Staff Publications

Staff Publications

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

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

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

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

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    Socio-ecological analysis of multiple-use forest management in the Bolivian Amazon
    Soriano Candia, Marlene - \ 2017
    Wageningen University. Promotor(en): G.M.J. Mohren, co-promotor(en): M. Peña Claros; N. Ascarrunz. - Wageningen : Wageningen University - ISBN 9789463436557 - 220
    forest management - timber production - nuts - multiple use - bertholletia excelsa - forest ecology - amazonia - sustainability - community forestry - bosbedrijfsvoering - houtproductie - noten - meervoudig gebruik - bertholletia excelsa - bosecologie - amazonia - duurzaamheid (sustainability) - gemeenschapsbosbouw

    Community families throughout tropical regions derive an important share of their income from multiple forest products, with generally positive outcomes on their livelihoods. The production of these products in a multiple-use forest management scheme (MFM, the production of multiple forest products within a single management unit) encompasses many (yet) unknown socioeconomic and ecological feedbacks. In particular, MFM entailing timber and non-timber production may be affecting the future availability of valuable timber and non-timber tree species due to the extraction of vital plant components, which may have undesired outcomes on the income that community families derive from forests. In this thesis, I evaluated the social, economic, and ecological viability of an important MFM scheme widely practiced by community households in the Bolivian Amazon: the production of Amazon or Brazil nut (Bertholletia excelsa) and timber from other tree species. Data was obtained from a two-year (2014 and 2015) survey questionnaires of 24 community households in six campesino communities with community forest management plans (CFMPs) and from ecological surveys of 72 2 ha permanent research transects (three transects per household forest) harvested at varying Amazon nut and logging intensities. A CFMP entails the planning and execution of logging activities in compliance with formal rules intended to secure the long-term provision of timber at community-owned forest. Household-level decisions to harvest Amazon nut and to log timber allowed us to account for household forest as our sampling unit. We used multi-model inference and structural equation modelling techniques to determine the impact of socio-ecological factors on the income that community families derived from Amazon nut and timber (chapter 2), and regression and matrix modelling techniques to determine the impact of Amazon nut harvest and logging intensity on Bertholletia (chapter 3) and commercial timber species (chapter 4).

    In general, we found that few socioeconomic and biophysical factors of community households, together with a general positive response of studied species to timber logging and customary silvicultural intervention, make the production of Amazon nut and timber production of other tree species viable in a MFM scheme. In chapter 2, we found that community households could reduce their dependency on forest resources by increasing income opportunities from other existing livelihood activities. Amazon nut represented the largest source of household income (44% of the total household net income); and off-farm (salary, business and gifts; 21%), husbandry (generally subsistence agriculture, animal rising, and agroforestry; 21%), and timber (9%) incomes were complementary to their livelihood. Increased skills and ecological knowledge of community households enhanced household income derived from forest products. For example, an increase in the number of management practices reduced the need for timber income by increasing Amazon nut production; decreasing further pressure on timber of other tree species.

    In chapter 3, logging intensity was found to increase Bertholletia’s seedlings and saplings growth rate, and liana cutting was found to increase Amazon nut production rate. Both, logging and liana cutting intensities played a key role on Bertholletia population growth rate. Increased logging and liana cutting intensities counteracted the negative impact of Amazon nut harvesting intensity on the number of new recruits (i.e., due to nut harvest), indicating a trade-off between logging, liana cutting and Amazon nut harvesting intensities.

    Considering the overall stem density of commercial timber species (chapter 4), we found that 17% of the species present at unlogged sites (3 species out of 17: Swietenia macrophylla, Tabebuia impetiginosa and Terminalia sp.) were not present at sites six years after logging; and a larger percentage (71%) of the species present at unlogged sites in the harvestable size (trees>minimum diameter cutting – MDC) were not present at sites six years after logging, e.g., Cedrela spp. Stem density and timber volume of five of the eight most abundant commercial timber species under study differed among community-owned forests, after accounting for the effects of logging intensity and time since logging as indicated by our best models; whereas, potentially harvestable and harvestable timber volume differed between communities for only two and three species, respectively. Best models indicated that logging intensity increased either stem density or timber volume of Apuleia leiocarpa, Cedrela odorata, Dipteryx micrantha and Hymenaea parvifolia, decreased potentially harvestable timber volume of T. serratifolia, and had no effect on the other three species investigated. We also investigated the impact of logging intensity on congeneric species given that lumping congeneric species for logging is a common simplification during forest inventories and censuses, and is accepted in CFMPs assuming that closely related species respond to timber logging in a similar way. However, logging intensity had a differentiated effect on congeneric species. Logging intensity favoured growth rate of C. odorata trees >10 cm DBH and had no effects on Cedrela fissilis. Regarding Hymenaea congeneric species, logging intensity favoured H. parvifolia survival of individuals <10 cm DBH, but decreased growth rates of H. courbaril trees >10 cm DBH.

