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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Rain downpours affect survival and development of insect herbivores: the specter of climate change?
Chen, Cong ; Harvey, Jeffrey A. ; Biere, Arjen ; Gols, Rieta - \ 2019
Ecology 100 (2019)11. - ISSN 0012-9658
climate change - development - global warming - glucosinolates - insect herbivores - phytochemistry - plant–insect interactions - rain - secondary plant metabolites

Changes in the frequency, duration, and intensity of rainfall events are among the abiotic effects predicted under anthropogenic global warming. Heavy downpours may profoundly affect the development and survival of small organisms such as insects. Here, we examined direct (physically on the insects) and indirect (plant-mediated) effects of simulated downpours on the performance of caterpillars of two lepidopteran herbivores (Plutella xylostella and Pieris brassicae) feeding on black mustard (Brassica nigra) plants. Host plants were exposed to different rainfall regimes both before and while caterpillars were feeding on the plants in an attempt to separate direct and indirect (plant-mediated) effects of rainfall on insect survival and development. In two independent experiments, downpours were simulated as a single long (20 min) or as three short (5 min) daily events. Downpours had a strong negative direct effect on the survival of P. xylostella, but not on that of P. brassicae. Direct effects of downpours consistently increased development time of both herbivore species, whereas effects on body mass depended on herbivore species and downpour frequency. Caterpillar disturbance by rain and recorded microclimatic cooling by 5°C may explain extended immature development. Indirect, plant-mediated effects of downpours on the herbivores were generally small, despite the fact that sugar concentrations were reduced and herbivore induction of secondary metabolites (glucosinolates) was enhanced in plants exposed to rain. Changes in the frequency of precipitation events due to climate change may impact the survival and development of insect herbivores differentially. Broader effects of downpours on insects and other arthropods up the food chain could seriously impair and disrupt trophic interactions, ultimately destabilizing communities.

Seasonal drivers of understorey temperature buffering in temperate deciduous forests across Europe
Zellweger, Florian ; Coomes, David ; Lenoir, Jonathan ; Depauw, Leen ; Maes, Sybryn L. ; Wulf, Monika ; Kirby, Keith J. ; Brunet, Jörg ; Kopecký, Martin ; Máliš, František ; Schmidt, Wolfgang ; Heinrichs, Steffi ; Ouden, Jan den; Jaroszewicz, Bogdan ; Buyse, Gauthier ; Spicher, Fabien ; Verheyen, Kris ; Frenne, Pieter De - \ 2019
Global Ecology and Biogeography (2019). - ISSN 1466-822X
canopy density - climate change - forest composition - forest structure - global warming - macroclimate - microclimate - temperature buffering - understorey

Aim: Forest understorey microclimates are often buffered against extreme heat or cold, with important implications for the organisms living in these environments. We quantified seasonal effects of understorey microclimate predictors describing canopy structure, canopy composition and topography (i.e., local factors) and the forest patch size and distance to the coast (i.e., landscape factors). Location: Temperate forests in Europe. Time period: 2017–2018. Major taxa studied: Woody plants. Methods: We combined data from a microclimate sensor network with weather-station records to calculate the difference, or offset, between temperatures measured inside and outside forests. We used regression analysis to study the effects of local and landscape factors on the seasonal offset of minimum, mean and maximum temperatures. Results: The maximum temperature during the summer was on average cooler by 2.1 °C inside than outside forests, and the minimum temperatures during the winter and spring were 0.4 and 0.9 °C warmer. The local canopy cover was a strong nonlinear driver of the maximum temperature offset during summer, and we found increased cooling beneath tree species that cast the deepest shade. Seasonal offsets of minimum temperature were mainly regulated by landscape and topographic features, such as the distance to the coast and topographic position. Main conclusions: Forest organisms experience less severe temperature extremes than suggested by currently available macroclimate data; therefore, climate–species relationships and the responses of species to anthropogenic global warming cannot be modelled accurately in forests using macroclimate data alone. Changes in canopy cover and composition will strongly modulate the warming of maximum temperatures in forest understories, with important implications for understanding the responses of forest biodiversity and functioning to the combined threats of land-use change and climate change. Our predictive models are generally applicable across lowland temperate deciduous forests, providing ecologically important microclimate data for forest understories.

