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.

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    The historical origins of palaeotropical intercontinental disjunctions in the pantropical flowering plant family Annonaceae
    Thomas, D.C. ; Chatrou, L.W. ; Stull, G.W. ; Johnson, D.M. ; Harris, D.J. ; Thongpairoj, U. ; Saunders, R.M.K. - \ 2015
    Perspectives in plant ecology, evolution and systematics 17 (2015)1. - ISSN 1433-8319 - p. 1 - 16.
    long-distance dispersal - out-of-africa - molecular phylogenetics - southeast-asia - northern-hemisphere - vicariance analysis - tropical africa - dna-sequences - biogeography - miocene
    Geographic isolation of sister taxa in the African and Asian tropics (palaeotropical intercontinental disjunction; PID) is a major biogeographic pattern explained by four competing hypotheses: rafting on the Indian tectonic plate (‘Gondwanan vicariance hypothesis’); migration facilitated by a northern mid-latitude corridor of frost-free climates during the Eocene (‘boreotropical migration hypothesis’); overland dispersal across Arabia associated with the Miocene Climatic Optimum; and transoceanic dispersal. The explanatory challenges posed by PIDs are addressed here using the pantropical flowering plant family Annonaceae as a study system. Molecular dating and ancestral area reconstructions were undertaken using plastid DNA sequence data (ca. 6 kb) derived from an extensive taxon sampling, incorporating ca. 75% of all genera, with phylogenetically informed sampling of species within genera that are distributed across the African and Asian tropics. Statistical dispersal-vicariance analysis and likelihood reconstructions indicated 12 intercontinental dispersal events between Africa and Asia. All but one of these dispersals were from Africa to Asia. Between 10 and 12 vicariance events were inferred, ranging from the late Palaeocene to the late Miocene, with mean divergence times of seven events in the Miocene. Although migration through the Eocene boreotropics has previously been highlighted as the predominant process underlying intercontinental disjunctions in Annonaceae, our results indicate that post-boreotropical processes have also had a major impact on shaping PIDs. Palaeogeographic reconstructions and the fossil record from the Arabian Peninsula support the plausibility of a hypothesized window of overland dispersal opportunity for lowland tropical forest taxa prior to climate deterioration commencing in the late Middle Miocene, providing an alternative to transoceanic dispersal. The patterns observed underscore the hypothesis that intercontinental floristic exchange, facilitated by both the Eocene boreotropics and the erosion of oceanic and climatic biogeographic barriers between Africa and Asia in the Miocene, had a substantial impact on the assembly of palaeotropical forest floras.
    Mapping Ecosystem Services for Land Use Planning, the Case of Central Kalimantan
    Sumarga, E. ; Hein, L.G. - \ 2014
    Environmental Management 54 (2014)1. - ISSN 0364-152X - p. 84 - 97.
    tropical forests - west kalimantan - southeast-asia - united-states - east-asia - indonesia - conservation - emissions - peat - deforestation
    Indonesia is subject to rapid land use change. One of the main causes for the conversion of land is the rapid expansion of the oil palm sector. Land use change involves a progressive loss of forest cover, with major impacts on biodiversity and global CO2 emissions. Ecosystem services have been proposed as a concept that would facilitate the identification of sustainable land management options, however, the scale of land conversion and its spatial diversity pose particular challenges in Indonesia. The objective of this paper is to analyze how ecosystem services can be mapped at the provincial scale, focusing on Central Kalimantan, and to examine how ecosystem services maps can be used for a land use planning. Central Kalimantan is subject to rapid deforestation including the loss of peatland forests and the provincial still lacks a comprehensive land use plan. We examine how seven key ecosystem services can be mapped and modeled at the provincial scale, using a variety of models, and how large scale ecosystem services maps can support the identification of options for sustainable expansion of palm oil production.
