Dissertations / Theses on the topic 'Human-modified landscapes'

Abstract Alteration of natural habitat usually has two kinds of effects on the populations living in the area. No single organism is able to survive or reproduce without its habitat, so it is very easy to understand and predict direct habitat loss effects. Moreover, fragmentation effects can enhance the effects of pure habitat loss, and in some cases, the effects of fragmentation can exceed the effects of habitat loss. In addition, harvesting by humans has significantly shaped wildlife populations and done so probably well before any other human activity. Different types of anthropogenic change in nature often happen simultaneously and their separate effects are not necessarily easily disentangled. I studied the effects of forest fragmentation on bird populations and communities on different levels, as well as the effects of harvesting on grouse populations. My results suggest that in natural systems there is always a multitude of factors influencing the population distribution and abundance. This complexity makes it difficult to discern and predict the consequences of human activities, and any additional human activity, such as habitat fragmentation or harvesting, can cause seemingly unexpected population consequences. My results also suggest that considering protected areas in isolation of the matrix is not sufficient to understanding species distribution and abundance within the conservation network. All management practices in commercial forests affect the landscape where protected areas are embedded, but simultaneously, conservation actions also influence the management planning. Therefore, an integrated approach is needed to sustain forest biodiversity. Finally, I showed that there are marked differences in responses to fragmentation among regions and among ecologically different species, which are partly associated with the evolutionary history of the biota in different regions. Therefore, patterns and processes in one region may not be transferrable to other regions. Moreover, disentangling the fragmentation effects on bird species requires careful consideration when selecting for research a combination of life-history variables that can distinguish among the underlying demographic mechanisms, because the mechanisms and the variables susceptible to these mechanisms may vary among regions
Tiivistelmä Eliön habitaatin muokkaamisella on yleensä kahdentyyppisiä seurauksia. Habitaatin hävittämisen seuraukset ovat suoraviivaisia, koska yksikään laji ei pysty säilymään elossa tai lisääntymään ilman lajityypillistä habitaattiaan. Pirstoutumisvaikutukset puolestaan voivat voimistaa habitaatin hävittämisen vaikutusta ja olla joissakin tapauksissa jopa niitä voimakkaampia. Lisäksi metsästys on muokannut eläinpopulaatioita luultavasti ensimmäisenä ihmistoiminnan muotona. Erilaiset ihmistoiminnan vaikutukset ovat usein yhtäaikaisia, eikä niiden vaikutuksia ole aina helppoa erottaa toisistaan. Tutkin väitöskirjatyössäni metsien pirstoutumisen vaikutuksia lintupopulaatioihin ja – yhteisöihin sekä metsästyksen vaikutuksia kanalintupopulaatioihin. Tulosteni mukaan luonnonoloissa on aina useita tekijöitä vaikuttamassa populaation kokoon ja levinneisyyteen. Tämä tekee ihmistoiminnan vaikutuksista hyvin vaikeasti ennustettavia. Niin ikään tulosteni mukaan suojelualueiden lajiston levinneisyyttä ja runsautta ei voi ymmärtää, mikäli ympäröivien alueiden ominaisuuksia ei oteta huomioon. Osoitin myös, että vasteissa pirstoutumiseen on huomattavia eroja maantieteellisten alueiden ja ekologisesti erilaisten linturyhmien välillä, mitkä osaltaan johtuvat eri alueiden erilaisesta evolutiivisesta historiasta. Tästä syystä vasteita pirstoutumiseen ei voida välttämättä yleistää alueelta toiselle. Tulosteni mukaan pirstoutumisvaikutusten erottelu vaatii huolellista tutkimuksen suunnittelua, jotta lajeihin vaikuttavat demografiset tekijät voidaan tunnistaa, koska näissä voi olla huomattavaa alueellista vaihtelua

The destruction of tropical forests is the most concerning current threat to biodiversity. Although protected areas have long been used as the primary tool for biodiversity conservation, there is an increasing need to find suitable conservation strategies for the growing area of human-modified land. This thesis addresses three themes that have been identified as the most pressing areas for research in human-modified landscapes: biodiversity conservation beyond protected areas, forest restoration, and the human–environment relationship. By studying the interactions between birds, plants, and people with isolated Ficus (Moraceae) trees in Assam, India, this thesis reports several important findings: 1) isolated Ficus trees are extraordinarily important to frugivorous bird communities that inhabit human-modified landscapes; 2) the frugivores visiting these isolated trees still sustained the majority of ecological function found in trees close to the forest edge; 3) isolated Ficus trees are also exceptionally important feeding sites for insectivorous birds in human-modified landscapes, compared to other trees; 4) Ficus trees are better restoration nuclei than other isolated trees; 5) although the sacred status of Ficus trees in Assam has a major influence on their abundance and distribution, faith-based values are insufficient in ensuring their conservation. In conclusion, this thesis finds that isolated Ficus trees are critically important micro-sites for conservation in human-modified landscapes, the loss of which may lead to avifaunal collapse and a reduction in restoration potential. However, by stressing their ecological and cultural properties, it may be possible to build a strong case for the conservation of isolated Ficus trees in Assam and elsewhere.

