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Reproductive adaptations to reduce locomotor costs in viviparous fish (Poeciliidae)
Fleuren, Mike - \ 2017
University. Promotor(en): Johan van Leeuwen, co-promotor(en): Bart Pollux. - Wageningen : Wageningen University - ISBN 9789463438025 - 204
fishes - poeciliidae - reproduction - adaptation - vivipary - locomotion - biomechanics - zoology - vissen - voortplanting - adaptatie - levendbarend - voortbeweging - biomechanica - zoölogie
Viviparity, a live-bearing mode of reproduction, has evolved over 100 times independently in vertebrate animals. Despite its frequent evolution, viviparity has a number of hypothesised disadvantages compared to the ancestral mode of reproduction, oviparity (egg-laying). One of these disadvantages is a reduction in locomotor performance during pregnancy, the period of internal development of the embryos. Adaptations to a live-bearing reproductive mode could have evolved to reduce these locomotor costs. In this thesis, I aim to find whether matrotrophy, post-fertilization nutrient provisioning (e.g. through a placental structure), and superfetation, the presence of multiple broods of different developmental stages, reduce the locomotor performance decline during pregnancy in the Poeciliidae, live-bearing fishes.
In Chapter 2, we review the literature on the effects of pregnancy on morphology, performance and fitness. The biomechanics of each mode of locomotion (walking, swimming or flying) are distinct, and are affected differently by the added mass and volume of pregnancy. Furthermore, we list the possible adaptations that have evolved to reduce the locomotor costs of pregnancy, and divide them into three different categories: adaptations that reduce the locomotor costs of live-bearing, adaptations with which the locomotor costs of live-bearing are avoided, and adaptations to the life history of the animal. Lastly, we discuss hiatuses in the literature and experimental procedures to quantify the hypothesised benefit of adaptations.
In Chapter 3, we compare the morphological changes during pregnancy in two closely-related species of live-bearing fish: Poeciliopsis turneri and Poeciliopsis gracilis. These species mainly differ in their mode of nutrient provisioning: P. gracilis is lecithotrophic and P. turneri is an extensive matrotroph. We tracked the morphological changes in 3D using a non-invasive method that creates three-dimensional body models. We find that P. turneri is more slender during the early stages of pregnancy, but increase in size more rapidly. This is in line with the locomotor costs hypothesis, which predicts that matrotrophic fish are more slender during the early stages of pregnancy, but that the difference between the body shapes of lecithotrophic and matrotrophic fish diminishes as pregnancy progresses. Our results indicate that matrotrophy could indeed provide a morphological advantage during pregnancy.
Fast-start performance, a manoeuvre fish deploy to escape predatory strikes, is important for individual survival. In Chapter 4, we use state-of-the-art biomechanical methods to, for the first time, quantify this manoeuvre in three-dimensional space in adult fish (Heterandria formosa). We show that fish can orient their escapes in up- and downwards direction, and that this is correlated with a change in pitch angle of the body. Changes in roll angle of the body were not correlated with orientation of the fish. We furthermore demonstrate that stage 1 of the fast start, often described as a preparatory stage, can already contribute to propulsion. The results from Chapter 4 indicate that three-dimensional measurements of fast-start manoeuvres provide novel insights that were often overlooked.
Measuring fast starts in three-dimensional space is relevant in determining the adverse effects of pregnancy on locomotor performance. We did this by comparing three species of live-bearing fish: P. turneri, H. formosa and Phalloptychus januarius. In Chapter 5, we show that pregnancy-induced changes in abdominal width are correlated with a reduction in performance in the horizontal plane (maximal horizontal speed, change in yaw angle), but less so in the vertical plane (maximal vertical speed, change in pitch angle). Furthermore, we demonstrate that an increase in abdominal width is correlated with a decrease in abdominal curvature and, for some species, in a decrease in maximal curvature rate in the abdomen. Lastly, we show that the pregnancy-induced morphological changes depend on the level of superfetation: species with a high level of superfetation experience higher frequency, but smaller amplitude changes in the shape of the abdomen. Whether superfetation actually results in a more slender body shape, as predicted by the locomotor costs hypothesis, depends on the level of reproductive investment.
In this thesis, I show that pregnancy induces changes in morphology which comes with a cost in fast-start performance. Both matrotrophy and superfetation affect how body shape changes due to pregnancy, but whether the latter provides beneficial changes depends on the level of reproductive investment. Furthermore, I reveal that fast starts can have a substantial three-dimensional component which is relevant both to biomechanicists that aim to understand the physical and physiological mechanisms underlying this manoeuvre and to evolutionary biologists that strive to answer performance-related questions.
Sensitivity analysis methodologies for analysing emergence using agent-based models
Broeke, Guus ten - \ 2017
University. Promotor(en): Jaap Molenaar, co-promotor(en): George van Voorn; Arend Ligtenberg. - Wageningen : Wageningen University - ISBN 9789463436991 - 211
mathematics - computational mathematics - mathematical models - dynamic modeling - sensitivity analysis - adaptation - methodology - simulation - wiskunde - computerwiskunde - wiskundige modellen - dynamisch modelleren - gevoeligheidsanalyse - adaptatie - methodologie - simulatie
Many human and natural systems are highly complex, because they consist of many interacting parts. Such systems are known as complex adaptive systems (CAS). Understanding CAS is possible only by studying the interactions between constituent parts, rather than focussing only on the properties of the parts in isolation. Often, the possibilities for systematically studying these interactions in real-life systems are limited. Simulation models can then be an important tool for testing what properties may emerge, given various assumptions on the interactions in the system. Agent-based models (ABMs) are particularly useful for studying CAS, because ABMs explicitly model interactions between autonomous agents and their environment.
Currently, the utility of ABMs is limited by a lack of available methodologies for analysing their results. The main tool for analysing CAS models is sensitivity analysis. Yet, standard methods of sensitivity analysis are not well-suited to deal with the complexity of ABMs. Thus, there is a need for sensitivity analysis methodologies that are specifically developed for analysing ABMs. The objective of this thesis is to contribute such methodologies. Specifically, we propose methodologies for (1) detecting tipping points, (2) analysing the effects of agent adaptation, and (3) analysing resilience of ABMs.