    In conclusion, Amazon nut harvest and timber logging of other tree species are compatible under certain socioeconomic and biophysical conditions, and as long as commercial timber species differential response to harvesting are accounted for in managing these species in a MFM scheme. This compatibility is due to existing socioeconomic complementarity of both activities and to the positive impact of logging intensity levels as practiced in the region on Amazon nut production and on most commercial timber species. Community families’ better negotiation skills to obtain better prices for Amazon nut, and increased implementation of management practices to increase Amazon nut production (e.g., liana cutting) helped families to increase their income and also decrease pressure on timber. These results highlight the need to look at both socioeconomic and ecological aspects when assessing the long-term sustainability of MFM schemes.

    Results of this research have important implications for policy to support the sustainable development of community forestry in the Bolivian Amazon. The compatibility found between Amazon nut and timber production calls for the investigation of the compatibility of timber production with other valuable NTFPs commonly harvested by community families throughout the tropics. We argue that management needs to be done at species-specific level, rather than at the level of products or at the level of species groups. This may result prohibitively expensive for communities and smallholders. Thus, we urge governments and the international community to revalorize local ecological knowledge of community people to manage their forests, while supporting the development of technologies, such as the ones based on hyperspectral LiDAR technology, to develop tools that could help reduce management costs of tropical forests at the required level. Such policies need to be accompanied by capacity building programs on different management tasks and negotiation skills to enhance the income obtained from MFM schemes. The research approaches used here could be used in other contexts and scales involving natural resources management to get a better understanding of the systems.

    Administrative co-management in special use forests of Vietnam
    Dung, Nguyen Kim - \ 2017
    Wageningen University. Promotor(en): Arthur Mol, co-promotor(en): Simon Bush. - Wageningen : Wageningen University - ISBN 9789462579866 - 183
    forests - forest administration - forest management - nature conservation - environmental protection - vietnam - bossen - bosbeheer - bosbedrijfsvoering - natuurbescherming - milieubescherming - vietnam

    To protect its natural heritage and biodiversity, Vietnam has established a system of ‘special use forest’ (SUFs) which is “the backbone of the national protected areas”. The ineffective management of SUFs based solely on the state leads to a decline in biodiversity and density of the forests. Recognizing this, collaborative or ‘co’-management for SUFs is advocated to get more participation and shared responsibilities and rights between government and non-state actors. However, it is widely noted that co-management is a particularly great challenge in Vietnam because of the nature of strong state control, decades of SUF conflicts, and the lack of capacity and initiatives of communities to negotiate with the government in co-management arrangements. This PhD thesis questions the degree to which co-management can be put in Vietnamese SUFs and the degree of ‘adaptiveness’ it can engender. Conditions of the economic, political and social context surrounding SUFs becomes key to any understanding of how co-management can be implemented, including insights into how co-management may need to be amended to adjust to ‘fit’ the context of mono-organisational states.

