Showing papers by "Swiss Federal Institute for Forest, Snow and Landscape Research published in 2015"
University of Colorado Boulder1, University of Notre Dame2, Commonwealth Scientific and Industrial Research Organisation3, University of Minnesota4, Queensland University of Technology5, Martin Luther University of Halle-Wittenberg6, Iowa State University7, University of Nebraska–Lincoln8, University of Kentucky9, University of California, Berkeley10, Swiss Federal Institute for Forest, Snow and Landscape Research11, Lancaster University12
TL;DR: The results suggest that elevated N and P inputs lead to predictable shifts in the taxonomic and functional traits of soil microbial communities, including increases in the relative abundances of faster-growing, copiotrophic bacterial taxa, with these shifts likely to impact belowground ecosystems worldwide.
Abstract: Soil microorganisms are critical to ecosystem functioning and the maintenance of soil fertility. However, despite global increases in the inputs of nitrogen (N) and phosphorus (P) to ecosystems due to human activities, we lack a predictive understanding of how microbial communities respond to elevated nutrient inputs across environmental gradients. Here we used high-throughput sequencing of marker genes to elucidate the responses of soil fungal, archaeal, and bacterial communities using an N and P addition experiment replicated at 25 globally distributed grassland sites. We also sequenced metagenomes from a subset of the sites to determine how the functional attributes of bacterial communities change in response to elevated nutrients. Despite strong compositional differences across sites, microbial communities shifted in a consistent manner with N or P additions, and the magnitude of these shifts was related to the magnitude of plant community responses to nutrient inputs. Mycorrhizal fungi and methanogenic archaea decreased in relative abundance with nutrient additions, as did the relative abundances of oligotrophic bacterial taxa. The metagenomic data provided additional evidence for this shift in bacterial life history strategies because nutrient additions decreased the average genome sizes of the bacterial community members and elicited changes in the relative abundances of representative functional genes. Our results suggest that elevated N and P inputs lead to predictable shifts in the taxonomic and functional traits of soil microbial communities, including increases in the relative abundances of faster-growing, copiotrophic bacterial taxa, with these shifts likely to impact belowground ecosystems worldwide.
867 citations
University of Lorraine1, Institut national de la recherche agronomique2, United States Department of Energy3, Clark University4, Hungarian Academy of Sciences5, Helmholtz Centre for Environmental Research - UFZ6, Lund University7, University of Hasselt8, Universidade Federal de Viçosa9, University of Lyon10, University of Turin11, King Abdulaziz University12, Aix-Marseille University13, University of Oslo14, Swedish University of Agricultural Sciences15, Max Planck Society16, University of Bremen17, Harvard University18, Swiss Federal Institute for Forest, Snow and Landscape Research19, Pierre-and-Marie-Curie University20, University of Cologne21
TL;DR: Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of myCorrhiza-induced genes.
Abstract: To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.
799 citations
Yale University1, University of Helsinki2, Imperial College London3, University of La Frontera4, Food and Agriculture Organization5, University of Kent6, Operation Wallacea7, Centre national de la recherche scientifique8, Landcare Research9, Swiss Federal Institute for Forest, Snow and Landscape Research10, Wageningen University and Research Centre11, University of Hamburg12, Masaryk University13, Oeschger Centre for Climate Change Research14, University of Bayreuth15, University of Göttingen16, Lancaster University17, Peking University18
TL;DR: This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate, and the globalNumber of trees has fallen by approximately 46% since the start of human civilization.
Abstract: The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.
542 citations
Commonwealth Scientific and Industrial Research Organisation1, Cooperative Institute for Research in Environmental Sciences2, University of Minnesota3, Queensland University of Technology4, Utah State University5, University of Washington6, University of California, San Diego7, United States Geological Survey8, University of KwaZulu-Natal9, University of Oxford10, Iowa State University11, University of Nebraska–Lincoln12, University of California, Berkeley13, University of Guelph14, University of Kentucky15, University of North Carolina at Chapel Hill16, Swiss Federal Institute for Forest, Snow and Landscape Research17, Lancaster University18
TL;DR: In this paper, the authors compared the diversity of plant, bacterial, archaeal and fungal communities in one hundred and forty-five 1 m 2 plots across 25 temperate grassland sites from four continents.
