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Mangroves are a group of woody plants that occur in the dynamic tropical and subtropical intertidal zones. Mangrove forests offer numerous ecosystem services (e.g. nutrient cycling, coastal protection and fisheries production) and support costal livelihoods worldwide. Rapid environmental changes and historical anthropogenic pressures have turned mangrove forests into one of the most threatened and rapidly vanishing habitats on Earth. Yet, we have a restricted understanding of how these pressures have influenced mangrove abundance, composition and functions, mostly due to limited availability of mangrove field data. Such knowledge gaps have obstructed mangrove conservation programs across the tropics. This thesis focuses on the plants of Earth’s largest continuous mangrove forest — the Sundarbans — which is under serious threat from historical and future habitat degradation, human exploitation and sea level rise. Using species, environmental, and functional trait data that I collected from a network of 110 permanent sample plots (PSPs), this thesis aims to understand habitat preferences of threatened mangroves, to explore spatial and temporal dynamics and the key drivers of mangrove diversity and composition, and to develop an integrated approach for predicting functional trait responses of plants under current and potential future environmental scenarios. I found serious detrimental effects of increasing soil salinity and historical tree harvesting on the abundance of the climax species Heritiera fomes. All species showed clear habitat preferences along the downstream-upstream gradient. The magnitude of species abundance responses to nutrients, elevation, and stem density varied between species. Species-specific density maps suggest that the existing protected area network (PAN) does not cover the density hotspots of any of the threatened mangrove species. Using tree data collected from different salinity zones in the Sundarbans (hypo-, meso-, and hypersaline) at four historical time points: 1986, 1994, 1999 and 2014, I found that the hyposaline mangrove communities were the most diverse and heterogeneous in species composition in all historical time points while the hypersaline communities were the least diverse and most homogeneous. I detected a clear trend of declining compositional heterogeneity in all ecological zones since 1986, suggesting ecosystem-wide biotic homogenization. Over the 28 years, the hypersaline communities have experienced radical shifts in species composition due to population increase and range expansion of the disturbance specialist Ceriops decandra and local extinction or range contraction of many endemics including the globally endangered H. fomes. Applying habitat-based biodiversity modelling approach, I found historical tree harvesting, siltation, disease and soil alkalinity as the key stressors that negatively influenced the diversity and distinctness of the mangrove communities. In contrast, species diversity increased along the downstream – upstream, and riverbank — forest interior gradients, suggesting late successional upstream and forest interior communities were more diverse than the early successional downstream and riverbank communities. Like the species density hotspots, the existing PAN does not cover the remaining biodiversity hotspots. Using a novel integrated Bayesian modelling approach, I was able to generate trait-based predictions through simultaneously modelling trait-environment correlations (for multiple traits such as tree canopy height, specific leaf area, wood density and leaf succulence for multiple species, and multiple environmental drivers) and trait-trait trade-offs at organismal, community and ecosystem levels, thus proposing a resolution to the ‘fourth-corner problem’ in community ecology. Applying this approach to the Sundarbans, I found substantial intraspecific trade-offs among the functional traits in many tree species, detrimental effects of increasing salinity, siltation and soil alkalinity on growth related traits and parallel plastic enhancement of traits related to stress tolerance. My model predicts an ecosystem-wide drop in total biomass productivity under all anticipated stress scenarios while the worst stress scenario (a 50% rise in salinity and siltation) is predicted to push the ecosystem to lose 30% of its current total productivity by 2050. Finally, I present an overview of the key results across the work, the study’s limitations and proposals for future work.

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The high floristic biodiversity value of ancient woodland is widely acknowledged, as is its status as a fragmented habitat of limited spatial extent. The distinctive vegetation of ancient woodland is an important factor in its conservation. Specifically, Ancient Woodland Indicator (AWI) species have been shown to be poor dispersers and incompatible with a fragmented habitat that is subject to environmental change. In recognition of their ecological importance, both Ancient Semi-Natural Woodland (ASNW) and Ancient Replanted Woodland (ARW) are protected by legislation. This thesis took the novel approach of examining the distinctiveness and community ecology of vegetation communities in all three woodland types of ASNW, ARW, and recent woodland. Importantly, analyses were based on new high-granularity primary vegetation and soil data. To address questions raised in the literature regarding the accuracy of ancient woodland and AWI identification, this research examined the metrics used to distinguish these habitats and species. Increasingly, the literature calls for further understanding of the ecological drivers of ancient woodland vegetation distinctiveness. In response, this research tested for differences in species composition of canopy, shrub, herb layer, AWI, and moss communities across all three woodland types. For AWI species, biotic, abiotic, and biogeographical variables were analysed for their contribution to community distinctiveness. Results highlighted the importance of consistency in metric selection when assessing the distinctiveness of ancient woodland and determining indicator species. In addition to the usual alpha scale measure of distinctiveness, assessing richness and community composition at the beta and gamma scales is recommended to inform conservation. Life traits and dispersal mechanisms were important differentiators for herb layer community composition among the woodland types. AWI richness was equally strongly explained by biogeographical variables as by ASNW, ARW, and recent status. Overall, this thesis supported ecological and biogeographical explanations for the distinctiveness of ancient woodland vegetation.

