Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies (ClimEx)
    Halbritter, Aud H. ; Boeck, Hans J. De; Eycott, Amy E. ; Reinsch, Sabine ; Robinson, David A. ; Vicca, Sara ; Berauer, Bernd ; Christiansen, Casper T. ; Estiarte, Marc ; Grünzweig, José M. ; Gya, Ragnhild ; Hansen, Karin ; Jentsch, Anke ; Lee, Hanna ; Linder, Sune ; Marshall, John ; Peñuelas, Josep ; Kappel Schmidt, Inger ; Stuart-Haëntjens, Ellen ; Wilfahrt, Peter ; Vandvik, Vigdis ; Abrantes, Nelson ; Almagro, María ; Althuizen, Inge H.J. ; Barrio, Isabel C. ; Beest, Mariska Te; Beier, Claus ; Beil, Ilka ; Carter Berry, Z. ; Birkemoe, Tone ; Bjerke, Jarle W. ; Blonder, Benjamin ; Blume-Werry, Gesche ; Bohrer, Gil ; Campos, Isabel ; Cernusak, Lucas A. ; Chojnicki, Bogdan H. ; Cosby, Bernhard J. ; Dickman, Lee T. ; Djukic, Ika ; Filella, Iolanda ; Fuchslueger, Lucia ; Gargallo-Garriga, Albert ; Gillespie, Mark A.K. ; Goldsmith, Gregory R. ; Gough, Christopher ; Halliday, Fletcher W. ; Hegland, Stein Joar ; Ploeg, Martine van der; Verbruggen, Erik - \ 2020
    Methods in Ecology and Evolution 11 (2020)1. - ISSN 2041-210X - p. 22 - 37.
    best practice - coordinated experiments - data management and documentation - ecosystem - experimental macroecology - methodology - open science - vegetation

    Climate change is a world-wide threat to biodiversity and ecosystem structure, functioning and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate change impacts across the soil–plant–atmosphere continuum. An increasing number of climate change studies are creating new opportunities for meaningful and high-quality generalizations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re-use, synthesis and upscaling. Many of these challenges relate to a lack of an established ‘best practice’ for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change. To overcome these challenges, we collected best-practice methods emerging from major ecological research networks and experiments, as synthesized by 115 experts from across a wide range of scientific disciplines. Our handbook contains guidance on the selection of response variables for different purposes, protocols for standardized measurements of 66 such response variables and advice on data management. Specifically, we recommend a minimum subset of variables that should be collected in all climate change studies to allow data re-use and synthesis, and give guidance on additional variables critical for different types of synthesis and upscaling. The goal of this community effort is to facilitate awareness of the importance and broader application of standardized methods to promote data re-use, availability, compatibility and transparency. We envision improved research practices that will increase returns on investments in individual research projects, facilitate second-order research outputs and create opportunities for collaboration across scientific communities. Ultimately, this should significantly improve the quality and impact of the science, which is required to fulfil society's needs in a changing world.

    The ecology of infrastructure decommissioning in the North Sea: what we need to know and how to achieve it
    Fowler, A.M. ; Jørgensen, A.M. ; Coolen, J.W.P. ; Jones, D.O.B. ; Svendsen, J.C. ; Brabant, R. ; Rumes, B. ; Degraer, S. - \ 2020
    ICES Journal of Marine Science 77 (2020)3. - ISSN 1054-3139 - p. 1109 - 1126.
    artificial reefs - biodiversity - conservation - decommissioning - ecosystem - marine policy - North Sea - offshore infrastructure - platform - sustainability - wind farm
    As decommissioning of oil and gas (O&G) installations intensifies in the North Sea, and worldwide, debate rages regarding the fate of these novel habitats and their associated biota—a debate that has important implications for future decommissioning of offshore wind farms (OWFs). Calls to relax complete removal requirements in some circumstances and allow part of an O&G installation to be left in the marine environment are increasing. Yet knowledge regarding the biological communities that develop on these structures and their ecological role in the North Sea is currently insufficient to inform such decommissioning decisions. To focus debate regarding decommissioning policy and guide ecological research, we review environmental policy objectives in the region, summarize existing knowledge regarding ecological aspects of decommissioning for both O&G and OWF installations, and identify approaches to address knowledge gaps through science–industry collaboration. We find that in some cases complete removal will conflict with other policies regarding protection and restoration of reefs, as well as the conservation of species within the region. Key ecological considerations that are rarely considered during decommissioning decisions are: (i) provision of reef habitat, (ii) productivity of offshore ecosystems, (iii) enhancement of biodiversity, (iv) protection of the seabed from trawling, and (v) enhancement of connectivity. Knowledge gaps within these areas will best be addressed using industry infrastructure and vessels for scientific investigations, re-analysis of historical data held by industry, scientific training of industry personnel, joint research funding opportunities, and trial decommissioning projects.
