latter by the former. A close spatial correlation between fully established P. incana and severe forms of soil erosion was observed. Loss of patchiness and expansion of inter-patch bare areas promote runoff connectivity erosion. As most of the runoff becomes run out, hillslopes tend towards dysfunctional systems. Greater soil moisture storage after rainstorms under P. incana tussocks than the adjacent bare areas signifies the shrub’s water harvesting capabilities. The tussocks could thus serve as a starting-pointbuilding- block for the rehabilitation of dysfunctional hillslope systems.

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Lawlor, Sarah E. "Using Advanced Land Imager (ALI) and Landsat Thematic Mapper (TM) for the detection of the invasive shrub Lonicera maackii in southwestern Ohio forests." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1303831778.

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McKinney, Amy Marie. "Pollinator-mediated interactions between the invasive shrub Lonicera maackii and native herbs: The roles of shade, flowering phenology, spatial scale, and floral density." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276309342.

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Srinivasan, Madhusudan P. "THE ECOLOGY OF DISTURBANCES AND GLOBAL CHANGE IN THE MONTANE GRASSLANDS OF THE NILGIRIS, SOUTH INDIA." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/213.

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Biodiversity rich regions worldwide face threats from various global change agents. This research quantifies environmental influences on vegetation, and the impacts of exotic woody plant invasion and anthropogenic nitrogen (N) deposition in a global biodiversity hotspot. The study was conducted in the montane grasslands of the Nilgiris, Western Ghats, and outlines potential management options for this region. Specifically, I examined (1) the role of environmental factors in influencing native plant distribution and ecosystem properties, (2) the status and impact of exotic shrub (Scotch broom, henceforth broom) invasion, (3) the role of disturbances in the success of broom, (4) the role of fire in restoring invaded grasslands, and (5) the impacts of terrestrial N loading on the grassland ecosystem. I used experiments and surveys to assess these. Distributions of several key species were explained by a few complex environmental gradients. In invaded-grasslands, broom populations consisted mainly of intermediate size and age classes, with no clear indication of population decline. Invasion negatively impacted plant community structure and drastically changed composition, favoring shade-tolerant and weedy species. However, invasion did not greatly alter ecosystem function. Fire successfully eliminated mature broom stands, but resulted in a short-term increase in broom seedling recruitment. At the end of 18 months, the fire effects on uninvaded-grasslands were not apparent, but there was no conclusive evidence of the formerly invaded patches attaining the composition of uninvaded-grasslands following burning. N fertilization strongly influenced soil N dynamics, and shoot N concentrations, but effects on aboveground production were weak. Surprisingly, N enrichment had positive effects on diversity in the short-term. It is clear that these grasslands need immediate management intervention to forestall degradation from invasion. Fire could be used to eliminate mature broom stands and deplete persistent seedbanks, which will facilitate colonization by shade-intolerant grassland plants. Active restoration should be mindful of environmental preferences of framework species. Long-term studies of the impacts of N deposition in the context of disturbances will help determine realistic critical thresholds and utilize disturbances to buffer the potential adverse effects of increasing N loading.

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Scriver, Bryn Muree. "Consequences of oak savanna restoration techniques on the re-invasion of non-native invasive shrubs, particularly Rhamnus cathartica L. (common buckthorn)." 2005. http://catalog.hathitrust.org/api/volumes/oclc/64381568.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 2005.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 106-118).

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(11205324), Benjamin Joseph Rivera. "The Establishment, Control, and Post-Control Response of Amur Honeysuckle (Lonicera maackii)." Thesis, 2021.

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Amur honeysuckle (Lonicera maackii) is a shrub endemic to East Asia which has become invasive and nearly ubiquitous to the forest ecosystems of eastern North America. Through its extended growing season, competitive ability, and potential allelopathy, Amur honeysuckle alters native herbaceous-layer plant communities and inhibits the regeneration of native tree species. As such, it is representative of a range of invasive shrub species imported from East Asia. My thesis contributes to questions fundamental to the understanding this and other invasive shrubs: 1) How do species become invasive? 2) How can the invasions of the species be effectively controlled? 3) How does the ecosystem respond to treatment of the invasive species?

First, I examined the role of self-compatibility within Amur honeysuckle. I compared the berry production, seed production, and germination rates between closed-pollinated and open-pollinated flowering branches of Amur honeysuckle individuals across multiple types of invasions (heavy, light, and sprouting). I found that Amur honeysuckle not only possesses the ability to self-pollinate, but that it can produce viable self-pollinated seed sets. This ability may help explain how Amur honeysuckle able to invade isolated forest patches far removed from the main invasion.

Second, I evaluated the effectiveness of a novel herbicide adjuvant in reducing the amount of herbicide needed in the ‘cut-stump’ method of controlling Amur honeysuckle. Combining various concentrations of the most common herbicide in the world, glyphosate, with concentrations of cellulases derived from fungi, 2XL, I examined whether the cellulases improved the effectiveness of glyphosate, potentially by increasing glyphosate movement into the vascular tissue of Amur honeysuckle through the degradation of cell walls. While 2XL was not an effective adjuvant, glyphosate concentrations of less than half the recommended dosages were equally effective as higher concentrations in preventing sprouting of treated stumps. The ineffectiveness of 2XL may imply a need for protein-mitigated diffusion of glyphosate across cell walls and into the vascular tissue of the plant, which would be inhibited by the breakdown of cell walls.