    Importance of bistatic SAR features from TanDEM-X for forest mapping and monitoring
    Schlund, M. ; Poncet, F. von; Hoekman, D.H. ; Kuntz, S. ; Schmullius, C. - \ 2014
    Remote Sensing of Environment 151 (2014)sp. issue. - ISSN 0034-4257 - p. 16 - 26.
    land-cover - southeast-asia - feature-selection - polarimetric sar - tropical-forest - decision tree - alos palsar - rain-forest - sir-c - classification
    Deforestation and forest degradation are one of the important sources for human induced carbon dioxide emissions and their rates are highest in tropical forests. For man-kind, it is of great importance to track land-use conversions like deforestation, e.g. for sustainable forest management and land use planning, for carbon balancing and to support the implementation of international initiatives like REDD + (Reducing Emissions from Deforestation and Degradation). SAR (synthetic aperture radar) sensors are suitable to reliably and frequently monitor tropical forests due to their weather independence. The TanDEM-X mission (which is mainly aimed to create a unique global high resolution digital elevation model) currently operates two X-band SAR satellites, acquiring interferometric SAR data for the Earth's entire land surface multiple times. The operational mission provides interferometric data as well as mono- and bistatic scattering coefficients. These datasets are homogenous, globally consistent and are acquired in high spatial resolution. Hence, they may offer a unique basic dataset which could be useful in land cover monitoring. Based on first datasets available from the TanDEM-X mission, the main goal of this research is to investigate the information content of TanDEM-X data for mapping forests and other land cover classes in a tropical peatland area. More specifically, the study explores the utility of bistatic features for distinguishing between open and closed forest canopies, which is of relevance in the context of deforestation and forest degradation monitoring. To assess the predominant information content of TanDEM-X data, the importance of information derived from the bistatic system is compared against the monostatic case, usually available from SAR systems. The usefulness of the TanDEM-X mission data, i.e. scattering coefficients, derived textural information and interferometric coherence is investigated via a feature selection process. The resulting optimal feature sets representing a monostatic and a bistatic SAR dataset were used in a subsequent classification to assess the added value of the bistatic TanDEM-X features in the separability of land cover classes. The results obtained indicated that especially the interferometric coherence significantly improved the separability of thematic classes compared to a dataset of monostatic acquisition. The bistatic coherence was mainly governed by volume decorrelation of forest canopy constituents and carries information about the canopy structure which is related to canopy cover. In contrast, the bistatic scattering coefficient had no significant contribution to class separability. The classification with coherence and textural information outperformed the classification with the monostatic scattering coefficient and texture by more than 10% and achieved an overall accuracy of 85%. These results indicate that TanDEM-X can serve as a valuable and consistent source for mapping and monitoring tropical forests.
    Reducing emissions from land use in Indonesia: motivation, policy instruments and expected funding streams
    Noordwijk, M. van; Agus, F. ; Dewi, S. ; Purnomo, H. - \ 2014
    Mitigation and Adaptation Strategies for Global Change 19 (2014)6. - ISSN 1381-2386 - p. 677 - 692.
    redd plus - forest degradation - multifunctional landscapes - southeast-asia - carbon stocks - co2 emissions - fallow model - deforestation - opportunities - incentives
    Land-based emissions of carbon dioxide derive from the interface of forest and agriculture. Emission estimates require harmonization across forest and non-forest data sources. Furthermore, emission reduction requires understanding of the linked causes and policy levers between agriculture and forestry. The institutional forestry traditions dominated the emergence of the discourse on Reducing Emissions from Deforestation and forest Degradation (REDD+) whilemore holistic perspectives on land-based emissions, including agriculture, found a home in international recognition for Nationally Appropriate Mitigation Actions (NAMAs). We tested the hypothesis that, at least for Indonesia, the NAMA framework provides opportunities to resolve issues that REDD+ alone cannot address.We reviewed progress on five major challenges identified in 2007 by the Indonesian Forest Climate Alliance: 1) scope and ‘forest’ definition; 2) ownership and tenurial rights; 3) multiplicity and interconnectedness of drivers; 4) peatland issues across forest and non-forest land categories; and 5) fairness and efficiency of benefitdistribution mechanisms across conservation, degradation and restoration phases of tree-cover transition. Results indicate that the two policy instruments developed in parallel with competition rather than synergy. Three of the REDD+ challenges can be resolved by treating REDD+ as a subset of the NAMA and national emission reduction plans for Indonesia.We conclude that two issues, rights and benefit distribution, remain a major challenge, and require progress on a motivational pyramid of policy and polycentric governance. National interest in retaining global palm oil exports gained priority over expectations of REDD forest rents. Genuine concerns over climate change motivate a small but influential part of the ongoing debate.
