• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1315
  • 744
  • 298
  • 99
  • 69
  • 40
  • 35
  • 32
  • 27
  • 17
  • 16
  • 11
  • 11
  • 11
  • 11
  • Tagged with
  • 3183
  • 952
  • 709
  • 671
  • 578
  • 474
  • 378
  • 354
  • 342
  • 326
  • 304
  • 251
  • 249
  • 219
  • 205
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Antiproliferative Natural Products from the Madagascar Rainforest

Hou, Yanpeng 27 October 2009 (has links)
As part of an International Cooperative Biodiversity Groups (ICBG) program and a continuing search for anticancer natural products from the Madagascar rainforest, twenty extracts from Madagascar were selected for investigation based on their antiproliferative activity. Bioassay-guided fractionation of five of the extracts yielded sixteen new compounds, and their structures were determined using a combination of 1D and 2D NMR experiments, including COSY, HSQC/HMQC, HMBC, and ROESY/NOESY sequences, mass spectrometry, and chemical conversion. In addition, ten known compounds were obtained from five of the extracts. Studies on the remaining extracts were suspended due to various reasons. A multi-step synthesis of the sesquiterpenoid, (7R*)-opposite-4(15)-ene-1beta,7-diol, was also described. The first chapter of this dissertation reviews the new compounds isolated from Malagasy plants and marine organism in the last two decades. Chapters II to VI discuss the isolation, structure elucidation and bioactivities of new compounds from Scutia myrtina, Cordyla madagascariensis ssp. madagascariensis, Elaeodendron alluaudianum, Cassipourea lanceolata, and Sclerocarya birrea subsp. caffra. Chapter VII describes the synthesis and bioactivity of the sesquiterpenoid,(7R*)-opposite-4(15)-ene-1beta,7-diol. The isolation of known compounds is discussed briefly in the last chapter. / Ph. D.
182

The Application and Exploration of the City Biodiversity Index through a Case Study of the City of Starkville, Mississippi

Moma, Leslie Rhea 08 December 2017 (has links)
During the 21st century, more people will reside in cities than in rural areas for the first time in human history. As cities expand to accommodate their growing population, pressure is mounting on local biodiversity and the ecosystems they support. This prompted the U.N. Convention on Biological Diversity - in collaboration with the City of Singapore - to develop a biodiversity index specifically for cities. In 2014, the final draft of the City Biodiversity Index was released. Twenty-three indicators comprise three categories that assess: native biodiversity, ecosystem services, and municipal support for local biodiversity. A case-study was designed for Starkville, MS to better understand the merits of the index and its application to small rural town planning. The research illuminated the breadth and flexibility of the index across multiple scales and the availability of local resources to deliver a meaningful biodiversity analysis.
183

Biodiversity and Business : Multiple Case-Studies on Biodiversity Strategy in Sweden