Fragmentation of forest habitat by urban and rural development has had profound effects on the distribution and abundance of many native species; however, little is known about the ecological processes driving patterns in community structure (species richness and composition) of host-specialised herbivores in modified habitats. I examined patterns in community structure of 9 specialist and 19 generalist invertebrate herbivores of cabbage trees (Cordyline australis Laxmanniaceae) across a highly-modified landscape. I found that, although species richness of specialists was highest in forest sites, the majority of host-specialised species were not restricted to forest habitats and were as widespread as many generalists. In terms of site occupancy, only two specialist and four generalist species were rare. I show that patterns of species occupancy and abundance reflect differing susceptibility to habitat modification, with landscape-level variation an important predictor of abundance for nearly all species. When species occurrences and life history traits were considered I did not find strong evidence for the importance of dispersal ability, which suggests that habitat variability had a stronger organising effect on the community. In a replicated common garden experiment, I found distinct regional patterns in the community structure of the specialist invertebrates occurring on different phylogenetic groups of C. australis. In contrast, community structure of generalist herbivores did not differ significantly among host genotypes. I speculate these patterns are due to historical changes in the distribution of cabbage trees in the Southern phylogenetic region that caused specialised herbivores to become locally adapted on populations of low genetic diversity following expansion after the last glacial maximum. However, this consistent selection pressure did not occur in the Northern region where C. australis habitat has been more consistently available over the past tens of thousands of years, reflected in higher host genetic diversity. This study has advanced our understanding of the patterns in community structure of an indigenous, host-specialised fauna in a highly modified and fragmented urban and rural landscapes.

Tropical land-use change via rainforest degradation and agricultural expansion is driving a global extinction crisis. Understanding community dynamics, functional diversity (FD) and species interactions in relation to these land-use changes is essential to both conservation actions and ecological theory. Landscapes are altered at multiple scales, and the changing landscape mosaic impacts biodiversity and in turn potential functional processes and ecosystem services (or dis-services). I use field data combined with functional and modelling statistical approaches, and primarily examine dung beetle communities, but also use bird and ant assemblages to compliment my investigations. I study these communities across a land-use gradient of primary rainforest, selectively logged forest, and adjacent oil palm plantations in Malaysian Borneo. Logging caused significant shifts in community composition but FD of dung beetles and birds was at similar levels compared to primary rainforest. Along logging roads edge effects penetrated 100m into the logged forest interior, with significant declines in species richness, abundance and biomass with increasing proximity to road edges, and a marked change in species composition. Logged forest communities were predominately randomly assembled across three taxonomic groups, with a strong influence of dispersal assembly for dung beetles. The conversion of forest to oil palm, however lead to a significant reduction in FD, greater influence of habitat filtering in the assembly of dung beetle communities, and significant segregation in dung beetle and bird community assembly. The extent of forest cover and proximity to forest were not significant predictors of oil palm yield. Understanding the stability and resilience of FD and the dominant assembly processes emphasises the high value of logged forests as refugia for biodiversity. Nevertheless, better landscape design practices for forestry, specifically road planning, and in-situ habitat conservation within plantations is strongly encouraged. Critically a functional approach to land-use change gives conservation a complete and practical focus.

The European water vole (Arvicola amphibius) has undergone widespread declines across much of the UK and a major consideration for their future conservation is facilitating the admixture of individuals in modified landscapes to promote population growth, restore geographical distribution and ensure long term viability. However implementing remedial management strategies for these purposes requires knowledge of how populations are affected by, and respond to, fragmented and perceptively hostile landscapes. This thesis uses non-invasive genetic tools in conjunction with a live capture study to investigate the population structure, genetic variation and social systems of both natural and reintroduced water vole populations living within modified landscapes in southeastern England. In particular this research determines; a) whether non-invasive hair capture tubes are effective at collecting samples for genetic monitoring of water voles; b) whether there is a quantifiable difference in the demographic performance (survival, recruitment, population growth), neutral genetic variation and kin structure of populations occupying linear habitats compared to unmodified non-linear wetland habitats and c) identify the spatial pattern of variation in microsatellite and mitochondrial DNA amongst water vole populations to investigate natural and human mediated factors effecting historical and contemporary distribution. Non-invasive hair capture tubes proved to be a successful and efficient method for obtaining hair samples from wild populations of water voles with one genetic sample taking 0.53 man hours and costing £0.80, which was four times more efficient and 13 times more cost effective than live capture methods. However, DNA degradation, low quantities of DNA template and small sample sizes were identified as limiting factors when applying this method to genetic studies on water voles. Different patterns in demography and kin structure of water voles were observed between populations occupying linear and non-linear wetlands. Water voles in linear wetlands showed higher overall survival and dispersal of young, but were characterised by a significantly lower proportion of breeding females in spring which resulted in higher levels of female philopatry and incidents of inbreeding. Populations occupying non-linear wetlands were comprised of more breeding females in spring which had a positive influence on population growth. There was also evidence to suggest that when the abundance of overwintered females was high, the sexual maturation of female young was suppressed which concurred with fewer breeding female relatives being observed after the breeding season in populations occupying non-linear habitat types. Tolerance between female kin was reduced in both habitats types with increasing abundance of voles and no spatial avoidance between opposite sex mates was observed. Genetic diversity was similar between populations occupying linear and non-linear wetlands and significant temporal variation in genetic composition was observed, particularly in linear wetlands, suggesting a high turnover of individuals. Between populations, genetic variance at microsatellite loci was partitioned amongst river catchments, which concurred with patterns in mitochondrial variation across southeast England. Reintroduced populations exhibited significantly higher genetic diversity in terms of heterozygosity and allelic richness, however spatial analyses across the study sites suggest that reintroductions have homogenised the genetic variation at microsatellite loci and evidence of captive breeding between divergent lineages that have no geographical affiliation to the study area highlight that reintroductions can contribute to the loss of genetic heritage and diversity.