    EUROBATS : Analyse van de resoluties die zijn aangenomen tijdens de vergadering van de partijen (Meeting of the Parties) in 2014
    Ottburg, F.G.W.A. ; Adrichem, N.H.C. van; Limpens, H.J.G.A. ; Schillemans, M.J. - \ 2016
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport ) - 31
    chiroptera - wildbescherming - monitoring - bosbedrijfsvoering - milieubeleid - nederland - chiroptera - wildlife conservation - monitoring - forest management - environmental policy - netherlands
    Nederland is Party van ‘the Agreement on the Conservation of Populations of European Bats’, ofwel EUROBATS. De EUROBATS-agreement is een verdrag onder de conventie van Bern en met name de conventie van Bonn, de ‘Convention on the Conservation of Migratory Species of Wild Animals’. EUROBATS is een instrument bij de uitvoering van de verplichtingen vanuit de Europese Habitatrichtlijn. De Scientific Advisory Committee ontwikkelt resoluties, welke door de overheden van de Party-States van de EUROBATS-Agreement gezamenlijk worden aangenomen. Deze resoluties benoemen – specifiek vanuit de ecologie van de vleermuizen – knelpunten, speciale aandachtspunten en kansen, welke helpen de uitvoering van wet- en regelgeving in het kader van de Flora- en faunawet en Habitatrichtlijn effectief te focussen. De voorliggende rapportage geeft een overzicht van de resoluties en maakt inzichtelijk wat de Rijksoverheid, provincies of andere organisaties reeds doen voor vleermuizen. Tevens is een kennisagenda opgenomen met aanbevelingen ten behoeve van vleermuizen voor de nabije toekomst.
    Boseigendom in Twente en Salland : resultaten van een enquête onder kleine boseigenaren in Twente en Salland
    Clerkx, A.P.P.M. ; Hengeveld, G.M. ; Schelhaas, M. ; Helmink, A.T.F. - \ 2016
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2731) - 57
    bossen - bosbezit - bosbedrijfsvoering - biomassa - opbrengsten - salland - twente - forests - forest ownership - forest management - biomass - yields - salland - twente
    In de regio Twente/Salland is onderzoek uitgevoerd naar het boseigendom en motivatie van boseigenaren. Alle eigenaren met bosbezit van ten minste 0,5 ha hebben een enquête ontvangen met persoonlijke vragen over de eigenaar, het eigendom, beheer en oogst. Daarnaast is gekeken hoe gevoelig de eigenaren zijn voor verschillende strategieën die gericht zijn op vergroting van de houten biomassaoogst uit hun bos. Met deze antwoorden is voor de regio een indeling in eigenaarsgroepen gemaakt. Voor elke groep is een schatting gemaakt van het effect van de mobilisatiestrategieën en de hoeveelheid extra te mobiliseren hout.
    Biodiversity and the functioning of tropical forests
    Sande, M.T. van der - \ 2016
    Wageningen University. Promotor(en): Lourens Poorter, co-promotor(en): Marielos Pena Claros; Eric Arets. - Wageningen : Wageningen University - ISBN 9789462578029 - 282
    tropical forests - biodiversity - forest ecology - forest management - climatic change - tropische bossen - biodiversiteit - bosecologie - bosbedrijfsvoering - klimaatverandering

    Tropical forests are the most diverse terrestrial ecosystems. Moreover, their capacity for removal of carbon from the atmosphere makes them important for climate change mitigation. Theories predict that species use resources in a different way, and therefore high species diversity would result in more efficient resource use and higher total carbon removal. These theories, however, have yet not been clearly demonstrated for tropical forests. In this thesis, I evaluated how biodiversity of plants and their traits influenced carbon removal. I used data collected in different tropical forest types and at different spatial and temporal scales. I found that biodiversity was important for carbon removal especially at large spatial scales (e.g. the Amazon) where biodiversity varies strongly, and at long temporal scales (e.g. >200 years) where high biodiversity functions as a buffer for changing environmental conditions. In this way biodiversity contributes to long-term stable forests and a safe climate.

    Ghana's high forests : trends, scenarios and pathways for future developments
    Oduro, K.A. - \ 2016
    Wageningen University. Promotor(en): Frits Mohren; Bas Arts, co-promotor(en): B. Kyereh. - Wageningen : Wageningen University - ISBN 9789462577824 - 171
    forests - forest ecology - forest management - high forest system - forest resources - forestry - ghana - bossen - bosecologie - bosbedrijfsvoering - hoog opgaand bos - bosbestanden - bosbouw - ghana

    Deforestation and forest degradation in the tropics have been receiving both scientific and political attention in recent decades due to its impacts on the environment and on human livelihoods. In Ghana, the continuous decline of forest resources and the high demand for timber have raised stakeholders concerns about the future timber production prospects in the country. The principal drivers of deforestation and forest degradation in Ghana are agricultural expansion (50%), wood harvesting (35%), population and development pressures (10%), and mining and mineral exploitation (5%). Various measures are being pursued that are targeted at addressing the drivers of deforestation and forest degradation and at increasing the forest resource base. Understanding the key driving forces behind current forest resource development trends will help to gain insights into the possible courses of action to take to improve the developments of the resources, especially where actions that are being taken today will have an impact on the forest resources for many years to come.