Data from: Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
Velthuis, Mandy ; Kosten, S. ; Aben, Ralf ; Kazanjian, Garabet ; Hilt, Sabine ; Peeters, E.T.H.M. ; Donk, Ellen van; Bakker, Elisabeth S. - \ 2019
carbon cycle - decomposition - global warming - mineralization - phenology - primary production - sedimentation - submerged aquatic plant
Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year‐round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year‐round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 year−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte‐dominated systems, while not necessarily affecting net carbon burial on a system scale.
Meta-analysis reveals enhanced growth of marine harmful algae from temperate regions with warming and elevated CO2 levels
Brandenburg, Karen M. ; Velthuis, Mandy ; Waal, Dedmer B. Van de - \ 2019
Global Change Biology 25 (2019)8. - ISSN 1354-1013 - p. 2607 - 2618.
climate change - global warming - harmful algal blooms - ocean acidification - sea surface temperature

Elevated pCO2 and warming may promote algal growth and toxin production, and thereby possibly support the proliferation and toxicity of harmful algal blooms (HABs). Here, we tested whether empirical data support this hypothesis using a meta-analytic approach and investigated the responses of growth rate and toxin content or toxicity of numerous marine and estuarine HAB species to elevated pCO2 and warming. Most of the available data on HAB responses towards the two tested climate change variables concern dinoflagellates, as many members of this phytoplankton group are known to cause HAB outbreaks. Toxin content and toxicity did not reveal a consistent response towards both tested climate change variables, while growth rate increased consistently with elevated pCO2. Warming also led to higher growth rates, but only for species isolated at higher latitudes. The observed gradient in temperature growth responses shows the potential for enhanced development of HABs at higher latitudes. Increases in growth rates with more CO2 may present an additional competitive advantage for HAB species, particularly as CO2 was not shown to enhance growth rate of other non-HAB phytoplankton species. However, this may also be related to the difference in representation of dinoflagellate and diatom species in the respective HAB and non-HAB phytoplankton groups. Since the proliferation of HAB species may strongly depend on their growth rates, our results warn for a greater potential of dinoflagellate HAB development in future coastal waters, particularly in temperate regions.

Nothing Else Matters : Towards an Ontological Concept of the Materiality of the Earth in the Age of Global Warming
Blok, Vincent - \ 2019
Research in Phenomenology 49 (2019)1. - ISSN 0085-5553 - p. 65 - 87.
affordance - conativity - earth - global warming - world

If the world in which we are intentionally involved is threatened by climate change, this raises the question about our place on Earth. In this article, we argue that the ecological crisis we face today draws our attention to the Earth as ontic-ontological condition of our being-in-the-world. Because the Earth is often reflected upon in relation to human existence, living systems or material entities in the philosophical tradition, we argue for an ontological concept of the materiality of the Earth as un-correlated being in this article. We develop five principles of the materiality of the Earth: the conativity, non-identity, responsiveness, performativity and eventuality of the Earth. We will argue that it is this notion of Earth that matters to us in the age of global warming.

Stedelijke hittestress
Spijker, Joop - \ 2018
heat resistance - heat - climatic change - drought - global warming - policy - green roofs
Gastcollege Hogeschool Van Hall Larenstein
Tropical land carbon cycle responses to 2015/16 El Niño as recorded by atmospheric greenhouse gas and remote sensing data
Gloor, Emanuel ; Wilson, Chris ; Chipperfield, Martyn P. ; Chevallier, Frederic ; Buermann, Wolfgang ; Boesch, Hartmut ; Parker, Robert ; Somkuti, Peter ; Gatti, Luciana V. ; Correia, Caio ; Domingues, Lucas G. ; Peters, Wouter ; Miller, John ; Deeter, Merritt N. ; Sullivan, Martin J.P. - \ 2018
Philosophical Transactions of the Royal Society B. Biological sciences 373 (2018)1760. - ISSN 0962-8436 - 12 p.
carbon cycle - fire - global warming - tropical forests

