Academic literature on the topic 'Seedling recruitment'
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Journal articles on the topic "Seedling recruitment"
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Chauhan, Bhagirath S., Gurjeet Gill, and Christopher Preston. "Seedling recruitment pattern and depth of recruitment of 10 weed species in minimum tillage and no-till seeding systems." Weed Science 54, no. 4 (2006): 658–68. http://dx.doi.org/10.1614/ws-05-135r.1.
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Differences in periodicity and depth of weed seedling recruitment due to agronomic management practices, such as reduced tillage, have implications for weed competitive ability and management strategies. Periodicity and depth of seedling recruitment of 10 different weed species was measured in the field in 2004 and 2005. The seedling recruitment of rigid ryegrass, threehorn bedstraw, and wild radish seedlings was higher under minimum tillage than under no-till scenarios. In contrast, the seedling recruitment of Oriental mustard, annual sowthistle, squirreltail fescue, little mallow, and turnipweed was higher under the no-till system. The seedling recruitment of wild oat and African mustard was not influenced by the tillage system. The mean seedling recruitment depth of wild oat, rigid ryegrass, threehorn bedstraw, wild radish, and turnipweed was greater under minimum tillage than under the no-till system. These weeds are able to emerge from deeper in the soil profile. In contrast, the seedling recruitment depth under minimum-tillage and no-till systems was similar for African mustard, Oriental mustard, annual sowthistle, little mallow, and squirreltail fescue. These are all small-seeded species, which failed to emerge from deeper depths under either tillage system. In addition, all of these species except African mustard showed higher total seedling recruitment under the no-till system. Results of this study will facilitate weed-control timing decisions and provide validation data for weed seedling recruitment models.
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John Bullied, W., Rene C. Van Acker, and Paul R. Bullock. "Review: Microsite characteristics influencing weed seedling recruitment and implications for recruitment modeling." Canadian Journal of Plant Science 92, no. 4 (2012): 627–50. http://dx.doi.org/10.4141/cjps2011-281.
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Bullied, W. J., Van Acker, R. C. and Bullock, P. R. 2012. Review: Microsite characteristics influencing weed seedling recruitment and implications for recruitment modeling. Can. J. Plant Sci. 92: 627–650. A weed seedling recruitment microsite is the location of a weed seed in the soil profile which affects germination, time of emergence and seedling establishment. The relationship between the recruitment of seedlings and their physical environment, including microclimate, soil, topography, and residue cover can provide the key to understanding the timing of seedling recruitment. The variability that exists in germination and establishment requirements within and among weed species raises important questions for recruitment research addressing multiple species, as well as regional models of genetic variability within species. Current weed recruitment research focuses mainly on summer annual species in annual cropping systems. However, with changes in cropping systems, climate, and weed biology, there will be an increasing demand for the management of both summer and winter annual weeds that develop very early in the spring. Many studies to date take an average of microsite conditions, particularly for soil depth, to describe the seedling recruitment zone. Whereas this practice of under-sampling expedites lengthy and difficult soil environmental measurements, it limits the description of the microsite for predictive purposes. Because soil disturbance disperses seeds to microsites throughout the vertical profile of the shallow seedling recruitment zone, seeds are subjected to gradients of temperature and water that create diverse microsites with depth in the recruitment zone. Research on the interactions of microclimate, field topography, soil properties and agronomic practices can further our knowledge base of the seedling recruitment microsite to better understand weed ecology and population dynamics generally, as well as enhance our ability to predict seedling recruitment specifically.
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Arai, Nobumasa, and Tomohiko Kamitani. "Seed rain and seedling establishment of the dioecious tree Neolitsea sericea (Lauraceae): effects of tree sex and density on invasion into a conifer plantation in central Japan." Canadian Journal of Botany 83, no. 9 (2005): 1144–50. http://dx.doi.org/10.1139/b05-089.
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We studied the effects of differences in parent sex and density on seed rain and seedling and (or) sapling recruitment in a dioecious tree species (Neolitsea sericea (Bl.) Koidz.) with bird-dispersed seeds. We established four microhabitats: male or female trees inside or outside a single patch. The density of bird-disseminated seeds was significantly higher beneath females and inside the patch than beneath males and single trees outside the patch; this led to higher density of emerged seedlings inside the patch. The survival rate of germinated seedlings was also higher inside the patch than below single trees. In contrast, the survival rate of saplings was highest beneath males outside the patch, although very few seeds are dispersed beneath single males. Seedling and sapling recruitment beneath females and inside the patch will be accelerated owing to higher density of dispersed seeds, high seedling survival, and greater sapling density. In contrast, recruitment beneath males will be very slow. However, microhabitats beneath males are probably more suitable for seedling and sapling recruitment than microhabitats beneath females, since the survival rate of saplings was higher beneath males. Parental sex-biased seed rain and seedling and (or) sapling recruitment in dioecious plants may explain the regeneration pattern at a local scale.
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Van Acker, R. C., W. J. Bullied, and M. J. du Croix Sissons. "Tillage index predicts weed seedling recruitment depth." Canadian Journal of Plant Science 84, no. 1 (2004): 319–26. http://dx.doi.org/10.4141/p03-074.
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The influence of tillage on the depth of weed seedling recruitment has implications for species competitive ability, weed management strategy development, and the modeling of weed emergence; characterization of this relationship could aid in the creation of field-specific models of weed seedling recruitment. A tillage index based on the percentage of residue cover remaining on the soil surface after tillage events was assessed for 44 zero-tillage and 44 conventional-tillage fields across Manitoba, Canada. This index was related to in situ measurements of seedling recruitment depth from the same fields for five annual weed species. The modeled relationship was linear and unique for each species (R2 values ranged from 0.38 to 0.71). The relationship did not differ between pre- and post-seeding measurements, or between years, except for green foxtail. Slopes of the regression lines were greater for species such as volunteer wheat, which can recruit from a great range of depths. The results of this study show that recent tillage strongly influences mean weed seedling recruitment depth, and that the recruitment depth of summer annual weed seedlings is related in a continuous and reliable manner to a simple estimation of the relative level of tillage (including seeding) applied in one season. Key words: Recruitment depth, tillage index, weed emergence, weed seedlings
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Duchesneau, Robin, and Hubert Morin. "Early seedling demography in balsam fir seedling banks." Canadian Journal of Forest Research 29, no. 10 (1999): 1502–9. http://dx.doi.org/10.1139/x99-090.
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Following the 1995 mast year, we conducted detailed seedling demography surveys to characterize some ecological factors affecting germination and early establishment in understory balsam fir (Abies balsamea (L.) Mill.) seedling banks and verify if recruitment from a cohort can potentially renew the balsam fir seedling bank. Twenty-five seed traps paired with 32 demography subplots were located in each of four permanent plots and regularly monitored over a 2-year period. Spatial patterns of newly emerged seedlings generally corresponded to those found for seed dispersal. However, at the end of the monitoring period, the spatial pattern of surviving seedlings was independent of the seed dispersal pattern. Seedbed types and understory light environments were the main factors explaining seedling mortality. Sphagnum mosses and decaying wood were the most favorable seedbeds for early establishment. The 0- to 25-cm seedling populations grew in size because of the addition of new recruits. If, in the years to come, mortality rates of the 1995 cohorts were similar to those of already established 0- to 25-cm seedlings, mast years of seed production, at least during endemic periods, would be crucial for recruitment and renewal of balsam fir seedling banks.