This thesis is concerned with the changes to a forest landscape, that of St. Leonard's Forest, Horsham, West Sussex, changes that were wrought by human activity over two and half centuries. In order to uncover and understand these changes the author has focused on five private estates within the Forest core, Holmbush, Buchan Hill, St. Leonard's, Coolhurst and Leonardslee, and two villages in the Forest, Colgate and Lower Beeding. The five estates are considered with regard to ownership and control, land use and workers on the estates. The two villages are examined for their growth, the profile of the population, poverty and wealth. The establishment and endowments of the parish churches are outlined along with the development of the parish of Lower Beeding and its ties to Magdalen College, Oxford. Paternalism was a theme in the Victorian and Edwardian period, and the 1900 Footpath Dispute demonstrated a move away from these attitudes towards a more individualistic concern with private property rights. For the first time this study pulls together the numerous and complex strands which make up the landscape history of St. Leonard's Forest. It explores the factors both social and economic which impacted on the Forest. The juxtaposition of the nearby expanding market town of Horsham with its large common, improving communications, sales of land, and the attitudes of individual Forest landowners all combined to transform the Forest from a wild barren heathland in 1750 to a place of desirable picturesque estates and expanding villages by 1914, before the impact of the Great War was to change the Forest landscape yet again.

This study is the first comprehensive survey of a frog assemblage in the central Amazon. Forty-three species of frog were found in a 2,000 hectare tract of primary forest near Manaus, Brazil. Breeding habitat affiliation, breeding phenology, spatial distribution, and relative abundance were determined for most species principally by counting calling males along variable-width strip transects. Frogs were also censused with visual detection methods and in litter plots. However, these techniques were not as powerful as audio transects for assessing species composition, habitat occupancy, and abundances throughout a large area. Anuran species and generic richnesses are similar throughout the Amazon except for Eleutherodactylus which is depauperate in the central and lower Amazon. As many species were abundant in the study area as were rare. The distribution of breeding habitat abundance parallels the distribution of species-abundance and so breeding habitat availability seems the best candidate to explain the relative abundances of species in the study area. / There is pervasive correlation between life history variables, particularly reproductive mode and habitat affiliation, and phylogeny in tropical forest anurans. This association supports a hypothesis that, at a regional scale, the history of an area's colonization and speciation rates of the colonists influenced the distribution of habitat use by frogs in forest assemblages more than selection. / Litter plot sampling was biased in favour of conspicuously behaving litter species. Since the proportion of the litter fauna that is conspicuously behaving is much lower in southeast Asia than the Neotropics, there is no evidence that litter frogs per se are more abundant in the Neotropics. However, abundances of conspicuously behaving species are higher in the Neotropics. Practically all abundant species at Manaus undergo terrestrial development. It appears that terrestrial reproduction releases frog populations from dependence on limited aquatic habitat. Since two prominent Neotropical families of litter frog reproduce terrestrially whereas terrestrial development is not associated with any southeast Asian taxon, the historical colonization of these regions by different lineages explains inter-regional abundance differences most parsimoniously. / Source: Dissertation Abstracts International, Volume: 52-04, Section: B, page: 1904. / Major Professor: Daniel Simberloff. / Thesis (Ph.D.)--The Florida State University, 1991.

No description available.

Thesis (M.S.)--Oregon State University, 1970. / Typescript. Includes bibliographical references (leaves 43-45). Also available on the World Wide Web.

Thesis (M.S.)--State University of New York at Binghamton, Biological Sciences Department, 2005. / Includes bibliographical references.

<p>The main cause of environmental disturbance in the Fennoscandian boreal forests today is forestry. Natural disturbances are important to maintain diversity, but anthropogenic disturbance, such as forestry, differs in many ways from the natural ones. Forestry is a big industry in Sweden and only a small remnant of old-growth forest is left. Several studies have shown an initial decrease in e.g. dragonfly diversity a few years after logging, followed by an increase up to numbers comparable with the original species number. In this study I examined whether the new, quite diverse, species composition is similar to the one present before the logging or if some species are disappearing and are replaced with other, maybe opportunistic species. Other factors such as ongoing changes in climate also will be considered. A resampling of 34 (and an additional 4) lakes that also were sampled in 1996-97 was done during summer of 2006. Analyses of data from the two sampling occasions were done. I found that even if the diversity is just temporarily affected (or not affected at all), it is not always the same species involved. This means that the diversity in a single lake can appear to be high, but the total diversity in Sweden, or Scandinavia, is declining. I also found some interesting new species for the area, such as Nehalennia speciosa, Sympecma fusca and Aeshna mixta.</p>