    The uncertain climate footprint of wetlands under human pressure
    Petrescu, A.J. ; Lohila, A. ; Tuovinen, J.P. ; Baldocchi, D.D. ; Desai, A.R. ; Veenendaal, E.M. ; Schrier-Uijl, A. - \ 2015
    Proceedings of the National Academy of Sciences of the United States of America 112 (2015)15. - ISSN 0027-8424 - p. 4594 - 4599.
    methane emissions - carbon-dioxide - peatlands - ecosystem - fluxes - variability - dynamics - drainage - balance - cycle
    Significant climate risks are associated with a positive carbon–temperature feedback in northern latitude carbon-rich ecosystems, making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO2 and CH4 fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH4 emissions in natural ecosystems are in the long term (i.e., several centuries) typically offset by CO2 uptake, although with large spatiotemporal variability. Using a space-for-time analogy across ecological and climatic gradients, we represent the chronosequence from natural to managed conditions to quantify the “cost” of CH4 emissions for the benefit of net carbon sequestration. With a sustained pulse–response radiative forcing model, we found a significant increase in atmospheric forcing due to land management, in particular for wetland converted to cropland. Our results quantify the role of human activities on the climate footprint of northern wetlands and call for development of active mitigation strategies for managed wetlands and new guidelines of the Intergovernmental Panel on Climate Change (IPCC) accounting for both sustained CH4 emissions and cumulative CO2 exchange.
    15N in tree rings as a bio-indicator of changing nitrogen cycling in tropical forests: an evaluation at three sites using two sampling methods
    Sleen, J.P. van der; Vlam, M. ; Groenendijk, P. ; Anten, N.P.R. ; Bongers, F. ; Bunyavejchewin, S. ; Hietz, P. ; Pons, T.L. ; Zuidema, P. - \ 2015
    Frontiers in Plant Science 6 (2015). - ISSN 1664-462X
    rain-forest - natural-abundance - soil-nitrogen - isotope fractionation - wood deterioration - growth-rates - n deposition - dynamics - ecosystem - lowland
    Anthropogenic nitrogen deposition is currently causing a more than twofold increase of reactive nitrogen input over large areas in the tropics. Elevated N-15 abundance (delta N-15) in the growth rings of some tropical trees has been hypothesized to reflect an increased leaching of N-15-depleted nitrate from the soil, following anthropogenic nitrogen deposition over the last decades. To find further evidence for altered nitrogen cycling in tropical forests, we measured long-term delta N-15 values in trees from Bolivia, Cameroon, and Thailand. We used two different sampling methods. In the first, wood samples were taken in a conventional way: from the pith to the bark across the stem of 28 large trees (the "radial" method). In the second, delta N-15 values were compared across a fixed diameter (the "fixed-diameter" method). We sampled 400 trees that differed widely in size, but measured delta N-15 in the stem around the same diameter (20 cm dbh) in all trees. As a result, the growth rings formed around this diameter differed in age and allowed a comparison of delta N-15 values over time with an explicit control for potential size-effects on delta N-15 values. We found a significant increase of tree-ring delta N-15 across the stem radius of large trees from Bolivia and Cameroon, but no change in tree-ring delta N-15 values over time was found in any of the study sites when controlling for tree size. This suggests that radial trends of delta N-15 values within trees reflect tree ontogeny (size development). However, for the trees from Cameroon and Thailand, a low statistical power in the fixed-diameter method prevents to conclude this with high certainty. For the trees from Bolivia, statistical power in the fixed-diameter method was high, showing that the temporal trend in tree-ring delta N-15 values in the radial method is primarily caused by tree ontogeny and unlikely by a change in nitrogen cycling. We therefore stress to account for tree size before tree-ring delta N-15 values can be properly interpreted.
