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Microsite disturbances – including mounds created by burrowing mammals – increase local plant community diversity by supporting unique species assemblages. I investigated whether Richardson’s ground squirrel (Urocitellus richardsonii) mounds support unique plant assemblages within five Manitoba prairie pastures, and explored the factors contributing to the plant assemblages documented. Richardson’s ground squirrel mounds supported unique species assemblages relative to bare-ground disturbances with removal of vegetation but no soil disturbance. These detectable shifts in plant community structure on mounds appear to be attributable to mound-specific environmental conditions responsible for delaying vegetative recolonization and facilitating establishment of early-succession species. In contrast, seed bank distribution did not appear to influence species assemblages on mounds. Further investigation into site-specific changes in species distribution on Richardson’s ground squirrel mounds is needed to appreciate the role of these burrowing mammals in pastureland communities. / February 2017

Book Summary:Issues: Understanding Controversy and Society brings important issues in today's world to students' attention, highlighting the complete historical background, contemporary status, and global view of each. It provides students authoritative context, diverse expert perspectives, and carefully selected primary and secondary sources for truly understanding the issues that currently affect much of our global society, and for developing informed positions on those engendering controversy.

Book Summary: The business of food and drink is for better and worse the business of our nation and our planet, and to most consumers how it works remains largely a mystery. This encyclopedia takes readers as consumers behind the scenes of the food and drink industries. The contributors come from a wide range of fields, and the scope of this encyclopedia is broad, covering from food companies and brands to the environment, health, science and technology, culture, finance, and more. The more than 150 essay entries also cover those issues that have been and continue to be of perennial importance. Historical context is emphasized and the focus is mainly on business in the United States. Most entries include Further Reading. The frontmatter includes an Alphabetical List of Entries and a Topical List of Entries to allow the reader to quickly find subjects of interest. Numerous cross-references in the entries and blind entries provide other search strategies. The person and subject index is another in-depth search tool.

Exclosure plots were monitored to investigate the impact of browsing on seedling recruitment by Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus on seedlings under Leptospermum scoparium and Kunzea ericoides plantings in two Auckland Regional Council Parks (ARC), Shakespear and Wenderholm. The number of woody seedlings that established over a 17-month period was recorded. Gaps within the same Leptospermum scoparium and Kunzea ericoides canopy were created to investigate the influence of the canopy on seedling recruitment. Soil samples were taken to investigate the existing seed bank beneath the same Leptospermum scoparium and Kunzea ericoides canopies.At Wenderholm, net change in seedling density differed among treatments (P=0.014). Seedling density increased within the plots that excluded Trichosurus vulpecula and Oryctolagus cuniculus and within plots that additionally excluded Rattus rattus, but declined in the control plots. In contrast at Shakespear, although seedling density increased more within both the exclosure plots than in the control plots, this result was not statistically significant (P=0.728). At Wenderholm, the average seedling height increased within both types of exclosure plots, but declined in the control plots. However, these differences among treatments were not statistically significant (P=0.204). At Shakespear, seedlings increased in height within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures and declined marginally in the other two treatments. Again, differences in height change among treatments were not statistically significant (P=0.202).At both regional parks, the greatest cause of mortality within the exclosures excluding Trichosurus vulpecula and Oryctolagus cuniculus was desiccation. All of the mortalities within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures was unidentifiable. However, within the control plots, at Wenderholm, the greatest identified cause of mortality was browsing and at Shakespear, the only cause of mortality within the control plots was browsing.Seedbanks at Wenderholm and Shakespear under the Leptospermum scoparium and Kunzea ericoides plantings were dominated by forb species. A total of 1308 seedlings germinated from soil taken from Wenderholm, with exotic species making up 99.4% of germinations, with exotic species making up 97.9% of germinations. Similarly a total of 801 seedlings germinated from soil samples taken from Shakespear.At Wenderholm, the number of native seedling germinations within the gaps created in the Leptospermum scoparium and Kunzea ericoides canopy, was more than twice the number that germinated under the closed canopy. However, this difference was marginally non-significant (P=0.065). At Shakespear, the number of native seedling germinations within gaps created in the Leptospermum scoparium and Kunzea ericoides canopy was similar to the number that germinated under the closed canopy (P=0.2603).The results suggest that at Wenderholm, despite ongoing predator control, Trichosurus vulpecula and/or Oryctolagus cuniculus have had an adverse effect on the survival and growth of seedlings. The results also suggest that at Shakespear, Rattus rattus have had an adverse effect on the survival and growth of seedlings under the Leptospermum scoparium and Kunzea ericoides canopy. The distance from mature forest may also have had an impact on the dispersal of native seeds within the Leptospermum scoparium and Kunzea ericoides canopy. The implication of these results for the future management of restoration plantings in regional parks is discussed.