Abstract: Aboveground–belowground interactions exert critical controls on the composition and function of terrestrial ecosystems, yet the fundamental relationships between plant diversity and soil microbial diversity remain elusive. Theory predicts predominantly positive associations but tests within single sites have shown variable relationships, and associations between plant and microbial diversity across broad spatial scales remain largely unexplored. We compared the diversity of plant, bacterial, archaeal and fungal communities in one hundred and forty-five 1 m 2 plots across 25 temperate grassland sites from four continents. Across sites, the plant alpha diversity patterns were poorly related to those observed for any soil microbial group. However, plant beta diversity (compositional dissimilarity between sites) was significantly correlated with the beta diversity of bacterial and fungal communities, even after controlling for environmental factors. Thus, across a global range of temperate grasslands, plant diversity can predict patterns in the composition of soil microbial communities, but not patterns in alpha diversity.
526 citations
TL;DR: Current knowledge about responses of tree roots to drought supports the view that tree roots are well equipped to withstand drought situations and maintain morphological and physiological functions as long as possible.
Abstract: The ongoing climate change is characterized by increased temperatures and altered precipitation patterns In addition, there has been an increase in both the frequency and intensity of extreme climatic events such as drought Episodes of drought induce a series of interconnected effects, all of which have the potential to alter the carbon balance of forest ecosystems profoundly at different scales of plant organization and ecosystem functioning During recent years, considerable progress has been made in the understanding of how aboveground parts of trees respond to drought and how these responses affect carbon assimilation In contrast, processes of belowground parts are relatively underrepresented in research on climate change In this review, we describe current knowledge about responses of tree roots to drought Tree roots are capable of responding to drought through a variety of strategies that enable them to avoid and tolerate stress Responses include root biomass adjustments, anatomical alterations, and physiological acclimations The molecular mechanisms underlying these responses are characterized to some extent, and involve stress signaling and the induction of numerous genes, leading to the activation of tolerance pathways In addition, mycorrhizas seem to play important protective roles The current knowledge compiled in this review supports the view that tree roots are well equipped to withstand drought situations and maintain morphological and physiological functions as long as possible Further, the reviewed literature demonstrates the important role of tree roots in the functioning of forest ecosystems and highlights the need for more research in this emerging field
501 citations
Agricultural Research Service1, Commonwealth Scientific and Industrial Research Organisation2, University of Nebraska–Lincoln3, University of Washington4, University of Minnesota5, University of Guelph6, Utah State University7, Trinity College, Dublin8, Lanzhou University9, University of California, Los Angeles10, University of New Mexico11, University of Colorado Boulder12, University of Illinois at Urbana–Champaign13, Queensland University of Technology14, University of Maryland, College Park15, University of KwaZulu-Natal16, Utrecht University17, University of North Carolina at Chapel Hill18, Colorado State University19, Chinese Academy of Sciences20, University of Kentucky21, Monash University22, La Trobe University23, Swiss Federal Institute for Forest, Snow and Landscape Research24, Lancaster University25, University of California, Davis26
TL;DR: It is suggested that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment, and significant variations in the type and degree of nutrient limitation are pointed to.
Abstract: Terrestrial ecosystem productivity is widely accepted to be nutrient limited(1). Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP) 2,3, the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized(4-8). However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+mu), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+mu co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.
383 citations
University of Bern1, Centre national de la recherche scientifique2, Paul Scherrer Institute3, University of Mainz4, Natural Environment Research Council5, Swiss Federal Institute for Forest, Snow and Landscape Research6, Forschungszentrum Jülich7, Stanford University8, National Center for Atmospheric Research9, University of Exeter10, Columbia University11, University of Basilicata12, University of Vienna13, University of Barcelona14, Finnish Environment Institute15, American Museum of Natural History16, AGH University of Science and Technology17, Swansea University18, Silesian University of Technology19, Vytautas Magnus University20, University of Naples Federico II21, Anglia Ruskin University22
TL;DR: In this article, the authors used long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2 caused by atmospheric CO2 (Ca) trends.