Large carnivore populations are recovering in Europe after centuries of population decline. The Cantabrian brown bear Ursus arctos population is endangered, and it is a good example of a large carnivore inhabiting a human-modified landscape. In order to study the impact of human landscape elements on bear behaviour we analysed 10 years of Cantabrian brown bear records. Human activity and structures do not appear to have an impact on the duration or appearance of vigilance behaviour. While bears avoid direct contact with humans, the mere presence of human infrastructure and activities don't not appear to impact its vigilance behaviours. The brown bear seems to be adapted to human coexistence and this should give a different perspective in future conservation efforts; Comportamento do Urso-Pardo em paisagens modificadas pelo Homem: o caso da população Cantábrica em perigo, NO Espanha Resumo: As populações de grandes carnívoros estão a recuperar por toda a Europa após séculos de declínio populacional. A população Cantábrica de urso pardo Ursus arctos encontra-se em perigo e é um bom exemplo de um grande carnívoro que habita uma paisagem modificada pelo Homem. A fim de estudar o impacto dos elementos da paisagem humanizada no comportamento do urso pardo, analisamos 10 anos de registos de comportamento de urso pardo Cantábrico. A atividade e estruturas humanas não parecem ter impacto na duração ou no aparecimento do comportamento de vigilância. O urso-pardo evita o contato direto com os seres humanos, no entanto a mera presença de infraestruturas e atividades humanas não parece ter impacto no comportamento de vigilância. O urso-pardo parece estar adaptado à coexistência humana e isso deverá dar uma perspetiva diferente a futuros esforços de conservação.

Despite the importance of disease as a wildlife management challenge, baseline research on the epidemiology of pathogens occurring in wildlife populations within both rural and urban landscapes has received little attention to date. The aim of this study was to improve our understanding of wildlife health in human-modified landscapes in South Africa, by providing comparisons of body condition, host-attached tick diversity and tick-borne pathogen (TBP) epidemiology of two common mesocarnivore species, the black-backed jackal (Canis mesomelas) and caracal (Caracal caracal). Jackals (n=46) and caracals (n=27) were sampled from small livestock farmlands in the Central Karoo region, in addition to caracals from farmlands in Namaqualand (n=14), and the urban matrix of the Cape Peninsula (n=16). Body condition was evaluated using both ratio (Body Mass Index) and residual (Ordinary Least Squares) methods, and morphometry was compared with historical datasets for each species. There was no apparent effect of sex, age class or location on body condition of jackals or caracals. Host-attached tick diversity was highest in urban caracals compared with the two other caracal populations, possibly indicating that they are exposed to a greater diversity of potential tick vectors. Molecular methods (mPCR/RLB; conventional PCR screening and phylogenetic analysis) used to screen for selected pathogens of veterinary and/or zoonotic concern, including Ehrlichia, Anaplasma, Babesia and Theileria species, revealed that Central Karoo jackals exhibited a lower prevalence of TBPs, compared with sympatric caracals. Hepatozoon canis, a ubiquitous pathogen of domestic and wild canids globally, was observed in 46.5% of jackals. Theileria ovis, a piroplasm of small livestock, was found in 4.7% of jackals. Jackals and caracals appear to be distinct in their TBP epidemiological roles, despite sharing similar tick communities. Pathogens found in caracals include Hepatozoon felis, Babesia felis, Babesia leo and a potentially undescribed Babesia species, genetically similar to B. venatorum, an emerging zoonosis. An Anaplasma species previously described in South African domestic dogs was also found in the urban caracals. All caracals were infected with at least one TBP. Together, these findings suggest that land use does not significantly influence the body condition of these adaptable predators, but that there is a health cost associated with living in the urban space. Cape Peninsula caracals show substantially higher rates of TBP co-infection (81% versus 14.8% and 0% in farmlands) and greater pathogen diversity compared to farmland caracals. The findings of this study include numerous examples of previously undescribed genetic diversity of tick-borne pathogens infecting South African mesocarnivores living in transformed landscapes. This work adds to our understanding of wildlife health within the 'One Health' framework and represents the first detailed examination of TBPs in jackals on farmlands and is also the first work that focuses specifically on TPBs in caracals anywhere in the world.