Exclosure plots were monitored to investigate the impact of browsing on seedling recruitment by Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus on seedlings under Leptospermum scoparium and Kunzea ericoides plantings in two Auckland Regional Council Parks (ARC), Shakespear and Wenderholm. The number of woody seedlings that established over a 17-month period was recorded. Gaps within the same Leptospermum scoparium and Kunzea ericoides canopy were created to investigate the influence of the canopy on seedling recruitment. Soil samples were taken to investigate the existing seed bank beneath the same Leptospermum scoparium and Kunzea ericoides canopies.At Wenderholm, net change in seedling density differed among treatments (P=0.014). Seedling density increased within the plots that excluded Trichosurus vulpecula and Oryctolagus cuniculus and within plots that additionally excluded Rattus rattus, but declined in the control plots. In contrast at Shakespear, although seedling density increased more within both the exclosure plots than in the control plots, this result was not statistically significant (P=0.728). At Wenderholm, the average seedling height increased within both types of exclosure plots, but declined in the control plots. However, these differences among treatments were not statistically significant (P=0.204). At Shakespear, seedlings increased in height within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures and declined marginally in the other two treatments. Again, differences in height change among treatments were not statistically significant (P=0.202).At both regional parks, the greatest cause of mortality within the exclosures excluding Trichosurus vulpecula and Oryctolagus cuniculus was desiccation. All of the mortalities within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures was unidentifiable. However, within the control plots, at Wenderholm, the greatest identified cause of mortality was browsing and at Shakespear, the only cause of mortality within the control plots was browsing.Seedbanks at Wenderholm and Shakespear under the Leptospermum scoparium and Kunzea ericoides plantings were dominated by forb species. A total of 1308 seedlings germinated from soil taken from Wenderholm, with exotic species making up 99.4% of germinations, with exotic species making up 97.9% of germinations. Similarly a total of 801 seedlings germinated from soil samples taken from Shakespear.At Wenderholm, the number of native seedling germinations within the gaps created in the Leptospermum scoparium and Kunzea ericoides canopy, was more than twice the number that germinated under the closed canopy. However, this difference was marginally non-significant (P=0.065). At Shakespear, the number of native seedling germinations within gaps created in the Leptospermum scoparium and Kunzea ericoides canopy was similar to the number that germinated under the closed canopy (P=0.2603).The results suggest that at Wenderholm, despite ongoing predator control, Trichosurus vulpecula and/or Oryctolagus cuniculus have had an adverse effect on the survival and growth of seedlings. The results also suggest that at Shakespear, Rattus rattus have had an adverse effect on the survival and growth of seedlings under the Leptospermum scoparium and Kunzea ericoides canopy. The distance from mature forest may also have had an impact on the dispersal of native seeds within the Leptospermum scoparium and Kunzea ericoides canopy. The implication of these results for the future management of restoration plantings in regional parks is discussed.

Made available in DSpace on 2014-06-11T19:32:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-09Bitstream added on 2014-06-13T19:22:48Z : No. of bitstreams: 1 klein_dk_dr_botib.pdf: 427517 bytes, checksum: 69b36be9a11ed0b66d6a420111b90ee9 (MD5) / Para um melhor entendimento dos processos que determinam a dinâmica das florestas tropicais, estudos que investigam tanto a vegetação (parte aérea) como o banco de sementes do solo, são necessários. Através de estudos de banco de semente pode-se avaliar, por exemplo, a capacidade de regeneração natural de uma dada vegetação, a viabilidade das sementes existentes no solo e sua influência na estrutura da vegetação. No entanto, pouco se sabe sobre os processos que podem provocar variações na estrutura do banco de sementes, especialmente em florestas semideciduais. O presente estudo teve como objetivo conhecer a composição do banco de sementes do solo em um trecho de Floresta Estacional Semidecídual, bem como investigar possíveis processos capazes de gerar variações em sua estrutura. Além disso, determinou-se o grau de similaridade entre a parte aérea e o banco de sementes. Primeiramente, a densidade (número de plântulas), a riqueza, a diversidade e a composição de espécies foram comparadas entre áreas em diferentes estágios sucessionais, bem como entre diferentes profundidades do solo e estações do ano (chuvosa e seca). Em seguida, a similaridade entre o banco de sementes e a vegetação local foi comparada. Constatou-se que a principal fonte de variação do número de plântulas, da riqueza e da diversidade de espécies presentes no banco de sementes foi a profundidade na qual as sementes foram amostradas. De forma geral, as amostras obtidas da serrapilheira continham, significativamente, um maior número de plântulas, uma maior riqueza e maior diversidade de espécies do que as amostras provenientes das profundidades de 0-10cm e 10-20cm, tanto na estação chuvosa como seca. Comparações da riqueza e da diversidade de espécies entre a estação seca e chuvosa... / For a better understanding of the processes that determine tropical forest dynamics, studies that investigate vegetation both above and below ground are needed. By studying seed banks it is possible to determine, for example, the natural regeneration capacity of vegetation, the viability of the soil seed bank as well as its influence at structuring plant communities. However, little is known about the processes that can generate variation in the seed bank structure, particularly in semideciduous forests. The main aim of this study was to know the soil seed bank composition in a semideciduous seasonal forest fragment, and also to investigate some processes that may generate variations in this structure. Besides, it was determined below (seed bank) and above ground (vegetation) similarity. Firstly, the density (seedling numbers), the richness, and the diversity and species composition were compared among areas of different sucessional stages, and among different soil depths and season (rainy and dry season). After that, the similarity between the soil seed bank and local vegetation was compared. It was observed that the main source of variation of seedling numbers, richness, and species diversity was the depth at which seed samples were obtained. In overall, samples from the litterfall had significantly higher seedling numbers, species richness and diversity than the other depths (0-10cm and 10-20cm); this difference occurred at both in the rainy and dry season. Comparisons of species richness and diversity between the rainy and dry season showed that both significantly differed between seasons, and higher values were observed in the rainy season. Seedling numbers did not differ between seasons. Species composition was more similar between pairs of samples from depths near to each other; for example, for both seasons... (Complete abstract click electronic access below)