Goaied, Amna, Sjöland, Christian January 2019 (has links)
Biodiversity loss has been stated as one of the greatest risks for the future society according to the World Economic Forum (2018, p. 5). A million species is risking extinction due to current societies’ practices according to a report published during the conduction of this study(Brondizio et al., 2019, p. 3). This situation of biodiversity has led an increasing amount of countries to enforce legislation which requires companies that work with land development to comply with no net loss goal. In Sweden, no such legislation existed with regards to biodiversity. Against this background, a group of seven companies in Sweden voluntarily chose to strive toward the goal of biodiversity net gain. According to BNG strategy, a company does not only avoid, minimise, restore and offset to reach the point where zero net loss of biodiversity is achieved, but goes farther to create a net gain. As it is not sufficient for companies to stop emissions in order to halt the loss of biodiversity, BNG practices can help mend and even reverse the negative impacts until a gain of biodiversity is attained. A greater understanding of the opportunities that companies can benefit from implementing BNG helps spread this practice across industries. No previous research within the business literature explains companies’ voluntary initiatives to embrace BNG. Therefore, this explorative study suggested the research question of what the drivers are encouraging companies to voluntarily work towards achieving biodiversity-net-gain in Sweden. Due to the lack of previous research about companies’ drivers to engage with BNG, our theoretical framework was found based on the drivers from business case for sustainability and CSR approaches as a factor to generate change. To be able to answer the research question, it was necessary to establish what BNG is and how it has developed from the concept of ecosystem services. Having an interpretivistic standpoint, this study was completed according to an inductive and deductive approach. This was in order to facilitate the exploratory nature that our qualitative and comparative study. We conducted a multiple-case study through semi-structured interviews with seven large companies in the context of Sweden. These businesses are considered as the most ambitious in working towards BNG’s goal. The findings from the primary data was complemented by secondary data about the companies, the status of current legislation in Sweden and the sustainability status in Sweden. As a result of this thesis, we found that cost and cost reduction, risk and risk reduction, sales and profit margin, reputation and brand value, attractiveness as employer, innovative capabilities, stakeholders and health and well-being of future society to all be drivers for BNG. By applying our theoretical framework in the Swedish context, the seven companies were identified to engage in a proactive corporate biodiversity behaviour. Business cases for biodiversity were identified in some of the companies.
184

Biodiversity Offsets in a Public Lands Context: A Romantic Concept or a Practical Tool to Balance Economic Development and Biodiversity Conservation Goals?

Gomez Wichtendahl, Carla C. January 2018 (has links)
Economic development through the exploitation of natural resources has led to biodiversity loss among other environmental issues around the world. The use of biodiversity offsets to balance economic development and biodiversity conservation goals has significantly increased during the last three decades. A recent report of the Organization for Economic Cooperation and Development (OECD) released in December of 2016 identified at least 56 countries with laws or policies requiring the use of these types of instruments worldwide. There are over 100 biodiversity offset programs operating in countries such as United States of America, France, New Zealand, Mexico, Australia and others, which are injecting over 3 USD billion per year into the world’s economy. Experiences of different jurisdictions indicate that biodiversity offsets can become a promising tool in addressing the biodiversity loss issue in their territories. Canada and some of its provinces such as Alberta and British Columbia, which have important oil and gas sectors, and are home to important wildlife species, have been part of the biodiversity offsets debate, and have been exploring their use. This research derives from the observation that although some of the international biodiversity offset experiences have been vastly studied, there is little experience analyzing the legal challenges of implementing biodiversity offset systems, including biodiversity banks (a type of biodiversity offset that creates biodiversity markets) on public lands. The very nature of public land, where multiple users may simultaneously access the land and conduct a variety of potentially incompatible activities, can create extra legal challenges with respect to the implementation of biodiversity offsets. Through an Alberta-focused case study, the thesis explores the characteristics that a planning and legal framework of a province with a majority of public lands would need to have in order to support the use of biodiversity offsets and a biodiversity banking system. It also identifies and analyzes the legal issues and challenges of implementing long lasting biodiversity offsets in that context. Under the system studied by this dissertation, the main users of Alberta’s public forests (forest operators and oil and gas developers) become the biodiversity bankers or suppliers, and buyers of biodiversity credits, respectively. This thesis is therefore a contribution to knowledge about how biodiversity offsets, specifically biodiversity banks, can be applied on provincial public lands, used by multiple users. It focuses on the legal frameworks, property right issues, permanence, and additionality needed for a potential biodiversity banking system for a province such as Alberta.
185

Comparison of the benthic fauna within the littoral in two affected lakes situated in central Sweden