    In this thesis, I used interdisciplinary research methods to provide insights into the current status of the forest resource base in Ghana and into its likely and possible future developments. I addressed 5 research questions: (1) What are the trends and changes associated with the growing stock in the timber production areas? (2) What driving forces account for current trends and future developments of timber resources in Ghana? (3) What different scenarios can be identified and how will these affect future developments of timber resources in the high forest zone? (4) What factors motivate farmers to engage in on-farm tree planting and management? (5) To what extent do the current trends of forest resources drive forest transition in Ghana?

    National forest inventory data, timber harvesting data and forest plantation establishment data showed that the growing stock in both on- and off-reserve production areas have been declining since 1990. Ghana’s average forest growing stock of 40m3 per ha is much lower than the 195 m3 per ha for the Western and Central Africa sub-region. Timber harvesting records also indicate that, in recent decades, total timber harvests have mostly been substantially higher than the annual allowable cut, resulting in an increasing gap between national timber demand and supply, which drives illegal logging. Current plantation establishment efforts are not sufficient to bridge the gap between demand and supply of timber, partly due to low establishment rates and lack of appropriate management of newly established plantations. Forest governance system and resource demand are the two key driving forces that affect the current trends and future developments of forest resources in the high forest zone of Ghana. Four scenarios were developed: (1) legal forestry scenario with emphasis on improving the resource base to meet high demand; (2) forest degradation, which implies a business-as-usual scenario; (3) forest transition, with emphasis on expanding the resource base in response to environmental concerns; and (4) timber substitution scenario seeking to provide wood substitutes to conserve the resource base. Across two on-farm tree planting schemes, I found that financial benefits, educational campaigns by project teams, knowledge about current environmental issues, ownership of timber for family use and access to land, grants, farming inputs, seedlings, capacity building, and market for agricultural produce are the factors that motivated farmers to engage in on-farm tree planting and management. Currently, there is no strong force toward a forest transition through any of the five generic pathways (economic development; forest scarcity; globalization; state forest policy; and smallholder, tree-based land use intensification). This is because the existing trends of forest resources developments are either too small-scale or too ineffective. In order to accelerate a forest transition in Ghana, policy and management options should target measures that reduce current degradation of natural forests, increase the area and productivity of commercial forest plantations, promote sustainable forest management, and support and encourage forest conservation and integration of trees into farming systems.

    Conservation genetics of the frankincense tree
    Bekele, A.A. - \ 2016
    Wageningen University. Promotor(en): Frans Bongers, co-promotor(en): Rene Smulders; K. Tesfaye Geletu. - Wageningen : Wageningen University - ISBN 9789462576865 - 158
    boswellia - genomes - dna sequencing - tropical forests - genetic diversity - genetic variation - genetics - forest management - plant breeding - boswellia - genomen - dna-sequencing - tropische bossen - genetische diversiteit - genetische variatie - genetica - bosbedrijfsvoering - plantenveredeling

    Boswellia papyrifera is an important tree species of the extensive Combretum-Terminalia dry tropical forests and woodlands in Africa. The species produces a frankincense which is internationally traded because of its value as ingredient in cosmetic, detergent, food flavor and perfumes productions, and because of its extensive use as incense during religious and cultural ceremonies in many parts of the world. The forests in which B. papyrifera grows are increasingly overexploited at the expense of the economic benefit and the wealth of ecological services they provide. Populations of B. papyrifera have declined in size and are increasingly fragmented. Regeneration has been blocked for the last 50 years in most areas and adult productive trees are dying. Projections showed a 90% loss of B. papyrifera trees in the coming 50 years and a 50% loss of frankincense production in 15 years time.

    This study addressed the conservation genetics of B. papyrifera. Forty six microsatellite (SSR) markers were developed for this species, and these genetic markers were applied to characterize the genetic diversity pattern of 12 B. papyrifera populations in Ethiopia. Next to this, also the generational change in genetic diversity and the within-population genetic structure (FSGS) of two cohort groups (adults and seedlings) were studied in two populations from Western Ethiopia. In these populations seedlings and saplings were found and natural regeneration still takes place, a discovery that is important for the conservation of the species.