Chapter 2 introduces traditional methods of sensitivity analysis. These methods are demonstrated by applying them to rank the most influential parameters of an ODE model of predator-prey interaction. Furthermore, the role of sensitivity analysis in model validation is discussed.
In Chapter 3 we investigate the use of sensitivity analysis for detecting tipping points. Whereas bifurcation analysis methods are available for detecting tipping points in ODE models, these methods are not applicable to ABMs. Therefore, we use an ODE model to verify the results from sensitivity analysis against those of bifurcation analysis. We conclude that one-factor-at-a-time sensitivity analysis (OFAT) is a helpful method for detecting tipping points. However, OFAT is a local method that considers only changes in individual parameters. It is therefore recommended to supplement OFAT with a global method to investigate interaction effects. For this purpose, we recommend all-but-one-at-a-time sensitivity analysis (ABOS) as a graphical sensitivity analysis method that takes into account parameter interactions and can help with the detection of tipping points.
In Chapter 4 we introduce a basic ABM model of agents competing in a spatial environment for a renewable resource. This basic model will be extended in the subsequent chapters, and will serve as a testing case for various sensitivity analysis methods. In Chapter 4, it is used to assess the utility of existing sensitivity analysis methods for ABMs. The results show that traditional methods of sensitivity are not sufficient to analyse the ABM, due to the presence of tipping points and other strong non-linearities in the model output. In contrast, OFAT is found to be helpful for detecting tipping points, as was suggested in Chapter 3. Based on these outcomes, OFAT is recommended as a starting point for sensitivity analysis of ABMs, preferably supplemented by a global method to investigate interaction effects.
In Chapter 5 we extend the ABM of Chapter 4 by adding agent adaptation in the form of a mechanism of natural selection. On short time-scales, the model behaviour appears to be similar to the non-adaptive model version. On longer time-scales, the agent adaptation causes the state of the model to gradually change as agents continue to adapt to their surroundings. We propose a sensitivity analysis method to measure the effects of this adaptation. This method is based on a quantification of the difference between probability density functions of model version with and without adaptation. Using this method, we show that this adaptation increases the resilience of the system by giving it the flexibility needed to respond to pressures.
In Chapter 6 we further extend the test-case by giving agents the option to harvest either cooperatively or individually. Cooperation increases the potential yields, but introduces the risk of defection of the interaction partner. It is shown that ecological factors, which are usually not considered in models on cooperation, strongly affect the level of cooperation in the system. For example, low levels of cooperation lead to a decreased population size, and causes the formation of small groups of agents with a higher level of cooperation. As a result, cooperation persists even without any mechanisms to promote it. Nevertheless, the inclusion of such mechanisms in the form of indirect reciprocity does further increase the level of cooperation. Furthermore, we show that the resulting high levels of cooperation, depending on the circumstances, can increase the resilience of the agent population against shocks.
To conclude, in this thesis several methodologies have been proposed to help with ABM analysis. Specifically, OFAT and ABOS are recommended for detecting tipping points in ABMs, and in Chapter 5 a protocol is introduced for quantifying the effects of adaptation. By suggesting these methodologies, this thesis aims to contribute to the utility of ABMs, especially for studying CAS.
Marine complex adaptive systems : theory, legislation and management practices
Bigagli, Emanuele - \ 2017
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.
Climate Change in Southern Africa: Farmers’ Perceptions and Responses
Kuivanen, K. ; Alvarez, S. ; Langeveld, C.A. - \ 2015
Wageningen UR - 46 p.
climatic change - farmers - attitudes - knowledge systems - adaptation - rural communities - southern africa - klimaatverandering - boeren - kennissystemen - adaptatie - plattelandsgemeenschappen - zuidelijk afrika
Southern Africa is characterized by natural climate variability onto which human-induced climate change is being superimposed. Rural communities that depend heavily on rain-fed agriculture for their livelihood are particularly vulnerable to the effects of climate-related change. This report takes stock of existing perceptions of- and responses to climate change among smallholder farmers in the region, in the hope of contributing to a better understanding of the complexities of local knowledge- and adaptation systems.
Adaptation and acclimation of seed performance
Souza Vidigal, D. De - \ 2015
University. Promotor(en): Harro Bouwmeester, co-promotor(en): Leonie Bentsink; Henk Hilhorst. - Wageningen University - ISBN 9789462575943 - 156
zaden - zaadkwaliteit - zaadkieming - klimaatverandering - adaptatie - arabidopsis - kiemrust - klimaatadaptatie - seeds - seed quality - seed germination - climatic change - adaptation - seed dormancy - climate adaptation
Adaptation of the brown planthopper, Nilaparvata lugens (Sta°l), to resistant rice varieties
Ferrater, J.B. - \ 2015
University. Promotor(en): Marcel Dicke, co-promotor(en): F.G. Horgan; Peter de Jong. - Wageningen : Wageningen University - ISBN 9789462575592 - 200
insectenplagen - nilaparvata lugens - adaptatie - oryza sativa - rijst - cultivars - plaagresistentie - symbionten - gisten - endosymbionten - insect pests - adaptation - rice - pest resistance - symbionts - yeasts - endosymbionts
This thesis examines the three-way interaction between yeast-like symbionts, an insect herbivore [Nilaparvata lugens (Stål)] and its rice (Oryza sativa L.) host, during adaptation of the herbivore to resistant rice varieties. A long-term selection study (20 generations of continuous rearing, ca. 24 months) was conducted with N. lugens populations on four rice varieties (IR22, a susceptible variety and IR65482, IR62, and PTB33, three resistant varieties). Planthopper performance and the abundance of yeast-like symbionts (YLS) were monitored throughout the selection process. N. lugens populations adapted to the resistant varieties as noted by increasing body size and increased egglaying. Xylem feeding was observed as a possible behavioural adaptation of N. lugens: planthoppers on resistant plants had relatively high levels of xylem feeding compared with planthoppers on susceptible plants. Planthoppers selected on resistant varieties, had clear differences in YLS densities that were not related to fitness on the varieties and, therefore, did not support a YLS density-mediated adaptation hypothesis.