The outstanding tropical land climate characteristic over the past decades is rapid warming, with no significant large-scale precipitation trends. This warming is expected to continue but the effects on tropical vegetation are unknown. El Niño-related heat peaks may provide a test bed for a future hotter world. Here we analyse tropical land carbon cycle responses to the 2015/16 El Niño heat and drought anomalies using an atmospheric transport inversion. Based on the global atmospheric CO2 and fossil fuel emission records, we find no obvious signs of anomalously large carbon release compared with earlier El Niño events, suggesting resilience of tropical vegetation. We find roughly equal net carbon release anomalies from Amazonia and tropical Africa, approximately 0.5 PgC each, and smaller carbon release anomalies from tropical East Asia and southern Africa. Atmospheric CO anomalies reveal substantial fire carbon release from tropical East Asia peaking in October 2015 while fires contribute only a minor amount to the Amazonian carbon flux anomaly. Anomalously large Amazonian carbon flux release is consistent with downregulation of primary productivity during peak negative near-surface water anomaly (October 2015 to March 2016) as diagnosed by solar-induced fluorescence. Finally, we find an unexpected anomalous positive flux to the atmosphere from tropical Africa early in 2016, coincident with substantial CO release.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
Velthuis, Mandy ; Kosten, Sarian ; Aben, Ralf ; Kazanjian, Garabet ; Hilt, Sabine ; Peeters, Edwin T.H.M. ; Donk, Ellen van; Bakker, Elisabeth S. - \ 2018
Global Change Biology 24 (2018)11. - ISSN 1354-1013 - p. 5231 - 5242.
carbon cycle - decomposition - global warming - mineralization - phenology - primary production - sedimentation - submerged aquatic plant

Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year-round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year-round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 yaer−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte-dominated systems, while not necessarily affecting net carbon burial on a system scale.

Carbon dioxide fertilization offsets negative impacts of climate change on Arabica coffee yield in Brazil
Verhage, Fabian - \ 2017
Arabica coffee yield simulation model - productivity - elevated CO2 concentration - carbon dioxide fertilization - climate change impact assessment - global warming - irrigation
This collection unites the most important files used to assess the impact of climate change on Arabica coffee in Brazil under a RCP4.5 scenario by 2040-2070, as described by Verhage, Anten & Sentelhas (2017). These files are provided to encourage the further verification, development and application of the Arabica coffee yield simulation model. In addition, the collection includes a short description and try-out of the agro-ecological zoning model, developed by Doorenbos & Kassam (1979) for the Food and Agriculture Organization (FAO), applied on Arabica coffee. This model was excluded from the final study, but the work might still be of use to other researchers.
Data from: Warming advances top-down control and reduces producer biomass in a freshwater plankton community
Velthuis, Mandy ; Senerpont Domis, Lisette de; Frenken, Thijs ; Stephan, Susanne ; Kazanjian, Garabet ; Aben, Ralf ; Hilt, Sabine ; Kosten, Sarian ; Donk, Ellen van; De Waal, Dedmer B. Van - \ 2017
chytrid dynamics - global warming - phytoplankton community dynamics - seasonal succession - zooplankton phenology - Synedra - Dinobryon - Keratella - Bosmina
Global warming has been shown to affect ecosystems worldwide. Warming may, for instance, disrupt plant herbivore synchrony and bird phenology in terrestrial systems, reduce primary production in oceans, and promote toxic cyanobacterial blooms in freshwater lakes. Responses of communities will not only depend on direct species-specific temperature effects, but also on indirect effects related to bottom-up and top-down processes. Here, we investigated the impact of warming on freshwater phytoplankton community dynamics, and assessed the relative contribution of nutrient availability, fungal parasitism, and grazing therein. For this purpose, we performed an indoor mesocosm experiment following seasonal temperature dynamics of temperate lakes and a warmed (+4°C) scenario from early spring to late summer. We assessed phytoplankton biomass, C:N:P stoichiometry and community composition, dissolved nutrient availabilities, fungal parasite (i.e., chytrid) prevalence, and zooplankton abundance. Warming led to an overall reduction in phytoplankton biomass as well as lower C:P and N:P ratios, while phytoplankton community composition remained largely unaltered. Warming resulted in an earlier termination of the diatom spring bloom, and an epidemic of its fungal parasite ended earlier as well. Furthermore, warming advanced zooplankton phenology, leading to an earlier top-down control on phytoplankton in the period after the spring bloom. Linear model analysis showed that most of the observed variance in phytoplankton biomass was related to seasonal temperature dynamics in combination with zooplankton abundance. Our findings showed that warming advanced grazer phenology and reduced phytoplankton biomass, thereby demonstrating how bottom-up and top-down related processes may shape future phytoplankton dynamics.
Safeguarding water availability for food and ecosystems under global change : modelling and assessment of the role of environmental flows
Pastor, Amandine V. - \ 2017
Wageningen University. Promotor(en): P. Kabat, co-promotor(en): F. Ludwig; H. Biemans. - Wageningen : Wageningen University - ISBN 9789463431767 - 177
water availability - water management - flow - water deficit - food security - food production - global warming - aquatic ecosystems - waterbeschikbaarheid - waterbeheer - stroming - watertekort - voedselzekerheid - voedselproductie - opwarming van de aarde - aquatische ecosystemen

