Biodiversity and ecosystem service losses driven by land-use change are expected to intensify as a growing and more affluent global population requires more agricultural and forestry products, and teleconnections in the global economy lead to increasing remote environmental responsibility. By combining global biophysical and economic models, we show that, between the years 2000 and 2011, overall population and economic growth resulted in increasing total impacts on bird diversity and carbon sequestration globally, despite a reduction of land-use impacts per unit of gross domestic product (GDP). The exceptions were North America and Western Europe, where there was a reduction of forestry and agriculture impacts on nature accentuated by the 2007-2008 financial crisis. Biodiversity losses occurred predominantly in Central and Southern America, Africa and Asia with international trade an important and growing driver. In 2011, 33% of Central and Southern America and 26% of Africa's biodiversity impacts were driven by consumption in other world regions. Overall, cattle farming is the major driver of biodiversity loss, but oil seed production showed the largest increases in biodiversity impacts. Forestry activities exerted the highest impact on carbon sequestration, and also showed the largest increase in the 2000-2011 period. Our results suggest that to address the biodiversity crisis, governments should take an equitable approach recognizing remote responsibility, and promote a shift of economic development towards activities with low biodiversity impacts.

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.

In the last few decades, a growing literature has examined how biodiversity influences ecosystem functioning. This body of work has greatly improved our understanding of ecosystem functioning and its modulation by biodiversity. In particular, there is nowadays large consensus that biodiversity increases ecosystem productivity, and stabilises ecosystems. Early investigations were largely theoretical or involved simple experiments run in laboratory conditions, but over time biodiversity ecosystem-functioning experiments evolved to more realistic field experiments that better represent the real conditions found in natural ecosystems. In particular, these experiments are often run on larger spatial scales and over longer time frames allowing for the effect of environmental heterogeneity and temporal fluctuations to be explored. The designs of these experiments evolved along with the questions addressed in this field of research. However, the analytical tools used in the analyses of these experiments followed a slightly different path. In particular, most of the metrics currently used to analyse biodiversity ecosystem functioning experiments are not entirely suited to properly deal with the complexity of modern designs as they make a number of assumptions that are not met any more. In my thesis I developed a unified framework, based on the tailored use of Linear Mixed Effects Models, to analyse biodiversity-ecosystem functioning experiments such that the new complexities of these experiments can be taken into account. This thesis aimed to bring the focus of the analysis back to the biological interpretation of the results. I successfully applied my approach to several data sets. The framework developed here is expected to improve greatly our understanding of ecosystem functioning and how biodiversity modulates it. It also sheds new light on past research in this field. The great flexibility of the new approach makes it possible to let these experiments to evolve such that new biological questions can be addressed.

In this article we develop a comprehensive conceptual framework for resource efficiency indicators with a consistent link of resource use to the socio-economic system and activities therein as well as to the natural system and its ecosystem functioning. Three broad groups of indicators are defined: (1) resource use indicators representing pressures on the environment; (2) resource efficiency indicators relating resource use indicators to the socio-economic side; and (3) environmental impact indicators linking resource use impacts on the state of the natural system. Based on this conceptual framework we develop a structure for possible resource efficiency indicators and conduct a RACER evaluation on the Relevance, Acceptance, Credibility, Easiness and Robustness of indicators. With the RACER evaluation, we identify areas where indicators are well established and available as well as areas where indicators still need further development or even need to be designed first.

Increasing human populations results in fast-growing urbanization. Natural and semi-natural landscapes are replaced with urban landscape features like roads, sidewalks, industrial and residential buildings. The remnants of the natural landscapes are left fragmented and are often managed by frequent mowing and trimming of the vegetation. This development has had a negative impact on pollinators such as bees and wasps. Bees and wasps are pollinating insects providing an ecosystem service that sustain the global food supply. Pollinators are important also in urban landscapes where their services are needed for ecological stability and biodiversity. This study compares 23 locations in Sollentuna municipality, to investigate if species richness and abundance of bees and wasps are correlated with local factors, landscape factors or both. The available food resources are measured in buffer zones with 200m radius. Local variables are: dead wood, exposed sand, extended edge zones, flowering plant species richness and unmanaged habitat. The result showed that the landscape factor of food availability was more important for the abundance of pollinators while local variables together with the landscape factor of food availability had a positive effect on the species richness.