    Intensive agriculture reduces soil biodiversity across Europe
    Tsiafouli, M.A. ; Thébault, E. ; Sgardelis, S. ; Ruiter, P.C. de; Putten, W.H. van der; Birkhofer, K. ; Hemerik, L. ; Vries, F.T. de; Bardgett, R.D. ; Brady, M. ; Bjornlund, L. ; Bracht Jörgensen, H. ; Christensen, S. ; Herfelt, T. D'; Hotes, S. ; Hol, W.H.G. ; Frouz, J. ; Liiri, M. ; Mortimer, S.R. ; Setälä, H. ; Stary, J. ; Tzanopoulos, J. ; Uteseny, C. ; Wolters, V. ; Hedlund, K. - \ 2015
    Global Change Biology 21 (2015)2. - ISSN 1354-1013 - p. 973 - 985.
    food-web structure - land-use intensity - taxonomic distinctness - community structure - phylogenetic diversity - arthropod communities - temporal variability - 7-year period - ecosystem - management
    Soil biodiversity plays a key role in regulating the processes that underpin the delivery of ecosystem goods and services in terrestrial ecosystems. Agricultural intensification is known to change the diversity of individual groups of soil biota, but less is known about how intensification affects biodiversity of the soil food web as a whole, and whether or not these effects may be generalized across regions. We examined biodiversity in soil food webs from grasslands, extensive, and intensive rotations in four agricultural regions across Europe: in Sweden, the UK, the Czech Republic and Greece. Effects of land-use intensity were quantified based on structure and diversity among functional groups in the soil food web, as well as on community-weighted mean body mass of soil fauna. We also elucidate land-use intensity effects on diversity of taxonomic units within taxonomic groups of soil fauna. We found that between regions soil food web diversity measures were variable, but that increasing land-use intensity caused highly consistent responses. In particular, land-use intensification reduced the complexity in the soil food webs, as well as the community-weighted mean body mass of soil fauna. In all regions across Europe, species richness of earthworms, Collembolans, and oribatid mites was negatively affected by increased land-use intensity. The taxonomic distinctness, which is a measure of taxonomic relatedness of species in a community that is independent of species richness, was also reduced by land-use intensification. We conclude that intensive agriculture reduces soil biodiversity, making soil food webs less diverse and composed of smaller bodied organisms. Land-use intensification results in fewer functional groups of soil biota with fewer and taxonomically more closely related species. We discuss how these changes in soil biodiversity due to land-use intensification may threaten the functioning of soil in agricultural production systems.
    Enhanced Input of Terrestrial Particulate Organic Matter Reduces the Resilience of the Clear-Water State of Shallow Lakes: A Model Study
    Lischke, B. ; Hilt, S. ; Janse, J.H. ; Kuiper, J.J. ; Mehner, T. ; Mooij, W.M. ; Gaedke, U. - \ 2014
    Ecosystems 17 (2014)4. - ISSN 1432-9840 - p. 616 - 626.
    climate-change - food webs - humic substances - resource use - fresh-water - loch ness - land-use - carbon - ecosystem - phosphorus
    The amount of terrestrial particulate organic matter (t-POM) entering lakes is predicted to increase as a result of climate change. This may especially alter the structure and functioning of ecosystems in small, shallow lakes which can rapidly shift from a clear-water, macrophyte-dominated into a turbid, phytoplankton-dominated state. We used the integrative ecosystem model PCLake to predict how rising t-POM inputs affect the resilience of the clear-water state. PCLake links a pelagic and benthic food chain with abiotic components by a number of direct and indirect effects. We focused on three pathways (zoobenthos, zooplankton, light availability) by which elevated t-POM inputs (with and without additional nutrients) may modify the critical nutrient loading thresholds at which a clear-water lake becomes turbid and vice versa. Our model results show that (1) increased zoobenthos biomass due to the enhanced food availability results in more benthivorous fish which reduce light availability due to bioturbation, (2) zooplankton biomass does not change, but suspended t-POM reduces the consumption of autochthonous particulate organic matter which increases the turbidity, and (3) the suspended t-POM reduces the light availability for submerged macrophytes. Therefore, light availability is the key process that is indirectly or directly changed by t-POM input. This strikingly resembles the deteriorating effect of terrestrial dissolved organic matter on the light climate of lakes. In all scenarios, the resilience of the clear-water state is reduced thus making the turbid state more likely at a given nutrient loading. Therefore, our study suggests that rising t-POM input can add to the effects of climate warming making reductions in nutrient loadings even more urgent.