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Kunstler, Georges, Joël Chaduf, Etienne K. Klein, Thomas Curt, Monique Bouchaud, and Jacques Lepart. "Tree colonization of sub-Mediterranean grasslands: effects of dispersal limitation and shrub facilitation." Canadian Journal of Forest Research 37, no. 1 (2007): 103–15. http://dx.doi.org/10.1139/x06-225.
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Encroachment of trees into low-productivity grasslands is a serious threat to grassland biodiversity throughout Europe. Although the rate of encroachment of trees into grassland is variable and poorly understood, it is thought to result from variation in tree seedling recruitment, which is limited mainly by the availability of safe sites and the dispersal distances of propagules. In this study, we established spatially explicit models of seedling recruitment for two major sub-Mediterranean trees: Quercus pubescens Willd. and Fagus sylvatica L. We quantified the spatial distribution of Q. pubescens and F. sylvatica seedlings up to 20 years old at three grassland sites. We also quantified the spatial distribution and size of mature trees and of the two dominant species of shrubs, Buxus sempervirens L. and Juniperus communis L., at each of the three sites. Ninety-eight percent of the regeneration took place under shrub canopy. Quercus pubescens seedlings showed higher seedling production per unit of canopy area and longer mean effective dispersal distances than did F. sylvatica seedlings. Quercus pubescens seedlings also had a large advantage over F. sylvatica seedlings for establishment in open areas. Juniperus shrubs were better safe sites for the establishment of Q. pubescens and F. sylvatica seedlings than were Buxus shrubs. We calculated indices of seedling dispersal limitation and safe site availability for recruitment for four dates. In the dolomitic Causse grasslands examined in this study, the availability of safe sites for germination and survival was far more important than seedling dispersal limitation for recruitment of both tree species.
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Moss, Melissa, and Luise Hermanutz. "Postfire seedling recruitment at the southern limit of lichen woodland." Canadian Journal of Forest Research 39, no. 12 (2009): 2299–306. http://dx.doi.org/10.1139/x09-150.
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Although fire is the primary mechanism driving regeneration in open black spruce ( Picea mariana (Mill.) BSP) lichen woodland, there are limited data concerning the sources of seedling mortality across the range of burn severity. We monitored planted seedlings in areas of high and low burn severity in Terra Nova National Park (Newfoundland, Canada) to determine sources and patterns of mortality of black spruce seedlings among burn treatments following a recent burn (2002). The importance of herbivory by small mammals as a source of seedling mortality was evaluated using small cages that excluded voles and non-native snowshoe hare. Overall seedling mortality was high (79%) in all areas; mortality was similar in areas of low (73%) and high (76%) burn severity, and highest in edge areas adjacent to closed-canopy forest (90%). Drought, rather than herbivory, was the most common cause of mortality during the first two seasons following germination. Seedling mortality at the southern edge of the lichen woodland was comparable to that found in other studies, but sources differed, emphasizing the spatially variable nature of mortality. Based on the level of seedling recruitment, our results suggest lichen woodland will return at this site.
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Williams, Charles E., and W. Carter Johnson. "Factors affecting recruitment of Pinuspungens in the southern Appalachian Mountains." Canadian Journal of Forest Research 22, no. 6 (1992): 878–87. http://dx.doi.org/10.1139/x92-117.
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Factors affecting the establishment and recruitment of seedlings of the Appalachian endemic Pinuspungens Lamb were studied in pine–oak forests of dry, southwesterly mountain slopes in southwestern Virginia, United States. Recruitment of P. pungens was not limited by seedfall from serotinous cones or by postdispersal seed predation. Total viable seedfall ranged from 35 000 to 69 000 seeds/ha in 1988 and was concentrated in the spring and summer months. Low availability of suitable seedling habitat strongly limited recruitment of P. pungens seedlings. The distributions of habitat variables for P. pungens seedlings and random points in the forest overlapped little, indicating that suitable microsites were relatively rare. Seedlings occurred in microsites characterized by shallow pine litter, low ground and canopy covers, and larger nearest neighbor distances than occurred at random. Summer drought also contributed to low seedling survivorship, particularly in young seedlings. Our results suggest that optimal recruitment and population maintenance of P. pungens in pine–oak forests is unlikely in the absence of fire.
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Paine, C. E. Timothy, Kyle E. Harms, and Jesús Ramos. "Supplemental irrigation increases seedling performance and diversity in a tropical forest." Journal of Tropical Ecology 25, no. 2 (2009): 171–80. http://dx.doi.org/10.1017/s0266467408005798.
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Abstract:Diversity is positively correlated with water availability at global, continental and regional scales. With the objective of better understanding the mechanisms that drive these relationships, we investigated the degree to which variation in water availability affects the performance (recruitment, growth and survival) of juvenile trees. Precipitation was supplemented throughout two dry seasons in a seasonal moist forest in south-eastern Peru. Supplementing precipitation by 160 mm mo−1, we increased soil moisture by 17%. To generate seedling communities of known species composition, we sowed 3840 seeds of 12 species. We monitored the fates of the 554 seedlings recruited from the sown seeds, as well as 1856 older non-sown seedlings (10 cm ≤ height < 50 cm), and 2353 saplings (> 1 m tall). Watering significantly enhanced young seedling growth and survival, increasing stem density and diversity. Watering diminished the recruitment of species associated with upland forests, but increased the survival of both upland- and lowland-associated species. Though supplemental watering increased the growth of older seedlings, their density and diversity were unaffected. Sapling performance was insensitive to watering. We infer that variation in dry-season water availability may affect seedling community structure by differentially affecting recruitment and increasing overall survival. These results suggest that differential seedling recruitment and survival may contribute to the observed relationships between water availability, habitat associations and patterns of tree species richness.
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Boudreau, S., and M. J. Lawes. "Density- and distance-dependent seedling survival in a ballistically dispersed subtropical tree species Philenoptera sutherlandii." Journal of Tropical Ecology 24, no. 1 (2008): 1–8. http://dx.doi.org/10.1017/s026646740700466x.
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Abstract:We examine the density- and distance-dependent seedling survival of Philenoptera sutherlandii, a common pod-bearing and dehiscent legume (Fabaceae) in Ongoye Forest, South Africa. Short-range ballistic dispersal causes seed to fall beneath the parent tree, where density- or distance-dependent mortality effects are expected to be concentrated. One hundred and eighty marked seedlings were monitored in a 0.5-ha plot containing 30 adults. Our survival data do not support the escape hypothesis. Predation levels declined with increasing seedling density (positive density-dependent survival), but seedling survival after 15 mo was not distance-dependent. Nevertheless, a unimodal (hump-shaped) recruitment curve, typically associated with decreasing seedling density and increasing seedling survival with distance, was observed. In the context of ballistic dispersal, this recruitment curve may indicate a hump-shaped dispersal kernel with predator satiation at high seedling densities near a parent tree. This recruitment curve likely arises because generalized insect seedling predators while attracted to the adult trees also tend to forage farther away. Short dispersal distances, in turn generate the high densities needed to satiate seed and seedling predators. Predator satiation results in long-term survival rates in P. sutherlandii similar to more widely dispersed and less common tree species.