Root processes – decomposition, production, and mortality – are intrinsic parts of ecosystem carbon cycling and yet have been understudied in the context of biodiversity-ecosystem functioning relationships. In a long-term grassland diversity experiment (the Jena Experiment), I investigated (1) whether and how plant diversity affected root decomposition and (2) how plant diversity enhanced standing root biomass and influenced root turnover. Plant diversity may affect root decomposition via three non-mutually exclusive pathways: (1) root litter quality, (2) soil biota, and/or (3) soil abiotic conditions. In Chapter 3, via three decomposition experiments, I demonstrate that plant species richness negatively affects root decomposition via the root litter quality pathway and the soil environment pathway (including soil biotic and abiotic conditions). The presence of grasses negatively affects root decomposition while the presence of legumes positively affects root decomposition. In Chapter 4, I further explored the pathways driving the relationship between plant diversity and root decomposition using structural equation modeling. The final structural equation model suggests that root chemistry is a universal pathway for explaining the effects of plant diversity on root decomposition and that Oribatida are also involved in root decomposition. Most importantly, I directly show that different measures of plant diversity influence root decomposition via different pathways. In Chapter 5, I shift my focus to root production and mortality which collectively determine standing root biomass. I monitored in situ root dynamics biweekly for one growing season using minirhizotrons. I show that plant species richness consistently enhances standing root length throughout the observational period. However, plant species richness did not affect rates of root length production, mortality, or turnover. Only root lifespan increased with increasing plant species richness. The lack of significant diversity effect on root length-based measures may be due to the age of the studied communities. In mature grasslands, plant species richness may only have a minor effect on root turnover and one growing season may be too short to detect such a small effect. The results of this dissertation collectively provide new insights into the relationship between plant species richness and soil carbon stock in mature grasslands. Based on the new paradigm of soil carbon formation, plant species richness may enhance soil carbon stock through a greater input of partially decomposed root residuals (reduced root decomposition) and a higher input of root exudates (increased standing root biomass).:ACKNOWLEDGEMENTS .......................................................................................III 1 GENERAL INTRODUCTION ............................................................................... 1 1.1 Biodiversity-Ecosystem Functioning Research in the Context of Global Biodiversity Loss ……........................................................................................... 1 1.2 Biodiversity-Ecosystem Functioning Relationships .............................................................................................................................. 2 1.3 Effects of Plant Diversity on Decomposition ................................................... 6 1.4 Effects of Plant Diversity on Root Turnover .................................................. 10 1.5 Scope and Contents of this Dissertation ...................................................... 14 2 GENERAL METHODS ......................................................................................17 2.1 The Jena Experiment ................................................................................... 17 2.2 Root Decomposition Experiments ................................................................ 18 2.3 Applying Structural Equation Modeling to Understand the Diversity-Decomposition Relationships ............................................................................. 22 2.4 In-situ Monitoring of Root Turnover Using Minirhizotrons ............................. 25 3 PLANT SPECIES RICHNESS NEGATIVELY AFFECTS ROOT DECOMPOSITION IN GRASSLANDS ................................................................................................27 4 ROOT CHEMISTRY AND SOIL FAUNA, BUT NOT SOIL ABIOTIC CONDITIONS EXPLAIN THE EFFECTS OF PLANT DIVERSITY ON ROOT DECOMPOSITION..44 5 THE EFFECTS OF PLANT SPECIES RICHNESS ON ROOT TURNOVER IN EXPERIMENTAL GRASSLANDS...........................................................................74 6 GENERAL DISCUSSION..................................................................................105 6.1 Summary of Contents in this Dissertation.................................................... 105 6.2 Advancing Our Understanding of Root Decomposition in BEF Research.... 106 6.3 Time Matters for the Diversity–Root Turnover Relationship......................... 112 6.4 Outlook........................................................................................................ 117 REFERENCES...................................................................................................120 SUMMARY .........................................................................................................137 ZUSAMMENFASSUNG .......................................................................................142 LIST OF PUBLICATIONS....................................................................................148 AUTHOR CONTRIBUTION STATEMENTS..........................................................150 DECLARATION OF INDEPENDENT WORK........................................................159 CURRICULUM VITAE .........................................................................................160

Ecological opportunity—the availability of open niche space to an evolving lineage—has long been thought to modulate the extent of adaptive diversification. Many microbial evolution experiments have confirmed that ecological opportunity drives diversification of initially homogeneous populations into communities of ecologically distinct sub-lineages (ecotypes). Interactions among ecotypes are crucial for both community function and the maintenance of the ecological diversity produced during adaptive diversification, however the factors influencing the evolution of these interactions remain unexplored. We assessed the influence of ecological opportunity on this process by studying communities of the bacterium Pseudomonas aeruginosa that were evolved in either nutritionally complex (COM) or simple (SIM) environments. We measured the net ecological interactions in these communities by comparing the cellular productivity and competitive fitness of whole communities from each environment to that of their component isolates in both complex and simple media. On average, COM communities had both higher productivity and fitness than their component isolates in complex media, indicating that the components of these communities share net positive interactions. The same was not true of SIM communities, which did not differ in either measure from their component isolates. Follow-up experiments revealed that high fitness in two COM communities was driven by rare variants (frequency < 0.1%) that secrete compounds during growth which inhibit PA14, the strain used as a common competitor for fitness assays. Taken together, our results suggest that environments with high levels of ecological opportunity drive diversification into ecotypes that share net positive ecological interactions. The strong effect of diversity on productivity and fitness we found in newly diversified communities has a number of implications for evolutionary ecology as well as the treatment of P. aeruginosa infections.