Abstract: Considering the combined effects of CO2 fertilization and climate change drivers on plant physiology leads to a modest increase in simulated European forest transpiration in spite of the effects of CO2-induced stomatal closure. The Earth’s carbon and hydrologic cycles are intimately coupled by gas exchange through plant stomata1,2,3. However, uncertainties in the magnitude4,5,6 and consequences7,8 of the physiological responses9,10 of plants to elevated CO2 in natural environments hinders modelling of terrestrial water cycling and carbon storage11. Here we use annually resolved long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2 (Ci) caused by atmospheric CO2 (Ca) trends. When removing meteorological signals from the δ13C measurements, we find that trees across Europe regulated gas exchange so that for one ppmv atmospheric CO2 increase, Ci increased by ∼0.76 ppmv, most consistent with moderate control towards a constant Ci/Ca ratio. This response corresponds to twentieth-century intrinsic water-use efficiency (iWUE) increases of 14 ± 10 and 22 ± 6% at broadleaf and coniferous sites, respectively. An ensemble of process-based global vegetation models shows similar CO2 effects on iWUE trends. Yet, when operating these models with climate drivers reintroduced, despite decreased stomatal opening, 5% increases in European forest transpiration are calculated over the twentieth century. This counterintuitive result arises from lengthened growing seasons, enhanced evaporative demand in a warming climate, and increased leaf area, which together oppose effects of CO2-induced stomatal closure. Our study questions changes to the hydrological cycle, such as reductions in transpiration and air humidity, hypothesized to result from plant responses to anthropogenic emissions.
349 citations
TL;DR: In this article, the nutritional status of the main European tree species, to identify growth-limiting nutrients and to assess changes in tree nutrition during the past two decades was analyzed.
Abstract: The response of forest ecosystems to increased atmospheric CO2 is constrained by nutrient availability. It is thus crucial to account for nutrient limitation when studying the forest response to climate change. The objectives of this study were to describe the nutritional status of the main European tree species, to identify growth-limiting nutrients and to assess changes in tree nutrition during the past two decades. We analysed the foliar nutrition data collected during 1992-2009 on the intensive forest monitoring plots of the ICP Forests programme. Of the 22 significant temporal trends that were observed in foliar nutrient concentrations, 20 were decreasing and two were increasing. Some of these trends were alarming, among which the foliar P concentration in F. sylvatica, Q. Petraea and P. sylvestris that significantly deteriorated during 1992-2009. In Q. Petraea and P. sylvestris, the decrease in foliar P concentration was more pronounced on plots with low foliar P status, meaning that trees with latent P deficiency could become deficient in the near future. Increased tree productivity, possibly resulting from high N deposition and from the global increase in atmospheric CO2, has led to higher nutrient demand by trees. As the soil nutrient supply was not always sufficient to meet the demands of faster growing trees, this could partly explain the deterioration of tree mineral nutrition. The results suggest that when evaluating forest carbon storage capacity and when planning to reduce CO2 emissions by increasing use of wood biomass for bioenergy, it is crucial that nutrient limitations for forest growth are considered.
263 citations
TL;DR: It is found that the degree of specialisation, mobility and their interaction, greatly influenced species’ responses to urbanisation, with highly mobile specialist species of all taxonomic groups being affected most.
Abstract: Urbanisation has an important impact on biodiversity, mostly driving changes in species assemblages, through the replacement of specialist with generalist species, thus leading to biotic homogenisation. Mobility is also assumed to greatly affect species’ ability to cope in urban environments. Moreover, specialisation, mobility and their interaction are expected to greatly influence ecological processes such as metacommunity dynamics and assembly processes, and consequently the way and the spatial scale at which organisms respond to urbanisation. Here we investigate urbanisation impacts on distinct characteristics of species assemblages – namely specialisation degree in resource use, mobility and number of species, classified according to both characteristics and their combination – for vascular plants, butterflies and birds, across a range of spatial scales (from 1 × 1 km plots to 5 km-radius buffers around them).
We found that the degree of specialisation, mobility and their interaction, greatly influenced species’ responses to urbanisation, with highly mobile specialist species of all taxonomic groups being affected most. Two different patterns were found: for plants, urbanisation induced trait divergence by favouring highly mobile species with narrow habitat ranges. For birds and butterflies, however, it reduced the number of highly mobile specialist species, thus driving trait convergence. Mobile organisms, across and within taxonomic groups, tended to respond at larger spatial scales than those that are poorly mobile. These findings emphasize the need to take into consideration species’ ecological aspects, as well as a wide range of spatial scales when evaluating the impact of urbanisation on biodiversity. Our results also highlight the harmful impact of widespread urban expansion on organisms such as butterflies, especially highly mobile specialists, which were negatively affected by urban areas even at great distances.
186 citations
TL;DR: A detailed field study concerning the attitude of local people to the management of traditional agricultural landscapes (TAL) in Slovakia was conducted in three case study areas as discussed by the authors, showing that 50% of the TAL area is regularly managed, 34% is partly abandoned, and 16% is abandoned.