    Despite the threats the populations are experiencing, ample genetic variation was present in the adult trees of the populations, including the most degraded populations. Low levels of population differentiation and isolation-by-distance patterns were detected. Populations could be grouped into four genetic clusters: the North eastern (NE), Western (W), North western (NW) and Northern (N) part of Ethiopia. The clusters corresponded to environmentally different conditions in terms of temperature, rainfall and soil conditions. We detected a low FSGS and found that individuals are significantly related up to a distance of 60-130 m.

    Conservation of the B. papyrifera populations is urgently needed. The regeneration bottlenecks in most existing populations are an urgent prevailing problem that needs to be solved to ensure the continuity of the genetic diversity, species survival and sustainable production of frankincense. Local communities living in and around the forests should be involved in the use and management of the forests. In situ conservation activities will promote gene flow among fragmented populations and scattered remnant trees, so that the existing level of genetic diversity may be preserved. Geographical distance among populations is the main factor to be considered in sampling for ex situ conservation. A minimum of four conservation sites for B. papyrifera is recommended, representing each of the genetic clusters. Based on the findings of FSGS analyses, seed collection for ex situ conservation and plantation programmes should come from trees at least 100 m, but preferably 150 m apart.

    Tropical forests in a changing world
    Zuidema, P.A. - \ 2015
    Wageningen : Wageningen University - ISBN 9789462573765 - 24
    tropical forests - forests - forest ecology - climatic change - forest management - tropische bossen - bossen - bosecologie - klimaatverandering - bosbedrijfsvoering
    Oogst in het Nederlandse bos : Analyse van niet-geoogste plots uit de Zesde Nederlandse Bosinventarisatie
    Clerkx, A.P.P.M. ; Schelhaas, M. ; Zwart, J. - \ 2015
    Alterra, Wageningen-UR (Alterra-rapport 2610) - 33
    forestry - forest inventories - forest management - forests - netherlands - bosbouw - bosinventarisaties - bosbedrijfsvoering - bossen - nederland
    Vanuit de overheid zijn al sinds de jaren 80 van de vorige eeuw acties genomen om de oogst in het
    Nederlandse bos te promoten, maar het niveau van de oogst is al enkele decennia min of meer
    constant. Uit de Zesde Nederlandse Bosinventarisatie is gebleken dat op ruim 40% van de punten niet
    is geoogst sinds de inventarisatie van het Meetnet Functievervulling. De eigenaren van deze punten
    zijn gevraagd naar de redenen waarom daar niet is geoogst en wanneer zij wel over zullen gaan op
    oogst. Met deze gegevens is een schatting gemaakt van de hoeveelheid hout die mogelijk meer zal
    kunnen worden geoogst
    Long-term trends in tropical tree growth: a pantropical study
    Groenendijk, P. - \ 2015
    Wageningen University. Promotor(en): Pieter Zuidema; Frans Bongers. - Wageningen : Wageningen University - ISBN 9789462572362 - 244
    bosbomen - tropische bossen - bomen - groei - jaarringen - bosecologie - bosbedrijfsvoering - centraal-afrika - forest trees - tropical forests - trees - growth - growth rings - forest ecology - forest management - central africa

    Tropical forests cover only 7% of the earth’s land surface, but harbour almost half of the world’s biodiversity. These forests also provide many ecosystem services, such as the storage of carbon and the regulation of local and regional climate, and many goods such as timber and fruits. Furthermore, tropical forests contribute disproportionately to the global carbon cycle, storing an estimated 25% of the carbon stocks on land and accounting for a third of the terrestrial net primary productivity. Therefore, changes in forest cover or in the net uptake or loss of carbon by forests directly influences the global carbon cycle. Tropical forests are under increasing anthropogenic pressure and are undergoing rapid changes due to deforestation, conversion to other land uses and logging. Additionally, there is evidence that pristine and intact tropical forests are undergoing changes due to the effects of climate change. Concerted increases in biomass and tree growth have been found in studies monitoring intact tropical forests, suggesting that they acted as considerable carbon sinks over the past decades. On the other hand, decreasing or fluctuating forest growth and biomass have also been noted. These different changes have been attributed to different climatic drivers: growth increases have been suggested to arise from growth stimulation by increasing atmospheric CO2 concentrations, while growth decreases have been interpreted to reflect the limiting effects of increased temperature on growth. As monitoring plots usually cover only a few decades, it is still unclear whether these changes are pervasive or whether they simply reflect the effect of short-term climatic fluctuations on tree growth. Assessing whether changes have occurred over centennial scales is thus crucial to understanding whether and how tropical forests are reacting to climatic changes.