    Water for forests to restore environmental services and alleviate poverty in Vietnam: a farm modeling approach to analyze alternative PES programs
    Damien, J. ; Boere, E.J.M. ; Berg, M.M. van den; Dang, D. ; Cu, T.P. ; Affholder, F. ; Pandey, S. - \ 2014
    Land Use Policy 41 (2014). - ISSN 0264-8377 - p. 423 - 437.
    sustainable land-use - ecosystem services - southeast-asia - agricultural intensification - payments - impact - issues - deforestation - technologies - population
    Most forested areas in South East Asia are located in mountainous areas, where they are reservoirs of biodiversity and have important watershed regulating functions. However, the continuing provision of these environmental services may be jeopardized by land use changes. To re-establish natural or productive forests, programs are being proposed in which participating farmers can set aside some of their cultivated sloping land and receive payment for maintaining the newly forested land. This paper compares two types of payments for ecosystems services (or PES)-type programs designed to favor reforestation by farming households: “Payments for forests” (PFF) and “Terraces for forests” (TFF). Both programs involve setting aside sloping land for reforestation but differ in the type and amount of compensation offered. PFF offers annual payments per area of retired land. TFF offers to cover the cost of converting a certain amount of a farm's sloping land into terraces, combined with annual payments per unit area of retired land. The main objective of the paper is to compare the two types of programs in terms of cost-efficiency – can we get the same amount of forest at lower cost? – and equity – will the poorest farmers participate? Using mathematical programming, we developed a set of farm models corresponding to typical farms in a mountainous district in Northern Vietnam. We simulated participation rates of different types of farms in the two types of PES programs. For each PES, we assessed the amount of land converted into forest, the cost of the program, and its impacts on land use and household revenues, at individual farm and village level. Results of our simulations showed that increasing access to irrigated terraces as a way of compensating for converting land to forest increased the participation of the poorest farmers and was more cost efficient than pure cash payments. This suggests that existing PFF programs are biased against the smallest landholders in the region whereas they could be transformed into win–win programs likely to increase forested areas and reduce inequalities among farm households. Our paper demonstrates that PES schemes, when fine-tuned to the South East Asian context, could not only be used to restore ecosystem services, but also to alleviate poverty.
    Canal blocking strategies for hydrological restoration of degraded tropical peatlands in Central Kalimantan, Indonesia
    Ritzema, H.P. ; Limin, S. ; Kusin, K. ; Jauhiainen, J. ; Wösten, H. - \ 2014
    Catena 114 (2014). - ISSN 0341-8162 - p. 11 - 20.
    peat swamp forest - carbon-dioxide - southeast-asia - fluxes - land - co2 - fires - n2o - ch4
    In the 1990s the Government of Indonesia derided to develop one million hectares of peatlands for agriculture in Central Kalimantan on the Island of Borneo. The construction of thousands of kilometres of canals resulted in over-drainage and targets for agricultural production failed. Abandoned, the area has been subject to severe forest and peat fires. Restoration of degraded peatlands normally starts with restoring the water table to rewet the surface in order to control fire and to initiate reforestation. Canal blocking strategies are a potential means for accomplishing this. In a test plot in the Northern part of Block C of the former Mega Rice Project (MRP), a series of dams were constructed and (ground)water tables and subsidence rates were monitored to assess the effects of dam construction on peatland hydrology. The resulting higher water tables did not completely compensate for the negative effects of increased subsidence near the canals. The canals, which are "eating" themselves into the peatland, create depressions in the peatland surface leading to interception of overland- and interflow and increased risk of overtopping of dams during extreme rainfall events. The lessons learned are being used to improve blocking strategies and dam design. The changes in peatland topography caused by drainage, however, need to be better understood in order to further refine strategies for hydrological restoration of degraded peatlands in Indonesia. (C) 2013 Elsevier B.V. All rights reserved.