Dissertations / Theses on the topic "Seedling recruitment"
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Henshaw, Alex. "Factors Influencing Future Canopy Composition at Tiromoana Bush, North Canterbury, New Zealand." Thesis, University of Canterbury. School of Forestry, 2012. http://hdl.handle.net/10092/7092.
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The purpose of this study was to investigate seedling recruitment beneath kanuka forest at Tiromoana Bush, North Canterbury. The regeneration of broadleaved tree species is evident throughout Tiromoana Bush. This research aimed to quantify the biotic and abiotic factors influencing the distribution of small and large seedlings of canopy tree species, their relative growth rates, their survival, abundance and composition throughout the forest understorey of Tiromoana Bush. Tiromoana Bush is a forest restoration area of 410 hectares adjacent to the Kate Valley landfill.
To determine the future tree species composition at Tiromoana Bush, seedling recruitment, growth and survival was quantified through remeasuring tagged seedlings in 26 permanent vegetation monitoring plots located in the major forest patches at Tiromoana Bush. In addition, seedling data from 78 temporary vegetation survey plots established in three major forest patches were used to assess the influence of different factors on seedling abundance.
At Tiromoana Bush, the most common canopy tree species as seedlings in the permanent vegetation monitoring plots was mahoe followed by fivefinger. Mahoe seedling density was significantly affected by canopy openness, distance to seed sources, light index, shrub cover and slope, but not by aspect, basal area and time. For fivefinger, seedlings increased in abundance with time, but the difference was not statistically significant. The relative growth rate of mahoe in the 20-49cm height class (in which most seedlings occurred) was significantly affected by shrub cover, light index and canopy
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openness. Mahoe seedling recruits were significantly affected by light index and canopy openness. Survivability of mahoe was affected by aspect. For fivefinger, individual relative growth rates were significantly affected by canopy openness and light index.
Similar results were found for tree species seedlings present in the temporary survey plots provided with mahoe and fivefinger again the most common species, followed by kohuhu. Light index significantly affected golden akeake small seedlings as well as canopy openness. Light index significantly affected ngaio large seedling distribution. Aspect was the only significant factor for kohuhu large seedling distribution. Distance from seed sources significantly affected fivefinger small seedling distribution as seedlings are dependent upon dispersal away from the parent trees. Slope significantly affected the distribution of red matipou small seedlings.
The most important environmental attribute influencing seedling abundance is light. This is evident in both the permanent seedling monitoring plots and the temporary vegetation survey plots. Based on data from the temporary vegetation survey plots, mahoe, fivefinger and kohuhu are most abundant suggesting that these three canopy tree species will dominate the forest canopy at Tiromoana Bush once the kanuka starts to senesce.
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Mansor, Asyraf. "Determinants of Seedling Recruitment in Mimosa Pigra L." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506819.
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Mimosa pigra L., a semi-aquatic woody legume, is a well known invasive plant in the tropics. Originating from Latin America, this species has spread to various localities around the globe and caused serious problems, both environmental and economical, in its new environment. I carried out a survey to assess the current status of Mimosa infestation in Peninsula Malaysia. Manipulative field experiments on the effect of soil disturbance, competitor identities, sown seed densities and defoliation on Mimosa seedling recruitment and survival were conducted as well. I found that although disturbance may not be an essential factor for seedling emergence in Mimosa, it significantly increase seedling establishment and survival. Recruitment in Mimosa was negatively affected when seedlings were grown together with vine (Centrosema) and creeper (Ipomoea), suggesting the importance of interspecific competition in reducing seedling emergence and establishment. The seed-sowing treatment showed that recruitment in Mimosa was both seed-limited and microsite-limited. While the number of seedlings emerging increased with the density of sown seeds, the proportion of emergence remained constant across the sown seed densities. Herbivory (through artificial defoliation) reduced seedling survival in Mimosa, although some seedlings proved to be resilient to even the highest intensity and frequency of defoliation. In general, I argued that Mimosa invasion in Peninsula Malaysia is not a serious problem since its populations were mostly restricted to disturbed ground and abandoned land. I would like to suggest that current best course of option is to continue monitoring its population and evaluate its spread, as control of established stands without destruction of the seed bank is likely to cause insignificant impact on subsequent population. One recommendation is to restrict the movement of topsoil from Mimosa infested sites. Future researches, if they were to be conducted shoUld try to establish method(s) that will reduce the Mimosa seed bank.
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Welling, P. (Pirjo). "Regeneration by seeds and vegetation structure in alpine plant communities, subarctic Finland." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:951426861X.
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Abstract
The aims were to examine the importance of regeneration by seeds, the
influence of plant traits and disturbances, and the role of seed-seedling
conflicts in regeneration and in the determination of vegetation structure.
The study was carried out at in a subarctic alpine area (Kilpisjärvi
69°01'N 20°50E', Finland).
Seed bank and seedling densities were high in many plant communities
(ranges 99 -1109 viable seeds/m2 and 0.2-227
seedlings/m2, respectively). Effective seedling
recruitment is reflected in vegetation as a high proportion of plants with
poor or no vegetative reproduction ability. This development may take place
in meadows and snowbeds where herbs (e.g. Gnaphalium
supinum, Sibbaldia procumbens,
Veronica alpina and Viola
biflora) are abundant. On the other hand, the low proportion of
these plants in heath vegetation reflects ineffective seedling
recruitment.
Floristic similarities between the consecutive phases in the
regeneration pathway may be low despite effective seedling recruitment.
Clonality, large and small seed sizes and appendaged diaspores limit the
movement of species from phase to phase.
Generally, disturbances facilitate effective regeneration by seeds.
Grazing promotes species with large seed banks and is therefore one reason
for high seed bank densities. Freezing and melting processes negate a
negative influence of altitude on seed bank densities in the phase of
seedlings. However, if disturbances are severe and continuous and the soil
is compact, unstable or dry, disturbances are not beneficial. The same is
true if there is a shift in the species composition of seedlings from gaps
to closed vegetation. This phenomenon occurred in a rich meadow.
Seed-seedling conflicts limit regeneration by seeds in low-herb
snowbeds and Ranunculus glacialis-Gymnomitrion
snowbeds. Vegetative reproduction and infrequent pulses of seedling
recruitment negate an influence of short-term seedling recruitment on the
spatial structure of vegetation. Extreme conditions, such as low
temperatures, instability of the soil and late snowmelt modify the
influence of factors that are important in more moderate conditions.
To conclude, all transitions limit regeneration by seeds. However,
favourable conditions (e.g. moist conditions in a meadow) partly eliminate
the obstacles against seedling emergence. Regeneration by seeds therefore
has a major impact on the dynamics and structure of vegetation. In heath
vegetation, where bare soils are dry and the moss cover is thick, large
seed banks and seed rains do not guarantee effective seedling recruitment.
The regeneration process is reduced in the early phases, and plants that reproduce primarily by seeds have a minor role in vegetation. The accumulation of seed banks is effective in these circumstances.