    Extending one-dimensional models for deep lakes to simulate the impact of submerged macrophytes on water quality
    Sachse, R. ; Petzoldt, T. ; Blumstock, M. ; Moreira, S. ; Pätzig, M. ; Rücker, J. ; Janse, J.H. ; Mooij, W.M. ; Hilt, S. - \ 2014
    Environmental Modelling & Software 61 (2014). - ISSN 1364-8152 - p. 410 - 423.
    shallow eutrophic lakes - phytoplankton biomass - nutrient dynamics - phosphorus - ecosystem - growth - state - fish - zooplankton - vegetation
    Submerged macrophytes can stabilise clear water conditions in shallow lakes. However, many existing models for deep lakes neglect their impact. Here, we tested the hypothesis that submerged macrophytes can affect the water clarity in deep lakes. A one-dimensional, vertically resolved macrophyte model was developed based on PCLake and coupled to SALMO-1D and GOTM hydrophysics and validated against field data. Validation showed good coherence in dynamic growth patterns and colonisation depths. In our simulations the presence of submerged macrophytes resulted in up to 50% less phytoplankton biomass in the shallowest simulated lake (11 m) and still 15% less phytoplankton was predicted in 100 m deep oligotrophic lakes. Nutrient loading, lake depth, and lake shape had a strong influence on macrophyte effects. Nutrient competition was found to be the strongest biological interaction. Despite a number of limitations, the derived dynamic lake model suggests significant effects of submerged macrophytes on deep lake water quality.
    Effects of Dichrostachys cinerea (L.) Wight & Arn (Fabaceae) on herbaceous species in a semi-arid rangeland in Zimbabwe
    Mudzengi, C. ; Kativu, S. ; Dahwa, E. ; Poshiwa, X. ; Murungweni, C. - \ 2014
    Nature Conservation 7 (2014). - ISSN 1314-6947 - p. 51 - 60.
    plant - invasibility - vegetation - invasions - ecosystem - botswana
    Anthropogenic alteration of an environment and other disturbance regimes may enable the expansion of some native species into new geographical areas, a phenomenon observed with Dichrostachys cinerea. Five D. cinerea invaded sites, each approximately one hectare in size were assessed for the effects of D. cinerea on native herbaceous species diversity, richness, basal cover, litter cover, top hamper and plant vigour. The same attributes were studied in five uninvaded sites adjacent to, and equal in size to each invaded site. Forty herbaceous species were identified in the area. There were significant differences (P <0.05) noted in species richness, basal cover, litter cover, top hamper, plant vigour, and species diversities between invaded and uninvaded sites, with uninvaded sites recording higher values than invaded sites. Altitude, erosion and the edaphic variables pH, N, P and K, which were included as explanatory variables, also differed significantly (P
    Pricing rainbow, green, blue and grey water: tree cover and geopolitics of climatic teleconnections
    Noordwijk, M. van; Namirembe, S. ; Catacutan, D. ; Williamson, D. ; Gebrekirstos, A. - \ 2014
    Current Opinion in Environmental Sustainability 6 (2014). - ISSN 1877-3435 - p. 41 - 47.
    tropical deforestation - vapor transport - land-surface - policy - precipitation - management - ecosystem - dynamics - forests - africa
    Atmospheric moisture (“rainbow water”) is the source of all green, blue and grey water flows. Current water-related legislation and policies have moved beyond blue (water allocation) and grey (waste water treatment) water concerns to incorporate the green water concept of additional water use by fast-growing trees; it may require further change to incorporate rainbow water relations as evident in recent literature on short-cycle rainfall derived from evapotranspiration over land. Specific teleconnections relate rainfall dynamics at any specific site to land use and sea conditions elsewhere. Government-mandated water use charges for payments for ecosystem services (PES) exist in some African countries but their use in enhancing actual water related ecosystem services covering the full hydrological cycle is still evolving as rainbow water science is new.