Fauna conservation outside protected areas can make an important complementary contribution to conservation within reserves. This thesis aimed to contribute new information and analytical frameworks to the science of fauna conservation in human-modified landscapes. Two approaches were used: (1) empirical data collection and analysis, and (2) the discussion and development of conceptual landscape models. ¶ Empirical work focused on lizard distribution patterns in two production landscapes in southeastern Australia. Lizards were targeted because ectotherms are frequently neglected by conservation biologists. The “Nanangroe grazing landscape” was used for sheep and cattle grazing. In this landscape, approximately 85% of pre-European woodland cover had been cleared, and understorey vegetation was sparse. Lizards were surveyed at 16 landscape units, which were stratified by aspect, topographic position and amount of tree cover. Each landscape unit contained three sites, and each site contained three plots. Regression modelling showed that different species responded differently to their environment. For example, the four-fingered skink (Carlia tetradactyla) and Boulenger’s skink (Morethia boulengeri) were more likely to occur at woodland sites with northerly aspects, whereas the striped skink (Ctenotus robustus) and olive legless lizard (Delma inornata) were more likely to inhabit sites with a simple microhabitat structure. Statistical analysis further showed that the habitat attributes that lizards were related to varied continuously through space, and over different spatial scales. For example, invertebrate abundance (a proxy for food availability) varied most strongly over tens of metres, whereas the amount of grass cover varied most strongly over hundreds to thousands of metres. Thus, work at Nanangroe revealed spatially complex patterns of lizard occurrence and habitat variables. ¶ The “Tumut plantation landscape” was a spatial mosaic of native eucalypt (Eucalyptus) forest patches embedded within a plantation of the introduced radiata pine (Pinus radiata). In this landscape, thirty sites were surveyed for lizards. Sites were stratified by forest type and patch size, and included eucalypt patches, pine sites, and extensive areas of eucalypt forest adjacent to the plantation. Regression modelling showed that lizard species responded to various habitat attributes, including elevation, the amount of eucalypt forest within 1 km of a site, invertebrate abundance and ground cover. Variables related to habitat fragmentation often were significant predictors of lizard occurrence. However, work at Tumut suggested that important additional insights into lizard distribution patterns could be obtained by considering variables related to food and shelter resources, and climatic conditions. ¶ The Nanangroe and Tumut landscapes were in close proximity, but together spanned an altitudinal gradient of 900 m. An investigation of changes in lizard community composition with altitude showed that (1) only one species was common to Nanangroe and Tumut, (2) different species had different altitudinal preferences, and (3) ecologically similar species replaced one another with increasing altitude. These results highlighted that even in highly modified landscapes, natural gradients (such as climate) can play an important role in shaping animal assemblage composition and species distribution patterns. ¶ Empirical work suggested that, in some landscapes, the frequently used “fragmentation model” is a relatively weak conceptual basis for the study of animal distribution patterns. The fragmentation model implicitly assumes that “habitat patches” can be defined unequivocally across many species, and that patches are located within a relatively inhospitable matrix. Where these assumptions are breached, conservation guidelines arising from the fragmentation model may be too simplified. In spatially complex production landscapes, it may be more appropriate to maintain habitat heterogeneity at multiple spatial scales than to focus solely on the management of large, pre-defined patches. ¶ Given the potential limitations of the fragmentation model, a new, more holistic landscape model was developed. The “continuum model” was derived from continuum theory as developed for plant ecology. The continuum model recognises (1) spatial continua of environmental variables, and (2) species’ individualistic responses to these variables. For animals, key environmental variables may be related to the availability of food, shelter, sufficient space, and suitable climatic conditions. Unlike the fragmentation model, the continuum model is inherently process-based and thus may help to link the perceived gap between patterns and processes in landscape ecology. ¶ Three general conclusions arise from this thesis: 1. Some heterogeneous production landscapes support many native species, and therefore represent important conservation opportunities. 2. In some modified landscapes, the fragmentation model does not capture the complexity of animal distribution patterns. In those landscapes, conservation recommendations derived from the fragmentation model may be overly simplistic. 3. The continuum model may be a useful extension of the fragmentation model. It provides a process-based conceptual basis for empirical work on animal distribution patterns.

Understanding the impacts of land-use change on biodiversity and the ecosystem services that it provides is of great importance given unprecedented growth of the human population. Past studies attempting to explore these impacts have described the overall structure of communities (i.e. species richness and trait diversity) across gradients of local scale degradation and fragmentation, and have sought to identify whether the loss of species following land-use change is non-random. Yet, despite a wealth of research we still lack a generalised understanding of how land-use change impacts on traits responsible for determining species sensitivity and their role within ecosystems, particularly for vertebrates. Moreover, despite the importance of niche-based processes in the assembly of communities, we have not yet elucidated whether these are important in mediating the collapse of communities in human-dominated landscapes. To fill these existing research gaps, I collated comprehensive avian species inventories from fragmented and degraded forests and compared their structure with communities existing in continuous forests. In Chapter 2, I tested whether sensitivity of species to forest fragmentation varies between the temperate zone and the tropics and whether there are key differences in the size of fragments required to maintain ecosystem processes in these regions. I found that sensitivity to fragmentation varies according to functional group and body mass, with the prevalence of insectivores and large frugivores declining in relation to fragment size, particularly in tropical fragments smaller than 100 ha. In Chapter 3, I tested whether functional diversity and the mean position of trait diversity of insectivores and frugivores, changed across a gradient of intensifying land-use change. I found a decline in the functional diversity of forest species and a shift in the mean community traits for both forest and non-forest species. In Chapter 4, I tested whether the structure of tropical bird communities are influenced by species interactions in a fragmented landscape. I found increasing over-dispersion in functional and phylogenetic trait relatedness among species with decreasing fragment size, suggesting that competitive interactions are important in the disassembly of avian communities. In Chapter 5, I modelled the impact of forest cover change on ecosystem function across the Brazilian Amazon, focusing on seed dispersal by birds. Furthermore, I tested whether ecosystem function declined linearly with decreased forest cover after accounting for differences in the underlying pools of species. I found the lowest levels of functional diversity along the southern arc of deforestation and that the dispersal of large seeds showed some resilience to declining forest cover. Taken together, my results suggest that the loss of species from communities in degraded and fragmented landscapes is strongly non-random. Insectivores and large frugivores are most sensitive to land-use change, with species located in the densest parts of trait space being most threatened by a decline in forest patch size, suggesting that species interactions regulate the collapse of avian diversity in human-modified forests. I conclude that land-use change has important implications for the provisioning of ecosystem services, including seed dispersal and the control of insect herbivores. The impact of future land-use change is likely to be mediated by the composition of the original pool of species and the amount of redundancy in the ecosystem services that they provide. I discuss the relevance of my findings to land-use management strategies and policy interventions, and in particular conclude that these should, where possible, maintain pristine forest patches above 1000 ha, improve connectivity among habitat patches, and ensure greater protection for logged and burnt forests. Future studies should focus on clarifying the link between shifts in vertebrate community structure and the functioning of forest ecosystems.

