Showing papers by "Andy Hector published in 2018"
University of Zurich1, Alexander von Humboldt Biological Resources Research Institute2, Lüneburg University3, Dresden University of Technology4, Chinese Academy of Sciences5, Martin Luther University of Halle-Wittenberg6, Leipzig University7, University of Freiburg8, University of Tübingen9, Helmholtz Centre for Environmental Research - UFZ10, East China Normal University11, Wenzhou University12, University of Kiel13, Peking University14, University of Bern15, University of Minnesota16, University of Oxford17, Central South University Forestry and Technology18, Zhejiang University19, Zhejiang Normal University20
TL;DR: The first results from a large biodiversity experiment in a subtropical forest in China suggest strong positive effects of tree diversity on forest productivity and carbon accumulation, and encourage multispecies afforestation strategies to restore biodiversity and mitigate climate change.
Abstract: Biodiversity experiments have shown that species loss reduces ecosystem functioning in grassland. To test whether this result can be extrapolated to forests, the main contributors to terrestrial primary productivity, requires large-scale experiments. We manipulated tree species richness by planting more than 150,000 trees in plots with 1 to 16 species. Simulating multiple extinction scenarios, we found that richness strongly increased stand-level productivity. After 8 years, 16-species mixtures had accumulated over twice the amount of carbon found in average monocultures and similar amounts as those of two commercial monocultures. Species richness effects were strongly associated with functional and phylogenetic diversity. A shrub addition treatment reduced tree productivity, but this reduction was smaller at high shrub species richness. Our results encourage multispecies afforestation strategies to restore biodiversity and mitigate climate change.
359 citations
National Museum of Natural History1, Smithsonian Conservation Biology Institute2, United States Geological Survey3, University of Aberdeen4, Chinese Academy of Sciences5, United States Department of Agriculture6, National University of Colombia7, University of Hong Kong8, National Taiwan University9, University of Montana10, University of Oxford11, Smithsonian Institution12, Centre national de la recherche scientifique13, Sewanee: The University of the South14, Far Eastern University15, Harvard University16, National Ecological Observatory Network17, Royal Society18, Council of Agriculture19
TL;DR: Because large-diameter trees constitute roughly half of the mature forest biomass worldwide, their dynamics and sensitivities to environmental change represent potentially large controls on global forest carbon cycling.
Abstract: Aim: To examine the contribution of large-diameter trees to biomass, stand structure, and species richness across forest biomes. Location: Global. Time period: Early 21st century. Major taxa studied: Woody plants. Methods: We examined the contribution of large trees to forest density, richness and biomass using a global network of 48 large (from 2 to 60 ha) forest plots representing 5,601,473 stems across 9,298 species and 210 plant families. This contribution was assessed using three metrics: the largest 1% of trees >= 1 cm diameter at breast height (DBH), all trees >= 60 cm DBH, and those rank-ordered largest trees that cumulatively comprise 50% of forest biomass. Results: Averaged across these 48 forest plots, the largest 1% of trees >= 1 cm DBH comprised 50% of aboveground live biomass, with hectare-scale standard deviation of 26%. Trees >= 60 cm DBH comprised 41% of aboveground live tree biomass. The size of the largest trees correlated with total forest biomass (r(2) 5.62, p < .001). Large-diameter trees in high biomass forests represented far fewer species relative to overall forest richness (r(2) = 5.45, p < .001). Forests with more diverse large-diameter tree communities were comprised of smaller trees (r(2) = 5.33, p < .001). Lower large-diameter richness was associated with large-diameter trees being individuals of more common species (r(2) =5.17, p=5.002). The concentration of biomass in the largest 1% of trees declined with increasing absolute latitude (r(2) = 5.46, p < .001), as did forest density (r(2) = 5.31, p < .001). Forest structural complexity increased with increasing absolute latitude (r(2) = 5.26, p < .001). Main conclusions: Because large-diameter trees constitute roughly half of the mature forest biomass worldwide, their dynamics and sensitivities to environmental change represent potentially large controls on global forest carbon cycling. We recommend managing forests for conservation of existing large-diameter trees or those that can soon reach large diameters as a simple way to conserve and potentially enhance ecosystem services.
297 citations
Leipzig University1, Utah State University2, Utrecht University3, University of Minnesota4, Helmholtz Centre for Environmental Research - UFZ5, University of Innsbruck6, University of Bayreuth7, Max Planck Society8, ETH Zurich9, Yonsei University10, University of Southampton11, Applied Science Private University12, VU University Amsterdam13, University of Zurich14, University of Jena15, Swansea University16, University of Oxford17, University of Greifswald18, Sewanee: The University of the South19, Colorado State University20, Technische Universität München21, University of Oldenburg22, Vrije Universiteit Brussel23, Moscow State University24, Agricultural Research Service25, Wageningen University and Research Centre26, Algoma University27, Leiden University28, Iowa State University29
TL;DR: It is found that high species richness and phylogenetic diversity stabilize biomass production via enhanced asynchrony in the performance of co-occurring species and enhances ecosystem stability directly, albeit weakly.
