Darwin's "Principle of divergence" and the link between biodiversity and ecosystem functioning

Urbanisation is increasing worldwide and regarded a main driver of environmental change. Urban development and associated factors like increased spatial isolation, reduced habitat size and various types of disturbances can alter the dynamics of plant and animal populations in the remaining green areas. Furthermore, changes in abiotic site conditions (e.g. temperature, moisture content) can influence habitat quality and, consequently, the species richness, species composition and functional diversity of plants and animals, which in turn can affect the functioning of ecosystems. Nonetheless, urban areas can harbour a remarkably high species richness and can be of high conservation value by serving as a refugia for many rare and threatened species. It is, therefore, of central importance in conservation biology to disentangle the various drivers of biodiversity in urban landscapes. Within the scope of this thesis, three studies were conducted to examine the consequences of urbanisation on the biodiversity and ecosystem functioning of green areas in the urban region of Basel, Switzerland.
\nThe aim of the first study was to assess the impacts of habitat size and landscape composition of the closer surroundings on the species diversity of three taxonomic groups differing in trophic rank (vascular plants, Orthoptera and Lepidoptera) in meadows and ruderal sites. I also related the response of three traits (body size, dispersal ability and food specialisation) to habitat size in Orthoptera and Lepidoptera. For this purpose, I analysed data of species from the natural heritage inventory of Basel. I found that the response of different groups of species considerably varied depending on the habitat type, taxonomic group and species trait examined. The species richness of Orthoptera and Lepidoptera was positively related to meadow size but not to the size of ruderal sites, while the opposite was true for plants. For Lepidoptera in ruderal sites, the percentage of ruderal sites in the closer surroundings was a better predictor of species richness than habitat size per se.
\nForests belong to the most frequent green areas in urban landscapes and provide a wide range of ecosystem functions and thus play a major role for human well-being in cities. The aim of the second study was to examine the potential effects of degree of urbanisation, forest size and the corresponding interaction on the species diversity and functional diversity of vascular plants, ants and spiders. The two arthropod groups do not show species-specific mutualistic or exploitative relationships with plants in contrast to those in the first study. I conducted vegetation surveys and pitfall trapping to sample soil surface-active ants and spiders. In plants, species richness decreased with the degree of urbanisation. Ants and spiders at higher trophic rank showed more pronounced shifts in species composition with increasing degree of urbanisation, while the percentage of forest specialists in both arthropod groups was positively related to forest size. Local site characteristics were also important determinants for species diversity and functional diversity. 
\nIn forests, the decomposition of leaf litter is an important component of the process of nutrient cycling and the formation of soil. In this way, litter decomposition contributes to the maintenance of several other ecosystem functions and services. The third study aimed to investigate the effects of urbanisation on leaf litter decomposition process in forests. Standardised litter of Fagus sylvatica leaves was used to assess the impact of urbanisation-related factors on the early stage of decomposition and seasonal microbial activity. I found combined effects of degree of urbanisation and forest size on the decomposition rate of leaf litter (klitter) indicating that forests of similar size differed in abiotic and biotic forest characteristics depending on the degree of urbanisation in the closer surroundings. Furthermore, moisture content of litter was the best predictor of microbial activity, followed by forest size.
\nThe findings of this thesis highlight the necessity to consider different taxonomic groups and functional groups in urban planning to maximise conservation value of urban green areas. In addition to degree of urbanisation, also habitat size was important for the diversity of some groups and leaf litter decomposition process in forests. It was also encouraging to find that even small green sites have the potential to make a significant contribution to biodiversity conservation and essential ecosystem functions in urban landscapes. I recommend that urban planners develop more flexible management strategies to satisfy the different requirements of various groups of species in the corresponding habitat type. Locally adapted management practices may provide a way forward to enhance habitat quality in a way to maximise species diversity and thus ensure the functioning of ecosystems; albeit large-scale factors also remain important.
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The link between biodiversity and ecosystem functioning is a relatively new research area motivated by forecasts of ongoing biodiversity loss. However, the intellectual link between biodiversity and ecosystem processes was first inferred by Darwin based on his Principle of Divergence. In the notes for his Big Species Book Darwin explicitly states that communities composed of organisms developed under many and widely differing forms should have higher rates of productivity and decomposition. Darwin also cites supporting evidence in the form of the Hortus Gramineus Woburnensis: a grass garden at Woburn Abbey in the South of England that arguably contains the earliest known ecological experiments.