165 citations
TL;DR: In this paper, the authors validate and compare three hydrological models of different complexity to investigate whether their performance varies accordingly, using runoff and also soil moisture measurements, from several sites across Switzerland.
TL;DR: In this article, the authors developed new methods for separately quantifying how trends in both streamflow and channel capacity have affected flood frequency at gauging sites across the United States Flood frequency was generally nonstationary, with increasing flood hazard at a statistically significant majority of sites.
Abstract: Flooding is a major hazard to lives and infrastructure, but trends in flood hazard are poorly understood. The capacity of river channels to convey flood flows is typically assumed to be stationary, so changes in flood frequency are thought to be driven primarily by trends in streamflow. We have developed new methods for separately quantifying how trends in both streamflow and channel capacity have affected flood frequency at gauging sites across the United States Flood frequency was generally nonstationary, with increasing flood hazard at a statistically significant majority of sites. Changes in flood hazard driven by channel capacity were smaller, but more numerous, than those driven by streamflow. Our results demonstrate that accurately quantifying changes in flood hazard requires accounting separately for trends in both streamflow and channel capacity. They also show that channel capacity trends may have unforeseen consequences for flood management and for estimating flood insurance costs.
TL;DR: In this paper, a data-based approach using multiple linear regression and a simulation based approach using a hydrological model was used to assess to which extent these streamflow trends can be attributed to changes in air temperature or precipitation, and the results showed that the observed changes in streamflow were consistent with the changes in temperature and precipitation.
Abstract: Observed streamflow of headwater catchments of the Tarim River (Central Asia) increased by about 30% over the period 1957–2004 This study aims at assessing to which extent these streamflow trends can be attributed to changes in air temperature or precipitation The analysis includes a data-based approach using multiple linear regression and a simulation-based approach using a hydrological model The hydrological model considers changes in both glacier area and surface elevation It was calibrated using a multiobjective optimization algorithm with calibration criteria based on glacier mass balance and daily and interannual variations of discharge The individual contributions to the overall streamflow trends from changes in glacier geometry, temperature, and precipitation were assessed using simulation experiments with a constant glacier geometry and with detrended temperature and precipitation time series The results showed that the observed changes in streamflow were consistent with the changes in temperature and precipitation In the Sari-Djaz catchment, increasing temperatures and related increase of glacier melt were identified as the dominant driver, while in the Kakshaal catchment, both increasing temperatures and increasing precipitation played a major role Comparing the two approaches, an advantage of the simulation-based approach is the fact that it is based on process-based relationships implemented in the hydrological model instead of statistical links in the regression model However, data-based approaches are less affected by model parameter and structural uncertainties and typically fast to apply A complementary application of both approaches is recommended
Lancaster University1, University of Minnesota2, University of Oxford3, University of New Mexico4, University of Washington5, Lanzhou University6, University of Colorado Boulder7, Queensland University of Technology8, University of Oldenburg9, Yale University10, University of Guelph11, University of Kentucky12, La Trobe University13, University of Wisconsin-Madison14, Commonwealth Scientific and Industrial Research Organisation15, Swiss Federal Institute for Forest, Snow and Landscape Research16
TL;DR: In this article, the authors used an international multiscale data set to show that atmospheric nitrogen deposition is positively correlated to aboveground net primary production (ANPP) observed at the 1-m 2 level across a wide range of herbaceous ecosystems.
Abstract: Humans dominate many important Earth system processes including the nitrogen (N) cycle. Atmospheric N deposition affects fundamental processes such as carbon cycling, climate regulation, and biodiversity, and could result in changes to fundamental Earth system processes such as primary production. Both modelling and experimentation have suggested a role for anthropogenically altered N deposition in increasing productivity, nevertheless, current understanding of the relative strength of N deposition with respect to other controls on production such as edaphic conditions and climate is limited. Here we use an international multiscale data set to show that atmospheric N deposition is positively correlated to aboveground net primary production (ANPP) observed at the 1-m 2 level across a wide range of herbaceous ecosystems. N deposition was a better predictor than climatic drivers and local soil conditions, explaining 16% of observed variation in ANPP globally with an increase of 1 kg Nha � 1 � yr � 1 increasing ANPP by 3%. Soil pH explained 8% of observed variation in ANPP while climatic drivers showed no significant relationship. Our results illustrate that the incorporation of global N deposition patterns in Earth system models are likely to substantially improve estimates of primary production in herbaceous systems. In herbaceous systems across the world, humans appear to be partially driving local ANPP through impacts on the N cycle.