Furthermore, this study examined whether YLS density affected the capacity of planthoppers to switch between hosts on which they have been selected for several generations (natal plant) to new varieties (exposed plants) under normal YLS densities (symbiotic) and after reduction of YLS densities by heat treatment (aposymbiotic). The results suggested that YLS do not mediate host plant switching in planthoppers as removal of symbionts influenced body weight but not the relative capacity of nymphs to feed on different plants. This study also tested if virulence is acquired by shared feeding sites with virulent and avirulent planthoppers. In the study, planthoppers with varying levels of virulence affected the host plants differently: The most virulent hoppers appeared to suppress rice defences to a greater extent than non-virulent planthoppers. Planthoppers attained highest weights on those plants on which virulent planthoppers had previously fed which suggests that feeding by the virulent planthoppers facilitated subsequent planthopper feeding on the same plant. Our preliminary results indicate that feeding by mixed virulent-avirulent populations could potentially accelerate adaptation by N. lugens to resistant rice varieties.
The capacity of virulent and avirulent planthoppers to feed on a range of 24 resistant rice varieties was examined using a series of bioassays. Planthoppers were observed to feed and lay eggs on all the varieties tested, many of which have never been widely deployed in the field. Furthermore, planthoppers selected on resistant varieties often had increased fitness on other resistant varieties, even when these possess different resistance genes. However, there was no strong evidence that once planthoppers have adapted to a resistant variety, they will exhibit fitness costs on other varieties with dissimilar genes. The mechanisms underlying insect virulence are complex and further research on planthopper adaptation is necessary to help conserve genetic resources and prolong the durability of available resistant varieties.
Inauguratie Koen Kramer
Kramer, K. - \ 2015
adaptatie - genetische diversiteit - bossen - modelleren - klimaatverandering - bosbescherming - bosproducten - bosecologie - adaptation - genetic diversity - forests - modeling - climatic change - protection of forests - forest products - forest ecology
Nieuwe en bestaande bossen kunnen door gebruik te maken van de genetische diversiteit van bomen hun functionaliteit behouden bij klimaatverandering. Dat stelt prof. dr. Koen Kramer bij zijn oratie als buitengewoon hoogleraar Kwantitatieve bosgenetica aan Wageningen University op donderdag 8 oktober
Adaptive collaborative governance of Nepal's community forests: shifting power, strenghtening livelihoods
McDougall, C.L. - \ 2015
University. Promotor(en): Cees Leeuwis, co-promotor(en): J.L.S. Jiggins. - Wageningen : Wageningen University - ISBN 9789462572881 - 322
bewonersparticipatie - governance - sociale samenwerking - sociaal leren - natuurlijke hulpbronnen - bosbouw - gemeenschappen - middelen van bestaan - adaptatie - sociaal kapitaal - vrouwen - armoede - nepal - community participation - social cooperation - social learning - natural resources - forestry - communities - livelihoods - adaptation - social capital - women - poverty
Cynthia McDougall--PhD Dissertation
Knowledge, Technology, &Innovation Chairgroup (WASS)
Adaptive collaborative governance of Nepal’s community forests: Shifting power, strengthening livelihoods
Community-based natural resource governance has taken root around the globe. And, yet, as demonstrated by community forestry in Nepal, such programmes have generally not yet lived up to their goals and expectations. After decades of implementation, community forestry in Nepal faces several key challenges. Central to these challenges are: the need to increase equity in community forest user group decision making and benefit sharing; and, to increase the livelihood benefits from community forestry overall. The research project on which this study is based sought to address these challenges at the community forest user group scale. The research objective was to contribute empirically-based insights regarding if and how adaptive collaborative governance of community forests in Nepal can constructively influence engagement, livelihoods, social capital and conflict—especially in regard to women and the poor. Further, the research aimed to elucidate the underlying issue of power in community-based natural resource governance. In particular, it sought to contribute deeper, theoretically-based understanding of the persistence of power imbalances in community forestry, and of the potential of adaptive collaborative governance to shift such imbalances.
Light harvesting, light adaptation and photoprotection in aquatic photosynthesis studies by time-resolved fluorescence spectroscopy
Chukhutsina, V. - \ 2015
University. Promotor(en): Herbert van Amerongen. - Wageningen : Wageningen University - ISBN 9789462572454 - 190
licht - adaptatie - bacillariophyta - cyanobacteriën - verdedigingsmechanismen - fotochemie - spectrofluorimetrie - light harvesting complexen - light - adaptation - cyanobacteria - defence mechanisms - photochemistry - spectrofluorimetry - light harvesting complexes
Aquatic photosynthetic organisms unavoidably experience light fluctuations that vary in amplitude, duration and origin, compromising their photosynthetic efficiency. Weather conditions and underwater flow cause continuous changes in irradiance to which the organisms have to adapt. Many light-adaptation strategies of photosynthetic organisms, such as light acclimation, photoprotection and state transitions are still not well understood. In this thesis, time-resolved fluorescence spectroscopy is used to obtain insight into the response of diatoms and cyanobacteria, both aquatic photosynthetic organisms, to changing light conditions.
In chapter 2, photoacclimation (long-term acclimation to irradiance conditions) of the diatom Cyclotella meneghiniana is discussed. It is shown that the diatom cells fine-tune the amount of absorbed light energy by modifying their antenna size: cells grown in high light intensity have smaller antennas than those grown in low light. At the same time, the increase of growth light intensity leads to a decrease of the relative amount of photosystem I (PSI) as compared to PSII. Such a strategy might be beneficial for diatoms, since they are known to have an electron transfer cycle around PS II to release excess electrons produced in high light intensities. Besides discussing photoacclimation, we give a detailed description the fluorescence kinetics in C. meneghiniana. It is concluded that the diatom antenna, represented by light-harvesting fucoxanthin chlorophyll proteins (FCPs), transfer their excitation energy predominantly to PSII. FCPs associated with PSII are slightly richer in red-absorbing fucoxanthin than the FCPs associated with PSI, suggesting that PSII antennas (partly) constitute the antenna form FCPb (i.e. oligomeric antenna complexes).