    Ungulate herbivory overrides rainfall impacts on herbaceous regrouth and residual biomass in a key resource area
    Muthoni, F.K. ; Groen, T.A. ; Skidmore, A.K. ; Oel, P.R. van - \ 2014
    Journal of Arid Environments 100-101 (2014). - ISSN 0140-1963 - p. 9 - 17.
    net primary productivity - papyrus cyperus-papyrus - lake naivasha - nonequilibrium concepts - semiarid savanna - kenya - vegetation - grassland - ecosystem - plants
    Key grazing lands that provide dry season forage to both resident and migrating ungulates may experience heavy grazing impacts during the dry season, thereby jeopardizing future forage productivity. In this study a herbivore exclosure experiment was used to quantify the effects of grazing by large ungulates on herbaceous regrowth and residual aboveground biomass in a fragmented key resource area; the fringe zone around Lake Naivasha, Kenya. Top-down control mechanisms were prevalent in both the dry and wet seasons suggesting the existence of a high resident herbivore density. Intense grazing significantly reduced residual biomass that in turn reduced plant regrowth. An increased frequency of defoliation reduced regrowth during the dry season demonstrating the negative effect resulting from high herbivore densities during the dry season. This study indicates that grazing exerts a higher control on regrowth than rainfall as heavily grazed residual biomass did not recover during the following wet season.
    Drivers of extinction risk in African mammals: the interplay of distribution state, human pressure, conservation response and species biology
    Marco, M. Di; Buchanan, G.M. ; Szantoi, Z. ; Holmgren, M. ; Grottolo Marasini, G. ; Gross, D. ; Tranquili, S. ; Boitani, L. ; Rondini, C. - \ 2014
    Philosophical Transactions of the Royal Society B. Biological sciences 369 (2014). - ISSN 0962-8436 - 12 p.
    protected areas - population declines - tropical forest - human footprint - time-series - land-cover - strategy - deforestation - 21st-century - ecosystem
    Although conservation intervention has reversed the decline of some species, our success is outweighed by a much larger number of species moving towards extinction. Extinction risk modelling can identify correlates of risk and species not yet recognized to be threatened. Here, we use machine learning models to identify correlates of extinction risk in African terrestrial mammals using a set of variables belonging to four classes: species distribution state, human pressures, conservation response and species biology. We derived information on distribution state and human pressure from satellite- borne imagery. Variables in all four classes were identified as important predictors of extinction risk, and interactions were observed among variables in different classes (e.g. level of protection, human threats, species distribution ranges). Species biology had a key role in mediating the effect of external variables. The model was 90% accurate in classifying extinction risk status of species, but in a few cases the observed and modelled extinction risk mismatched. Species in this condition might suffer from an incorrect classification of extinction risk (hence require reassessment). An increased availability of satellite imagery combined with improved resolution and classification accuracy of the resulting maps will play a progressively greater role in conservation monitoring.
    Counting whales in a challenging, changing environment
    Williams, R. ; Kelly, N. ; Boebel, O. ; Friedlaender, A. ; Herr, H. ; Kock, K.H. ; Lehnert, L.S. ; Maksym, T. ; Roberts, J. ; Scheidat, M. ; Siebert, U. ; Brierley, A. - \ 2014
    Scientific Reports 4 (2014). - ISSN 2045-2322 - 6 p.
    antarctic sea-ice - abundance - extent - ocean - krill - ecosystem - shelf - edge
    Estimating abundance of Antarctic minke whales is central to the International Whaling Commission's conservation and management work and understanding impacts of climate change on polar marine ecosystems. Detecting abundance trends is problematic, in part because minke whales are frequently sighted within Antarctic sea ice where navigational safety concerns prevent ships from surveying. Using icebreaker-supported helicopters, we conducted aerial surveys across a gradient of ice conditions to estimate minke whale density in the Weddell Sea. The surveys revealed substantial numbers of whales inside the sea ice. The Antarctic summer sea ice is undergoing rapid regional change in annual extent, distribution, and length of ice-covered season. These trends, along with substantial interannual variability in ice conditions, affect the proportion of whales available to be counted by traditional shipboard surveys. The strong association between whales and the dynamic, changing sea ice requires reexamination of the power to detect trends in whale abundance or predict ecosystem responses to climate change.
    Shifting nature conservation approaches in Natura 2000 and the implications for the roles of stakeholders
    Ferranti, F. ; Turnhout, E. ; Beunen, R. ; Behagel, J.H. - \ 2014
    Journal of Environmental Planning and Management 57 (2014)11. - ISSN 0964-0568 - p. 1642 - 1657.
    policy - participation - governance - implementation - netherlands - empowerment - ecosystem - network - power
    This paper analyses Natura 2000 as a shifting configuration of different approaches to nature conservation and discusses the consequences of these shifts for the roles of the stakeholders affected by this policy. Natura 2000 started with a technocratic approach that privileged conservation experts and marginalised socio-economic stakeholders. Over time, this approach has been complemented with participatory and economic approaches that offered scope for the inclusion of land users and business actors. However, the analysis also shows that the selective inclusion of economic values and stakeholders in the Natura 2000 framework risks marginalising other important socio-environmental actors.