In a context of future population increase and intensification of water cycle by climate change, water demand for irrigation is projected to double. However, freshwater resources have been degraded the last decades especially in rivers via fragmentation, dam contraction and pollution. Flow alteration and degradation lead to 80% of freshwater ecosystem species loss. In this thesis, a robust and reliable Environmental Flow (EF) method was developed for global scale: the Variable Monthly Flow (VMF) method. This method allowed estimating EF deficit at global scale including its origin, timing, frequency and magnitude. By setting EFRs as priority user in a global vegetation and hydrological model (LPJmL), irrigation loss due to EFRs implementation were assessed at 30% leading to 5% global calorie loss. To maintain water allocation to humans and ecosystems under global change, food imports would require to increase by 15% especially from Latin America to South of Asia.

Marine complex adaptive systems : theory, legislation and management practices
Bigagli, Emanuele - \ 2017
Wageningen University. Promotor(en): Arnold Bregt, co-promotor(en): M. Craglia. - Wageningen : Wageningen University - ISBN 9789463431255 - 160
marine areas - marine environment - adaptation - environmental management - oceans - climate - environmental legislation - global warming - climatic change - mariene gebieden - marien milieu - adaptatie - milieubeheer - oceanen - klimaat - milieuwetgeving - opwarming van de aarde - klimaatverandering

Anthropogenic and climate-related stressors challenge the health of nearly every part of the global oceans. They affect the capacity of oceans to regulate global weather and climate, as well as ocean productivity and food services, and result in the loss or degradation of marine habitats and biodiversity. Moreover, they have a negative impact on maritime economic sectors and on the social welfare of dependent coastal populations. In order to overcome the deficiencies of traditional single-sector management, in the recent decades several scientific approaches emerged, based on the view of marine systems as Complex Adaptive Systems (CAS), i.e. systems where components interact in non-linear, path dependent ways, with lock-in and feedback loop mechanisms, and unpredictable effects also across scales. These approaches have been introduced into the texts of several international agreements related to marine CAS, and related management practices, with contrasting results in relation to effectiveness and integration of governance.

This thesis evaluates for the first time the current international and European legal frameworks from the perspective of marine CAS. To accomplish this objective, four research objectives are formulated: (1) Develop a framework for marine CAS assessment and management; (2) Evaluate the entire European Union (EU) legal framework against the framework developed; (3) Evaluate the international legal framework for the assessment and management of the global oceans against the framework developed; and (4) Evaluate the implementation of the EU and global legal frameworks into practice.