In chapter 3 the process of non-photochemical quenching (NPQ, thermal dissipation of excess absorbed light energy) of chlorophyll a fluorescence was studied in the same diatom species. Diatoms can rapidly switch on/off NPQ to respond to fast light-intensity changes in moving waters. They are capable to induce higher NPQ values than plants or other photosynthetic organisms. The reason for such high NPQ values, however, is not clear. We performed picosecond fluorescence measurements at 77K on cells locked in three different states: Besides using conventional unquenched and quenched states of the cells (in the absence and presence of the total NPQ component, respectively), we also performed measurements on the dark-adapted state directly following NPQ. In this state, diatoxantin (Dtx, a carotenoid related to NPQ), accumulated during the NPQ period and Dtx-related NPQ persists, while ΔpH-related NPQ has relaxed. In this way we revealed the following sequence of events during full development of NPQ. First, the pH gradient across the thylakoid membrane induces quenching of FCP trimers (FCPa complexes), while they are still part of PSII. This is followed by (partial) detachment of FCPa from PSII after which quenching persists. The pH gradient also causes the formation of Dtx, which leads to further quenching of isolated PSII cores and some aggregated FCPa. To summarize, quenching of PSII -both cores and complexes- and FCPa substantially contribute to NPQ in diatoms. The FCPb antenna form on the other hand does not contribute to the NPQ process.
Certain aquatic photosynthetic organisms, such as cyanobacteria and green algae, can also cope with changing light conditions by dynamically varying the relative antenna size of PSI and of PSII. Consequently, a redistribution of light energy between the PSs is achieved. This phenomenon is called “state transitions”. It is known to be driven via a change in the redox status of electron carriers between PSII and PSI. In cyanobacteria, this redox change can be achieved via dark-light transitions. However, the cascade of microscopic events that lead to subsequent energy redistribution in cyanobacteria is still not completely clear. In chapter 4, a study on dark-light transitions using the cyanobacterium Synechocystis sp. PCC 6803 as a model organism is described. It is demonstrated that during dark to light transitions, there is mainly detachment of phycobilisomes (PBSs) (cyanobacterial antennas) from PSI, generally not followed by their attachment to PSII: only 15 % of the PBSs that detach from PSI actually move to PSII, while the major part remains detached from both PSs. We conclude that PSI-PSII-PBS megacomplexes, which were recently isolated using chemical cross-linking, are not involved in dark/light state transitions, suggesting that, if present, they are only transiently formed in cyanobacteria. To summarize, the findings presented in chapter 4 suggest that in cyanobacteria, unlike in green algae or higher plants, the main role of state transitions is to change the absorption cross-section of PSI, rather than that of PSII.
In chapter 5, a study of the role of flv4-2 operon-encoded proteins in Synechocystis is described. Three genes are found in the operon: Flv4, Sll0218, and Flv2. Only recently flv4-2 operon-encoded proteins were found to constitute an additional photoprotective mechanism in a number of cyanobacteria by safeguarding PSII activity via an alternative electron chain. Its contribution becomes vital for the cells in high light and in air-level CO2, when the photosynthetic electron transport chain is over-reduced. It is demonstrated that deletion of the operon induces 20% PBS detachment. The reduced PSII dimer to monomer ratio, as a result of the absence of the small Sll0218 protein, favors a relative decrease of the PSII dimer content of about 20%, showing a direct correlation between PSII dimer destabilization and PBS detachment from reaction centers. On the other hand, the suggested binding of the Flv2/Flv4 heterodimer closely to the quinone B (QB) pocket in PSII increases the QB redox potential, thereby promoting forward electron transfer and increasing the charge separation rates in PSII. This activity of the Flv2/Flv4 heterodimer in combination with its earlier reported role as an electron acceptor in alternative electron chain provides more oxidized state of the PQ pool in high light and in air-level CO2.
Governing Congo Basin forests in a changing climate: actors, discourses and institutions for adaptation and mitigation
Somorin, O.A. - \ 2014
University. Promotor(en): Bas Arts, co-promotor(en): Ingrid Visseren-Hamakers; D.J. Sonwa. - Wageningen : Wageningen University - ISBN 9789462571280 - 250
bossen - klimaatverandering - adaptatie - mitigatie - beleid - bosbouw - bosbeleid - congo - forests - climatic change - adaptation - mitigation - policy - forestry - forest policy
Governing Congo Basin Forests in a Changing Climate: Actors, Discourses and Institutions for Adaptation and Mitigation
The thesis deals with the central question of the governance processes of making tropical forests deliver climate change adaptation and mitigation outcomes of sustainable livelihoods, biodiversity conservation and enhanced carbon stocks. Using the case of the Congo Basin forests, it analyzes the nexus between forest and climate change, particularly on the governance processes of using the forests to respond to climate change. The thesis questions the dominant frames and discourses shaping the policymaking processes of adaptation and mitigation strategies in the Congo Basin. The research is informed by past (and still current) debates among different actors on the forms of institutional and policy frameworks required for policy making on adaptation and mitigation in the Congo, given the region’s context of weak human and governance capacities.
Drawing from the theoretical perspective of discursive institutionalism which takes into account the institutional context in which discourses emerge and the way in which they are institutionalized in social practices. Conceptually, the thesis employs the analytical elements of discursive institutionalism: discourses, actors and institutions in terms of their consequences for governance process analysis. The focus is to understand the types of actors involved along with their capacity and competence to contribute to the policy processes; the overarching global to local discourses on the issues; and the institutional structures considered relevant for adaptation and mitigation in the Congo Basin.
Despite the framing of adaptation as a priority for the Congo Basin region due to the high vulnerability (and low adaptive capacity) of the population to climate risks, the thesis finds more significant policy attention is rather given to mitigation. The dominance of the mitigation discourses is largely due to elements of financial resources, knowledge and influence employed by their actor coalitions to advance the policymaking process. While mitigation policy debates among state and non-state actors on institutional and governance frameworks exist at the national level, adaptation strategies including sustaining food security, income generation and livelihood diversification, are already in practice at the local levels. Ultimately, policy actors’ interest to match the multiple opportunities that mitigation offers with the priorities of adaptation underlines the deliberate actions towards fostering synergy. The thesis concludes that the future of the Congo Basin forests under a changing climate lies in how the actors are able to develop policy frameworks and governance arrangements to foster mitigative adaptation and adaptive mitigation.