Abstract: A substantial body of evidence has demonstrated that biodiversity stabilizes ecosystem functioning over time in grassland ecosystems. However, the relative importance of different facets of biodiversity underlying the diversity-stability relationship remains unclear. Here we use data from 39 grassland biodiversity experiments and structural equation modelling to investigate the roles of species richness, phylogenetic diversity and both the diversity and community-weighted mean of functional traits representing the 'fast-slow' leaf economics spectrum in driving the diversity-stability relationship. We found that high species richness and phylogenetic diversity stabilize biomass production via enhanced asynchrony in the performance of co-occurring species. Contrary to expectations, low phylogenetic diversity enhances ecosystem stability directly, albeit weakly. While the diversity of fast-slow functional traits has a weak effect on ecosystem stability, communities dominated by slow species enhance ecosystem stability by increasing mean biomass production relative to the standard deviation of biomass over time. Our in-depth, integrative assessment of factors influencing the diversity-stability relationship demonstrates a more multicausal relationship than has been previously acknowledged.
248 citations
Utrecht University1, University of Minnesota2, Martin Luther University of Halle-Wittenberg3, University of Guelph4, Lancaster University5, Utah State University6, National Scientific and Technical Research Council7, University of Washington8, Michigan State University9, Trinity College, Dublin10, University of Toronto11, University of Lisbon12, University of Buenos Aires13, Sun Yat-sen University14, University of Sydney15, Commonwealth Scientific and Industrial Research Organisation16, University of Queensland17, University of Oulu18, Agricultural Research Service19, Queensland University of Technology20, University of KwaZulu-Natal21, University of Oldenburg22, University of Nebraska–Lincoln23, Smithsonian Institution24, University of Kentucky25, La Trobe University26, University of Tartu27, Charles Sturt University28, Swiss Federal Institute for Forest, Snow and Landscape Research29, Tata Institute of Fundamental Research30, University of Leeds31, Murdoch University32, University of Oxford33
TL;DR: Analysis of 65 grasslands worldwide from the Nutrient Network experiment reveals that plant communities with higher α- and β-diversity have higher levels of ecosystem multifunctionality, and that this effect is amplified across scales.
Abstract: Biodiversity is declining in many local communities while also becoming increasingly homogenized across space. Experiments show that local plant species loss reduces ecosystem functioning and services, but the role of spatial homogenization of community composition and the potential interaction between diversity at different scales in maintaining ecosystem functioning remains unclear, especially when many functions are considered (ecosystem multifunctionality). We present an analysis of eight ecosystem functions measured in 65 grasslands worldwide. We find that more diverse grasslands—those with both species-rich local communities (α-diversity) and large compositional differences among localities (β-diversity)—had higher levels of multifunctionality. Moreover, α- and β-diversity synergistically affected multifunctionality, with higher levels of diversity at one scale amplifying the contribution to ecological functions at the other scale. The identity of species influencing ecosystem functioning differed among functions and across local communities, explaining why more diverse grasslands maintained greater functionality when more functions and localities were considered. These results were robust to variation in environmental drivers. Our findings reveal that plant diversity, at both local and landscape scales, contributes to the maintenance of multiple ecosystem services provided by grasslands. Preserving ecosystem functioning therefore requires conservation of biodiversity both within and among ecological communities.
158 citations
TL;DR: A new approach is developed and applied to estimate these previously unquantified insurance effects of biodiversity on ecosystem functioning that arise due to species turnover across times and places, and it is found that total insurance effects are positive in sign and substantial in magnitude.
Abstract: Biodiversity loss decreases ecosystem functioning at the local scales at which species interact, but it remains unclear how biodiversity loss affects ecosystem functioning at the larger scales of space and time that are most relevant to biodiversity conservation and policy. Theory predicts that additional insurance effects of biodiversity on ecosystem functioning could emerge across time and space if species respond asynchronously to environmental variation and if species become increasingly dominant when and where they are most productive. Even if only a few dominant species maintain ecosystem functioning within a particular time and place, ecosystem functioning may be enhanced by many different species across many times and places (β-diversity). Here, we develop and apply a new approach to estimate these previously unquantified insurance effects of biodiversity on ecosystem functioning that arise due to species turnover across times and places. In a long-term (18-year) grassland plant diversity experiment, we find that total insurance effects are positive in sign and substantial in magnitude, amounting to 19% of the net biodiversity effect, mostly due to temporal insurance effects. Species loss can therefore reduce ecosystem functioning both locally and by eliminating species that would otherwise enhance ecosystem functioning across temporally fluctuating and spatially heterogeneous environments.