Chapter 2 develops a framework for marine CAS, based on the combination of two promising theoretical approaches: Adaptive Management (AM) and Transition Management (TM). The framework is based on the idea that AM and TM have the potential to overcome each other’s limitations, which are related to the insufficient attention to micro-level socio-economic components, and to the limited incorporation of environmental aspects into socio-technical assessments, respectively. More into detail, the proposed framework is articulated into three components. First, the two sets of marine social-ecological systems and connected socio-technical systems (e.g. fisheries, maritime transportation, coastal tourism and energy) must be clearly identified, and the complex interactions and influences between socio-economic patterns of production and consumption, and ecological components must be assessed. Second, the achievement of ecological resilience of a marine social-ecological system should be performed in coordination with transitions of unsustainable connected socio-technical systems. This implies that sustainability should be evaluated in relation to the pressures socio-technical systems generate on the ecological resilience of connected social-ecological systems, and related impacts. Third, the implementation of the two approaches should be articulated into iterative, learning- and science-based policy cycles, with mechanisms to foster coordination between the policy cycles of social-ecological and socio-technical systems. The benefits of this framework are threefold. First, the assessment of the two sets of social-ecological and socio-technical systems, taken together, allows to overcome current AM limitations and include micro-level socio-economic components into the assessment of ecological resilience. Second, by linking AM managers with established transition arenas, it is possible to overcome TM limitations and streamline the consideration of ecological aspects into the TM process. Third, by linking AM and TM policy cycles, it is possible to reduce the current legal and policy fragmentation.

Chapters 3 and 4 apply the framework proposed in Chapter 2 to evaluate the EU and global legal frameworks for the assessment and management of marine CAS. Chapter 3 presents the first comprehensive review ever realised of the entire EU legal framework, composed of more than 12,000 EU legal acts, from the perspective of marine CAS assessment and management. It concludes that the EU legislation does not provide a fully coherent framework for the assessment and management of EU marine CAS. Although the Marine Strategy Framework Directive (MSFD; 2008/56/EC) is a major step towards this purpose, the present research highlights three major limitations: (1) the limited capacity of the MSFD to support the coordination between Member States sharing the same marine region or sub-region; (2) the insufficient characterisation of marine ecological resilience, in particular in relation to socio-economic elements, ecosystem services, human benefits and cross-scale interactions; and (3) the limited capacity of the MSFD to tackle the fragmentation of the EU legal framework and integrate ecological resilience into the objectives of sector-based laws and policies.

Chapter 4 reviews 500 multilateral agreements, evaluated for the first time from the perspective of marine CAS. It shows that there is no international agreement aiming at the ecological resilience of the global oceans social-ecological system. Instead, the international legal framework is fragmented along two dimensions. On the one side, global agreements focus on specific objectives for determined socio-economic activities, ecological features or anthropogenic pressures. On the other side, regional agreements are in place for 18 ocean regions of the world, with a varying level of inclusion of elements of marine CAS assessment and management. The need is highlighted for a reformed global ocean governance framework, which should be based on a bio-geographical approach to the ecological resilience of the global oceans, and build on iteration, learning, and science-based advice to policy and management.

Chapter 5 evaluates the implementation of the EU and global legal frameworks into the practice of assessment and management of a case-study area, the Adriatic Sea. It shows the importance of the MSFD as the first policy trying to deliver a CAS approach to marine assessment and management. However, the case-study investigation confirms the three limitations of the MSFD, laying in: 1) an insufficient geographical approach, where implementation is driven at national level and the requirement of cross-border cooperation is weak; 2) the vagueness of legal requirements, and the limited capacity to include socio-economic aspects into the required assessment; and 3) an insufficient capacity to coordinate with other laws, policies and programmes at various levels of governance. Based on the identified limitations, suggestions are advanced on how to strengthen the implementation of the MSFD, both at Adriatic and EU level. These suggestions are further advanced in Chapter 6, which includes detailed proposals on how to foster integrated large-scale marine monitoring in the EU, in order to contribute to the implementation of the MSFD in an efficient and effective way, also in relation to costs.

Chapter 7 synthesizes the major findings of this thesis and evaluates the capacity of the framework to deliver a CAS approach to marine systems. It concludes that AM and TM, although holding different visions on sustainability and referring to different principles, have the potential to be put in synergy at the practical level. Further scientific research and management practices should focus on the need for AM and TM to overcome the relative isolation and foster synergies across sector-based management, in order to integrate environmental considerations into economic sectors. Suggestions are advanced to improve legal frameworks and policy practices at the global and EU level. They focus on the need: (i) to fill the gaps in the geographical scope of legal texts and to foster international cooperation at the right social-ecological scale; (ii) to increase guidance in translating complex scientific requirements into clear management objectives, and improve related data collection and sharing; and (iii) to reduce current legal and policy fragmentation through targeted, ecological resilience-based marine environmental impact assessments and maritime spatial planning. Lines for further scientific research are suggested, focusing on: (i) improving the evidence-base through additional case-studies; (ii) analysing legal frameworks and governance regimes in place for other marine social-ecological systems, like e.g. the United States of America, Canada, Australia and China; (iii) improving existing tools, or creating new ones for marine ecological resilience assessment; and (iv) developing innovative instruments and mechanisms to strengthen global oceans governance.