Rösth, John January 2016 (has links)
The benthic animals have important roles in benthic communities. Indicator organisms can tell things about a lakes status. Many of them are sensitive to acidification but there are also tolerant taxa. Some prefer eutrophic environments. The benthic fauna can therefore decide a lakes status since some species prefer different environments. The focus of this study was to compare benthic fauna within the littoral in the lakes Sidsjön and Vintertjärnen. They are situated a little south of Sundsvall, central Sweden and belong to the water system of Selångersån. The comparison was done at eight random locals in each lake at two occasions, during early and late summer to analyze if the benthic fauna differed between the two lakes and if it changed through the season. Five of the locals in each lake were protected and had soft bottoms and the remaining were exposed locals with hard bottom. Sidsjön is bigger than Vintertjärnen and has more variated bottom types so the biodiversity should be higher in Sidsjön. I also expect that the number of taxa should decrease during the later occasion due to hatchings. Three statistical analyses were done to see if these hypotheses were right or if they should be rejected. The two first analyses were ANOVA analyses, two-way with replication. The first ANOVA was for number of taxa and the second was for number of animals. The third analysis was a DCA analysis with the variables lakes, bottom types and emergent plants. ASPT index and Eq was also calculated and pH was measured during autumn for the lakes. The conclusion is that the there is no difference between the lakes but a significant effect when it comes to seasons according to the first ANOVA analysis. The second ANOVA analysis show that the lakes are not differing, that no factor is significant and there are no interactions. According to the DCA analysis there are differences between lakes and occasions when it comes to the variables. / <p>Datum för godkännande 2016-03-31</p>
186

Heterospecific social interactions of the invasive guppy (Poecilia reticulata) : a potential trait to enhance invasion success

Camacho-Cervantes, Morelia January 2015 (has links)
From all the species that arrive to a novel environment, very few manage to form a viable population. The guppy, a very successful invader, is a highly social species that performs some of its vital tasks (e.g., foraging, avoiding predators) in groups. This thesis aimed to quantify heterospecific association benefits that enhance invasion success. Interactions between invaders and natives could be one of the environmental characteristics of a place that increase its risk of invasion. I evaluated the tendency of an invasive species to associate with native individuals with similar ecological requirements. I tested the hypothesis that invaders gain exploring, acquisition of information and foraging benefits when socializing with natives. In these experiments I used the guppy as the invasive model species and endangered native Mexican topminnows (Poeciliopsis infans, Skiffia bilineata, Ameca splendens, Zoogoneticus tequila, Xenotoca eiseni and Girardinichthys viviparous). I found that guppies shoal with other species in Trinidad (Poecilia picta and Poecilia sphenops), where they are native (Chapter 2) and that this trait remains when they are invasive (Chapter 3). Guppies are equally willing to explore novel environments when accompanied by heterospecifics or conspecifics. Guppies are more willing to explore complex environments than simple ones. Moreover, when exploring simple environments they have a higher association tendency, regardless of the partner' species (Chapter 4), which could lead them to acquire the benefits of grouping behaviour and avoid Allee effects - the disadvantages of being part of a small group. In the contexts in which they were tested guppies gained as much information by associating with heterospecifics as with conspecifics (Chapter 5). Finally, I found that when shoaling in bigger shoals guppies are able to locate food faster and spent more time foraging. The benefits of increased shoal size were maintained when the additional guppies were replaced with heterospecifics. However, they derive more benefits from the species they are more willing to associate with (Chapter 6). These results uncover a mechanism enabling founding individuals to survive during the most vulnerable phase of an invasion and help explain why guppies have established viable populations in many parts of Mexico as well as in every continent except Antarctica.
187

Effectiveness of protected areas and implications for conservation of biodiversity and ecosystem services