    Comparison of Soil Respiration in Typical Conventional and New Alternative Cereal Cropping Systems on the North China Plain
    Gao, B. ; Ju, X.T. ; Su, F. ; Gao, F.B. ; Cao, Q.S. ; Oenema, O. ; Christie, P. ; Chen, X.P. ; Zhang, F.S. - \ 2013
    PLoS ONE 8 (2013)11. - ISSN 1932-6203
    carbon-dioxide - water-content - temperature - nitrogen - dependence - ecosystem - tillage - forest - management - moisture
    We monitored soil respiration (Rs), soil temperature (T) and volumetric water content (VWC%) over four years in one typical conventional and four alternative cropping systems to understand Rs in different cropping systems with their respective management practices and environmental conditions. The control was conventional double-cropping system (winter wheat and summer maize in one year - Con. W/M). Four alternative cropping systems were designed with optimum water and N management, i.e. optimized winter wheat and summer maize (Opt. W/M), three harvests every two years (first year, winter wheat and summer maize or soybean; second year, fallow then spring maize - W/M-M and W/S-M), and single spring maize per year (M). Our results show that Rs responded mainly to the seasonal variation in T but was also greatly affected by straw return, root growth and soil moisture changes under different cropping systems. The mean seasonal CO2 emissions in Con. W/M were 16.8 and 15.1 Mg CO2 ha(-1) for summer maize and winter wheat, respectively, without straw return. They increased significantly by 26 and 35% in Opt. W/M, respectively, with straw return. Under the new alternative cropping systems with straw return, W/M-M showed similar Rs to Opt. W/M, but total CO2 emissions of W/S-M decreased sharply relative to Opt. W/M when soybean was planted to replace summer maize. Total CO2 emissions expressed as the complete rotation cycles of W/S-M, Con. W/M and M treatments were not significantly different. Seasonal CO2 emissions were significantly correlated with the sum of carbon inputs of straw return from the previous season and the aboveground biomass in the current season, which explained 60% of seasonal CO2 emissions. T and VWC% explained up to 65% of Rs using the exponential-power and double exponential models, and the impacts of tillage and straw return must therefore be considered for accurate modeling of Rs in this geographical region.
    Microclimate moderates plant responses to macroclimate warming
    Frenne, P. De; Rodríguez-Sánchez, F. ; Coomes, D. ; Baeten, L. ; Verstraeten, G. ; Hommel, P.W.F.M. - \ 2013
    Proceedings of the National Academy of Sciences of the United States of America 110 (2013)46. - ISSN 0027-8424 - p. 18561 - 18565.
    recent climate-change - forest - vegetation - communities - ecosystem - scale - debt
    Recent global warming is acting across marine, freshwater, and terrestrial ecosystems to favor species adapted to warmer conditions and/or reduce the abundance of cold-adapted organisms (i.e., “thermophilization” of communities). Lack of community responses to increased temperature, however, has also been reported for several taxa and regions, suggesting that “climatic lags” may be frequent. Here we show that microclimatic effects brought about by forest canopy closure can buffer biotic responses to macroclimate warming, thus explaining an apparent climatic lag. Using data from 1,409 vegetation plots in European and North American temperate forests, each surveyed at least twice over an interval of 12–67 y, we document significant thermophilization of ground-layer plant communities. These changes reflect concurrent declines in species adapted to cooler conditions and increases in species adapted to warmer conditions. However, thermophilization, particularly the increase of warm-adapted species, is attenuated in forests whose canopies have become denser, probably reflecting cooler growing-season ground temperatures via increased shading. As standing stocks of trees have increased in many temperate forests in recent decades, local microclimatic effects may commonly be moderating the impacts of macroclimate warming on forest understories. Conversely, increases in harvesting woody biomass—e.g., for bioenergy—may open forest canopies and accelerate thermophilization of temperate forest biodiversity.