TL;DR: The results go beyond previous assessments of the sensitivity of soil microbes and ecosystem processes to global change, and demonstrate the existence of general links between the responses of soil microbial abundance and ecosystem functioning.
Abstract: In recent years, there has been an increase in research to understand how global changes' impacts on soil biota translate into altered ecosystem functioning. However, results vary between global change effects, soil taxa, and ecosystem processes studied, and a synthesis of relationships is lacking. Therefore, here we initiate such a synthesis to assess whether the effect size of global change drivers (elevated CO2, N deposition, and warming) on soil microbial abundance is related with the effect size of these drivers on ecosystem functioning (plant biomass, soil C cycle, and soil N cycle) using meta-analysis and structural equation modeling. For N deposition and warming, the global change effect size on soil microbes was positively associated with the global change effect size on ecosystem functioning, and these relationships were consistent across taxa and ecosystem processes. However, for elevated CO2, such links were more taxon and ecosystem process specific. For example, fungal abundance responses to elevated CO2 were positively correlated with those of plant biomass but negatively with those of the N cycle. Our results go beyond previous assessments of the sensitivity of soil microbes and ecosystem processes to global change, and demonstrate the existence of general links between the responses of soil microbial abundance and ecosystem functioning. Further we identify critical areas for future research, specifically altered precipitation, soil fauna, soil community composition, and litter decomposition, that are need to better quantify the ecosystem consequences of global change impacts on soil biodiversity.
TL;DR: In this article, the authors review and synthesize findings from six important areas of landscape research in Europe and discuss how these findings may advance the study of ecosystem change and society and its thematic key priorities: linkages between people and the environment in landscapes, landscape structure and land-use intensity, long-term landscape history, driving forces, processes and actors of landscape change, landscape values and meanings, and landscape stewardship.
Abstract: Landscapes are closely linked to human well-being, but they are undergoing rapid and fundamental change. Understanding the societal transformation underlying these landscape changes, as well as the ecological and societal outcomes of landscape transformations across scales are prime areas for landscape research. We review and synthesize findings from six important areas of landscape research in Europe and discuss how these findings may advance the study of ecosystem change and society and its thematic key priorities. These six areas are: (1) linkages between people and the environment in landscapes, (2) landscape structure and land-use intensity, (3) long-term landscape history, (4) driving forces, processes, and actors of landscape change, (5) landscape values and meanings, and (6) landscape stewardship. We propose that these knowledge areas can contribute to the study of ecosystem change and society, considering nested multiscale dynamics of social-ecological systems; the stewardship of these systems and their ecosystem services; and the relationships between ecosystem services, human well-being, wealth, and poverty. Our synthesis highlights that knowledge about past and current landscape patterns, processes, and dynamics provides guidance for developing visions to support the sustainable stewardship of social-ecological systems under future conditions.
TL;DR: A critically evaluate the consistency, sensitivity, reliability and accuracy of four most widely used growth-trend detection methods and recommends SCI and RCS, as these methods showed highest reliability to detect long-term growth trends.
Abstract: Tree-ring analysis is often used to assess long-term trends in tree growth. A variety of growth-trend detection methods (GDMs) exist to disentangle age/size trends in growth from long-term growth changes. However, these detrending methods strongly differ in approach, with possible implications for their output. Here, we critically evaluate the consistency, sensitivity, reliability and accuracy of four most widely used GDMs: conservative detrending (CD) applies mathematical functions to correct for decreasing ring widths with age; basal area correction (BAC) transforms diameter into basal area growth; regional curve standardization (RCS) detrends individual tree-ring series using average age/size trends; and size class isolation (SCI) calculates growth trends within separate size classes. First, we evaluated whether these GDMs produce consistent results applied to an empirical tree-ring data set of Melia azedarach, a tropical tree species from Thailand. Three GDMs yielded similar results - a growth decline over time - but the widely used CD method did not detect any change. Second, we assessed the sensitivity (probability of correct growth-trend detection), reliability (100% minus probability of detecting false trends) and accuracy (whether the strength of imposed trends is correctly detected) of these GDMs, by applying them to simulated growth trajectories with different imposed trends: no trend, strong trends (-6% and +6% change per decade) and weak trends (-2%, +2%). All methods except CD, showed high sensitivity, reliability and accuracy to detect strong imposed trends. However, these were considerably lower in the weak or no-trend scenarios. BAC showed good sensitivity and accuracy, but low reliability, indicating uncertainty of trend detection using this method. Our study reveals that the choice of GDM influences results of growth-trend studies. We recommend applying multiple methods when analysing trends and encourage performing sensitivity and reliability analysis. Finally, we recommend SCI and RCS, as these methods showed highest reliability to detect long-term growth trends.