Duran, America Paz January 2014 (has links)
Protected areas (PAs) are considered a key strategy to ensure the in situ persistence of biodiversity and the ecosystem services (ES) that this provides. The coverage of PAs has exponentially expanded in the last 25 years, and they now account for approximately 13% of the Earth's surface. Alongside this expansion, PA research literature has also increased seeking to identify and assess the main factors that influence the effectiveness of PAs in sheltering biodiversity and ES from anthropogenic pressures. Spatial distribution, spatial design, management strategy and threats, have been widely acknowledged as key factors. However, despite significant progress, several aspects of these factors remain poorly explored. This thesis aims to identify and address some of the gaps, which I detail below. The second chapter contributes to understanding of how the distribution of PAs affects the representation of biodiversity and ES. To this end, the Chilean PA system was used as a case study as this has never been previously assessed in terms of ES. I found that the strong bias in Chilean PAs distribution toward southern areas, which contain mainly ice and bare rock, hampers the PA system in achieving effective representativeness. The third and fourth chapters address some gaps in PA spatial design. The third assesses for the first time the spatial design of the global PA system and provides new methodologies to achieve this at such a large scale. Focusing on the size, shape, level of fragmentation, occurrence of buffer zones and proximity to the closest PA, I demonstrate that PAs tend to be small, irregularly shaped and fragmented. However, they are often close to one another and generally have buffer zones. Using the methodology generated on third chapter, I explicitly test in the fourth chapter the combined and interactive effects of PA spatial features on their ability to represent biodiversity, which has never been tested before. Using South America as a model for study I show that the spatial design largely explains biodiversity representation and that the interaction between spatial features affects the latter. The fifth chapter focuses on threats to PAs, assessing the extent to which metal mining activities represent an actual conflict with the global PA system. Evidence suggests that the global terrestrial PA system has been effective at displacing metal mining activities from within its bounds. However, given the high proportion of mines found in the close surroundings of PAs, and the distances over which mining activities can have influences, it is highly likely that the conservation performance of a significant proportion of PAs is being affected. So far I have demonstrated that PAs are not always optimally distributed and they can compete with other land uses, which can undermine their functionality. In this regard, in the final analytical chapter I explore how using spatial conservation prioritization (SCP) tools it is possible to optimize the representation of conservation features by minimizing competition with other land uses. Specifically, I assess the consequences for biodiversity and ES representation of incorporating land use trade-offs in SCP analyses. I show that the dichotomist decision of treating a land use as a trade-off or not can have enormous consequences on biodiversity and ES representation, and the implications of such decisions have to be considered before policy recommendations. This thesis shows that distribution, spatial design and threats play an important role in PA representativeness, and that SCP techniques can make a significant contribution to balancing biodiversity and ES conservation with human activities, when trade-offs are treated comprehensively. Finally, I discuss the importance of prioritising the interactions between, rather than just individual effects of, factors in order to optimise PA effectiveness and the distribution of scarce conservation resources.
188

Ekosystemtjänstförvaltning i Sveriges kommuner : En jämförelse mellan tätort och glesbygd

Sporrong, Johan January 2016 (has links)
The concept of ecosystem services often is defined as a way where we as humans protect and preserve available ecosystems and at the same time can make use of these ecosystems for our own well-being. According to the UN report Millennium Ecosystem Assessment from 2005 the services can be classified into four categories: provisioning, regulating, cultural or supporting. This study is focusing on how Swedish municipalities are managing all of these services. The main aim was to examine if there is a difference among municipalities in general and between municipalities with a high and a low range of population density in particular. The reason for these potential differences was also discussed by interviews with representatives for a number of selected municipalities, complemented by studies of literature, this study showed that there are differences between Sweden’s more populated and less populated municipalities. Typically, the main difference was found in the area of the knowledge and the use of the concept in daily planning. Some municipalities seems to be almost unaware of that they partly already are planning for the maintenance of these services. In conclusion, there is still more work to do fully make use of the ecosystem service concept in planning to create a more resilient society, not least for the municipalities on the country side!
189