Historical changes in the importance of climate and land use as determinants of Dutch pollinator distributions
Aguirre-Gutiérrez, Jesús ; Kissling, W.D. ; Biesmeijer, Jacobus C. ; Wallis de Vries, Michiel ; Reemer, Menno ; Carvalheiro, Luísa G. - \ 2017
Journal of Biogeography 44 (2017)3. - ISSN 0305-0270 - p. 696 - 707.
biodiversity change - climate change - ecological niche models - environmental variable importance - global warming - habitat fragmentation - habitat loss - species distribution models
Aim: Species distribution models are often used to project species distributions to different environmental conditions. However, most models do not consider whether the importance of abiotic factors may change over time. If they change, this has implications for the assessment of how abiotic changes affect species distributions. Here, we use spatially explicit historical data on species occurrences, climate and land use to test whether the importance of different climatic and land-use drivers as determinants of species distributions has remained constant over a period of > 60 years (1951–2014). Location: The Netherlands. Methods: Using species distribution models and a comprehensive country-wide dataset at 5 × 5 km resolution, we modelled the distribution of a total of 398 pollinator species (bees, butterflies and hoverflies) for three periods (1951–1970, 1971–1990 and 1998–2014). We then evaluated whether the importance of variables related to climate (precipitation, temperature) and land use (landscape composition and habitat fragmentation) in determining pollinator distributions has changed over time. Results: Variables related to landscape composition were highly important in determining pollinator distributions in all periods. Precipitation was generally less important than temperature, and habitat fragmentation less than landscape composition. Land-use variables remained equally important across time for all pollinator groups, except for bees where the importance of habitat fragmentation decreased significantly over time. Among climate variables, the importance of precipitation did not change across time for any pollinator group. However, the importance of temperature increased significantly in recent times for bees and hoverflies. Main conclusions: Determinants of species distributions can change in their importance over time when changes in the magnitude and range of environmental conditions occur. Given future temperature rises, our results imply that species distribution models calibrated with current climatic conditions may not adequately predict the future importance of environmental factors in driving species distributions.
Arctic climate change and decadal variability
Linden, Eveline C. van der - \ 2016
Wageningen University. Promotor(en): Wilco Hazeleger, co-promotor(en): R. Bintanja. - Wageningen : Wageningen University - ISBN 9789462579453 - 197
climatic change - arctic regions - global warming - temperature - models - carbon dioxide - sea water - barents sea - klimaatverandering - arctische gebieden - opwarming van de aarde - temperatuur - modellen - kooldioxide - zeewater - barentszzee

High northern latitudes exhibit enhanced near-surface warming in a climate with increasing greenhouse gases compared to other parts of the globe, indicating an amplified climate response to external forcing. Decadal to multidecadal variability sometimes enhances and at other times reduces the long-term trends. Therefore, the influence of internal variability should be taken into account when externally forced climate signals are assessed.
This thesis contributes to our understanding of Arctic climate projections by clarifying the role of coupled ocean-sea-ice-atmosphere processes on the long-term trends and decadal variability of the Arctic climate system. Important mechanisms linked to the location of the sea ice margin and ocean heat transports into the Arctic have been identified and were shown to have a substantial effect on the Arctic's response to climate change.