Impacts of invasive plants on soil fungi and on above- and belowground plant diversity in temperate forests

The last two decades have seen a shift of emphasis in ecology; from a focus on the drivers of biodiversity change toward a consideration for its effects on ecosystem functioning. Ecosystem functioning is affected by individual species (i.e. species with functionally dominant biological traits), but can also be influenced by other factors, such as interspecific interactions. Current evidence suggests that biotic influence over marine ecosystem functioning is largely underpinned by the effects of individual species. However, there are indications that this might not constitute a complete understanding of the link between marine biodiversity and ecosystem function (BEF). For this thesis, I applied our current understanding of marine BEF relationships (i.e. the causal link between particular biological traits and particular ecological functions) to long-term benthic community time series and investigated the causes of ecological change and its consequences for ecosystem functioning. A shift in the taxonomic composition of the species assemblage was explained by underlying variation in extrinsic drivers. However, the long-term conservation of trait composition suggests that functioning can be sustained in the face of environmental and ecological change. Experiments conducted to test BEF relationships in intertidal marine benthos reaffirmed the functional importance of the biological traits of species, but also showed that interactions among species can influence the delivery of ecological functions in various ways, including facilitation (i.e. function delivery is enhanced) and antagonism (i.e. function delivery is reduced). The results suggest that biotic influence over marine ecosystem functioning is more complex than previously suggested, and that the impacts of biodiversity change (e.g. species extinctions or shifts in species densities) could be either exacerbated or mitigated depending on the composition of the affected assemblage and the ecological function considered. To produce more realistic results, future indirect assessments of ecosystem functioning would benefit from incorporating interactions among species as well as their biological traits.

Quantifying responses of aquatic insects to environmental change

In the current decade, the main goals for biodiversity conservation and environmental protection at the level of the European Union are set in the EU Biodiversity Strategy to 2020: halting biodiversity loss and restoring ecosystem services. A key requirement for the implementation of the Strategy in terms of targeting measures and funds, and monitoring trends is the construction of a biodiversity knowledge base, including spatially explicit information on biodiversity distribution and ecosystem condition. The work presented in this report is based on the analysis of two primary datasets on biodiversity and habitat status. The first one is the Habitats assessment carried out by EU Members States under Art.17 of the Habitats and Birds Directive. Information reported by Member States is analysed to derive the links between pressures and conservation status, showing that agriculture-related habitats have, on average, a worse conservation status when compared to other habitats. Consequently, threats and pressures having most influenced the status of the agricultural-related habitats can be identified. The second one is the global dataset on species threat status elaborated by The International Union for Conservation of Nature (IUCN). Spatially explicit representations of species distribution, status and richness across the EU 28 are provided, and most importantly the identification of wide geographic variables linked to ecological theory is presented, that explain to a large extent the continental trend in species richness. Finally, an example is presented of how the two exploited datasets can be jointly used by cross-tabulating data on habitats assessments and species threat status in a spatially explicit way at 10 km resolution, aiming at identifying hotspots were policy intervention is needed

Biodiversity and ecological functioning of mudflat macrofauna in the Anthropocene

The conversion of natural habitats into agriculture ones and the simplification of the structure of landscapes are the main causes of the global loss of biodiversity. Agroecosystems, especially monocultures, normally provide food resources and benefit organisms only when surrounded by forests. Mites (Arachnida: Acari) are one of the most diverse groups of arthropods and contribute to the function of ecosystems and agroecosystems. We aimed at determining the response of the coffee mite community to the distance from adjacent forest fragments. We evaluated leaves of coffee shrubs which were naturally found in the interior (0 m) and edge (25 m) of the fragments and in full sun coffee plantations located at 50 and 100 m in relation to the interior of the fragments. Although there was no pattern of reduction of mite abundance in relation to the distance from the centre of the forest fragments according with linear regressions, faunistic analyses revealed that abundance, dominance and frequency levels for some mite families were influenced by the distance from the centre of the forest fragments.