Assessing water stress of desert vegetation using remote sensing : the case of the Tamarugo forest in the Atacama Desert (Northern Chile)
Chávez Oyanadel, R.O. - \ 2014
University. Promotor(en): Martin Herold, co-promotor(en): Jan Clevers; E. Acevedo. - Wageningen : Wageningen University - ISBN 9789462570795 - 175
waterstress - woestijnen - vegetatie - remote sensing - bossen - waterbeheer - ecosystemen - droogte - adaptatie - chili - water stress - deserts - vegetation - forests - water management - ecosystems - drought - adaptation - chile
Water stress assessment of natural vegetation plays a key role in water management of desert ecosystems. It allows scientists and managers to relate water extraction rates to changes in vegetation water condition, and consequently to define safe water extraction rates for maintaining a healthy ecosystem. Previous research has shown that optical remote sensing constitutes a powerful tool for assessing vegetation water stress due to its capability of quantitatively estimating important parameters of vegetation such as leaf area index (LAI), green canopy fraction (GCF), and canopy water content (CWC). However, the estimation of these parameters using remote sensing can be challenging in the case of desert vegetation. Desert plants have to cope with high solar irradiation and limited water. In order to maintain an adequate water balance and to avoid photoinhibition, desert plants have evolved different adaptations. A common one is heliotropism or ‘solar tracking’, an ability of many desert species to move their leaves to avoid facing direct high solar irradiation levels during the day and season. This adaptation (paraheliotropism) can have an important effect on the canopy spectral reflectance measured by satellites as well as on vegetation indices such as the normalized difference vegetation index (NDVI). In this thesis, I propose a remote sensing based approach to assess water stress of desert vegetation, exemplified in the case of the Tamarugo (Prosopis tamarugo Phil) tree in the Atacama Desert (Northern Chile), a ‘solar tracker’ species, which is threatened by groundwater overexploitation.
In the first chapter of this thesis (general introduction), I explained the motivation of the PhD project and elaborated four research questions, which are later discussed in chapters 2, 3, 4, and 5. The thesis concluded with chapter 6, where I provide a synthesis of the main results, general conclusions and a final reflection and outlook.
In the second chapter, I studied the effects of water stress on Tamarugo plants under laboratory conditions and modelled the light-canopy interaction using the Soil-Leaf-Canopy radiative transfer model. I described for the first time pulvinar movement of Tamarugo and quantified its effects on canopy spectral reflectance with and without stress. I showed that different spectral indices have potential to assess water stress of Tamarugo by means of LAI and CWC. In the third chapter, I measured the effects of pulvinar movements on canopy reflectance for Tamarugos under field conditions and used high spatial resolution images to assess water stress at the tree level. I developed an automated process to first identify single trees and delineate their crowns, and secondly, to estimate LAI and GCF using spectral vegetation indices. These indices (NDVI and chlorophyll red-edge index) were negatively correlated to diurnal values of solar irradiation as a consequence of leaf pulvinar movements. For this reason, higher values of both vegetation indices are expected to occur in the morning and in winter (low solar radiation) than at midday or summer.
In the fourth chapter I studied the effects of diurnal pulvinar movements on NDVI time series from the MODIS-Terra satellite (acquired in the morning) and the MODIS-Aqua satellite (acquired at midday) for the period 2003-2012 and the seasonal effects of pulvinar movements on NDVI time series of Landsat images for the period 1998-2012 for Tamarugo areas with and without water stress. NDVI values measured by MODIS-Terra (morning) were higher than the NDVI values measured by MODIS-Aqua (afternoon) and the difference between the two, the ΔNDVImo-mi, showed good potential as water stress indicator. In a similar way, I observed a strong seasonal effect on the Landsat NDVI signal, attributed to pulvinar movements, and the difference between winter and summer, the ΔNDVIW-S, also showed good potential for detecting and quantifying water stress. The ΔNDVImo-mi, the ΔNDVIW-S and the NDVI itself measured systematically in winter time (NDVIW) were negatively correlated with in situ groundwater depth measurements.
In chapter five I used a dense NDVI time series of Landsat images for the period 1989-2013, combined with high spatial resolution satellite imagery and hydrogeological records, to provide a quantitative assessment of the water status of Tamarugo vegetation after 50 years of increasing groundwater extraction. The results showed that the NDVIW and ΔNDVIW-S of the Tamarugo vegetation declined 19% and 51%, respectively, as groundwater depleted (3 meters on average) for the period 1989-2013. Both variables were negatively correlated to groundwater depth both temporally and spatially. About 730.000 Tamarugo trees remained in the study area by 2011, from which 5.2% showed a GCF<0.25 which is associated to severe water stress. Based on this spatio-temporal analysis, I suggest that the survival of Tamarugo trees is limited to a maximum groundwater depth of 20 meters.
The main conclusions of this PhD thesis are summarized as follows:Heliotropism or leaf ‘solar tracking’, a common adaptation among desert plants, has an important impact on canopy spectral reflectance. As shown in the case of the Tamarugo trees, widely used vegetation indices such as the NDVI were negatively correlated to solar irradiation (the stimulus for leaf solar tracking), showing a distinct diurnal and seasonal cycle.An early symptom of water stress in paraheliotropic plants (leaves facing away the sun) is the decline of the amplitude of the diurnal and seasonal NDVI cycles. Thus, remote sensing estimations of this amplitude (e.g. the NDVI difference between winter and summer or the difference between midday and morning) can be used to detect and map early water stress of paraheliotropic vegetation.At the tree level, very high spatial resolution images combined with object based image analysis and in-situ data provided accurate estimations of the water status of small desert vegetation features, such as isolated trees. For monitoring purposes, careful consideration of the time during the day and the season at which the images are taken needs to be taken to avoid misleading interpretations.Time series analysis of historical satellite images combined with very high spatial resolution images and hydrogeological records can provide a quantitative spatio-temporal assessment of the effects of long-term groundwater extraction on desert vegetation.
