Author
Stef Weijers
Other affiliations: VU University Amsterdam, University of Amsterdam
Bio: Stef Weijers is an academic researcher from University of Bonn. The author has contributed to research in topics: Tundra & Shrub. The author has an hindex of 15, co-authored 24 publications receiving 2177 citations. Previous affiliations of Stef Weijers include VU University Amsterdam & University of Amsterdam.
Topics: Tundra, Shrub, Arctic, Cassiope tetragona, Global warming
Papers
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Université de Sherbrooke1, University of Alberta2, University of Lapland3, University of Victoria4, Wageningen University and Research Centre5, University of Alaska Fairbanks6, University of Oxford7, Université du Québec à Trois-Rivières8, Laval University9, St. John's University10, University of Amsterdam11, University of Vermont12, Aarhus University13, University of Zurich14, Swiss Federal Institute for Forest, Snow and Landscape Research15, University of Edinburgh16, La Trobe University17, Woods Hole Oceanographic Institution18, Lamont–Doherty Earth Observatory19, University of British Columbia20, University of Tromsø21, University of Alaska Anchorage22, Queen's University23, University of Virginia24
TL;DR: This article used repeat photography, long-term ecological monitoring and dendrochronology to document shrub expansion in arctic, high-latitude and alpine tundra.
Abstract: Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra
1,153 citations
University of Edinburgh1, National Ecological Observatory Network2, University of Colorado Boulder3, Woods Hole Oceanographic Institution4, University of Greifswald5, University of Copenhagen6, University of Alaska Fairbanks7, University of Vermont8, University of Oxford9, Norwegian University of Science and Technology10, Université du Québec11, Aarhus University12, University of Victoria13, St. John's University14, University of Bonn15, Adam Mickiewicz University in Poznań16, Texas A&M University17, Norwegian Polar Institute18, University of Zurich19, University of Basel20, University of Alberta21, Université de Sherbrooke22
TL;DR: In this article, the authors analyzed circumpolar data from 37 Arctic and alpine sites in 9 countries, including 25 species, and ∼42,000 annual growth records from 1,821 individuals, and demonstrated that the sensitivity of shrub growth to climate was heterogeneous, with European sites showing greater summer temperature sensitivity than North American sites, and higher at sites with greater soil moisture and for taller shrubs (for example, alders and willows) growing at their northern or upper elevational range edges.
Abstract: Rapid climate warming has been linked to increasing shrub dominance in the Arctic tundra. Research now shows that climate–shrub growth relationships vary spatially and according to site characteristics such as soil moisture and shrub height. Rapid climate warming in the tundra biome has been linked to increasing shrub dominance1,2,3,4. Shrub expansion can modify climate by altering surface albedo, energy and water balance, and permafrost2,5,6,7,8, yet the drivers of shrub growth remain poorly understood. Dendroecological data consisting of multi-decadal time series of annual shrub growth provide an underused resource to explore climate–growth relationships. Here, we analyse circumpolar data from 37 Arctic and alpine sites in 9 countries, including 25 species, and ∼42,000 annual growth records from 1,821 individuals. Our analyses demonstrate that the sensitivity of shrub growth to climate was: (1) heterogeneous, with European sites showing greater summer temperature sensitivity than North American sites, and (2) higher at sites with greater soil moisture and for taller shrubs (for example, alders and willows) growing at their northern or upper elevational range edges. Across latitude, climate sensitivity of growth was greatest at the boundary between the Low and High Arctic, where permafrost is thawing4 and most of the global permafrost soil carbon pool is stored9. The observed variation in climate–shrub growth relationships should be incorporated into Earth system models to improve future projections of climate change impacts across the tundra biome.
471 citations
Aarhus University1, University of Edinburgh2, National Ecological Observatory Network3, University of Colorado Boulder4, Institute of Arctic and Alpine Research5, Smithsonian Institution6, Lund University7, VU University Amsterdam8, University of Lapland9, Northern Arizona University10, Bigelow Laboratory For Ocean Sciences11, University of British Columbia12, University of Washington13, Grand Valley State University14, Swiss Federal Institute for Forest, Snow and Landscape Research15, Max Planck Society16, University of Zurich17, Université de Sherbrooke18, University of Greifswald19, University of Parma20, Memorial University of Newfoundland21, Université du Québec à Trois-Rivières22, University of Gothenburg23, Leiden University24, University of California, Riverside25, Qatar University26, Mississippi State University27, University of Barcelona28, Utrecht University29, Umeå University30, Adam Mickiewicz University in Poznań31, University of Alaska Anchorage32, Wageningen University and Research Centre33, Alaska Department of Fish and Game34, University of Tromsø35, University of Vienna36, University of Copenhagen37, University of Oulu38, Helmholtz Centre for Environmental Research - UFZ39, Spanish National Research Council40, Queen's University41, Saint Mary's University42, Oak Ridge National Laboratory43, University of Aberdeen44, University of Saskatchewan45, Vrije Universiteit Brussel46, University of Victoria47, Swiss Federal Institute of Aquatic Science and Technology48, Norwegian University of Science and Technology49, Research Institute for Nature and Forest50, Florida International University51, Moscow State University52, University of Alaska Fairbanks53, University of Waterloo54, Laval University55, Deakin University56, University of Bonn57, United States Forest Service58, Simon Fraser University59, University Centre in Svalbard60, University of Iceland61, United States Fish and Wildlife Service62, Colorado State University63, University of Texas at El Paso64, University of Stirling65, University of Innsbruck66, Rocky Mountain Biological Laboratory67, University of Oxford68, Pacific Northwest National Laboratory69, University of Camerino70, University of Insubria71, University of New South Wales72, University of Manchester73, National University of Cordoba74, University of Arizona75, Santa Fe Institute76, Harvard University77, King Juan Carlos University78, Estonian University of Life Sciences79, Kyoto University80, World Agroforestry Centre81, Radboud University Nijmegen82, Macquarie University83, Forschungszentrum Jülich84, University of Regensburg85, University of Minnesota86, University of Sydney87, Santa Clara University88, Algoma University89, Komarov Botanical Institute90, University of Wisconsin–Eau Claire91
TL;DR: Biome-wide relationships between temperature, moisture and seven key plant functional traits across the tundra and over time show that community height increased with warming across all sites, whereas other traits lagged behind predicted rates of change.