University of Minnesota1, University of Queensland2, University of California, San Diego3, University of Colorado Boulder4, Queensland University of Technology5, Martin Luther University of Halle-Wittenberg6, University of Guelph7, University of Wisconsin-Madison8, Commonwealth Scientific and Industrial Research Organisation9, Utah State University10, Wake Forest University11, University of Washington12, Iowa State University13, Agricultural Research Service14, Colorado State University15, Michigan State University16, University of Toronto17, Lanzhou University18, Dartmouth College19, Imperial College London20, University of California, Santa Barbara21, United States Geological Survey22, University of Maryland, College Park23, University of KwaZulu-Natal24, University of Oxford25, University of Oldenburg26, University of St. Thomas (Minnesota)27, University of Nebraska–Lincoln28, University of California, Berkeley29, University of New Mexico30, Oregon State University31, Chinese Academy of Sciences32, Southwest Forestry University33, University of Kentucky34, University of North Carolina at Chapel Hill35, Monash University36, La Trobe University37, Swiss Federal Institute for Forest, Snow and Landscape Research38, National Centre for Biological Sciences39, Lancaster University40, University of British Columbia41, Duke University42, University of California, Davis43
TL;DR: It is suggested that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands.
Abstract: Exotic species dominate many communities; however the functional significance of species' biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native diversity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands.
TL;DR: This article synthesizes current knowledge on the biophysical and physiological mechanisms influencing the short- to long-term variation in the most widely used wood-anatomical feature, namely conduit size and clarifies the strong mechanistic link between conduit-lumen size, tree hydraulic architecture and height growth.
Abstract: Trees are among the best natural archives of past environmental information. Xylem anatomy preserves information related to tree allometry and ecophysiological performance, which is not available from the more customary ring-width or wooddensity proxy parameters. Recent technological advances make tree-ring anatomy very attractive because time frames of many centuries can now be covered. This calls for the proper treatment of time series of xylem anatomical attributes. In this article, we synthesize current knowledge on the biophysical and physiological mechanisms influencing the short- to long-term variation in the most widely used wood-anatomical feature, namely conduit size. We also clarify the strong mechanistic link between conduit-lumen size, tree hydraulic architecture and height growth. Among the key consequences of these biophysical constraints is the pervasive, increasing trend of conduit size during ontogeny. Such knowledge is required to process time series of anatomical parameters correctly in order to obtain the information of interest. An appropriate standardization procedure is fundamental when analysing long tree-ring-related chronologies. When dealing with wood-anatomical parameters, this is even more critical. Only an interdisciplinary approach involving ecophysiology, wood anatomy and dendrochronology will help to distill the valuable information about tree height growth and past environmental variability correctly.
TL;DR: Increased soil temperature and reduced water content are associated with greater vascular plant biomass, in particular that of ericoids, and that this, in turn, is correlated with greater microbial biomass, which is characterized by an increasing dominance of fungi over bacteria with improved soil oxygenation.
Abstract: The ongoing expansion of shrub cover in response to climate change represents a unique opportunity to explore the link between soil microbial communities and vegetation changes. This link is particularly important in peatlands where shrub expansion is expected to feed back negatively on the carbon sink capacity of these ecosystems. Microbial community structure and function were measured seasonally in four peatlands located along an altitude gradient representing a natural gradient of climate and associated vascular plant abundance. We show that increased soil temperature and reduced water content are associated with greater vascular plant biomass, in particular that of ericoids, and that this, in turn, is correlated with greater microbial biomass. More specifically, microbial community structure is characterized by an increasing dominance of fungi over bacteria with improved soil oxygenation. We also found that the carbon and nitrogen stoichiometry of microbial biomass differs in relation to soil microbial community structure and that this is ultimately associated with a different investment in extracellular enzymatic activity. Our findings highlight the fact that the determination of the structural identity of microbial communities can help to explain the biogeochemical dynamics of organic matter and provide a better understanding of ecosystem response to environmental changes.