Vulnerability and adaptation to climate variability and change in smallholder farming systems in Zimbabwe
Rurinda, J. - \ 2014
University. Promotor(en): Ken Giller, co-promotor(en): P. Mapfumo; Mark van Wijk. - Wageningen : Wageningen University - ISBN 9789461739605 - 168
klimaatverandering - kleine landbouwbedrijven - bedrijfssystemen - klimaatadaptatie - adaptatie - klimaat - gewasopbrengst - zimbabwe - climatic change - small farms - farming systems - climate adaptation - adaptation - climate - crop yield
Keywords: Climate change; Increased climate variability; Vulnerability; Smallholder farmers; Adaptation
Climate change and increased climate variability are currently seen as the major constraints to the already stressed smallholder farming livelihood system in southern Africa. The main objectives of this study were first to understand the nature and sources of vulnerability of smallholder farmers to climate variability and change, and second to use this knowledge to evaluate possible farm-level management options that can enhance the adaptive capacity of smallholder farmers in the face of increased climate variability and long-term change in climate. The study was conducted in Makoni and Hwedza districts in eastern Zimbabwe. Local famers’ and expert empirical knowledge were combined using research tools that mainly included detailed field observations and surveys, systems analysis and field experimentation, and simulation modelling (the Agricultural Production Systems Simulator (APSIM)). To understand the nature and sources of vulnerability, long term climate data were analysed and farmers were interviewed individually and in groups. On-farm experimentation and simulation modelling were conducted to evaluate the impacts and interactions of adaptation options namely maize cultivar choice, staggered planting dates, and variable fertilizer rates, on maize yield under both short-term climate variability and long-term climate change. Another on-farm experiment was conducted to assess whether small grains (finger millet and sorghum) perform as well as maize under variable soil and rainfall conditions.
The long-term rainfall and temperature analyses closely supports farmers’ perceptions that the total annual rainfall has so far not changed, but variability in the rainfall distribution within seasons has increased. The number of rain days has decreased, and the frequency of dry spells within season increased. The mean daily minimum temperature increased by 0.2°C per decade in Makoni, and by 0.5°C per decade in Hwedza, over the period from 1962 to 2000. The surface air temperature is further projected to increase significantly in Makoni and Hwedza, by 2100. The impacts of rising temperatures and increased rainfall variability among smallholder households were highly differentiated because different households depend on varied farming livelihood sub-systems, which were exposed uniquely to aspects of climatic risk. For example, livestock production was sensitive to drought due to lack of feed, affecting resource-endowed farmers, who often own relatively large herds of cattle. Crop production was more sensitive to increased rainfall variability, affecting especially farmers with intermediate resource endowment. Availability of wild fruits and social safety nets were affected directly and indirectly by extreme temperatures and increased rainfall variability, impacting the livelihoods of poorer farmers. Farmers have also access to different biophysical and socioeconomic resources such as fertilizer and farm labour inputs, and as a result they respond variedly to impacts of a changing climate. Thus, alongside climate variability and change, farmers also faced biophysical and socioeconomic challenges, and these challenges had strong interactions with adaptation options to climate change.
Experimentation in this studydemonstrated that the maize cultivars currently on the market in Zimbabwe, and in many parts of southern Africa, exhibit narrow differences in maturity time such that they do not respond differently to prolonged dry spells. The yield performance for all three cultivars is projected to be similar in future change in climates, consistent with results from the experiments.In the current cropping system farmers can select any cultivar available on the market without a yield penalty. However, with climate change none of the available cultivars will be able to compensate for the decline in yield. Greater maize grain yields were obtained with both the early (25 October – 20 November) and normal (21 November – 15 December) plantings, with no significant differences between these planting windows(e.g. on average 5 t ha-1 in Makoni, and 3 t ha-1 in Hwedza for the high fertilization rate).Contrary to previous research findings, there is a reasonably wide planting window in which good yields can be obtained if the rains start on time, but if the start of the rains is delayed until after the beginning of December planting should be done as soon as possible. Regardless of the amount of fertilizer applied, yields were reduced strongly when planting was substantially delayed by four weeks after the start of the rainy season. Maize yielded more than finger millet and sorghum even when rainfall was poor in the 2010/2011 season. For example, maize yielded 2.4 t ha-1 compared with 1.6 t ha-1 for finger millet and 0.4 t ha-1 for sorghum in the 2010/2011 rainfall season in Makoni. Finger millet and sorghum failed to emerge unless fertilizer was applied. Application of manure alone failed to address this challenge of poor emergence until fertilizer was added. Sorghum suffered critical yield losses due to bird damage. The better performance of maize over finger millet and sorghum suggested that the recommendation to substitute small grains for maize as a viable adaptation option to a changing climate, will neither be the best option for robust adaptation nor attractive for farmers in southern Africa. Alternatively spreading crops across the farm and in time can be a viable strategy to spread climatic risk as well as improve human nutrition. Poor soil fertility constrained yield more strongly than rainfall and late planting, as demonstrated by the large yield gap (> 1.2 t ha-1) between the unfertilized and fertilized cultivars even in the poor rainfall season (2010/2011).
Fertilization increased yield significantly under both the baseline and future climates particularly when planting before mid-December.The maize response to mineral nitrogen is, however, projected to decline as climate changes, although effects only become substantial towards the end of the 21st Century. Soil fertility management is therefore likely to be a major entry point for increasing the adaptive capacity of smallholder farmers to climate change and increased climate variability. However, management of factors related to both nutrient resource access and farmers decisions to enhance resource use efficiencies are critical if agriculture is to be used as robust adaptation options to climate change by smallholder in Southern Africa.