    In this thesis we apply tree-ring analysis on a pantropical study to assess longterm changes in growth of tropical forest trees. Tree-ring analysis was used to measure long-term growth rates of ~1350 trees of different species coming from three sites across the tropics. Trends in growth over the last two centuries were then analysed using an established an a new trend-detection method. Additionally, we applied the long-term growth data from rings to improve the evaluation of forest management practices in Cameroon. All samples were collected and measured within the TROFOCLIM project led by Pieter Zuidema. The project also includes two other PhD theses and sample collection was divided among the three PhD projects and the three sites: in Bolivia (samples collected by Peter van der Sleen), Cameroon (by me) and in Thailand (by Mart Vlam). The main objectives of this thesis were: (1) to assess the potential for using treerings in a wet tropical forest in Central Africa; (2) to project timber yields in the next logging round for four Cameroonian tree species; (3) to evaluate the sensitivity and accuracy of four commonly used methods to detect long-term trends in tree-ring data; and (4) to detect whether growth rates of tropical forest trees have changed over the past ~150 years.

    In Chapter 2 of this dissertation, we evaluated whether growth rings are formed annually in the wood of tree species growing under very high levels of precipitation (>4000 mm) in an African tropical forest. For this purpose, we assessed whether ring structures are formed in the wood of the 22 commercially exploited tree species and found that ring structures are indeed formed by more than half of these species (in 14 species), though with varying ring clarity. On four species we proved the annual character of ring formation using radiocarbon bomb-peak dating. That rings are formed under such high levels of precipitation is surprising, as these conditions are considered improper to induce ring formation. These results suggest that the potential of tree-rings analysis is more or less similar across the tropics. Based on our results and that of other studies, we estimate that tree rings can be used to measure tree growth and ages for around a quarter to a third of tropical tree species.

    Worldwide, over 400 million hectares of tropical forests are set aside for timber production. Attaining sustainable use of these forests is very important, in the light of the important role of tropical forests in retaining biodiversity and storing carbon. Ensuring that timber species are not overexploited is key to ensure that forest use is sustainable and entails finding a balance between economic gains and the (ecological) sustainability of logging operations. In Chapter 3, we integrated growth data from tree-rings with logging inventory data to forecast whether timber yields can be sustained in the next harvest round for four timber species in Cameroon. Under current logging practices, future logging yields were predicted to reduce moderately to strongly for all species. These yield reductions are worrisome for forest conservation, as loss of economic value may lead to conversion of forests to other land uses. We recommend that such calculations are needed for more species and argue that these simulations should include the effects of logging and eventual silvicultural measures on the growth and survival of trees.

    Lifetime tree growth data – as acquired by tree-ring analysis – contains longterm trends in growth that reflect the ontogenetic development of an individual or species, i.e., these data contains an age/size signal in growth. In Chapter 4 we evaluate the sensitivity, accuracy and reliability to detect long-term trends in growth of four methods that are commonly used to disentangle these age/size trends from long-term growth trends. We applied these growth-trend detection methods to measured growth data from tree rings and to simulated growth trajectories on which increasing an decreasing trends were imposed. The results revealed that the choice of method influences results of growth-trend studies. We recommend applying two methods simultaneously when analysing long-term trends – the Regional Curve Standardization and Size Class Isolation – as these methods are complementary and showed the highest reliability to detecting long-term growth changes.

    In Chapter 5, we analysed long-term growth trends in tropical forest trees using a pantropical approach applying the two recommended growth-trend detection methods. We showed that growth rates for most of the 13 tropical tree species, from the three sites across the tropics, decreased over the last centuries. These species-level changes may have important demographic consequences and may eventually lead to shifts in the species composition of tropical forests. We found no strong growth changes when analysing trends aggregated per site or across sites: only weak growth reductions were detected for the Thai site and across sites. These findings contrast growth increases that would be expected if tree growth is stimulated by increased ambient CO2. These growth reductions suggest worsening growth conditions for several tropical tree species, and could result from the negative effect of temperature increases on tree growth, or reflect the effect of large-scale disturbances on these forests.