Masaryk University1, Sapienza University of Rome2, Hungarian Academy of Sciences3, University of Bayreuth4, Weihenstephan-Triesdorf University of Applied Sciences5, NatureServe6, University of Trieste7, University of Northern Colorado8, Complutense University of Madrid9, University of Franche-Comté10, University of Greifswald11, University of the Basque Country12, University of Western Australia13, University of North Carolina at Chapel Hill14, Montana State University15, Academy of Sciences of the Czech Republic16, Radboud University Nijmegen17, Karlsruhe Institute of Technology18, University of Geneva19, University of Alaska Fairbanks20, Swiss Federal Institute for Forest, Snow and Landscape Research21, Landcare Research22
TL;DR: A framework to facilitate comparisons between broad-scale plot-based classification approaches, based on the distinction of four structural elements (plot record, vegetation type, consistent classification section and classification system) and two procedural elements (classification protocol and classification approach).
Abstract: Aims: Classification of vegetation is an essential tool to
describe, understand, predict and manage biodiversity. Given
the multiplicity of approaches to classify vegetation, it is
important to develop international consensus around a set of
general guidelines and purpose-specific standard protocols.
Before these goals can be achieved, however, it is necessary to
identify and understand the different choices that are made
during the process of classifying vegetation. This paper
presents a framework to facilitate comparisons between
broad-scale plot-based classification approaches. -- Results:
Our framework is based on the distinction of four structural
elements (plot record, vegetation type, consistent
classification section and classification system) and two
procedural elements (classification protocol and classification
approach). For each element we describe essential properties
that can be used for comparisons. We also review alternative
choices regarding critical decisions of classification
approaches; with a special focus on the procedures used to
define vegetation types from plot records. We illustrate our
comparative framework by applying it to different broad-scale
classification approaches. -- Conclusions: Our framework will
be useful for understanding and comparing plot-based vegetation
classification approaches, as well as for integrating
classification systems and their sections.
University of Edinburgh1, Swedish University of Agricultural Sciences2, University of Copenhagen3, Wageningen University and Research Centre4, University of Vermont5, University of Bonn6, University of Victoria7, University of Alaska Fairbanks8, Texas A&M University9, Swiss Federal Institute for Forest, Snow and Landscape Research10, Adam Mickiewicz University in Poznań11, University of Oxford12, Université du Québec13, University of Greifswald14, University of Tromsø15
TL;DR: In this article, the authors present a review of existing and developing methods to measure radial and axial growth, estimate age, and assess growth dynamics in relation to environmental variables in arctic and alpine regions.
TL;DR: In this article, the aesthetic preferences of Swiss residents for typical agricultural landscape elements in the Swiss lowlands were investigated in a Swisswide photo survey, where photographs of seven ecological compensation areas (ECAs) and seven other elements (crops, high-intensity meadows and pastures) were selected.
TL;DR: In this paper, the authors used photogrammetric image correlation techniques based on the multispectral nadir and backward-looking sensor data to generate digital surface models of winter and summer terrains in the neighborhood of Davos, Switzerland.
Abstract: . Information on snow depth and its spatial distribution is crucial for numerous applications in snow and avalanche research as well as in hydrology and ecology. Today, snow depth distributions are usually estimated using point measurements performed by automated weather stations and observers in the field combined with interpolation algorithms. However, these methodologies are not able to capture the high spatial variability of the snow depth distribution present in alpine terrain. Continuous and accurate snow depth mapping has been successfully performed using laser scanning but this method can only cover limited areas and is expensive. We use the airborne ADS80 optoelectronic scanner, acquiring stereo imagery with 0.25 m spatial resolution to derive digital surface models (DSMs) of winter and summer terrains in the neighborhood of Davos, Switzerland. The DSMs are generated using photogrammetric image correlation techniques based on the multispectral nadir and backward-looking sensor data. In order to assess the accuracy of the photogrammetric products, we compare these products with the following independent data sets acquired simultaneously: (a) manually measured snow depth plots; (b) differential Global Navigation Satellite System (dGNSS) points; (c) terrestrial laser scanning (TLS); and (d) ground-penetrating radar (GPR) data sets. We demonstrate that the method presented can be used to map snow depth at 2 m resolution with a vertical depth accuracy of ±30 cm (root mean square error) in the complex topography of the Alps. The snow depth maps presented have an average accuracy that is better than 15 % compared to the average snow depth of 2.2 m over the entire test site.
TL;DR: Main advantages of the tiered approach are that it can be adapted to other ES, it supports the efforts toward a standardized ES assessment, and it provides information about relevant variables to be considered in long term monitoring at different scales.