140 citations
J. W. Ferry Slik1, Janet Franklin2, Víctor Arroyo-Rodríguez3, Richard Field4 +190 more•Institutions (118)
TL;DR: A global tropical forest classification that is explicitly based on community evolutionary similarity is provided, resulting in identification of five major tropical forest regions and their relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests.
Abstract: Knowledge about the biogeographic affinities of the world’s tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world’s tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.
140 citations
University of Minnesota1, Ghent University2, University of Freiburg3, Martin Luther University of Halle-Wittenberg4, Institut national de la recherche agronomique5, Leipzig University6, Université de Sherbrooke7, University of Oxford8, University of Göttingen9, University of Sassari10, Université du Québec en Outaouais11, Université du Québec à Montréal12, Katholieke Universiteit Leuven13, Smithsonian Institution14, University of Western Australia15, Université catholique de Louvain16, University of Sydney17, Swedish University of Agricultural Sciences18
TL;DR: Findings from TreeDivNet indicate that tree diversity experiments are extending BEF research across systems and scales, complementing previous BEF work in grasslands by providing opportunities to use remote sensing and spectral approaches to study BEF dynamics, integrate belowground and aboveground approaches, and trace the consequences of tree physiology for ecosystem functioning.
97 citations
Sun Yat-sen University1, Utah State University2, Washington University in St. Louis3, University of Canterbury4, University of Jos5, Smithsonian Conservation Biology Institute6, University of Aberdeen7, Xishuangbanna Tropical Botanical Garden8, Field Museum of Natural History9, Chinese Academy of Sciences10, University of Hong Kong11, University of Oxford12, University of California, Los Angeles13, Northeast Forestry University14, National Museum of Natural History15, Smithsonian Tropical Research Institute16, East China Normal University17, Centre national de la recherche scientifique18, University of São Paulo19, Harvard University20, Smithsonian Environmental Research Center21, South China Agricultural University22, National Dong Hwa University23, University of Minnesota24, University of California, Santa Cruz25, University of Puerto Rico26, Charles University in Prague27, Academy of Sciences of the Czech Republic28, Wilfrid Laurier University29, Michigan State University30, University of Alberta31
TL;DR: Results imply direct limitation of species diversity by climatic stress and more rapid (co-)evolution and narrower niche partitioning in warm climates, and support the idea that increased numbers of individuals associated with high primary productivity are partitioned to support a greater number of species.
Abstract: Climate is widely recognised as an important determinant of the latitudinal diversity gradient. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Using data from 35 large forest plots, we test hypothesised relationships amongst climate, topography, forest structural attributes (stem abundance, tree size variation and stand basal area) and tree species richness to better understand drivers of latitudinal tree diversity patterns. Climate influences tree richness both directly, with more species in warm, moist, aseasonal climates and indirectly, with more species at higher stem abundance. These results imply direct limitation of species diversity by climatic stress and more rapid (co-)evolution and narrower niche partitioning in warm climates. They also support the idea that increased numbers of individuals associated with high primary productivity are partitioned to support a greater number of species.
77 citations
TL;DR: This work encourages colleagues to establish new experiments on the relation between tree species diversity and forest ecosystem functioning, and to make use of the TreeDivNet platform for collaborative research.
Abstract: TreeDivNet is the largest network of biodiversity experiments worldwide, but needs to expand. We encourage colleagues to establish new experiments on the relation between tree species diversity and forest ecosystem functioning, and to make use of the platform for collaborative research.
73 citations
TL;DR: The results support the idea that competition in grasslands shifts from symmetric to asymmetric as fertility increases but that disturbance destroys this relationship, presumably by preventing the development of differences in canopy structure and reducing competition for light.
Abstract: Eutrophication is a major cause of biodiversity loss. In grasslands, this appears to occur due to asymmetric competition for light following the increases in aboveground biomass production. Here, we report the results of an experiment with five grass species that tests how well-competitive outcomes can be predicted under a factorial combination of fertilized and disturbed (frequent cutting) conditions. Under fertile conditions, our results confirm earlier success in predicting short-term competitive outcomes based on light interception in monocultures. This effect was maintained but weakened under less fertile conditions with competition becoming more symmetric. However, under disturbed conditions, competitive outcomes could not be predicted from differences in light interception in monocultures regardless of fertility. Our results support the idea that competition in grasslands shifts from symmetric to asymmetric as fertility increases but that disturbance destroys this relationship, presumably by preventing the development of differences in canopy structure and reducing competition for light.
17 citations