Knelpunten in wettelijke kaders en beleid voor klimaatadaptatie in het Waddengebied
Klostermann, J.E.M. ; Biesbroek, G.R. ; Broekmeyer, M.E.A. - \ 2013
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2452) - 60
klimaatverandering - adaptatie - dijken - wetgeving - veiligheid - innovaties - wadden - kustgebieden - noord-nederland - climatic change - adaptation - dykes - legislation - safety - innovations - tidal flats - coastal areas - north netherlands
Het doel van deze rapportage is het inventariseren en analyseren van de vigerende wet- en regelgeving die van invloed is op de besluitvorming rondom klimaatadaptatie in het Waddengebied, zoals nieuwe veiligheidsnormeringen voor primaire keringen en versterking van waterkeringen. In de eerste ronde is alle mogelijke wet- en regelgeving die van invloed is op de kust en zee geïnventariseerd. Daarna is de rechtsgeldige regelgeving die het meest direct van toepassing is geselecteerd en geclusterd. Van deze selectie van tien wetten is nagegaan welke inhoudelijke en procedurele knelpunten ze op zouden kunnen leveren voor innovatieve dijkconcepten. Tenslotte is een aanzet gegeven voor oplossingsrichtingen, gericht op de tijdshorizon van het Deltaprogramma. Voor alle wetten zijn oplossingen binnen de bestaande kaders mogelijk. De natuurwetgeving vormt daarop een uitzondering omdat deze belemmeringen kan opleveren die niet met zorgvuldige procedures en tijdige inhoudelijke aanpassingen kunnen worden opgelost.
Stress responses and digestive tract robustness of Lactobacillus plantarum
Bokhorst-van de Veen, H. van - \ 2013
University. Promotor(en): Michiel Kleerebezem, co-promotor(en): P.A. Bron. - [S.l. : S.n. - ISBN 9789461736291 - 192
lactobacillus plantarum - stressreactie - spijsverteringskanaal - genregulatie - adaptatie - stress response - digestive tract - gene regulation - adaptation
Lactobacillus plantarumis one of the most versatile lactic acid bacteria that can successfully inhabit a variety of environmental niches. It is a common inhabitant of the human and animal gastrointestinal (GI) tract and it is used as starter culture in various fermentation processes for different food raw-materials, including milk, fruits, vegetables, and meat. Moreover, L. plantarum is marketed as a health-promoting culture, i.e. a probiotic. In these different environments and processes the bacteria encounter stress conditions, such as heat, cold, acid, salt, and oxygen stress. Since starter cultures and probiotics require metabolic activity to contribute to the taste and texture of the fermented products, and/or viability to exert their in situ beneficial effect on the consumer, it is important to understand and improve the gene-regulatory adaptation that sustains their function and viability under these challenging conditions. Nowadays, genomic approaches are available that enable the global, genome-wide analysis of stress responses in lactic acid bacteria. The work presented in this thesis employs such tools and also developed some novel strategies to understand stress responses in L. plantarum.
During wine fermentation, L. plantarum is exposed to ethanol and global transcriptome profiling demonstrated the gene expression adaptation of this microorganism upon short and long term exposure to sublethal levels of this solvent. The results suggested that the ethanol induced activation of the CtsR-related stress regulon contributes to its adaptation to ethanol exposure which also provides cross-protection against heat stress. Transcriptome analyses under different growth conditions of gene deletion derivatives of the L. plantarum WCFS1 strain that lack the genes encoding the stress response regulators ctsR and/or hrcA, enabled the refinement of the gene regulation repertoire that is controlled by these central regulators of stress responses in this species. Notably, the deletion of both stress-regulators, elicited transcriptome changes that affected a large variety of additional gene-functions in a temperature-dependent manner, which prominently included genes related to cell-envelope remodelling.
Culturing of L. plantarum WCFS1 under different fermentation conditions led to large differences in GI-tract survival and robustness, which was addressed using a simple in vitro survival assay. Enhanced GI-tract survival and robustness could be associated with low salt and low pH conditions during the fermentations. The transcriptomes obtained for each of the fermentation conditions employed, were correlated with the observed GI-tract survival rates, enabling the identification of candidate genes involved in the robustness phenotype, including a transcription regulator involved in capsular polysaccharide remodelling (Lp_1669), a penicillin-binding protein (Pbp2A) involved in peptidoglycan biosynthesis, and a Na+/H+ antiporter (NapA3). A role of these candidate genes in actual survival in the GI-tract assay could be confirmed by mutation analysis, further confirming their contribution to GI-tract stress robustness in L. plantarum.
This thesis also describes the use of a novel, next-generation sequencing-based method, for the assessment of the in vivo GI-tract persistence of different L. plantarum strains that were administered to healthy human volunteers in specifically designed strain-mixtures. A remarkable consistency of the strain-specific in vivo persistence curves was observed when comparing data obtained from different volunteers. Moreover, a striking congruency was observed between the strain-specific in vivo persistence curves and the predicted GI-tract survival based on the simple in vitro assay. Finally, evolutionary adaptation of L. plantarum WCFS1 to the murine GI-tract was studied by extended exposure of the strain to the mice digestive tract through consecutive rounds of (re)feeding of the longest persisting bacterial colonies. Re-sequencing of the genomes of more persistent derivatives of the original strain, and the evaluation of the genomic modifications identified, implied that genes encoding cell envelope-associated functions and energy metabolism play an important role in the determination of GI-tract persistence in L. plantarum.
The results described in this thesis strive to obtain an improved understanding of the gene-regulatory adaptations of L. plantarum that allow its survival under stress conditions, including those associated with residence in the gastrointestinal tract of animals and humans, with the intention to exploit such understanding to rationally improve the robustness of these bacteria.
Affective foodscapes in an economy of passion : repetition, opposition and adaptation in Mexican restaurants in Amsterdam, Madrid and San Francisco
Matus Ruiz, M. - \ 2012
University. Promotor(en): Leontine Visser, co-promotor(en): Gerard Verschoor; K. Lindström. - [S.l. : s.n. - ISBN 9789461732828 - 274
mexicaanse kookkunst - restaurants - eetgelegenheden - amsterdam - nederland - spanje - pacifische staten van de vs - vs - voedselconsumptie - identiteit - landschap - adaptatie - stedelijke samenleving - mexico - mexican cookery - dining facilities - netherlands - spain - pacific states of usa - usa - food consumption - identity - landscape - adaptation - urban society
The main goal of my research was to analyze how the desire to affect and be affected by foreign signs relates to the commoditization of food products offered in Mexican restaurants in Amsterdam, Madrid and San Francisco. I conceive restaurants as foodscapes. Iargue that actors’ attachments to passionate networks enable their enactment. Foodscapes areintersemiotic translations of landscapes. In these translations, the commoditization of food has been based on its relationships with idealized entities from the Mexican and U.S. landscapes, giving rise to Tex‐Mex, Cal‐Mex, Mex‐Mex, Regional‐Mex and “Real”‐ Mex restaurants. The resulting foodscapes have the power to seduce consumers either by fixing their beliefs for certain foods or contaminating new passions. My approach is an innovative way to analyze the differentiation of markets in an economy that bases its reproduction in the contamination of desires and passions.