A expansão das atividades humanas está associada a várias ameaças antrópicas que afetam a biodiversidade tropical, especialmente a perda e fragmentação de habitat, o continuado crescimento populacional humano e a expansão de infraestrutura, como estradas e rodovias. Embora seja esperado que as ameaças antrópicas interajam e criem mosaicos de manchas de habitat de diferentes qualidades, há ainda poucos estudos sobre os efeitos aditivos e interativos de diferentes ameaças sobre a biodiversidade ou sobre a capacidade de espécies nativas de usar remanescentes de diferentes qualidades. De fato, a maioria dos estudos focaram em apenas uma ou poucas ameaças isoladas, na escala do fragmento em vez da escala da paisagem e não consideraram as variações na qualidade dos remanescentes. Mamíferos de maior porte são um bom modelo de estudo porque possuem um conjunto de características que os tornam particularmente vulneráveis a várias ameaças antrópicas. Dada a dificuldade de obter dados sobre estas espécies elusivas em escalas espaciais adequadas, entrevistas com moradores locais vêm sendo cada vez mais usadas para acessar a distribuição de mamíferos de maior porte, e podem fornecer informações confiáveis. Através da estimativa da ocorrência de 15 espécies de mamíferos de maior porte por meio de entrevistas com o chefe de 12 unidades domésticas em cada uma de 20 paisagens em uma região de pós-fronteira de 1 milhão ha na Amazônia, investigamos: (i) que tipo de habitat e em qual escala espacial está associado com a ocorrência das espécies, e (ii) os efeitos, a importância relativa e as interações de quatro ameaças antrópicas - cobertura de habitat, fragmentação de habitat, densidade populacional humana e densidade de estrada - sobre a persistência das espécies. Dados de presença/ausência nos arredores de 227 unidades domésticas foram analisados usando modelos lineares generalizados mistos e seleção de modelos baseada no Critério de Informação de Akaike em duas etapas. A persistência das espécies maiores e ameaçadas não foi necessariamente afetada pela qualidade do habitat, mas elas responderam majoritariamente a cobertura de habitat em escalas maiores. A chance de persistência de todas as espécies - mesmo das duas menores, que não responderam à perda de habitat isoladamente - foi afetada por alguma combinação das quatro ameaças antrópicas. Efeitos aditivos entre as ameaças antrópicas foram mais importantes do que as interações entre elas na determinação da ocorrência de mamíferos de maior porte. Enquanto os efeitos da perda de habitat foram mais fortes do que os efeitos da fragmentação de habitat per se, a densidade de estradas foi tão importante quanto à perda de habitat para a ocorrência das espécies. Por último, não houve um padrão claro em termos do grau de ameaça e do tamanho corpóreo por trás da reposta dos mamíferos de maior porte a ameaças antrópicas combinadas. Nosso estudo sugere que áreas protegidas em terras públicas ou privadas na Amazônia devem ser grandes para assegurar a persistência de mamíferos de maior porte, mas podem incluir mosaicos de florestas primárias e secundárias. Os resultados também ressaltam a necessidade de considerar os impactos acumulados de múltiplas ameaças simultaneamente - em especial, as consequências da expansão da malha viária - em planejamentos e manejos, de maneira a evitar subestimar a chance de extinções. Evitar que paisagens na Amazônia se tornem muito desmatadas e alteradas é fundamental, dado que a persistência até mesmo das espécies mais comuns pode ser prejudicada, afetando um dos serviços ecossistêmicos mais importantes para moradores locais - a carne de caça - e potencialmente erodindo o valor que estes atribuem às florestas
The expansion of human activities is associated to a myriad of anthropogenic threats that affect tropical biodiversity, especially habitat loss and fragmentation, the continued human population growth and the expansion of infrastructure, as roads and highways. Although anthropogenic threats are expected to interact and to create mosaics of patches of varying quality, their additive and interaction effects on biodiversity, as well as the extent native species are able to use remnants of distinct quality, have yet been poorly studied. Indeed most studies focused on only one or few threats in isolation, on the patch rather than the landscape scale and did not considered the varying quality of remnants. Large mammals are a good study model as they have a set of traits that make them particularly vulnerable to several anthropogenic threats. Due to the difficulties in gathering data on these elusive species at adequate spatial scales, interviews with local residents have increasingly being used to access their distribution and can provide reliable information. By estimating the occurrence of 15 large mammal species through interviews with the head of 12 households within each of 20 landscapes across a 1-million ha post-frontier region in Amazonia, we investigated: (i) which habitat type at which spatial scale is associated with species occurrence, and (ii) the effects, relative importance and interactions of four anthropogenic threats - habitat cover, habitat fragmentation, human population density and road density - on species persistence. Presence/absence data across the surroundings of 227 households was analyzed using generalized linear mixed-effects models, and a two-step model selection based on Akaike’s Information Criteria. The persistence of larger and endangered species was not necessarily affected by habitat quality, but they responded to habitat cover mostly at larger spatial scales. The chance of persistence of all species - even the two smallest that were not affected by habitat loss alone - was disrupted by some combination of the four anthropogenic threats. Additive effects between anthropogenic threats were more important than their interaction in determining the occurrence of large mammals. While the effects of habitat loss were stronger than the effects of habitat fragmentation per se, road density was as important as habitat loss to species occurrence. Finally, there was no clear pattern in threat status or body size underlying the response of large mammals to combined anthropogenic threats. Our study suggest that protected areas in public or private lands in Amazonia should be large to secure the persistence of large mammals, but may include mosaics of primary and secondary forest. The findings also highlight the need to take into account the accumulated impacts of multiple threats simultaneously - particularly, the consequences of the expansion of the road network - in planning and management, as a way to avoid underestimating the chance of extinctions. Preventing Amazonian landscapes to become heavily deforested and altered is critical, as the persistence of even common species can be impaired, affecting one of the most important ecosystem services provided to local residents - bushmeat - and potentially eroding the value people attribute to forests