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Clark, Connie Jane. "Factors that determine patterns of seedling recruitment in an Afrotropical forest." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024894.
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Dyson, David Samuel Loewenstein Edward F. "Influence of competition on longleaf pine seedling recruitment in selection silviculture." Auburn, Ala., 2010. http://hdl.handle.net/10415/2045.
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Lönnberg, Karin. "Effects of seed size and habitat on recruitment patterns in grassland and forest plants." Doctoral thesis, Stockholms universitet, Botaniska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-82384.
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A trade-off between seed size and seed number is central in seed ecology, and has been suggested to be related to a trade-off between competition and colonization, as well as to a trade-off between stress tolerance and fecundity. Large seeds endure hazards during establishment, such as shading, drought, litter coverage and competition from other plants, better than do small seeds, due to a larger amount of stored resources in the seed. Small seeds, however, are numerous and small-seeded species are therefore more fecund. Moreover, a pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed habitats has been reported in the literature. In this thesis I assess effects of seed size on recruitment, and how relationships between seed size and recruitment may relate to habitat conditions. Seed sowing experiments were performed in the field to assess inter- and intra-specific relationships between seed size and recruitment in open and closed habitats (Paper I and II). Seed removal experiments were performed in the field to assess what effects seed predation may have on a relationship between seed size and recruitment (Paper III). A garden experiment was performed based on contests between larger-seeded and smaller-seeded species, in order to examine different models on co-existence of multiple seed size strategies. The results showed that there was a weak positive relationship between seed size and recruitment in the field, and that this relationship was only weakly and inconclusively related to habitat (Paper I and II). Seed removal was negatively related to seed size in closed habitats and unrelated to seed size in open habitats (Paper III). This indicates that any positive relationship between seed size and recruitment may be an effect of higher seed removal in small-seeded species. However, when grown under controlled conditions in a garden experiment, there was a clear advantage of larger-seeded species over smaller-seeded species (Paper IV). This advantage was unaffected by seed density, indicating that there was no competitive advantage of the larger-seeded species. Instead, indirect evidence suggests that larger-seeded species exhibit higher tolerance to stress.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.</p><p> </p>
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Plenzler, Michael A. "Seedling Recruitment and Establishment of Lupinus perennis in a Mixed-Management Landscape." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1214238925.
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Johnson, Andrew James. "Unexplored Aspects of the Biotic Filter to Seedling Recruitment in Aquatic Environments." W&M ScholarWorks, 2019. https://scholarworks.wm.edu/etd/1563898631.
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Sexual reproduction provides submerged aquatic vegetation (SAV) populations unique opportunities for dispersal, genetic mixing, and resilience in the event of catastrophic population declines. Relative to asexual reproduction, sexual reproduction is a risky resource investment and can have a lower probability of success. A wide variety of abiotic and biotic interactions common in both terrestrial and aquatic environments can lead to significant mortality of seeds and seedlings. The goal of this dissertation is to explore the diversity of biological interactions that influence seed and seedling survival in SAV that drive the population dynamics and restoration success of SAV species. A combination of survey and experimental methods were used to test if three biological interactions, disturbance, herbivory, and competition, compromised seedling recruitment for three different SAV species growing in three different coastal environments. Chapter One explored the influence of sediment bioturbators on seedling establishment for the seagrass Posidonia australis in a marine environment. Field surveys demonstrated that dispersed seeds of P. australis overlap with a suite of sediment bioturbators that disturb the sediment in the coastal lagoons of Western Australia. The movement of sediment bioturbators found in these areas (sand dollars, sea stars, and heart urchins) dislodged and moved recently settled P. australis seeds. The overlap in habitat suitability between these animals and P. australis seeds suggests high densities of these animals consistently disturb non-dormant P. australis seeds and may act as a bottleneck to seedling recruitment. Chapter Two explored the role of grazers on seedling recruitment of a freshwater angiosperm. Field surveys recorded high grazing levels of isolated Vallisneria americana propagules in oligohaline areas of the James and Chickahominy Rivers, VA. Camera surveys identified the blue crab, Callinectes sapidus, as a likely herbivore. Subsequent surveys and experiments suggested C. sapidus in this system consumes SAV as part of their diet. The emergence of non-native SAV in the system, but not V. americana, suggests grazing prevents the recruitment of some SAV, but not others. Chapter Three evaluated interactions between adult plants and seedlings and how they impacted seedling establishment of an estuarine seagrass species. Field surveys consistently recorded seedlings establishing among existing Zostera marina shoots in a meso/polyhaline region of Chesapeake Bay, VA. Concurrent experiments indicated that seed supply influenced seedling establishment rates in some areas. Further surveys and experiments showed that negative interactions between seedlings and adult shoots influenced the subsequent survival of these seedlings within existing Z. marina meadows. Results from the research studies in this dissertation, conducted across three diverse coastal habitats, demonstrate that interactions between SAV seeds or seedlings and other biota can be very important in ultimately determining seed or seedling survival. The diverse mechanisms through which biota compromise seedling recruitment and sexual reproduction for SAV observed here suggest there may be many additional, unexplored biological interactions affecting successful sexual recruitment for many SAV species. Because sexual reproduction provides substantial benefits to SAV populations, incorporating risks associated with seedling recruitment into population models and restoration strategies may help better predict SAV population health, resiliency and expansion as well as help optimize SAV restoration efforts.
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Venn, Susanna Elizabeth, and Susanna Venn@nt gov au. "Plant recruitment across alpine summits in south-eastern Australia." La Trobe University. School of Life Sciences, 2007. http://www.lib.latrobe.edu.au./thesis/public/adt-LTU20080526.160815.
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This thesis investigated aspects of plant recruitment across an altitudinal gradient of mountain tops in the Victorian Alps, Australia, and provides a baseline for the patterns and processes of alpine plant recruitment in the absence of large-scale disturbance.
The patterns in alpine vegetation across the study sites were described in relation to abiotic environmental factors. Temperatures were lower and precipitation was higher at the high altitude sites. The vegetation did not differ significantly between the sites, although sites at low altitudes were shrubbier than those at high altitudes. Analysis of the soil seed bank revealed high mean densities of germinable seed (80 to 1400 seeds m-2) across the gradient of sites. The similarity between the seed bank samples and the standing vegetation was low (qualitative similarity: 0.08 to 0.2; quantitative similarity: 0.03 to 0.19).
In laboratory germination experiments, I found rapid and substantial germination. Final percent germination was above 90% for most species. One species, Aciphylla glacialis, showed evidence of dormancy mechanisms. In subsequent experiments, I found that innate primary seed dormancy in this species could be broken with cold-wet stratification.
There were no significant patterns in natural seedling recruitment across the altitudinal gradient. Similarities between the seedling flora and the standing vegetation
were low (qualitative similarity: 0.18 to 0.45: quantitative similarity 0.04 to 0.09). Mean seedling density was best predicted by a combination of soil wilting point, altitude and plant litter. In some cases, seedling density was greater than 80 seedlings m-2.
The relative importance of either negative (competitive) or positive (facilitative) interactions between seedlings with adjacent vegetation were investigated in relation to seed germination, seedling growth and seedling survival. Facilitative interactions were common at the higher altitude sites. At lower altitudes, facilitative and competitive interactions were common. Without close neighbours at high altitudes, seedlings were unlikely to survive into their second year.