Biodiversity conservation in a fragmented landscape : arthropod assemblages in smaller corridors within a production landscape

van Schalkwyk, Julia 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Habitat loss and fragmentation are major threats to global biodiversity. A cornerstone of traditional conservation involves setting aside land as formally protected areas (PAs). However, for effective biological conservation in the long term there needs to be connectivity between these PAs. When possible, improved connectivity can be achieved using natural corridors at a landscape scale. Even better is to establish a network of corridors and nodes in the form of ecological networks (ENs). ENs are currently being employed by commercial forestry companies in South Africa. While larger corridors and nodes are considered optimum, factors other than design, such as management and environmental heterogeneity, have also been found to be important for species maintenance. This study aims to explore the role of corridor width in driving the composition of invertebrate assemblages across a transformed landscape in KwaZulu-Natal, South Africa, and to investigate other possible environmental variables significant for species distributions. In Chapter 2, I investigated the contribution of smaller grassland corridors within a timber production matrix to overall biodiversity conservation using two important bioindicator taxa. Ants and dung beetles were sampled in grassland corridors of three size classes, plantation blocks and a nearby PA, iMpendle Nature Reserve. The two taxa showed differential responses to landscape level fragmentation. Dung beetles showed a decrease in species richness and corresponding increase in species turnover with increased fragmentation, while ants were unaffected, although counter intuitively smaller corridors even contained more unique ant species compared to larger corridors. Dung beetle assemblages also showed strong differences between the PA and grassland corridors. While the conservation effectiveness of large corridors undoubtedly exceeds that of smaller corridors, for ants it seems that smaller corridors contribute to their overall conservation within this production landscape. In Chapter 3, I explore the importance of spatial and environmental factors for species distribution across this landscape. Dung beetles were split into functional guilds according to size and nesting behaviour for analyses. Within grassland corridors, tunnelling dung beetle species richness was sensitive to landscape level fragmentation, especially for larger species, while elevation and vegetation type influenced ant species richness. Since rolling dung beetles showed a close association with the PA, the marked difference in dung beetle assemblages between these two land-uses may be due to the presence of pellet producing grazers in the protected area and their replacement by pat producing cattle in the grassland corridors. Other environmental variables that were found to be important for dung beetle species composition were elevation, vegetation type, and soil hardness. For ant species composition, only elevation was found to be important. In conclusion, as large corridors were comparable to the PA in dung beetle and ant species richness, ENs act as extensions of formally PAs, given that they are large enough. Nevertheless, smaller corridors had surprisingly high species richness. Including additional information other than species data improved our knowledge of the underlying factors that drive dung beetle species composition. Even though dung beetle and ant species responded differentially to habitat fragmentation, environmental heterogeneity seemed important for both taxa. Incorporating habitat heterogeneity into the current management scheme may improve the conservation