Abstract: Ecosystem services (ES) mapping make the benefits of nature spatially explicit The different methods used for ES mapping limit the comparability of outcomes and call for a more consistent but flexible approach We present a four step tiered approach for ES mapping supporting scholars to select the adequate combination of variables: First, the user, researcher or policy maker defines the goal of the ES assessment Second, a meta-analysis of relevant ES mapping studies is conducted to identify key variables for mapping the selected ES Third, the identified variables are attributed to the different levels of the multitier framework according to the level at which they best answer the policy or research question Finally, appropriate methods for mapping the ES are selected based on the reviewed studies We illustrate the approach for recreational services at three different tiers Main advantages of the tiered approach are that (i) it can be adapted to other ES, (ii) it supports the efforts toward a standardized ES assessment, (iii) it provides information about relevant variables to be considered in long term monitoring at different scales, (iv) it supports sustainable resource management as it ensures the inclusion of information relevant to decision makers at different levels
TL;DR: In this paper, the authors define five scenarios of future land-use for Switzerland along axes of Globalisation to Regionalization and Market-driven developments to high policy intervention, using the Dyna-CLUE land use modelling framework.
TL;DR: This paper focuses on the technical part of EWSs, i.e., the prediction and timely recognition of imminent hazards, as well as on monitoring slopes at risk and released mass movements, in order to establish and advance the state of practice in the application of early warning systems.
Abstract: . Rapid mass movements (RMM) pose a substantial risk to people and infrastructure. Reliable and cost-efficient measures have to be taken to reduce this risk. One of these measures includes establishing and advancing the state of practice in the application of early warning systems (EWSs). EWSs have been developed during the past decades and are rapidly increasing. In this paper, we focus on the technical part of EWSs, i.e., the prediction and timely recognition of imminent hazards, as well as on monitoring slopes at risk and released mass movements. Recent innovations in assessing spatial precipitation, monitoring and precursors of the triggering and deformation of RMM offer new opportunities for next-generation EWSs. However, technical advancement can only be transferred into more reliable, operational EWSs with an adequate well-instructed dedicated staff. To this end, an intense dialog between scientists, engineers and those in charge of warning, as well as further experience with new comprehensive prototype systems jointly operated by scientists and practitioners, will be essential.
TL;DR: It is found that five years of consecutive summer warming with peaks of +2 to +8°C led to a 50% reduction in the biomass of the dominant mixotrophs, the mixotrophic testate amoebae (MTA).
Abstract: Mixotrophic protists are increasingly recognized for their significant contribution to carbon (C) cycling. As phototrophs they contribute to photosynthetic C fixation, whilst as predators of decomposers, they indirectly influence organic matter decomposition. Despite these direct and indirect effects on the C cycle, little is known about the responses of peatland mixotrophs to climate change and the potential consequences for the peatland C cycle. With a combination of field and microcosm experiments, we show that mixotrophs in the Sphagnum bryosphere play an important role in modulating peatland C cycle responses to experimental warming. We found that five years of consecutive summer warming with peaks of +2 to +8°C led to a 50% reduction in the biomass of the dominant mixotrophs, the mixotrophic testate amoebae (MTA). The biomass of other microbial groups (including decomposers) did not change, suggesting MTA to be particularly sensitive to temperature. In a microcosm experiment under controlled conditions, we then manipulated the abundance of MTA, and showed that the reported 50% reduction of MTA biomass in the field was linked to a significant reduction of net C uptake (-13%) of the entire Sphagnum bryosphere. Our findings suggest that reduced abundance of MTA with climate warming could lead to reduced peatland C fixation.
Arlene P. Aaron-Morrison, Steven A. Ackerman1, Nicolaus G. Adams2, Robert F. Adler3 +470 more•Institutions (138)
TL;DR: The State of the Climate for 2014 as mentioned in this paper is a very low-resolution file and it can be downloaded in a few minutes for a high-resolution version of the report to download.
Abstract: Editors note: For easy download the posted pdf of the State of the Climate for 2014 is a very low-resolution file. A high-resolution copy of the report is available by clicking here. Please be patient as it may take a few minutes for the high-resolution file to download.
TL;DR: In this paper, the authors examined how land use and environmental amenities and disamenities affect rental prices across urban, suburban, periurban, and affluent communities in Switzerland and found that about 70 percent of the price variation is found at the apartment level and about 30 percent at the community level.