An understanding of plant recruitment can provide a useful basis for predicting species responses to large-scale disturbance and climate change.
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Sagra, Javier, Daniel Moya, Pedro Plaza-Álvarez, et al. "Predation on Early Recruitment in Mediterranean Forests after Prescribed Fires." MDPI AG, 2017. http://hdl.handle.net/10150/625399.
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Wildfires play a significant role in many different elements of Mediterranean forest ecosystems. In recent years, prescribed fires have started being used more often as a fuel reduction tool, and also as silvicultural treatment to help the regeneration and health improvement of stands. Apart from the fact that fire may alter microsite conditions, very little is known about the impact of prescribed burning on natural regeneration or plant species renewal in Mediterranean pine forests. Likewise, knowledge about the influence of seedling predators on post-fire regeneration is still scarce. In this study, we aimed to compare the effects of seedling predation on recruitment in earlier stages after prescribed burnings in three pine stands in Central Spain: a pure stand of Pinus nigra; a mixed stand of Pinus halepensis and Pinus pinaster and a mixed stand P. nigra with P. pinaster. In situ we superficially sowed seeds from two different species. In the sowing experiment, we tested two different seed provenances (drier and more humid spanish regions) for each species. In all, 60 plots (30 burned, 30 unburned) per site, with 10 seeding units per plot and more than 20,000 seeds, were used in the whole study. Seedling predation was evaluated by replicating the seeding units inside and outside a wire cage as protection for rodents and birds. Our results showed that prescribed fires alter initial seedling predation intensity: predation was significantly higher in the seedlings grown in the plots affected by prescribed fire. The individuals sown before the fire passed showed slightly more predation than those sown after fire passage. Provenances did not appear as an important predation drive. Understanding the role of the predation associated with these treatments can help improve Mediterranean pine forest management.
Books on the topic "Seedling recruitment"
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Landhäusser, Simon M. Rhizome recruitment of Calamagrostis canadensis into mounds created for tree seedling establishment: Final report 1997. Alberta Environmental Protection, 1997.
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Szewczyk, Janusz. Rola zaburzeń w kształtowaniu struktury i dynamiki naturalnych lasów bukowo-jodłowo-świerkowych w Karpatach Zachodnich. Publishing House of the University of Agriculture in Krakow, 2018. http://dx.doi.org/10.15576/978-83-66602-35-9.
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The aim of the study was to determine the influence of different disturbances (both natural and anthropogenic) on species composition and stand structure of old-growth mixed mountain forests in the Western Carpathians. These stands are usually dominated by beech, fir and spruce, mixed in different proportions. The tree main species represent different growth strategies, and they compete against each other. The longevity of trees makes the factors influencing the stand structure difficult to identify, even during longitudinal studies conducted on permanent research plots. That is why dendroecological techniques, based upon the annual variability of tree rings, are commonly used to analyze the disturbance histories of old-growth stands. Dendroecological methods make it possible to reconstruct the stand history over several centuries in the past by analyzing the frequency, intensity, duration and spatial scale of disturbances causing the death of trees. Combining the dendroecological techniques with the detailed measurements of stand structure, snag volume, CWD volume, and the analyses of regeneration species composition and structure allows us to identify the factors responsible for the changes in dynamics of mixed mountain forests. Various disturbance agents affect some species selectively, while some disturbances promote the establishment of tree seedlings of specific species by modifying environmental conditions. Describing the disturbance regime requires a broad scope of data on stand structure, on dead wood and tree regeneration, while various factors affecting all the stages of tree growth should be taken into consideration. On the basis of the already published data from permanent sample plots, combined with the available disturbance history analyses from the Western Carpathians, three research hypotheses were formulated. 1. The species composition of mixed mountain forests has been changing for at least several decades. These directional changes are the consequence of simultaneous conifer species decline and expansion of beech. 2. The observed changes in species composition of mixed mountain forests are the effect of indirect anthropogenic influences, significantly changing tree growth conditions also in the forests that are usually considered natural or near-natural. Cumulative impact of these indirect influences leads to the decrease of fir share in the tree layer (spruce decline has also been observed recently),and it limits the representation of this species among seedlings and saplings. The final effect is the decrease of fir and spruce share in the forest stands. 3. Small disturbances, killing single trees or small groups of trees, and infrequent disturbances of medium size and intensity dominate the disturbance regime in mixed mountain forests. The present structure of beech-fir-spruce forests is shaped both by complex disturbance regime and indirect anthropogenic influences. The data were gathered in permanent sample plots in strictly protected areas of Babia Góra, Gorce, and Tatra National Parks, situated in the Western Carpathians. All plots were located in the old-growth forest stands representing Carpathian beech forest community. The results of the measurements of trees, snags, coarse woody debris (CWD) and tree regeneration were used for detailed description of changes in the species composition and structure of tree stands. Tree ring widths derived from increment cores were used to reconstruct the historical changes in tree growth trends of all main tree species, as well as the stand disturbance history within the past two to three hundred years. The analyses revealed complex disturbance history in all of the three forest stands. Intermediate disturbances of variable intensity occurred, frequently separated by the periods of low tree mortality lasting from several decades up to over one hundred years. The intervals between the disturbances were significantly shorter than the expected length of forest developmental cycle, in commonly used theories describing the dynamics of old-growth stands. During intermediate disturbances up to several dozen percent of canopy trees were killed. There were no signs of stand-replacing disturbances, killing all or nearly all of canopy trees. The periods of intense tree mortality were followed by subsequent periods of increased sapling recruitment. Variability in disturbance intensity is one of the mechanisms promoting the coexistence of beech and conifer species in mixed forests. The recruitment of conifer saplings depended on the presence of larger gaps, resulting from intermediate disturbances, while beech was more successful in the periods of low mortality. However, in the last few decades, beech seems to benefit from the period of intense fir mortality. This change results from the influence of long-term anthropogenic disturbances, affecting natural mechanisms that maintain the coexistence of different tree species and change natural disturbance regimes. Indirect anthropogenic influence on tree growth was clearly visible in the gradual decrease of fir increments in the twentieth century, resulting from the high level of air pollution in Europe. Synchronous decreases of fir tree rings’ widths were observed in all three of the sample plots, but the final outcomes depended on the fir age. In most cases, the damage to the foliage limited the competitive abilities of fir, but it did not cause a widespread increase in tree mortality, except for the oldest firs in the BGNP (Babia Góra National Park) plot. BGNP is located in the proximity of industrial agglomeration of Upper Silesia, and it could be exposed to higher level of air pollution than the other two plots. High level of fir regeneration browsing due to the deer overabundance and insufficient number of predators is the second clear indication of the indirect anthropogenic influence on mixed mountain forests. Game impact on fir regeneration is the most pronounced in Babia Góra forests, where fir was almost completely eliminated from the saplings. Deer browsing seems to be the main factor responsible for limiting the number of fir saplings and young fir trees, while the representation of fir among seedlings is high. The experiments conducted in fenced plots located in the mixed forests in BGNP proved that fir and sycamore were the most preferred by deer species among seedlings and saplings. In GNP (Gorce National Park) and TNP (Tatra National Park), the changes in species composition of tree regeneration are similar, but single firs or even small groups of firs are present among saplings. It seems that all of the analysed mixed beech-fir-spruce forests undergo directional changes, causing a systematic decrease in fir representation, and the expansion of beech. This tendency results from the indirect anthropogenic impact, past and present. Fir regeneration decline, alongside with the high level of spruce trees’ mortality in recent years, may lead to a significant decrease in conifers representation in the near future, and to the expansion of beech forests at the cost of mixed ones.