Achieving global biodiversity goals by 2050 requires urgent and integrated actions

Relationship between mangrove forest diversity and ecosystem function

Indian Himalaya Region is regarded as highly fragile and vulnerable mountain ecosystems but represents a complex array of physical and geo-political environment, well known for geo-hydrological, biological, aesthetic and cultural values. Owing to a unique bio-geographic location i.e., at the junction of Palaearctic and Indo-Malayan Realms, wide altitudinal range, topographic variation and numerous habitats, the ecosystem harbours a rich array of flora and fauna. Notwithstanding the apparent remoteness and inaccessibility, much of the IHR has suffered from human-induced biodiversity loss. Steady increase in human population has been responsible for extensive clearing of forests and grasslands for cultivation, and extensive logging and extraction of timber. The situation has further aggravated with climate change resulting in loss of perpetual ice resources. Thus, environmental security is essential for the conservation of biodiversity and to management of natural resources in Himalayan mountain ecosystem. It started with sustainable development approach but, there are always exceptions which require careful management of political man and environment relations. Environmental security has potential to contribute significantly to biodiversity conservation, protection and natural resource management. Geopolitics of India‟s Policy toward achieving environmental security particularly focuses on reducing any adverse impact on Himalayan ecosystem. In the present paper an analysis of the different dimension of Himalaya n ecosystem and geopolitical perspective of environmental security issues has been done with the objective to monitor and evaluate the impact of anthropogenic interventions in Himalayan ecosystem and to identify the issues and problems that affects the future sustainability of Himalayan mountain environment. Key Words: Environmental security, Himalayan ecosystem, geopolitics, biodiversity conservation.

Direct, manipulative experiments can yield important insights into the role of biodiversity in ecosystem function, but they are intrinsically limited when it comes to aspects of this relationship that emerge over long temporal and large spatial scales. Natural experiments with model systems can be a powerful complement to direct, manipulative experiments, especially where the processes that regulate biodiversity have no more than modest direct impacts on ecosystem function. Mangrove ecosystems on continental land masses and isolated islands offer unusual potential as natural experiments for biodiversity and ecosystem function studies, largely because sites with similar physical environments can have clear contrasts in the diversity of the dominant autotrophs. These contrasts provide a starting point for exploring the role of species diversity of higher plants in modulating biogeochemical functions (e.g. production, nutrient cycling), ecological functions (e.g. habitat for organisms in different tropic levels), and anthropogenic functions (e.g. maintenance of fisheries, management of sediments), on a range of time scales.

The importance of declining mammalian fungal specialists for ectomycorrhizal fungal dispersal