The type of regional dynamics of a species can provide information on how to manage the species, and may be the only way that some rare species may persist in a given region. A metapopulation is a type of regional dynamic in which local extinction is counterbalanced by recruitment from nearby patches. Metapopulation studies were originally conducted on animals, but have been adapted to plants, and are generally restricted to single-season studies. Plant species may persist as a metapopulation in patchy habitats, such as in forest openings. Forest openings (commonly called barrens, hill prairies, or glades) are habitats found on ridgetops which are characterized by having thin or nutrient-poor soil, high sunlight exposure, and relatively low soil moisture when compared to nearby forest habitats. Forest openings commonly contain plant species more frequently found in prairies, and are often maintained by natural fires that prevents woody species encroachment. In the absence of natural fires due to human management and suppression, woody species have invaded some forest openings, dividing them into a series of patches. To determine whether it is possible for each species to persist as a metapopulation in forest openings, five studies were carried out at each of three sites within the Shawnee National Forest in southern Illinois: a plant survey and ordination using environmental variables, the use of incidence function models to determine which of the species had the potential to form a metapopulation, a metacommunity study to examine overall patterns at each site, a seed bank study, and a seed dispersal study. Forest openings were found to be separate habitats from the surrounding forest based upon canopy openness. Approximately 30% of the species fit the metapopulation model, and the metacommunities at each of the sites exhibited a Clementsian pattern, characterized by groups of co-occurring species that replace each other over the region due to turnover between the groups of species. Species that fit the metapopulation model tended to have seeds that emerge more frequently from the seed bank if annuals and less frequently in the seed bank than species not fitting the metapopulation model (non-metapopulation species) if longer-lived. Species fitting the metapopulation model dispersed equal numbers of seeds as non-metapopulation species at short (5m) and medium (10m) distances, and in some cases dispersed more seeds to longer distances than non-metapopulation species. These studies show that forest openings can be treated as islands of suitable habitat for some species, and that numerous (~30%) species (such as Scleria pauciflora, Stylosanthes biflora, and Manfreda virginica) may assume a metapopulation dynamic in any given year. Many species may have incidence patterns consistent with those of a metapopulation in multiple years; however, the exact habitat patches in which species occur in any given year may change from year to year. Species in forest openings tend to co-occur in groups (a Clementsian pattern), which means that management plans should consider the entire community rather than a single species.

Accelerated sea-level rise and increased intensity of tropical storm events have challenged the conventional approaches to conservation and restoration of coastal ecosystems. In coastal communities, where survival will depend largely on the ability of species to adapt to rapidly shifting conditions or become established farther inland, historic assemblages may be lost. Seed banks may be an important component of resilience and recovery in response to altered inundation regimes, should they contain species able to adapt or migrate inland. This study assess the ability of seed banks to act as ecological buffers to storm surge disturbances and to instill ecological resilience in degraded and vulnerable coastal ecosystems. Above-ground, seed bank and propagule assemblages were surveyed from historic communities at the Grand Bay National Estuarine Research Reserve. Artificial storm surge experiments revealed that that seed banks were not well distributed throughout the coastal transition communities and that seed bank responses following storm surges are likely to vary among the different plant communities. While some relict species are expected to respond following disturbances, ruderal species are especially dominant in the upland seed bank communities and may, at least in the short term, cause shifts away from the historical assemblages. The apparent absence of seaward species in the upland seed banks may make assisted migration an important tool for the survival of communities unable to keep pace. Community response following translocation of propagule bank application onto highly degraded buyout properties suggested that this technique may be an effective tool in introducing resilience into ecosystems already experiencing the effects of climate change. They resulted in the establishment of diverse and variable communities, containing indicator species from a number of historic communities with varying environmental tolerances. Long-term monitoring of community change and reproductive output of target species may indicate the utility of community translocation in creating resilient and future-adapted communities.