    CAMPFIRE and human-wildlife conflicts in local communities bordering northern Gonarezhou National Park, Zimbabwe
    Gandiwa, E. ; Heitkonig, I.M.A. ; Lokhorst, A.M. ; Prins, H.H.T. ; Leeuwis, C. - \ 2013
    Ecology and Society 18 (2013)4. - ISSN 1708-3087 - 15 p.
    health-promotion - psychology - dimensions - framework - ecosystem - justice - science - life
    Human-wildlife conflicts are a global problem, and are occurring in many countries where human and wildlife requirements overlap. Conflicts are particularly common near protected areas where societal unrest is large. To ease conflict, integrated conservation and development projects (ICDPs) have been implemented. The Communal Areas Management Programme for Indigenous Resources (CAMPFIRE) is an example of an ICDP. We hypothesized that (i) a higher perceived effectiveness of CAMPFIRE would be associated with a decline in human-wildlife conflicts, and (ii) local communities with higher perceived effectiveness of CAMPFIRE programs would have more favorable attitudes towards problematic wild animals. Four focus group discussions and interviews with 236 respondents were conducted in four local communities adjacent to northern Gonarezhou National Park, Zimbabwe from December 2010 to August 2011. Moreover, we included data on recorded incidences of human-wildlife conflicts and CAMPFIRE financial returns to study communities between 2000 and 2010. Our results indicate that local communities showed considerable differences in how CAMPFIRE effectiveness was perceived. Local communities with higher ratings of CAMPFIRE effectiveness generally perceived a decline in human-wildlife conflicts, although some people had experienced problems with wild animals. Attitudes towards main problematic wild animals varied across the study communities and were partly associated with perceived CAMPFIRE effectiveness. Our findings partly support both of our study hypotheses. Contextual factors across the four local communities seemed to influence the perceived effectiveness of CAMPFIRE programs and attitudes towards problematic wildlife species. We recommend that decisions and actions regarding the control of problem animals be devolved to the community level in order to help reduce human-wildlife conflicts in community-based natural resources management programs.
    Structure and composition of woody vegetation in two important bird areas in southern Zimbabwe
    Gandiwa, P. ; Chinoitezvi, E. ; Gandiwa, E. - \ 2013
    The JAPS 23 (2013)3. - ISSN 1018-7081 - p. 813 - 820.
    gonarezhou-national-park - african elephants - savanna woodlands - communities - diversity - population - australia - swaziland - ecosystem - adjacent
    This study assessed the status of woody vegetation structure and composition in two Important Bird Areas (IBA) i.e. Manjinji Pan and Save-Runde Junction located in southeastern Zimbabwe. The objectives of this study were to: (i) determine the woody vegetation structure and composition of the study areas and (ii) find out any differences and similarities in woody vegetation between the two IBAs. Data about woody vegetation were collected from 40 randomly placed sample plots from both study areas. Tree density was higher in Manjinji Pan IBA (406.67 +/- 16.86 trees ha(-1)) than Save-Runde Junction IBA (275.83 +/- 17.62 trees ha(-1)). In contrast, Save-Runde Junction IBA had higher numbers of stems per plant (2.88 +/- 0.22), species richness (59) and diversity (H' = 3.28) than Manjinji Pan IBA: numbers of stems per plant (2.16 +/- 0.12), species richness (43) and diversity (H' = 2.90). No significant differences were recorded in woody plant height, shrub and dead plant densities. The findings suggest that several factors including fires, herbivory and human activities could be influencing the woody vegetation in the two IBAs. However, further research is suggested to better understand the drivers of woody vegetation variation in IBAs occurring in savanna ecosystems. It is recommended that species richness and diversity of woody plants should be maintained and invasive plant species controlled for the conservation of endemic and migratory avifauna.
    Considerable environmental bottlenecks for species listed in the Habitats and Birds Directives in the Netherlands
    Wamelink, G.W.W. ; Knegt, B. de; Pouwels, R. ; Schuiling, C. ; Wegman, R.M.A. ; Schmidt, A.M. ; Dobben, H.F. van; Sanders, M.E. - \ 2013
    Biological Conservation 165 (2013)sept.. - ISSN 0006-3207 - p. 43 - 53.