Constructed wetlands remove nutrients, contaminants and pollutants from stormwater runoff, while also providing a habitat for wildlife such as macroinvertebrates and fish. Sampling constructed wetlands along a gradient of catchment urbanisation in Melbourne’s west and south east, my overall aim was to determine if increasing catchment imperviousness was related to wetland condition. To address this, I sampled macroinvertebrates to quantify biodiversity, tested fish tissue for heavy metal concentrations to ascertain if bioaccumulation was occurring, used stable isotope analysis to construct food webs, and evaluated ecosystem function using leaf packs to assess rate of decomposition. There was a significant negative relationship between total imperviousness (TI), an indicator of catchment urbanisation, and the abundance of aquatic invertebrates detected for sites in the west, but not in the south east. However, macroinvertebrate communities were relatively homogenous both within and between all study wetlands. Chironomidae (non-biting midges) was the most abundant family recorded at the majority of sites. Chironomids are able to tolerate a wide array of environmental conditions, including eutrophic and anoxic conditions. Their prevalence suggests that water quality is impaired in these systems, regardless of degree of urbanisation, although the causal mechanism is unclear. There was no relationship between TI and water and sediment concentrations of heavy metals with the exception of Zn. Concentrations of metals in fish tissues were highest in benthic species but levels declined with increasing body size and trophic level. Metabolic activity can differ between smaller and larger fish; however, smaller fish may also be feeding on a different food source. My results suggest that metals in these wetlands are not undergoing bioaccumulation. I found that as TI increased, there was a significant decrease in the abundance and diversity of macroinvertebrates and a significant increase in the values of δ13C and δ15N recorded for fishes and macroinvertebrates. An increase in TI was associated with a decrease in the mean trophic position of fishes and an increase in the mean trophic position of macroinvertebrates. My results suggest that sources of carbon differed between sites of low and high catchment imperviousness. A significant positive relationship existed between TI and rate of leaf litter breakdown in the south eastern wetlands. These results suggest that other parameters besides exposure to contaminants are likely to affect leaf litter breakdown. The overall findings of this study demonstrate that local conditions in wetlands such as morphology and vegetation, have at least as important a role in determining wetland biodiversity and ecosystem function as the degree of urbanisation of the catchment.

counts were not different among NH 4 + treatments and may reflect the need to query functional responses with other methodologies.Broadly, microbial-algal competitive interactions likely play an important role in net community interactions, the fixation of carbon, and the fate of nitrogen.PC1 -Percent variation explained 34.22% PC2 -Percent variation explained 26.23% PC1 -Percent variation explained 52.05% PC2 -Percent variation explained 22.21% PC1 -Percent variation explained 34.01%PC2 -Percent variation explained 23.38% PC1 -Percent variation explained 56.41% PC2 -Percent variation explained 16.52% 2013 2014 PC1 -Percent variation explained 27.78% PC2 -Percent variation explained 19.80% PC1 -Percent variation explained 48.34% PC2 -Percent variation explained 19.61% PC1 -Percent variation explained 13.00% PC2 -Percent variation explained 8.52% PC1 -Percent variation explained 16.84% PC2 -Percent variation explained 8.14%Taxa MDS1 MDS2 Costaria costata -0.490.15 Ralfsia verrucosa -0.490.15 Cymathere triplicata -0.46 0.18 Alaria sp.-0.31 0.02 Fucus gardneri -0.24 0.14 Nemertean worm -0.24 -0.14 Porphyra sp.-0.24 0.26 Barnacle recruits -0.22 0.27 Palmaria palmata -0.21 -0.10 Mazzaella splendens -0.20 -0.14 Leathesia difformis -0.20 0.30 Cryptosiphonia woodii -0.20 0.28 Halosaccion glandiforme -0.20 0.20 Mastocarpus crust -0.19 0.03 Desmarestia ligulata -0.19 -0.23 Phyllospadix serrulatus -0.18 0.25 Microcladia borealis -0.18 0.07 Odonthalia floccosa -0.18 -0.14 Endocladia muricata -0.17 0.15 Egregia menziesii -0.17 -0.16 Aplidium sp.-0.17 -0.24 Mastocarpus papillatus upright -0.17 -0.08 Bryozoans -0.17 -0.13 Saccharina sessile -0.16 -0.03 Osmundea sp.-0.15 -0.22 Cryptopleura ruprechtiana -0.14 -0.16 Ulva sp.-0.13 0.04 Orange sponge -0.12 -0.09Saccharina latissima -0.11 -0.21 Green sponge -0.11 -0.06 Semibalanus cariosus -0.09 -0.12 Urticina crassicornis -0.08 -0.01 Leptosynapta sp.-0.08 0.14 Juvenile Cancer sp.-0.07 -0.04 Katharina tunicata -0.07 0.05 Henricia leviuscula -0.06 -0.21 Corallina sp.-0.06 -0.02 Acmea mitra -0.04 -0.19 Eudistylia vancouveri -0.03 -0.13 Desmarestia viridis -0.03 -0.23 Leptasterias sp.-0.01 0.