Roots in the tundra : relations between climate warming and root biomass and implications for vegetation change and carbon dynamics
Wang, Peng - \ 2016
Wageningen University. Promotor(en): Frank Berendse, co-promotor(en): Monique Heijmans; Liesje Mommer. - Wageningen : Wageningen University - ISBN 9789462578609 - 168
roots - biomass - climatic change - vegetation - carbon - global warming - tundra - ecosystems - decomposition - siberia - wortels - biomassa - klimaatverandering - vegetatie - koolstof - opwarming van de aarde - toendra - ecosystemen - decompositie - siberië

Global climate has been warming up for the last decades and it will continue in this century. The Arctic is the part of the globe that warms fastest and is more sensitive to climate warming. Aboveground productivity of Arctic tundra has been shown to increase in response to warmer climates. However, belowground responses of tundra vegetation are still unclear. As the major part of plant biomass in tundra lies belowground, it is pivotal to investigate changes in the belowground parts of tundra vegetation for our understanding of climate warming effects on tundra ecosystems.

To get a general idea of how belowground plant biomass may change in a warmer climate, we synthesized published data on the belowground biomass of tundra vegetation across a broad gradient of mean annual air temperature from −20 to 0 °C. We found that aboveground biomass of tundra biomass indeed increases with mean annual temperature as well as summer air temperature, while belowground biomass did not show a significant relationship with temperature. The increases in the aboveground biomass were significantly larger than belowground biomass, resulting in reduced below/above ratios at higher temperatures. The shifted biomass allocation with temperature can influence the carbon dynamics of tundra ecosystems. Future tundra studies need to focus more on the species or functional type composition of belowground biomass and species or functional type specific belowground responses to climate warming.

To determine the seasonal changes and vertical distribution of root biomass of different plant functional types, we sampled roots at a Siberian tundra site in the early and late growing season, from vegetation types dominated by graminoids and shrubs respectively. We distinguished the roots of graminoids and shrubs, and found that shrub roots grew earlier and shallower than graminoid roots, which enables shrubs to gain advantage over graminoids at the early growing season when nutrient pulses occur during snowmelt and soil thaw. The deeper roots of graminoids can help them to be more competitive if climate warming induces more nutrient release in the deeper soil.

In a soil thawing and fertilization experiment, we further investigated the effects of increased thawing depth and nutrient supply in the upper soil, which can be the consequences of climate warming, on root biomass and its vertical distribution. In this study we distinguished between the roots of grasses, sedges, deciduous shrubs and evergreen shrubs. The study was done in a moist tussock tundra site with similar abundance of the different plant functional types. We found that only sedges benefited from the increased thawing depth, probably through their deepest root distribution among the four functional types, while the shrubs, which were shallower-rooted, benefited from the increased nutrient availability in the upper soil. The deep-rooted grasses had the highest plasticity in vertical root distribution, which enabled them also to benefit greatly from the fertilization. Our results show that tundra plants with different rooting strategies can show different responses to climate warming dependent on the relative warming impacts on the nutrient supply in shallow and deeper soil layers. This insight can help to predict future tundra vegetation dynamics.

The carbon balance of tundra ecosystems also depends on the decomposition of plant litter, particularly the root litter, which may account for a larger part of annual litter input than leaf litter in tundra ecosystems. Vegetation shifts also change litter quality which ultimately influences carbon dynamics. To investigate the differences in the decomposition of leaves and roots of graminoids and shrubs, we performed a litter transplant experiment. We found that although the decomposability of leaf litter did not differ between the graminoid and shrub, root decomposability might be lower for the shrub. However, this cannot be extrapolated to the overall decomposition in different vegetation types, as these different plant communities differ in rooting depths. We also found evidence of home-field advantage in the decomposition in Arctic tundra, and we show that the early stage of litter decomposition at our research site could be driven by the phosphorus concentration of the litter. To get a full understanding of the carbon balance of tundra ecosystems, much more efforts are needed to quantify litter input and decomposition.

In this thesis we show that belowground parts, which account for a major part of plant biomass in tundra, can show a different response to climate warming from aboveground parts. Belowground responses to climate warming can have crucial impacts on the competitive balance between tundra plants, and consequently result in vegetation shifts in tundra. Such shifts in species composition can have large effects on carbon dynamics through altered input and decomposability of plant litter, particularly root litter.