Book chapters on the topic "Seedling recruitment"
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Retana, Javier, Josep Maria Espelta, Marc Gracia, and Miquel Riba. "Seedling Recruitment." In Ecological Studies. Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58618-7_7.
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Shivanna, K. R., and Rajesh Tandon. "Seedling Recruitment." In Reproductive Ecology of Flowering Plants: A Manual. Springer India, 2014. http://dx.doi.org/10.1007/978-81-322-2003-9_12.
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Yi, X. F., and Y. Q. Yang. "Large acorns benefit seedling recruitment by satiating weevil larvae in Quercus aliena." In Plant Ecology in China. Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-9993-8_10.
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Milton, Suzanne J., and Thorsten Wiegand. "How Grazing Turns Rare Seedling Recruitment Events to Non-Events in Arid Environments." In Sustainable Land Use in Deserts. Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59560-8_20.
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Weltzin, Jake F., and Philip B. Allen. "Tree Seedling Recruitment in a Temperate Deciduous Forest: Interactive Effects of Soil Moisture, Light, and Slope Position." In Ecological Studies. Springer New York, 2003. http://dx.doi.org/10.1007/978-1-4613-0021-2_13.
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Comita, Liza, Ryan P. Dougherty, Salomon Aguilar, and Rolando Pérez. "Long-Term Census of Seedlings and Small Saplings in the Barro Colorado Island 50-ha Forest Dynamics Plot, Panama." In The First 100 Years of Research on Barro Colorado: Plant and Ecosystem Science. Smithsonian Institution Scholarly Press, 2024. https://doi.org/10.5479/si.26880712.
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Dynamics at early life stages play a critical role in shaping the composition and diversity of tropical tree communities. To better understand spatial and temporal patterns of recruitment, growth, and survival at early life stages, we established a long-term census of woody seedlings and small saplings in the Barro Colorado Island 50-ha Forest Dynamics Plot. Individuals ≥20 cm tall and <1cm diameter at breast height (dbh) were censused in 18,434 1-m 2 seedling plots every one to two years between 2001 and 2018, resulting in a dataset of 1,002,400 observations of 185,693 individuals of more than 400 tree, shrub, and liana species. Here, we present patterns of seedling density and diversity from this long-term census and review the main findings of published studies that have used this dataset.<p></p>
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Dekker, Jack. "Seed Dormancy, Germination, and Seedling Recruitment in Weedy Setaria." In Books in Soils, Plants, and the Environment. CRC Press, 2014. http://dx.doi.org/10.1201/b16675-4.
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"Seed Dormancy, Germination, and Seedling Recruitment in Weedy Setaria." In Handbook of Plant and Crop Physiology. CRC Press, 2014. http://dx.doi.org/10.1201/b16675-7.
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Wright, Joseph, Osvaldo Calderón, Andrés Hernández, and Helene Muller-Landau. "Flower and Seed Production, Seedling Dynamics, and Tree Life Cycles." In The First 100 Years of Research on Barro Colorado: Plant and Ecosystem Science. Smithsonian Institution Scholarly Press, 2024. https://doi.org/10.5479/si.26882626.
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We present highlights derived from 36 years of weekly observations of flower and seed production and 25 years of annual observations of seedling dynamics at Barro Colorado Island (BCI), Panama. Highlights concern levels and causes of spatial, temporal, and interspecific variation in flower production, seed production, seed dispersal, and seedling recruitment, growth, and survival as well as the consequences for plant regeneration and diversity. Full tree life cycles are assembled by combining seed production, seedling dynamics, and observations of larger plants from the 50-ha Forest Dynamics Plot and are used to evaluate the costs of dioecy, lifetime insights from functional traits, and interspecific variation in the impact of lianas among host tree species. A variety of results demonstrate the importance of long-term observations to understand forest dynamics and responses to rising atmospheric carbon dioxide concentrations and a changing climate.<p></p>
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Laughlin, Daniel C. "Plant Traits That Bolster Recruitment." In Plant Strategies. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780192867940.003.0012.
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Abstract Modeling plant recruitment is hard. Recruitment is often the weakest link in plant population models. If we can successfully integrate traits into our understanding of plant fecundity, then we can fill a critical gap in plant strategy theory. Traits of juveniles and traits of mature plants are decoupled. Seed mass can vary by 10 orders of magnitude globally. There is empirical support that large-seeded species performed better under grazing pressure, in nutrient-poor soils, and when planted deep in the soil or under litter. Some studies also found that large-seeded species perform better when growing in established vegetation, in deep shade, or in dry environments. A trait-filter framework was proposed for identifying traits that are important at each stage of the recruitment process, including seed production, dispersal, germination, emergence, seedling establishment, and clonality. Dormancy drives variable recruitment through time and dispersal drives variable recruitment through space. If we continue to focus most of our research effort into understanding the traits that govern growth and survival at the expense of recruitment, we are missing half of the story. We need to get the fecundity function right.
Conference papers on the topic "Seedling recruitment"
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BENJANKAR, ROHAN, ANDREW W. TRANMER, and DANIELE TONINA. "IMPACTS OF FLOWS ON RIPARIAN COTTONWOOD AND WILLOW SEEDLING RECRUITMENT IN THE SOUTH FORK BOISE RIVER, USA." In 38th IAHR World Congress. The International Association for Hydro-Environment Engineering and Research (IAHR), 2019. http://dx.doi.org/10.3850/38wc092019-1690.
Full textReports on the topic "Seedling recruitment"
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Livensperger, Carolyn, Rebecca Weissinger, Luke Gommermann, and Alice Wondrak Biel. Riparian monitoring of wadeable streams on the Fremont River, Capitol Reef National Park, 2009?2021. National Park Service, 2023. http://dx.doi.org/10.36967/2301391.