Abstract: The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature-trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming.
425 citations
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.
119 citations
TL;DR: In this paper, the authors measured annual shoot length increase of 32 plant samples of the circumarctic dwarf shrub species C. tetragona using the presence of wintermarksepta within the stems, resulting in a 169 year growth chronology (1840-2008) for a High Arctic site on Svalbard.
69 citations
Cited by
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National University of Cordoba1, SupAgro2, Joseph Fourier University3, University of Alaska Fairbanks4, VU University Amsterdam5, Kansas State University6, University of Western Australia7, University of Minnesota8, Wageningen University and Research Centre9, Macquarie University10, Stanford University11, Spanish National Research Council12, ETH Zurich13, University of Sheffield14, Utrecht University15, University of California, Los Angeles16, University of Arizona17, University of Regensburg18, Princeton University19, Centro Agronómico Tropical de Investigación y Enseñanza20
TL;DR: This new handbook has a better balance between whole-plant traits, leaf traits, root and stem traits and regenerative traits, and puts particular emphasis on traits important for predicting species’ effects on key ecosystem properties.
Abstract: Plant functional traits are the features (morphological, physiological, phenological) that represent ecological strategies and determine how plants respond to environmental factors, affect other trophic levels and influence ecosystem properties. Variation in plant functional traits, and trait syndromes, has proven useful for tackling many important ecological questions at a range of scales, giving rise to a demand for standardised ways to measure ecologically meaningful plant traits. This line of research has been among the most fruitful avenues for understanding ecological and evolutionary patterns and processes. It also has the potential both to build a predictive set of local, regional and global relationships between plants and environment and to quantify a wide range of natural and human-driven processes, including changes in biodiversity, the impacts of species invasions, alterations in biogeochemical processes and vegetation–atmosphere interactions. The importance of these topics dictates the urgent need for more and better data, and increases the value of standardised protocols for quantifying trait variation of different species, in particular for traits with power to predict plant- and ecosystem-level processes, and for traits that can be measured relatively easily. Updated and expanded from the widely used previous version, this handbook retains the focus on clearly presented, widely applicable, step-by-step recipes, with a minimum of text on theory, and not only includes updated methods for the traits previously covered, but also introduces many new protocols for further traits. This new handbook has a better balance between whole-plant traits, leaf traits, root and stem traits and regenerative traits, and puts particular emphasis on traits important for predicting species’ effects on key ecosystem properties. We hope this new handbook becomes a standard companion in local and global efforts to learn about the responses and impacts of different plant species with respect to environmental changes in the present, past and future.
2,744 citations
Boston University1, Peking University2, Huazhong Agricultural University3, Birla Institute of Technology and Science4, Karlsruhe Institute of Technology5, Max Planck Society6, Université Paris-Saclay7, University of Copenhagen8, Norwegian Polar Institute9, Indian Institute of Science10, Ames Research Center11
TL;DR: Using satellite data from 2000–2017, this study finds striking greening of both China and India, driven primarily by land-use change, with forest growth and cropland intensification more important in China andCropland moreimportant in India.
Abstract: Satellite data show increasing leaf area of vegetation due to direct (human land-use management) and indirect factors (climate change, CO2 fertilization, nitrogen deposition, recovery from natural disturbances, etc.). Among these, climate change and CO2 fertilization effect seem to be the dominant drivers. However, recent satellite data (2000-2017) reveal a greening pattern that is strikingly prominent in China and India, and overlapping with croplands world-wide. China alone accounts for 25% of the global net increase in leaf area with only 6.6% of global vegetated area. The greening in China is from forests (42%) and croplands (32%), but in India is mostly from croplands (82%) with minor contribution from forests (4.4%). China is engineering ambitious programs to conserve and expand forests with the goal of mitigating land degradation, air pollution and climate change. Food production in China and India has increased by over 35% since 2000 mostly due to increasing harvested area through multiple cropping facilitated by fertilizer use and surface/ground-water irrigation. Our results indicate that the direct factor is a key driver of the "Greening Earth", accounting for over a third, and likely more, of the observed net increase in green leaf area. They highlight the need for realistic representation of human land-use practices in Earth system models.
1,389 citations
University of Alberta1, Université de Sherbrooke2, University of Lapland3, University of Victoria4, Wageningen University and Research Centre5, University of Alaska Fairbanks6, University of Oxford7, Université du Québec à Trois-Rivières8, Laval University9, St. John's University10, University of Amsterdam11, University of Vermont12, Aarhus University13, University of Zurich14, Swiss Federal Institute for Forest, Snow and Landscape Research15, University of Edinburgh16, La Trobe University17, Woods Hole Oceanographic Institution18, Lamont–Doherty Earth Observatory19, University of British Columbia20, University of Tromsø21, University of Alaska Anchorage22, Queen's University23, University of Virginia24
TL;DR: This article used repeat photography, long-term ecological monitoring and dendrochronology to document shrub expansion in arctic, high-latitude and alpine tundra.
Abstract: Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra
1,153 citations
TL;DR: The extent of the trait data compiled in TRY is evaluated and emerging patterns of data coverage and representativeness are analyzed to conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements.
Abstract: Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
882 citations