The relationship between biodiversity and ecosystem functioning (BEF) is a central issue in soil and microbial ecology. To date, most belowground BEF studies focus on the diversity of microbes analyzed by barcoding on total DNA, which targets both active and inactive microbes. This approach creates a bias as it mixes the part of the microbiome currently steering processes that provide actual ecosystem functions with the part not directly involved. Using experimental extensive grasslands under current and future climate, we used the bromodeoxyuridine (BrdU) immunocapture technique combined with pair-end Illumina sequencing to characterize both total and active microbiomes (including both bacteria and fungi) in the rhizosphere of Trifolium pratense. Rhizosphere function was assessed by measuring the activity of three microbial extracellular enzymes (β-glucosidase, N-acetyl-glucosaminidase, and acid phosphatase), which play central roles in the C, N, and P acquisition. We showed that the richness of overall and specific functional groups of active microbes in rhizosphere soil significantly correlated with the measured enzyme activities, while total microbial richness did not. Active microbes of the rhizosphere represented 42.8 and 32.1% of the total bacterial and fungal taxa, respectively, and were taxonomically and functionally diverse. Nitrogen fixing bacteria were highly active in this system with 71% of the total operational taxonomic units (OTUs) assigned to this group detected as active. We found the total and active microbiomes to display different responses to variations in soil physicochemical factors in the grassland, but with some degree of resistance to a manipulation mimicking future climate. Our findings provide critical insights into the role of active microbes in defining soil ecosystem functions in a grassland ecosystem. We demonstrate that the relationship between biodiversity-ecosystem functioning in soil may be stronger than previously thought.

No description available.

The loss of biodiversity is affecting all ecosystems on Earth, one of the greatest threats to biodiversity being climate change. Forests have been highlighted for the potential to mitigate climate change by storing carbon above- and belowground in soils. In this thesis, I studied the effects of tree diversity on carbon cycling in subtropical Chinese forests. I aimed to explore the mechanisms behind tree diversity effects on carbon cycling by focusing on microbial-based processes and the consequences of tree diversity-induced spatial heterogeneity. First, my colleagues and I tested the effects of tree diversity on litterfall spatial patterns and the consequences for litter decomposition and quantified the importance of microbial community in decomposition processes. Second, we explored the effects of tree diversity on relationships between soil microbial facets and soil microbial functions. Third, we tested the effects of tree diversity on soil microbial biomass and carbon concentrations, and their mediation by biotic and abiotic conditions. Finally, we explored the consequences of diversifying forests for re-/afforestation initiatives and plantations to reduce atmospheric carbon levels, and the benefits of diversity for mitigating the effects of climate change on ecosystems and human well-being. We highlighted the positive effects of tree diversity on tree productivity. By increasing the amount and diversity of litterfall, tree diversity increased litter decomposition and subsequently the assimilation of tree products into the forest soils. Our investigation has shown the key role of microbial communities for forests carbon dynamics by carrying out litter decomposition, soil heterotrophic respiration, and soil carbon stabilization. Most notably, tree diversity effects on soil microbial respiration were mainly mediated by soil microbial biomass rather than soil microbial community taxonomic or functional diversity. The effects of tree diversity on microbial biomass were mediated by biotic and abiotic conditions. Taken together, we revealed the importance of considering space to understand biodiversity-ecosystem functioning relationships. Finally, we argued that tree diversity is a promising avenue to maximize the potential of re-/afforestation projects to mitigate increasing atmospheric carbon. Moreover, we highlighted that diversifying forests in re-/afforestation initiatives can help to reduce climate change effects on ecosystems: first, by increasing resistance and resilience to extreme climatic events, and second, by buffering microclimatic conditions in natural and urban areas. My investigation highlighted that tree diversity effects on ecosystem functioning could be explained by both mass and diversity effects on higher trophic levels and their functions. In addition, I showed the key role of tree diversity-induced spatial heterogeneity and the need to consider space and time in further research. Moreover, these results need to be combined with practitioner constraints to enable feasible restoration projects.:Summary table Bibliographic information .................................................................................... I ~ XV Main body ......................................................................................................... 1 ~ 212 Supplementary materials ..................................................................................... i ~ xv Scientific supplementary materials ............................................................. -1- ~ - 154- Table of Contents Table of figures .......................................................................................................... XI Table of scientific supplementary materials ............................................................. XIII Glossary ................................................................................................................... XV Introduction ................................................................................................................. 3 Chapter I - Tree diversity effects on litter decomposition are mediated by litterfall and microbial processes .................................................................................................. 35 Transition I - II ........................................................................................................... 67 Chapter II - Tree diversity and soil chemical properties drive the linkages between soil microbial community and ecosystem functioning................................................ 71 Transition II - III ....................................................................................................... 107 Chapter III - Abiotic and biotic drivers of scale-dependent tree trait effects on soil microbial biomass and soil carbon concentration ................................................... 111 Transition III - IV ..................................................................................................... 155 Chapter IV – Diverse forests are cool: promoting diverse forests to mitigate carbon emissions and climate change ............................................................................... 159 General discussion ................................................................................................. 173 Abstract .................................................................................................................. 195 General acknowledgments ..................................................................................... 209 Supplementary materials ..............................................................................................i