The Current Climate and Energy Policy in the EU and in Switzerland
Gerigk, J. ; Halbritter, K.S. ; Handgraaf, M.J.J. ; Manser, J. ; Ohndorf, M. ; Schubert, R. - \ 2012
Zürich : ETH Zürich
energie - kooldioxide - opwarming van de aarde - emissiereductie - europa - energy - carbon dioxide - global warming - emission reduction - europe
This working paper is to discuss policy instruments which would, in principle, lend themselves for a scale-up of employer-led incentive schemes. Given that such an implementation requires financial transfers, our focus is on project-based CO2-markets and direct subsidy schemes to end-consumers. Up to the present, only Switzerland has implemented a credit-based emissions trading scheme on the domestic level. While, currently, the Swiss regime does not provide for a potential pooling of small-scale reductions, extending the scheme accordingly would engender only low additional cost. Other eligible regulations are dominated rather by state-set incentives, like subsidies, directly provided to households. Such schemes would be suitable for a pass-through via the employer. Yet, such a redirection of subsidies via firms seems to be more difficult to be implemented from a political and legal perspective. Still, these programmes provide solid support for the presumption that financial transfers provided within an employer-led incentive scheme can considerably speed up switches toward the use of “greener” technologies within households.
'Klimaatverandering biedt ook kansen voor tuinbouw' : Jan Verhagen, klimaatonderzoeker aan de WUR
Verhagen, Jan - \ 2012
market gardens - cultural methods - horticultural crops - climatic change - greenhouse effect - global warming - greenhouse horticulture - measures
Denitrification in ditches, streams and shallow lakes
Veraart, A.J. - \ 2012
Wageningen University. Promotor(en): Marten Scheffer, co-promotor(en): Jeroen de Klein. - S.l. : s.n. - ISBN 9789461733115 - 208
denitrificatie - sloten - meren - waterlopen - zoetwaterecologie - milieufactoren - stikstofkringloop - waterplanten - opwarming van de aarde - denitrification - ditches - lakes - streams - freshwater ecology - environmental factors - nitrogen cycle - aquatic plants - global warming
Het Nederlandse oppervlaktewater wordt sterk belast met stikstof. Dit is afkomstig uit de landbouw, maar ook van industrie, verkeer en huishoudens. Door het teveel aan stikstof verslechtert de waterkwaliteit. In ondiepe meren leidt dit bijvoorbeeld tot overmatige algengroei met zuurstofloosheid en vissterfte tot gevolg. Denitrificatie, de omzetting van de stikstofverbinding nitraat naar stikstofgas, is een natuurlijk proces dat stikstof uit oppervlaktewater verwijdert.
Winterhardheid van boomkwekerijgewassen
Hoffman, M.H.A. - \ 2011
ornamental woody plants - forest nurseries - varieties - cultivars - species diversity - winter hardiness - frost resistance - cold tolerance - climatic change - global warming
Hoezo klimaatverandering : feiten, fabels en open vragen
Vellinga, P. - \ 2011
Amsterdam : Balans - ISBN 9789460033032 - 140
klimaatverandering - opwarming van de aarde - milieubeleid - climatic change - global warming - environmental policy
Moeten we ons wel zo druk maken over de opwarming van de aarde zolang het IJsselmeer nog dichtvriest en er wetenschappers zijn die voorspellen dat het kouder wordt? Zijn de klimaatwetenschappers niet een beetje aan het overdrijven? Net als destijds de Club van Rome, met zijn waarschuwingen over grondstoffen die snel op zouden raken en over bossen die dood zouden gaan. En de ozonlaag, daar hoor je ook niemand meer over. Politici maken ons bang met het einde van de wereld, maar hoe kunnen ze het klimaat over vijftig jaar eigenlijk zo precies voorspellen als de gewone weersverwachting er al regelmatig naast zit? Bovendien, de uitstoot van CO2 lijkt niet te stoppen. Wij kunnen hier wel spaarlampen gebruiken, maar in China gaat elke week een nieuwe kolencentrale open. Kunnen wij onze welvaart wel op peil houden met windmolens en zonneenergie? De vervuiling van de mens is toch nietig in vergelijking met die van vulkanen, zonnevlekken en dergelijke. Of toch niet? Pier Vellinga zet in 'Hoezo klimaatverandering' de belangrijkste feiten en fabels over klimaatverandering op een rij. Zonder de onzekerheden uit de weg te gaan geeft dit boek een helder inzicht in wat we weten over het broeikaseffect – en wat we ertegen kunnen doen.
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