    Green governmentality and swidden decline on Palawan Island
    Dressler, W.H. - \ 2014
    Transactions of the Institute of British Geographers 39 (2014)2. - ISSN 0020-2754 - p. 250 - 264.
    southeast-asia - land-use - conservation - philippines - management - resources - state
    Environmental governance initiatives increasingly extend to the rural Philippines as ‘devolved’ programmes that progress livelihood change, differentiation and market-based investments. This paper examines how the origins, rise and consequences of environmental governance initiatives in Palawan Island, the Philippines, facilitate forms of governmentality that intersect with, and rearticulate through, the local political economy to influence swidden-based livelihoods, social relations and landscape composition. Drawing on recent scholarship, I describe how the rise and substance of this governance agenda manifests spatially as a form of discursive green governmentality. I argue that this scaled, discursive process involves diverse institutions that decentre and deploy technical knowledge, values and rules in local spaces, influencing how farmers self-govern their behaviour and use of nature toward ‘sustainability’ (Goldman 2001). I draw on a case study to show how Tagbanua swidden farmers negotiate such green governmentality by adopting new landscape ideals through anti-swidden narratives inflected by local politics, economy and environmental change in villages around the Puerto Princesa Subterranean River National Park. I focus on how green governmentality has become systemic across scales to converge with local politics and economy, where governmental discourse is pliable, flexibly interpreted, though followed to affect the shift from long fallow to permanent cultivation. I conclude by showing that the ways government, non-governmental and local actors communicate and invest in such discourse facilitates convergence with the local political economy, reinforcing swidden decline, livelihood risk and marginalisation.
    Genome sequencing reveals fine scale diversification and reticulation history during speciation in Sus
    Frantz, L.A.F. ; Madsen, O. ; Megens, H.J.W.C. ; Paudel, Y. ; Bosse, M. ; Crooijmans, R.P.M.A. ; Groenen, M. ; Schraiber, J.G. - \ 2013
    Genome Biology 14 (2013)9. - ISSN 1474-7596 - 12 p.
    last glacial period - southeast-asia - recombination rates - complex speciation - maximum-likelihood - genetic-evidence - se asia - evolution - inference - reconstructions
    Background Elucidating the process of speciation requires an in-depth understanding of the evolutionary history of the species in question. Studies that rely upon a limited number of genetic loci do not always reveal actual evolutionary history, and often confuse inferences related to phylogeny and speciation. Whole-genome data, however, can overcome this issue by providing a nearly unbiased window into the patterns and processes of speciation. In order to reveal the complexity of the speciation process, we sequenced and analyzed the genomes of 10 wild pigs, representing morphologically or geographically well-defined species and subspecies of the genus Sus from insular and mainland Southeast Asia, and one African common warthog. Results Our data highlight the importance of past cyclical climatic fluctuations in facilitating the dispersal and isolation of populations, thus leading to the diversification of suids in one of the most species-rich regions of the world. Moreover, admixture analyses revealed extensive, intra- and inter-specific gene-flow that explains previous conflicting results obtained from a limited number of loci. We show that these multiple episodes of gene-flow resulted from both natural and human-mediated dispersal. Conclusions Our results demonstrate the importance of past climatic fluctuations and human mediated translocations in driving and complicating the process of speciation in island Southeast Asia. This case study demonstrates that genomics is a powerful tool to decipher the evolutionary history of a genus, and reveals the complexity of the process of speciation.