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The goal of Northern Colorado Plateau Network (NCPN) riparian monitoring is to deter-mine long-term trends in hydrologic, geomorphic, and vegetative properties of wadeable streams in the context of changes in other ecological drivers, stressors, and processes. This information is intended to provide early warning of resource degradation and determine natural variability of wadeable streams. This report summarizes NCPN monitoring of the Fremont River in Capitol Reef National Park (NP) from water years 2009 to 2021. The focus of this report is to (1) examine patterns in water availability at one monitoring reach from 2010 to 2021, and (2) present geomorphology and vegetation data from four reaches monitored from 2009 to 2021. Vegetation sampling and geomorphology surveys were completed at varying intervals throughout the time period; this report looks at changes within single reaches and establishes a baseline for future comparisons. There are four monitoring reaches established on the Fremont River: (1) F-01, approximately 2.5 kilometers upstream of a knickpoint (sharp change in channel slope) and associated waterfall that emerged following construction of State Highway 24 in 1964, (2) F-07, in a large oxbow that was cut off due to the highway construction, (3) F-04, approximately 1.5 kilometers downstream of the knickpoint, and (4) F-14, approximately 4.8 kilometers downstream of the knickpoint. Geomorphic and vegetation surveys took place at all reaches. Hydrologic monitoring occurred only at F-01. From 2001 to 2021, the entire range of flows recorded at a gaging station on the Fremont River upstream of the park near Bicknell, Utah, decreased, with the steepest decreases occurring in the highest flow percentiles. Continuous hydrologic monitoring at reach F-01 in the park from 2010 to 2021 showed perennial flows in the Fremont River, with lower flows during the irrigation season (April 1?October 31). The irrigation season was also characterized by greater evapotranspiration, which may be exacerbated in the future due to higher air temperatures. Lower observed inputs and greater evapotranspiration suggest the Fremont River is at risk for progressively lower flows over time. While overbank flows occurred infrequently in the monitoring reach, inhibiting cottonwood recruitment, groundwater levels remained shallow enough to support mature cottonwood trees. Protecting spring snowmelt flows of 94 cfs (the average annual maximum 14-day rolling mean at reach F-01), or greater should maintain the current wetland vegetated zone. Maintaining the hydrologic record was challenging due to high-magnitude flood events and turbid flows; the park should consider a gaging station for an accurate discharge record. Geomorphic surveys showed net sediment deposition at reaches F-01 and F-14 in the channels, banks, and floodplains from 2009 to 2021, with more deposition occurring earlier in the study period. A large flood event in 2013 resulted in high flows and deposition of close to one meter at F-01. Only localized erosion occurred, and thalweg surveys showed that stream channels were either stable or increasing in elevation. Reach F-07, the abandoned oxbow, exhibited little geomorphic change over the study period. Riparian vegetation was characteristic of a Fremont cottonwood woodland, with canopy closure up to 30% and a mixed understory of shrubs and herbaceous species. Obligate wetland vegetation cover of 5%?10% was present at reaches F-01, F-04, and F-14. Reach F-07, in the oxbow, has transitioned to an upland system, with little to no canopy cover and no obligate wetland species. While mature cottonwoods were present in reaches F-01, F-04, and F-14, there was limited evidence of seedlings or saplings graduating into larger size classes. Cottonwood seedlings are primarily resprouts from beaver-browsed trees, although one seedling recruitment event was observed in 2014, following high flows in late 2013. Protecting some cottonwoods with chicken wire may help protect the larger size classes and maintain a mixed-age woodland. Exotic plant species cover was less than 10% in reaches F-01, F-04, and F-14. Efforts to control Russian olive (Eleagnus angustifolia) along the Fremont River appear to have been successful in these reaches. In reach F-07, exotic plant cover ranged from 9% to 25%, with notable spikes in Russian thistle (Salsola tragus) and cheatgrass (Bromus tectorum) in 2010 and 2011, respectively.
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Zimmerman, Ephraim, and Staphanie Perles. Vegetation monitoring in relation to white-tailed deer browsing in First State National Historical Park: 2021 summary report. National Park Service, 2023. http://dx.doi.org/10.36967/2299655.
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Baseline information on canopy regeneration and plant community composition is needed in order to better understand white-tailed deer browsing impacts at First State National Historical Park (FRST). In 2021, the Pennsylvania Natural Heritage Program (PNHP) established 20 permanent vegetation monitoring plots following methods developed by the NPS Eastern Rivers and Mountains Network (ERMN) to assess and monitor trends in vegetation (Perles et al. 2014b; Perles et al. 2017). These protocols provided an efficient method of assessing the current status of native and non-native vegetation and deer browsing impact. This report documents the methodology used to quantify the vegetative composition of natural areas at FRST and provides a summary of the data collected in the first year of monitoring. This first year’s activities (2021) included the initial baseline vegetation assessment and summary of results from the baseline data analysis. A variety of metrics used to assess the impact of deer browsing on the vegetation were calculated and are presented. A second survey is proposed for 2024. PNHP used the NPS ERMN database and analysis methods (Perles et al. 2014b) to summarize the condition in year 1 (2021). In year 4 (2024), PNHP will investigate changes in the condition of browse-sensitive understory plants and tree seedlings. Plots occurred in a variety of settings, ranging from younger successional communities to more mature forest stands. Seventy-five percent (75%) of the plots occurred in Mature or Late Successional forests. Disturbances and stressors, such as deer browsing can strongly influence future forest structure as open woodlands mature. A large population of white-tailed deer may severely impact succession from the open woodlands towards closed canopy forest. In closed canopy, later successional forests, a large deer population may inhibit canopy tree recruitment leading to regeneration failure. Given that FRST managers desire to maintain the landscape as forest, it is important to maintain an adequate number of seedlings and saplings of tree species to ensure the persistence of canopy of native tree species as Mature and Late Successional Forests continue to age. The 20 permanent sampling plots occurred within 5 plant communities described by Ebert (2016) and were classified using agglomerative hierarchical clustering (HAC analysis) and indicator species analysis. The most common plant communities within the group of sampling plots were the Mixed oak – beech forest and Mesic mixed tulip – oak-hickory-beech forest. The remaining plots were found in successional Tuliptree woodland, Successional woodland, and Thicket types. All plots were assigned to these types described in Ebert (2016) and crosswalked to the National Vegetation Classification (USNVC). A total of 128 plant species were recorded from the 20 plots at FRST. Eighteen (18) species were found in over ½ of the plots surveyed, of which eight (8) were non-native. In all, 29 plants occurring in the plots (23% of total species richness) were considered introduced (non-native). Non-native plant cover ranged from 0–98% as measured in the monitoring plot quadrats. Indicators of deer browsing varied by plant community type at FRST. In general, the drier Mixed oak – beech forests showed substantially greater impact of deer browsing and fewer seedlings of canopy species in the understory. FRST monitoring protocols focus on a few plant species considered as preferred food for white-tailed deer. Sustained browsing may be affecting long-term viability of these species within the parks. Based on the status of these regeneration metrics in FRST, we suggest that the forest in FRST are in imminent regeneration failure. We define imminent failure as parks that are experiencing severe regeneration failure and are at risk of forest loss due to very low seedling and sapling abundance, as well as species mismatches between canopy and regeneration layers. Given the poor regeneration of canopy species across all community types at FRST, managers should seek opportunities to conduct adaptive management in the park’s forests, especially mixed oak – beech forest, to experiment with and monitor the effects of fire, browse exclosures, and canopy thinning to encourage native canopy tree regeneration.
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Whelan, Kevin, and Wendy Wright. Protocol implementation plan for monitoring mangrove soil surface elevation tables in South Florida / Caribbean Network parks. National Park Service, 2016. https://doi.org/10.36967/2230638.