In spite tropical forests are the most important terrestrial global carbon sinks due to carbon storage in aboveground biomass, it is also the primary target of deforestation. The conversion of Tropical forests into anthropogenic areas might disrupt biological flux and also lead to severe microclimatic changes at forest edges. These combined effects can trigger profound changes in plant composition through both high mortality of fragmentation-sensitive species and proliferation of disturbed-adapted species which will ultimately impacts carbon storage. Thus, our main objective in this study was understand the role of human-induced disturbances in modulate the dimension of biomass loss at tropical forests. We applied a systematic literature review searching for empirical evidences that edge effects can drive biomass loss in tropical forests (Chapter 2). Our findings highlighted the gap of knowledge about the pattern and process related to biomass loss in tropical forests. To strengthen this understanding, we formulated a conceptual model linking landscape structure and patch-level attributes to severity of edge effects affecting aboveground biomass. Our model hypothesizes that habitat amount, isolation, time since edge creation, and the synergism between edge distance, patch size, and matrix type are the main drivers of biomass loss in anthropogenic tropical forests. We thus used a large plant dataset (18 503 trees ≥ 10 cm dbh) from 146 sites distributed across four Mexican and four Brazilian rainforest regions to test our conceptual model predictions, specifically the influence of forest cover, site isolation, edge distance, patch size and type of matrix on biomass (Chapter 3). We observed that carbon-rich sites presented species that are typical of old-growth forests (shade-tolerant, large-seeded, zoocoric) contrasting to carbon-poor sites composed by disturbed-adapted species (pioneer occupying the understory). Large shade-tolerant trees (≥ 40 cm dbh) were impacted severely by the combination of forest loss and edge effects. Edge distance, patch size, and the amount of open-matrix strongly influence small shade-tolerant trees (≤ 20 cm dbh). Although our results do not fully corroborate the initial predictions of the conceptual model, they support the idea that landscape composition interact with patch structure and ultimately impacts biomass stocks in fragmented tropical forests. Finally, we further investigated if the disturbance level of the region influences plant-structure responses to forest loss (Chapter 4). Biomass, but not plant density, was affected by forest loss in regions with intermediate disturbance levels, i.e. regions showing a combination of moderate deforestation (20-40% of remaining forest cover) disturbed during the past 30-60 years, high defaunation but harboring relictual populations of large-mammals, and areas mostly composed by heterogeneous matrices. In general, our findings highlight that both landscape composition and patch structure are the main drivers of biomass loss in Neotropical forests, and that the landscape context must be considered to obtain more reliable estimations of carbon emissions due to forest degradation. Landscape planning (e.g. restoration of forest cover) should be included in conservation strategies in order to sustain carbon storage. Moreover, we advocate that conservation initiatives will be less costly and more effective if implemented in areas under intermediate disturbance levels
Apesar das florestas tropicais serem a mais importante fonte mundial de carbono da porção terrestre do globo devido ao armazenamento de carbono na biomassa acima do solo, elas são também o alvo primário do desmatamento. A conversão das florestas Tropicais em áreas antropogênicas pode interromper o fluxo biológico e também levar a severas mudanças microclimáticas na borda dos fragmentos. A combinação desses efeitos pode engatilhar profundas mudanças na composição da vegetação através tanto da mortalidade de espécies sensíveis à fragmentação como também pela proliferação de espécies adaptadas distúrbios, com impactos finais nos estoques de carbono. Assim, o maior objetivo desse estudo foi compreender o papel dos distúrbios induzidos pelo homem na modulação da dimensão da perda de biomassa em florestas Tropicais. Nós aplicamos uma revisão sistemática da literatura procurando por evidências empíricas de que o efeito de borda pode levar a perda de biomassa em florestas tropicais (Capítulo 2). Nossos resultados destacam a lacuna de conhecimento entre padrões e processos relacionados à perda de biomassa em florestas Tropicais. Para fortalecer esse conhecimento, nós formulamos um modelo conceitual conectando estrutura da paisagem e atributos na escala do fragmento à severidade do efeito de borda, e assim afetando a biomassa acima do solo. Nosso modelo hipotetiza que a quantidade de hábitat, o isolamento, o tempo desde a formação da borda e o sinergismo entre tamanho do fragmento, distância da borda e tipo de matriz são os principais condutores de perda de biomassa em florestas Tropicais antropogênicas. Utilizando um grande banco de dados (18 503 árvores ≥ 10 cm dap) provenientes de 146 locais distribuídos em quatro regiões de floresta úmida no México e quatro no Brasil, nós então testamos as predições do nosso modelo conceitual. Especificamente, a influência da cobertura florestal, isolamento, distância da borda, tamanho do fragmento e tipo de matriz sobre a biomassa (Capítulo 3). Nós observamos que áreas com muito carbono apresentaram espécies típicas de florestas maduras (tolerantes ao sombreamento, zoocóricas, com sementes grandes) contrastando com áreas com pouco carbono compostas por espécies adaptadas à distúrbio (pioneiras ocupando o sub-bosque). Árvores grandes tolerantes ao sombreamento (≥ 40 cm dap) foram impactadas severamente pela combinação de perda de cobertura florestal e efeitos de borda. Distância da borda, tamanho do fragmento e a extensão da área de matriz aberta influenciaram fortemente as árvores pequenas tolerantes a sombreamento (≤ 20 cm dap). Apesar dos nossos resultados não corroborarem completamente as predições iniciais do nosso modelo conceitual, eles dão suporte à ideia de que a composição da paisagem interage com a estrutura do fragmento com impactos finais nos estoques de biomassa em florestas Neotropicais. Por fim, nós investigamos se o nível de distúrbio da região pode influenciar nas respostas da estrutura da vegetação à perda de cobertura florestal. Biomassa, mas não a densidade de indivíduos, foi afetada pela perda de cobertura florestal em regiões com nível intermediário de distúrbio, i.e. regiões apresentando uma combinação de níveis moderados de desmatamento (20-40% de cobertura florestal remanescente) em que a perturbação ocorreu ao longo dos últimos 30-60 anos, com alto grau de defaunação mas ainda abrigando populações relictuais de grandes mamíferos e, em sua maioria, compostos por uma matriz heterogênea. Em geral, nossos resultados destacaram que tanto a composição da paisagem como a estrutura do fragmento são os principais condutores de perda de biomassa em florestas Neotropicais e que o contexto da paisagem deve ser considerado para se obter estimativas mais confiáveis de emissão de carbono devido à degradação florestal. O planejamento da paisagem (e.g. restauração da cobertura florestal) deve ser incluído em estratégias de conservação em ordem de sustentar o armazenamento de carbono. Além disso, nós defendemos que iniciativas de conservação serão menos custosas e mais efetivas se implementadas em áreas sob níveis intermediários de distúrbio