    How Biodiversity Conservation Policy Accelerates Agrarian Differentiation: The Account of an Upland Village in Vietnam
    Dressler, W.H. ; Xuan To, P. ; Mahanty, S. - \ 2013
    Conservation and Society 11 (2013)2. - ISSN 0972-4923 - p. 130 - 143.
    southeast-asia - neoliberal conservation - ecosystem services - central highlands - resource control - management - devolution - africa - land - governance
    This paper shows how the implementation of Vietnam«SQ»s recent biodiversity conservation policy in Ba Vi National Park has increased the economic value of nature, created sustained conflict, and exacerbated agrarian differentiation in an upland village in northern Vietnam. Increased global and national interest in biodiversity conservation has intersected with markets for ecosystem services that attempt to commoditise biodiversity resources in Ba Vi National Park and reconfigure conservation as market-based development. Efforts to marketise conservation have simultaneously increased the financial value of forestland and drawn new capital investments. In Ba Vi, local elites have captured these new forms of wealth through their connections to political parties, reinforcing the already unequal distributions of wealth and power. Coupled with political power, rising land value has also allowed local elites to become landlords, with the capacity to further dispossess other villagers. The resulting skewed access to natural resources has widened the gap between poor and wealthy villagers, and contributes to their over-exploitation of forests within the Park through informal agricultural expansion. The ensuing local conflicts have also negatively affected livelihoods and biodiversity resources.
    Carbon outcomes of major land-cover transitions in SE Asia: great uncertainties and REDD+ policy implications
    Ziegler, A.D. ; Phelps, J. ; Yuen, J.Q. ; Webb, E.L. ; Lawrence, D. ; Fox, J.M. ; Bruun, T.B. ; Leisz, S.J. ; Ryan, C.M. ; Dressler, W.H. ; Mertz, O. ; Pascual, U. ; Padoch, C. ; Koh, L.P. - \ 2012
    Global Change Biology 18 (2012)10. - ISSN 1354-1013 - p. 3087 - 3099.
    tropical forest biomass - slash-and-burn - southeast-asia - shifting cultivation - rain-forest - swidden cultivation - agricultural land - soil carbon - tm data - environmental consequences
    Policy makers across the tropics propose that carbon finance could provide incentives for forest frontier communities to transition away from swidden agriculture (slash-and-burn or shifting cultivation) to other systems that potentially reduce emissions and/or increase carbon sequestration. However, there is little certainty regarding the carbon outcomes of many key land-use transitions at the center of current policy debates. Our meta-analysis of over 250 studies reporting above- and below-ground carbon estimates for different land-use types indicates great uncertainty in the net total ecosystem carbon changes that can be expected from many transitions, including the replacement of various types of swidden agriculture with oil palm, rubber, or some other types of agroforestry systems. These transitions are underway throughout Southeast Asia, and are at the heart of REDD+ debates. Exceptions of unambiguous carbon outcomes are the abandonment of any type of agriculture to allow forest regeneration (a certain positive carbon outcome) and expansion of agriculture into mature forest (a certain negative carbon outcome). With respect to swiddening, our meta-analysis supports a reassessment of policies that encourage land-cover conversion away from these [especially long-fallow] systems to other more cash-crop-oriented systems producing ambiguous carbon stock changes – including oil palm and rubber. In some instances, lengthening fallow periods of an existing swidden system may produce substantial carbon benefits, as would conversion from intensely cultivated lands to high-biomass plantations and some other types of agroforestry. More field studies are needed to provide better data of above- and below-ground carbon stocks before informed recommendations or policy decisions can be made regarding which land-use regimes optimize or increase carbon sequestration. As some transitions may negatively impact other ecosystem services, food security, and local livelihoods, the entire carbon and noncarbon benefit stream should also be taken into account before prescribing transitions with ambiguous carbon benefits.
    Sustaining conservation values in selectively logged tropical forests: the attained and the attainable
    Putz, F.E. ; Zuidema, P.A. ; Synnott, T. ; Peña Claros, M. ; Pinard, M.A. ; Sheil, D. ; Vanclay, J.K. ; Sist, P. ; Gourlet-Fleury, S. ; Griscom, B. ; Palmer, J. ; Zagt, R. - \ 2012
    Conservation Letters 5 (2012)4. - ISSN 1755-263X - p. 296 - 303.