Finally, I tested how deeper intensities of mulching-head treatments affected the sprouting response of Amur honeysuckle and the response of the herbaceous-layer plant community after treatment. I found a negative relationship between the volume of sprouting Amur honeysuckle and increasing depth of mulching-head treatment. Additionally, increasing mulching-head intensities were correlated with increased herbaceous layer diversity and conservation value as represented by Floristic Quality Index. Mulching-head treatments are a promising tool in controlling heavy invasions of non-native shrubs.

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Ramarumo, Luambo Jeffrey. "Ethnobotanical survey of problem weeds, alien invasive plant species and their roles in Nzhelele, Makhado Local Municipality, Limpopo Province, South Africa." Diss., 2017. http://hdl.handle.net/11602/942.

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MSc (Botanty)
Department of Botany
Background: Problem plants and alien invasive weed species are part of today‟s ecological transformation. Ethnobotanical literature on ecological prominence and ethical values of problem alien weeds is scant and should be documented to avoid loss of valuable species. Aim: The study was aimed at documenting problem weeds and alien invasive plant species considered to be beneficial in deep rural communities. Materials and method: Purposeful triangulation research methods were used to ensure the proper gathering of both qualitative and quantitative data sets. Results and conclusion: Some problem weeds and alien invasive plant species are being utilized by local people to maintain their livelihood. A total of 78 plant species from 33 families were recorded. These plant species belonged to diverse growth habits, namely: climbers, herbaceous, succulents, shrubs, trees as well as creepers. Recorded problem weeds and alien invasive plant species were contributing towards ecological, medicinal and social values. These included being utilized as a source of food (14), fruits (4), medicinal (31), ornamentals (7), firewood (3), social (2) and multiple purposes (17). The main utilized families were Asteraceae (14.1%) and Solanaceae (14.1%). These families were mostly utilized for the purpose of medicinal and food. Plant species that were widely used are as follows: Achyrathes aspera L., Agave sisalana L., Amaranthus spinosus L., Anredera cordifolia L., Canna indica L., Centella asiatica L., Chenopodium album L., Chenopodium ambrosioides L. and Chromolaena odorata (L.) R. M. King and H. Rob. The dominant category for problem weeds and alien invasive plant species was 1b (44%) followed by weeds (35%), category 2 (9%), invaders (5%), category 3 (4%) and 1% for both category 1, 1a as well as X3. The results revealed that the legislative listing of plant species as problem weeds and alien invasive species was based on single knowledge basis system, rather than on multi-dimensional knowledge systems. Therefore, this study recommended that for judgment to be considered in decision-making, it should be based on species-specificity as well as multi-dimensional-knowledge basis. The reconciliation of inherent grapples among scientific and indigenous knowledge systems could possibly be underpinned by equal legislative consideration for the aforementioned knowledge systems especially in the establishment and implementation of environmental regulations. This could also aid with the provision to support transformation in South Africa and worldwide.

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39

(8067956), Caleb H. Redick. "Quantifying Impacts of Deer Browsing and Mitigation Efforts on Hardwood Forest Regeneration." Thesis, 2019.

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Due to overpopulation and resource-poor habitat structure, deer threaten the future of oak and other browse-sensitive species in hardwood forests. Appropriate tools must be used to ensure desirable, diverse, and ecologically stable regeneration of future forests and the sustainability of native plant communities. We performed two experiments and a review to examine the effectiveness of available methods for managing browse of hardwood seedlings and to discover how these interact with each other and other silvicultural methods. First, we examined how fencing interacts with controlled-release fertilization, seed source (genetically select and non-select), and site type (afforested and reforested sites) to enhance the regeneration of planted northern red oak (Quercus rubra L.), white oak (Quercus alba), black cherry (Prunus serotina), and black walnut (Juglans nigra) at five sites in Indiana. Fencing proved to be the greatest determinant of seedling growth, survival, and quality. Fertilizer enhanced the early growth of white oak and black cherry, though for black cherry this occurred only inside fences. Select seed sources grew better and showed greater quality; however, the survival of select seedlings was limited by deer browse in absence of fences. Trees at afforested sites had lower survival if left non-fenced. Secondly, we also investigated how fencing and invasive shrub removal affected natural regeneration, species richness, and ground-layer plant cover under closed-canopy forests. Honeysuckle (Lonicera maackii) removal had a variable effect depending on species and site. Positive effects were most common for shade-intolerant species, while negative effects occurred for a few shade-tolerant species at some sites. Deer fencing had a positive effect on cherry and hackberry seedling density, and a negative effect on elm seedling density. Honeysuckle and deer fencing interacted antagonistically in some instances. Fencing without honeysuckle removal resulted in lower elm abundance and herbaceous-layer cover. In the densest invasions, leaving honeysuckle intact resulted in a complete lack of recruitment into the sapling layer. Our experiment suggests that invasive shrub removal and fencing be done together. Finally, we synthesized the existing literature on browse management options for hardwood regeneration to evaluate their relative effectiveness. Fences, tree shelters, repellents, facilitation by neighboring plants, deer population control, timber harvest, and slash all had positive effects on height growth of regenerating seedlings under deer browse pressure. Fences were more effective at reducing browse than repellents, while fertilizers increased browse and had no effects on growth.

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Dissertations / Theses on the topic 'Invasive shrubs'

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