Adapt, move or perish : the interaction of genetics and demography in fragmented populations under climate change
Cobben, M.M.P. - \ 2012
University. Promotor(en): Rolf Hoekstra; Paul Opdam, co-promotor(en): Rene Smulders; Jana Verboom-Vasiljev. - S.l. : s.n. - ISBN 9789461731999 - 132
dendrocopos - habitats - habitatfragmentatie - biodiversiteit - populaties - klimaatverandering - adaptatie - genetica - demografie - modellen - verspreiding - habitat fragmentation - biodiversity - populations - climatic change - adaptation - genetics - demography - models - dispersal
In reactie op klimaatverandering verschuift van veel soorten het areaal, maar het is duidelijk dat dit voor lang niet alle soorten snel genoeg gaat. Habitatfragmentatie zal in het algemeen de noodzakelijke areaalverschuivingen vertragen. Er is geopperd dat de combinatie van areaalverschuivingen en de lokale aanpassing van soorten aan de veranderende omstandigheden hun overleving positief zal beïnvloeden
Social limitations to livelihood adaptation : responses of maize-farming smallholder households to neoliberal policy reforms in Morelos, Southern Veracruz, Mexico
Groenewald, S.F. - \ 2012
University. Promotor(en): Anke Niehof, co-promotor(en): Marrit van den Berg. - S.l. : s.n. - ISBN 9789461732217 - 222
huishoudens - landbouwhuishoudens - kleine landbouwbedrijven - markten - boerenmarkten - agrarische economie - ontwikkelingseconomie - levensstandaarden - adaptatie - middelen van bestaan - sociaal kapitaal - maïs - ontwikkelingslanden - mexico - households - agricultural households - small farms - markets - farmers' markets - agricultural economics - development economics - living standards - adaptation - livelihoods - social capital - maize - developing countries
This thesis describes the adaptation of smallholders to market changes shaped by neoliberal policy reforms in the Mexican maize sector. Contrary to expectations about smallholder responses to a liberalised maize market, in the study area maize still is the main source of income. Farmers did not leave the maize sector to produce more profitable crops neither did they exit agriculture. Special attention is given to the role of social capital in shaping households’ adaptation behaviour. By analysing the role of trust in adaptation processes, this study enhances our understanding of the importance of the social and historical context in contemporary livelihood decisions. It demonstrates that new forms of social capital are difficult to sustain if they do not link up with existing, local forms of social capital. Data collection in the field took place between March 2007 and May 2010. The research was conducted in Morelos, Veracruz, Mexico.
Adapting to climate change: examples from the Netherlands
Ritzema, H.P. - \ 2011
In: Proceeding 25th ICID European Regional Conference, Deltas in Europe, Integrated water management for multiple land use in flat coastal areas. - - p. A1 - 4-1-10.
klimaatverandering - hoogwaterbeheersing - kustgebieden - aanpassing - adaptatie - landgebruik - mitigatie - scenario-analyse - climatic change - flood control - coastal areas - adjustment - adaptation - land use - mitigation - scenario analysis
Higher water levels and more space for water will fundamentally change the way our coastal lowlands are being managed. Appropriate conservation, adaptation and mitigation actions need to take place in the context of sustainable development. In the Netherlands, adaptation measures focus on the water management system as well as the spatial planning. The selection of adaptation measures, mainly depends the type of land use. For the three major types of land types, i.e. the low-lying peatlands in the western part of the country, the higher sandy soil areas in the east and southeast and the marine clay areas in the reclaimed polder areas, adaptation measures, for both agriculture and nature, adaption strategies are discussed.
Robuuste multifunctionele rivierdijken : welke kansen en knelpunten zien stakeholders voor robuuste multifunctionele dijken langs de rivieren in het landelijk gebied?
Loon-Steensma, J.M. van - \ 2011
Wageningen : Alterra (Alterra-rapport 2228) - 110
dijken - kwaliteit - versterking - klimaatverandering - meervoudig gebruik - waterbeheer - adaptatie - gelderland - zuid-holland - dykes - quality - reinforcement - climatic change - multiple use - water management - adaptation
In dit rapport wordt op basis van literatuur, beleidsdocumenten en ervaringen van diverse betrokkenen een overzicht gegeven van de problematiek van het aanpassen van de waterkeringen in het rivierengebied aan onder andere een veranderend klimaat en het combineren van functies in een robuuste waterkeringszone. Daarnaast worden plannen voor een vijftal locaties in het landelijk gebied geschetst. Naar aanleiding van deze plannen zijn de belangrijkste stakeholders geïnterviewd. Op basis van de door de stakeholders gesignaleerde kansen, knelpunten, aandachtspunten en aanbevelingen is een sterkte-zwakte analyse gemaakt van robuuste multifunctionele waterkeringen. Ook zijn voor de vijf locaties sterkten, zwakten, kansen en bedreigingen benoemd en zijn aanbevelingen gedestilleerd voor de verdere strategieontwikkeling richting hoogwaterbescherming door multifunctionele klimaatbestendige dijkzones langs de rivieren in het landelijk gebied.
Climate change, mitigration, and adaptation : training of trainers : tailor made course for employees of Indonesia's state agency for Meteorology. Climatology, and Geo-Physics - Badan Meterologi, Klimatologi, dan Geofisika (BMKG)
Schrevel, A. - \ 2011
Wageningen : Alterra (Alterra report 2205) - 54
klimaatverandering - adaptatie - mitigatie - opleiding - indonesië - climatic change - adaptation - mitigation - training - indonesia