    rain-forest - southeast-asia - impact - biodiversity - disturbance - management - diversity - biomass - borneo - carbon
    Most tropical forests outside protected areas have been or will be selectively logged so it is essential to maximize the conservation values of partially harvested areas. Here we examine the extent to which these forests sustain timber production, retain species, and conserve carbon stocks. We then describe some improvements in tropical forestry and how their implementation can be promoted. A simple meta-analysis based on >100 publications revealed substantial variability but that: timber yields decline by about 46% after the first harvest but are subsequently sustained at that level; 76% of carbon is retained in once-logged forests; and, 85–100% of species of mammals, birds, invertebrates, and plants remain after logging. Timber stocks will not regain primary-forest levels within current harvest cycles, but yields increase if collateral damage is reduced and silvicultural treatments are applied. Given that selectively logged forests retain substantial biodiversity, carbon, and timber stocks, this “middle way” between deforestation and total protection deserves more attention from researchers, conservation organizations, and policy-makers. Improvements in forest management are now likely if synergies are enhanced among initiatives to retain forest carbon stocks (REDD+), assure the legality of forest products, certify responsible management, and devolve control over forests to empowered local communities.
    Epidemiological models to assist the management of highly pathogenic avian influenza
    Stegeman, J.A. ; Bouma, A. ; Jong, M.C.M. de - \ 2011
    Revue scientifique et technique / Office International des Epizooties 30 (2011)2. - ISSN 0253-1933 - p. 571 - 579.
    classical swine-fever - h7n7 virus - transmission dynamics - surveillance programs - pandemic influenza - commercial poultry - southeast-asia - h5n2 vaccine - netherlands - spread
    In recent decades, epidemiological models have been used more and more frequently as a tool for the design of programmes for the management of infectious diseases such as highly pathogenic avian influenza. Predictive models are used to simulate the effects of various control measures on the spread of the infection; analytical models are used to analyse data from outbreaks and experiments. A key parameter in these models is the reproduction ratio, which indicates to what degree the virus can be transmitted in the population. Parameters obtained from real data using the analytical models can be used subsequently in predictive models to evaluate control strategies or surveillance programmes. Examples of the use of these models are described in the current paper.
    Use of Epidemiologic Models in the Control of Highly Pathogenic Avian Influenza
    Stegeman, J.A. ; Bouma, A. ; Jong, M.C.M. de - \ 2010
    Avian Diseases 54 (2010)s1. - ISSN 0005-2086 - p. 707 - 712.
    h7n7 virus - transmission dynamics - surveillance programs - pandemic influenza - commercial poultry - southeast-asia - h5n1 - netherlands - vaccination - spread
    In the past decades, mathematical models have become more and more accepted as a tool to develop surveillance programs and to evaluate the efficacy of intervention measures for the control of infectious diseases such as highly pathogenic avian influenza. Predictive models are used to simulate the effect of various control measures on the course of an epidemic; analytical models are used to analyze data from outbreaks or from experiments. A key parameter in both types of models is the reproductive ratio, which indicates whether virus can be transmitted in the population, resulting in an epidemic, or not. Parameters obtained from real data using the analytical models can subsequently be used in predictive models to evaluate control strategies or surveillance programs. Examples of the use of these models are described here
    A light left in the dark: The practice and politics of pico-hydropower in the Lao PDR
    Smits, M. ; Bush, S.R. - \ 2010
    Energy Policy 38 (2010)1. - ISSN 0301-4215 - p. 116 - 127.
    southeast-asia - mekong basin - policy - resettlement - management - ecology
    The article describes the widespread use of an estimated 60,000 low-head pico-hydropower turbines and well-developed networks of supply and support in the Northern part of the Lao People's Democratic Republic (Lao PDR). This apparent widespread use is contrasted with the policy narratives of key actors in the government, multilateral organisations and the private sector which show an often simplified and overly negative attitude towards pico-hydropower. Based on empirical research carried out in three upland districts and the capital, Vientiane, the paper critically investigates the apparent disjuncture between policy and practice by placing pico-hydropower within the broader political context of rural electrification in the Lao PDR. It is argued that the neglect of pico-hydropower and other off-grid household electrification technologies is a result of an endemic lack of information on which to base policy decisions, the orientation of the government to facilitate large scale foreign investment in large hydropower dams, the universal applicability of solar home systems, and the broader state agenda of centralisation and control over service provision to remote upland areas.
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