Proboscis monkeys (Nasalis larvatus) are endemic to Borneo and live in habitats threatened by land clearance for agriculture, aquaculture and timber. This thesis examines the roles of structural and landscape characteristics on both short- and long-term habitat use through the first application of GPS tags to proboscis monkeys. In a comparison of four home range estimators, biased random bridges provided the best home range estimates given the GPS-collar dataset and landscape characteristics (Chapter 3). Differences in long-term ranging patterns of 10 individuals across a range of forest-block sizes and disturbance levels were examined, as well as daily and seasonal variation in movement and sleeping site selection. Using Light Detection and Ranging (LiDAR) structural metrics of the forest, as well as landscape characteristics, forest with taller canopies, forests in close proximity to river edges were found to be of particular importance to proboscis monkeys, and plantation edges were avoided (Chapter 4). Changes in daily and monthly movements were associated with seasonal changes in rainfall and potential food availability. Movement patterns also changed near forest edges, with faster, more direct movements near agricultural boundaries. Less rainfall, higher temperatures and brighter moon phases correlated with selection of sleeping sites in the forest interior (Chapter 5). By understanding the ranging requirements of proboscis monkeys, drone and GPS collar data were combined to inform conservation policy (Chapter 6). This thesis provides the most in-depth examination of proboscis monkey ecology to date. They appeared more generalist in their home range use and structural habitat requirements than previously realised, suggesting a higher degree of versatility and resilience to habitat loss and degradation. This study provides increased understanding of potential consequences of human-mediated disturbances and can be used to assist in the protection of this charismatic species and the management of degraded landscapes.

Protected areas (PAs) cover 12.9% of Earth’s land, while just 5.8% has strict protection for biodiversity (Earth’s variety of ecosystems, species, and genetic variation). Constraints of size and configuration, mismanagement, anthropogenic pressure, and climate change hamstring the capacity of PAs to conserve biodiversity. Increasingly, studies of biodiversity in human-modified landscapes provide an evidence base to support policies to make land outside of PAs as amenable as possible for biodiversity persistence. I reviewed research on biodiversity in sub-Saharan Africa’s human-modified landscapes within four ecosystem categorizations: rangelands, tropical forest, Cape Floristic Region, and urban and rural built environment. I found potential for humanmodified landscapes to contribute to conservation across ecosystems. Available research could guide policy-making; nonetheless, several issues require further investment, e.g. research deficiencies, implementation strategies, and conflict with biodiversity. I also conducted case studies that could support land-use planning in South Africa’s coastal forest, part of a biodiversity hotspot. By comparing herpetofaunal communities over a land-use gradient, I found old-growth forest harbored the highest richness and abundance. Richness was low in sugar cane cultivation and degraded forest but substantial in acacia woodland and eucalyptus plantation. Composition differed between natural and anthropogenic vegetation types. Functional group richness decreased monotonically along the gradient, driven by sensitivity of fossorial herpetofauna and vegetation-dwelling frogs. Environmental variables were good predictors of frog abundance, but less so for reptiles. Maintaining forest and preventing degradation is important for herpetofaunal conservation while restoration and plantations have more value than cultivation. Old-growth remnants and post-disturbance regenerating vegetation also provide habitat for birds. However, occurrence does not ensure persistence. I calculated population trends for 37 bird species and general trends in overall bird density in different vegetation types. Seventy-six percent of species assessed have declined, 57% significantly so at an average rate of 13.9% per year. Overall, bird density fell at 12.2% per year across vegetation types. Changes in rainfall, habitat area, and survey coverage may partly explain trends. However, species with larger range extents declined more sharply than others and may be responding to environmental changes on a broad scale. These results cast doubt on the future persistence of birds in this human-modified landscape and justify further study. Such studies can support sensible land-use management; however, biases in study topics should not lead to gaps in the evidence base. By reviewing the global literature, I demonstrated clear geographical bias among biomes and geopolitical regions and taxonomic bias among species groups. Furthermore, distribution of published papers did not generally reflect threats of low PA coverage, high land conversion, and high human population density. Forests were the subject of 87% of papers, and 75% focused on the Americas and Europe, while Africa and Asia were critically understudied. This thesis highlights that managing human-modified landscapes for biodiversity could contribute to conservation. However, responses to land uses are complex, locationand species-specific, and often poorly understood, hindering integration of information into policy recommendations. Further research is needed to elucidate what, where, and how biodiversity persists alongside humans to enhance conservation efficacy, especially in understudied regions.
Thesis (PhD)--University of Pretoria, 2014.
gm2014
Zoology and Entomology
unrestricted