effectiveness within this transformed landscape. / AFRIKAANSE OPSOMMING: Die vermindering en fragmentasie van natuurlike habitat is ‘n groot bedreiging vir globale biodiversiteit. ‘n Belangrike tradisionele benadering tot natuurbewaring behels die afbakening van land vir formele beskermde areas (BAs). Ten einde effektiewe biologiese bewaring oor die langtermyn te verseker moet daar verbinding wees tussen hierdie BAs. Indien moontlik kan verbeterde verbinding verkry word deur die gebruik van natuurlike gange op ʼn landskaps-vlak. Nog beter is om ʼn netwerk van gange en nodes in die vorm van ekologies netwerke (ENe) saam te stel. ENe word tans deur kommersiële bosboumaatskappye in Suid Afrika aangewend. Terwyl groter gange en nodes as optimaal beskou word, is ander faktore behalwe ontwerp, soos bestuur en omgewingsheterogeniteit, ook al gevind as belangrik vir die onderhouding van spesies. Hierdie studie is gemik daarop om die rol van gangwydte as dryfkrag vir die samestelling van invertebraatversamelings oor ʼn getransformeerde landskap in KwaZulu-Natal, Suid-Afrika, te ondersoek, asook ander moontlike omgewingsveranderlikes wat belangrik vir spesiesverpreidings kan wees. In Hoofstuk 2 het ek die bydrae van kleiner gange tot totale biodiversiteit-bewaring ondersoek deur twee belangrike bio-indikator taxa te bestudeer. Miere en miskruiers is versamel in grasland-gange van drie grootte-klasse, plantasie blokke en ‘n naby geleë BA, iMpendle Natuurreservaat. Die twee taxa het verskillende reaksies tot landskaps-vlak fragmentasie getoon. Miskruiers het ‘n verlaging in spesiesrykheid en ‘n gesamentlike verhoging in spesiesomset met verhoogde fragmentasie gewys, terwyl miere nie geaffekteer is nie, alhoewel kleiner gange het trouens meer unieke mierspesies bevat as groter gange. Die miskruierversamelings in die BA het ook opmerklik verskil van dié in die grasland-gange. Alhoewel die bewaringsdoeltreffendheid van groot gange beslis dié van kleiner gange oorskry, kom dit voor dat kleiner gange wel bydra tot die totale bewaring van miere binne hierdie produksielandskap. In Hoofstuk 3 het ek die belangrikheid van ruimtelike en omgewingsfaktore vir spesiesverspreiding oor hierdie landskap ondersoek. Miskruiers is ook in funksionele groepe verdeel volgens grootte en nes-gedrag vir aparte analise. Binne grasland-gange was tonnellende miskruierspesies sensitief vir landskaps-vlak fragmentasie, veral groter spesies, terwyl hoogte bo seevlak en vegetasie tipe mier spesiesrykheid beïnvloed het. Aangesien rollende miskruierspesies ‘n nabye assosiasie met die BA gewys het, mag die opmerklike verskil in miskruier versamelings tussen hierdie twee grondgebruike ʼn gevolg wees van die aanwesigheid van korrel-mis produserend beweiders in die BA en hulle vervanging deur nat-mis produserende beeste in die grasland-gange. Omgewingsveranderlikes uitsluitende ganggrootte wat belangrik gevind is vir miskruier spesiessamestelling was hoogte bo seevlak, vegetasie tipe en grond-hardheid. Vir mier spesiessamestelling was slegs hoogte bo seevlak belangrik. Om af te sluit, aangesien groot gange vergelykbaar was met die BA in miskruier en mier spesiesrykheid, tree ENe op as uitbreidings van BAs, mits hulle groot genoeg is. Desnieteenstaande het kleiner gange ‘n verbasende hoë spesiesrykheid gehad, veral onder miere. Die insluiting van addisionele inligting buiten spesiesdata het ons kennis van die onderliggende faktore wat miskruier spesiessamestelling dryf verbeter. Alhoewel miskruier- en mierspesies verskillend gereageer het op habitat fragmentasie, het dit voorgekom asof omgewingsheterogeniteit belangrik was vir die spesiesverspreiding van beide taxa. Die insluiting van habitatheterogeniteit binne die huidige bestuursplan mag die doeltreffendheid van bewaring binne hierdie getransformeerde landskap verbeter.
190