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The mangrove forest ecosystem is a critical coastal resource in South Florida’s Biscayne National Park (BISC); Salt River Bay National Historical Site and Ecological Preserve (SARI) in St. Croix, U.S. Virgin Islands; and the Virgin Islands National Park (VIIS) in St John, U.S. Virgin Islands. Mangrove wetlands provide flood control, storm protection, shore stabilization, water filtration (capturing soil runoff), carbon sequestration, and habitat for fish and wildlife communities. The economic value of the services derived from mangroves has been estimated as high as $200,000–$900,000 ha-1 (United States Dollar [USD]) (Wells et al. 2006, Gilman et al. 2009). There is a feedback loop between soil elevation, hydrology, and mangrove forest health. The soil elevation level in mangrove forests affects tidal inundation period, tidal inundation frequency, and overall hydroperiod, all of which affect mangrove seedling species recruitment, composition, and survival (Whelan 2009). Additionally, mangrove forest hydrology affects soil processes such as sedimentation, erosion, and the shrink and swell of soil materials. Due to the importance of soil elevation to mangroves, it is critical to understand the rate of change in soil elevation to better predict the long-term ability of mangrove forests to regenerate. Therefore, the National Park Service (NPS) South Florida / Caribbean (SFCN) Inventory and Monitoring (I&M) Network is establishing a long-term soil surface elevation monitoring program in Biscayne, Salt River Bay, and Virgin Islands national parks as part of the Coastal Geomorphology Vital Sign, as part of the vital signs monitoring program. The program aims to monitor rates of soil accretion and erosion, and determine if soil processes are keeping pace with relative sea level (RSL) which has been measured at 1.1–1.9 mm yr-1 in South Florida (Maul and Martin 1993). If the RSL rate is greater than the rate at which mangrove soil elevation increases then the current mangrove forest will transgress upslope and the current areas occupied by mangrove forest will eventually convert to shallow open-water marine habitats as the trees die off and there is no recruitment to replace them. For resource managers, it will be important to understand how this process is affecting mangrove forest in their park units. Local long-term monitoring is necessary to develop this understanding. This plan outlines the means by which monitoring data will be collected, managed, and reported for the monitoring of Mangrove Soil Surface Elevation Tables in SFCN parks and park units, as described in the approved SFCN monitoring plan (Patterson et al. 2008). The South Florida / Caribbean Network is implementing the Southeast Coast Network’s (SECN) peer-reviewed and approved Protocol for Monitoring Coastal Salt Marsh Elevation and Vegetation Communities in Southeast Coast Network Parks (DeVivo et al. 2015) as it relates to soil elevation monitoring. The South Florida / Caribbean Network did not implement the soil salinity component or the marsh vegetation sampling. The modifications made to the sampling process are minor but reflect necessary changes to implement the SECN sampling protocol in the park units of our network. We deviated from the SECN peer-reviewed protocol for a few of the standard operating procedures (SOPs). For example, we drew from the Northeast Coastal and Barrier Network protocol Measuring and Understanding Wetland Elevation Change using the Surface Elevation Table (SET) and Marker Horizon Techniques (Lynch et al. 2015) because we are using their SET Microsoft® Access relational database.
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Mendelsohn, Mark, John Tiszler, and Tarja Sagar. Vegetation monitoring in the Santa Monica Mountains and Simi Hills region: 2014?2020 annual report. National Park Service, 2023. http://dx.doi.org/10.36967/2300992.
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Our Inventory & Monitoring team surveyed over 200 Terrestrial Native Vegetation Monitoring Plots in the Santa Monica Mountains and Simi Hills (SAMO) Region over the first seven years of this program?s history, 2014?2020. During this period, the park experienced a large wildfire in 2013 followed by historic drought, and then in 2018 the largest wildfire in the region?s recorded history, succeeded by well-timed rainfall. The goal of this monitoring program is to detect and understand the nature of vegetation change, for example in drought or post-fire environments, providing a knowledge base for developing effective management strategies. Our metrics include vegetation cover, species richness, shrub/tree abundance, survival, and recruitment. In general, SAMO experienced widescale native shrub dieback during the extended drought. Dry shrublands that subsequently burned to the ground in 2018 converted into a rich and widespread green-up with the substantial rains received in 2019, producing a very diverse assemblage of wildflowers (including many fire followers not seen in many years) and a strong recruitment of our native shrubs via resprouting and seedlings into 2020 across most of the park?s more pristine areas. We documented post-fire expansions in several populations of the federally endangered Braunton?s milkvetch. Non-native herbaceous species such as mustards dominated previously disturbed lands and expanded their coverage following the 2018 wildfire. The data we collected will be available for advancing the science of fire ecology, and informing future park management and interpretation programs.
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Leis, Sherry. Vegetation community monitoring at Lincoln Boyhood National Memorial: 2011–2019. National Park Service, 2021. http://dx.doi.org/10.36967/nrr-2284711.
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Lincoln Boyhood National Memorial celebrates the lives of the Lincoln family including the final resting place of Abraham’s mother, Nancy Hanks Lincoln. Lincoln’s childhood in Indiana was a formative time in the life our 16th president. When the Lincoln family arrived in Indiana, the property was covered in the oak-hickory forest type. They cleared land to create their homestead and farm. Later, designers of the memorial felt that it was important to restore woodlands to the site. The woodlands would help visitors visualize the challenges the Lincoln family faced in establishing and maintaining their homestead. Some stands of woodland may have remained, but significant restoration efforts included extensive tree planting. The Heartland Inventory and Monitoring Network began monitoring the woodland in 2011 with repeat visits every four years. These monitoring efforts provide a window into the composition and structure of the wood-lands. We measure both overstory trees and the ground flora within four permanently located plots. At these permanent plots, we record each species, foliar cover estimates of ground flora, diameter at breast height of midstory and overstory trees, and tree regeneration frequency (tree seedlings and saplings). The forest species composition was relatively consistent over the three monitoring events. Climatic conditions measured by the Palmer Drought Severity Index indicated mild to wet conditions over the monitoring record. Canopy closure continued to indicate a forest structure with a closed canopy. Large trees (>45 cm DBH) comprised the greatest amount of tree basal area. Sugar maple was observed to have the greatest basal area and density of the 23 tree species observed. The oaks characteristic of the early woodlands were present, but less dominant. Although one hickory species was present, it was in very low abundance. Of the 17 tree species recorded in the regeneration layer, three species were most abundant through time: sugar maple (Acer saccharum), red bud (Cercis canadensis), and ash (Fraxinus sp.). Ash recruitment seemed to increase over prior years and maple saplings transitioned to larger size classes. Ground flora diversity was similar through time, but alpha and gamma diversity were slightly greater in 2019. Percent cover by plant guild varied through time with native woody plants and forbs having the greatest abundance. Nonnative plants were also an important part of the ground flora composition. Common periwinkle (Vinca minor) and Japanese honeysuckle (Lonicera japonica) continued to be the most abundant nonnative species, but these two species were less abundant in 2019 than 2011. Unvegetated ground cover was high (mean = 95%) and increased by 17% since 2011. Bare ground increased from less than 1% in 2011 to 9% in 2019, but other ground cover elements were similar to prior years. In 2019, we quantified observer error by double sampling two plots within three of the monitoring sites. We found total pseudoturnover to be about 29% (i.e., 29% of the species records differed between observers due to observer error). This 29% pseudoturnover rate was almost 50% greater than our goal of 20% pseudoturnover. The majority of the error was attributed to observers overlooking species. Plot frame relocation error likely contributed as well but we were unable to separate it from overlooking error with our design.