Anthropogenic infrastructure such as roads, ditches and culverts have strong impacts on hydrological processes, particularly surface drainage patterns. Despite this, these structures are often not present in the digital elevation models (DEMs) used to provide surface drainage data to hydrological models, owing to the coarse spatial resolution of many available DEMs. Modelling drainage patterns in human-modified landscapes requires very accurate, high-resolution DEM data to capture these features. Light Detection And Ranging (LiDAR) is a remote sensing technique that is used for producing DEMs with fine resolutions that can represent anthropogenic landscapes features such as human modifications on the landscape such as roadside ditches. In these data, roads act as a barrier to flow and are treated as dams, where on the ground culverts and bridges exist. While possible to locate and manually enforce flow across these roads, there is currently no automated technique to identify these locations and perform flow enforcement. This research improves the modelling of surface drainage pathways in rural anthropogenic altered landscapes by utilizing a novel algorithm that identifies ditches and culverts in LiDAR DEMs and enforces flow through these features by way of breaching. This breaching algorithm was tested on LiDAR datasets for two rural test sites in Southern Ontario. These analyses showed that the technique is an effective tool for efficiently incorporating ditches and culverts into the hydrological analysis of a landscape that has both a gradient associated with it, as well as a lack of densely forested areas. The algorithm produced more accurate representations of both overland flow when compared to outputs that excluded these anthropogenic features all together.

This thesis aimed to contribute new information and analytical frameworks to the science of fauna conservation in human-modified landscapes. Two approaches were used: (1) empirical data collection and analysis, and (2) the discussion and development of conceptual landscape models. ¶ Empirical work focused on lizard distribution patterns in two production landscapes in southeastern Australia. Lizards were targeted because ectotherms are frequently neglected by conservation biologists. The “Nanangroe grazing landscape” was used for sheep and cattle grazing. Lizards were surveyed at 16 landscape units, which were stratified by aspect, topographic position and amount of tree cover. ... ¶ The “Tumut plantation landscape” was a spatial mosaic of native eucalypt (Eucalyptus) forest patches embedded within a plantation of the introduced radiata pine (Pinus radiata). In this landscape, thirty sites were surveyed for lizards. ...

Landscape modification is a major global threat to terrestrial biodiversity. Managing human-modified landscapes in ecologically sustainable ways is crucial to avoid and mitigate biodiversity loss. However, practitioners (e.g. policymakers and developers) still urgently require research to inform targeted habitat protection policies, on-the-ground land management practices, and biodiversity offset strategies. My research focused on identifying ways to strategically maintain and perpetuate habitat structures for wildlife in modified landscapes. I had three objectives: (1) measure and compare the current and future availability of habitat structures; (2) quantify the biodiversity value of scattered trees; and (3) test the effectiveness of artificial nest boxes as a biodiversity offset tool. First, I conducted vegetation surveys at 300 plots in three dominant landscape contexts (reserves, pasture, urban greenspace). I found that in urban greenspace, the availability of multiple habitat structures (e.g. trees, logs, shrubs) depended upon by biota were significantly reduced compared with reserves, but comparable with agricultural land. Using a simulation model for tree populations, I also found that hollow-bearing trees were predicted to decline by an average of 87% in urban greenspace over the next 300 years under existing tree management policies. I identified that only a combination of tree management approaches can arrest this decline. Second, I completed wildlife surveys at 72 individual trees of three sizes (small, medium, large) located in four landscape contexts (reserves, pasture, urban parklands, urban built-up areas). I recorded high invertebrate, bat and bird abundance and richness at scattered trees, representing a diversity of functional guilds. Furthermore, the biodiversity value of scattered trees in modified landscapes, including even small trees, was comparable or greater than that of trees located in reserves. I also found that several smaller trees could provide habitat compensation equivalent to that of a single large tree for some bird species and in certain landscape contexts (reserves and urban built-up areas). However, this was not a suitable offset strategy for a quarter of bird species and in other landscape contexts (pasture and urban parklands). Finally, I conducted an experiment using 144 nest boxes with different entrance sizes (20, 35, 55, 75, 95 and 115 mm), secured to trees of three sizes (small, medium, large) located in four landscape contexts (reserves, pasture, urban parklands, urban built-up areas). I found that adding nest boxes to large trees resulted in an increase in tree visitation by hollow-nesting birds. However, the same response was not observed at small, medium or control trees. Nest boxes were also only occupied by common native and exotic species and are thus unlikely to be effective at ameliorating the residual impacts of hollow-bearing tree removal, especially for threatened taxa. Based on my collective findings, I recommend: (1) adopting spatial zoning tactics that aim to resolve human-habitat conflicts and retain multiple habitat structures; (2) prioritising the conservation of scattered trees over the long-term by balancing both re-vegetation and mature tree preservation strategies; and (3) exercising caution in the wide-scale application of nest box offsets. These recommendations could assist practitioners in establishing more biodiversity-sensitive modified landscapes.