The extent of forest fragmentation in New Zealand and its effects on arthropod biodiversity

Ewers, Robert Mark January 2004 (has links)
Historically, New Zealand was almost completely forested below the alpine treeline, but 1000 years of Polynesian and European colonisation has resulted in the destruction of nearly three-quarters of the original forest cover. I assessed historical patterns of deforestation and forest fragmentation in relation to all major topographical, climatic and anthropogenic variables that may drive forest loss. Much of the deforestation occurred in regions with drier climates, reflecting the fact that human population density has always been highest in areas with moderately dry climates and that dry forests burned much more readily and extensively. The large remaining tracts of forest are mainly restricted to high elevations, while the lowland forests have been fragmented into small, isolated remnants. Fragmentation of the surviving forests increases their susceptibility to edge effects and invasion by adventive species, indelibly altering the ecological communities they support. Although a large proportion of the remaining forest is owned or managed by the Department of Conservation, the distribution of that protection is greatly skewed towards areas of low economic value and is not representative of the relative conservation value of landscapes that differ in their environments and degree of forest cover. Forest cover in the majority of New Zealand landscapes has been reduced below the level of an expected extinction threshold of 30 % forest cover in the landscape, and ongoing deforestation threatens to force more landscapes below the critical threshold. Deforestation is still occurring across the country, and it is concerning that current deforestation rates in some areas are far greater than those observed in tropical, developing nations. I showed that the remaining forest fragments in New Zealand have complex, irregular shapes, and find ubiquitous evidence that core habitats within individual fragments are spatially discontinuous, comprising multiple, disjunct cores of small average area. Because population density of forest-interior species typically decreases with decreasing habitat area, multiple, disjunct cores support a lower total population size than a single, discrete core of the same total area. I found in a spatially explicit, landscape-level analysis of habitat fragmentation in New Zealand that simple core-area models consistently overestimate the carrying capacity of habitat fragments. Habitat fragmentation and habitat destruction are widely recognised as two of the leading threats to the continued maintenance of global biodiversity. The effects of habitat fragmentation on biodiversity fall into five categories that describe the spatial and landscape attributes of fragmented ecosystems; (1) fragment area, (2) edge effects, (3) fragment shape, (4) fragment isolation, and (5) matrix structure. Each attribute affects species individually according to their particular biological requirements and life history strategies, leading to complex, and often conflicting, sets of results in the empirical literature. Furthermore, it is now apparent that the effects of fragmentation can take many decades to become apparent and that the spatial arrangement of habitat fragments can interact with other ecological processes to magnify the detrimental impacts of fragmentation on species. I synthesised the published effects of habitat fragmentation on the morphology, distribution and abundance of invertebrate populations, species and communities, and present examples of time lags and synergies from the fragmentation literature. I explicitly considered the underlying mechanisms determining the responses ofindividuals to fragmentation and discussed the role of species traits in determining species vulnerability to changes in the spatial attributes of fragmented landscapes. I sampled 35,461 beetles from a fragmented forest and matrix system in New Zealand over very large gradients of fragment area (10-2 to 106 ha) and edge distances (up to 1,024 m from the forest edge into both the forest and the adjacent matrix interiors). The beetle fauna was very diverse, with 893 species identified in 65 families, representing nearly 20 % of the known species in New Zealand. Beetle communities were strongly structured by forest fragmentation, but in species-specific ways. Distance to edge was consistently shown to have the largest effect on community composition, but, surprisingly, an interaction between area and distance to edge had a stronger impact on community structure than fragment area alone. I developed a new method to partition the variance in community composition that was explained by putative area and edge effects. The method uses backwards stepwise regression to determine significant predictors of gradients in beetle species composition that were identified by canonical ordination. I found that edge effects were driven partially by small-scale alterations to microhabitat and microclimate and partially by changes in landscape composition that varied with distance to edge. In contrast, fragment area effects were driven primarily by edge effects, the strength of which varied significantly with fragment area. I took a novel approach to characterising the responses of 185 common species to habitat edges by modelling species abundances across edges with a general logistic model that described sigmoid trends in abundance for forest specialist and matrix specialist species, as well as unimodal trends in abundance for edge specialist species. I used the second derivatives of the logistic and unimodal models to statistically determine the width of species response zones to edge effects. Beetle species responses to forest edges occurred over far greater scales than previously suspected, with edge response zones for some species extending for more than 1 km. Average edge response zones were 194 m wide and, for many species, began in the forest but extended into the adjacent matrix. Species were categorised according to their responses to fragment area and distance to edge. Closely related species were expected to be placed in similar response categories because they are predicted to share suites of traits that determine their susceptibility or resilience to fragmentation by virtue of common ancestry. Despite many species exhibiting responses that could be grouped into categories, individual species responses to fragmentation were largely idiosyncratic with even closely related species exhibiting strongly contrasting responses to fragmentation.

Page generated in 0.0855 seconds