    nitrogen deposition - climate-change - changing biodiversity - provide connectivity - critical loads - large mammals - global change - vegetation - consequences - ecosystem
    Many habitats and species have their existence threatened, especially in densely populated areas such as Western Europe. To stop the decline of biodiversity, the Natura 2000 network is being set-up. The ultimate objective is to get all habitat types (of Annex I of the Habitats Directive) and species (of Annexes II, III and IV of the Habitats Directive and Annex I of the Birds Directive) in a favourable conservation status. In the Netherlands a national ecological network has been set up for this purpose which includes the designated Natura 2000 sites. The current amount of atmospheric nitrogen deposition, acidification and desiccation were compared with limit values per habitat type for nitrogen deposition load, soil pH and spring groundwater table respectively and subsequently presented together in one map. Fragmentation was tested for 80 species.For two-third of the examined natural surface the critical load for nitrogen deposition is exceeded, desiccation is present in over 90% of the area of groundwater dependent nature. Problems with acidification are less pronounced. Fragmentation is present causing regional problems for up to six species. When the four pressures are combined, about two third of the areas suffer from at least one pressure. Many areas suffer from a combination of nitrogen deposition and desiccation.We conclude that environmental and spatial conditions are insufficient to meet the biodiversity target set by the European Union for the Natura 2000 network, habitat types and species.
    Living dangerously on borrowed time during slow, unrecognized regime shifts
    Hughes, T.P. ; Linares-Palomino, P.J. ; Dakos, V. ; Leemput, I.A. van de; Nes, E.H. van - \ 2013
    Trends in Ecology and Evolution 28 (2013)3. - ISSN 0169-5347 - p. 149 - 155.
    climate-change - coral-reef - ocean acidification - ecological-systems - community dynamics - early warnings - phase-shifts - ecosystem - lag - biodiversity
    Regime shifts from one ecological state to another are often portrayed as sudden, dramatic, and difficult to reverse. Yet many regime shifts unfold slowly and imperceptibly after a tipping point has been exceeded, especially at regional and global scales. These long, smooth transitions between equilibrium states are easy to miss, ignore, or deny, confounding management and governance. However, slow responses by ecosystems after transgressing a dangerous threshold also affords borrowed time - a window of opportunity to return to safer conditions before the new state eventually locks in and equilibrates. In this context, the most important challenge is a social one: convincing enough people to confront business-as-usual before time runs out to reverse unwanted regime shifts even after they have already begun
    Quantifying structure of Natura 2000 heathland habitats using spectral mixture analysis and segmentation techniques on hyperspectral imagery
    Mücher, C.A. ; Kooistra, L. ; Vermeulen, M.H. ; Vanden Borre, J. ; Haest, B. ; Haveman, R. - \ 2013
    Ecological Indicators 33 (2013)suppl. C. - ISSN 1470-160X - p. 71 - 81.
    imaging spectroscopy - satellite imagery - biodiversity - indicators - california - vegetation - ecosystem - scale - space
    Monitoring of habitat types protected under the Annex I of the EU Habitats Directive requires every 6 years information to be reported on their conservation status (area, range, structure and function) in the member states. Hyperspectral imagery can be an important source of information to assist in the evaluation of the habitats’ conservation status, as it can provide continuous maps of habitat quality indicators (e.g., life forms, management activities, grass, shrub and tree encroachment) at the pixel level. Such local level information is highly needed for management purposes, e.g., the location of habitat patches and their sizes and quality within a protected site. This paper focuses on the use of continuous fraction images as derived from spectral mixture analysis of hyperspectral imagery (AHS-160), in combination with segmentation techniques, to facilitate habitat quality assessment in a heathland site in the Netherlands. This combined application of techniques on hyperspectral imagery demonstrates the usefulness of information from continuous fraction maps of grass abundance (Molinia caerulea) in heathlands – at and within the patch level – compared to traditional mapping techniques that assess grass encroachment in a limited number of abundance classes at the patch level. It therefore provides a better basis to monitor large areas for processes such as grass encroachment that largely determine the conservation status of Natura 2000 heathland areas. Timely, accurate and up-to-date spatial information on the encroachment of mosses, grasses, shrubs or trees (dominant species) can help conservation managers to take better decisions and to better evaluate the effect of taken measures. While discrepancies exist between the results of field-based vegetation surveys and the proposed remote sensing approach, we provide a discussion on the uncertainty of determining which of both methods is most accurate in relation to dominant species, which is in our case Molinia caerulea, and set forth several reasons why the remote sensing based approach might form a better basis for the monitoring of abundant species and patch evolution through time.
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