    If one image becomes clear from this thesis it is that long-term data are crucial to enhance the management of tropical forests and to quantify changes happening in these forests. Tree-ring analysis provides this long-term perspective for tree growth and is thus a great tool to evaluate changes in the growth of trees, including for tropical species. One of the most important finding of this thesis is that many tropical species show long-term decreases in growth. These results suggest that the commonly assumed growth increases tropical forests, based on measurements over the last couple of decades, may be incorrect. This discrepancy in results could have strong consequences, among others leading to erroneous predictions of the carbon dynamics of tropical forests under future climate change. Combining monitoring plot data (to analyse short-term changes in growth and species composition) with remotely sensed data (to accurately determine forest land cover) and with the long-term growth data from tree rings is probably the best way forward to relate recent findings of short-term changes in tree growth and forest biomass to changes over the past centuries. Such integrative approaches are needed to better quantify and understand the effects of climate change on tropical forests.

    Functional ecology of tropical forest recovery
    Lohbeck, M.W.M. - \ 2014
    Wageningen University. Promotor(en): Frans Bongers; M. Martínez-Ramos, co-promotor(en): Lourens Poorter. - Wageningen : Wageningen University - ISBN 9789462571617 - 223
    bosecologie - ecologie - tropische bossen - bossen - plantensuccessie - biodiversiteit - bosbedrijfsvoering - forest ecology - ecology - tropical forests - forests - plant succession - biodiversity - forest management

    Electronic abstract of the thesis for the library for the acquisitions department of Wageningen UR library (published as a html file so hyperlinks may be included)

    In English, one or 2 pages.

    Functional ecology of tropical forest recovery

    Currently in the tropics, the area of secondary forest exceeds that of mature forest, and the importance of secondary forest will probably continue to increase in the future. Understanding secondary forests’ potential for maintaining biodiversity and critical ecosystem functions is thereby vital. The aim of this study was to mechanistically link tropical forest succession with the recovery of ecosystem functioning after agricultural field abandonment using a trait-based approach. Such an approach makes use of functional traits; components of an organism’s phenotype that are key to assess ecosystem responses to global change drivers, and are at the same time indicators of how organisms drive changes in ecosystem functioning. Trait-based approaches could therefore provide a mechanistic way to scale up from organisms to ecosystems and thereby contribute towards a more predictive biodiversity and ecosystem functioning science. For this study, I made use of secondary forest data from a wet forest region in Chiapas (main study site), that cover the first 3 decades of succession, complemented with data from a dry forest region in Oaxaca, that cover the first 6 decades of succession. Both are tropical regions in Mexico, characterized by high biodiversity levels and rapid forest loss for agricultural expansion.

    In this study I found that functional diversity (the range of different functional traits) increases rapidly and functional composition (the weighted average functional trait value) changes directionally with succession (chapter 2 and 3). These reflect changing habitat filters (changing environmental gradients that underlie succession), and also a gradual shift from habitat filtering towards an increasing effect of competitively driven limiting trait similarity (chapter 4 and 5). Such successional changes in community functional properties suggest strong changes in ecosystem functions, however in situ ecosystem function rates were primarily explained by the total amount of biomass present rather than by biodiversity or functional trait properties of secondary forests (chapter 6). Only the more controlled ex situ decomposition rates were additionally significantly influenced by functional diversity and functional composition. When evaluating the identity of species that drive most of the ecosystem functions I found that different functions were largely driven by the same (dominant) species, implying a limited effect of biodiversity for multifunctionality at a given moment in time. This suggests that biodiversity is mainly important for maintaining multifunctional ecosystems across temporal and spatial scales (chapter 7).

    Deforestation is a major threat to natural forests and biodiversity, and I recognize that secondary forests are generally a poor substitute of mature forest. Nevertheless, I show that unassisted recovery through natural succession can be rapid, and contribute considerably to maintenance of biodiversity, functional strategies and ecosystem functions. So while protecting the remaining tracts of mature forests is vital, secondary forests are key components of multifunctional human-modified landscapes where synergies between biodiversity, ecosystem functions and human wellbeing can be optimized.

    Forest governance dynamics in Ethiopia : histories, arrangements, and practices
    Ayana, A.N. - \ 2014
    Wageningen University. Promotor(en): Bas Arts, co-promotor(en): Freerk Wiersum; A. Agrawal. - Wageningen : Wageningen University - ISBN 9789462570139 - 140
    bosbeleid - governance - bosdynamiek - geschiedenis - bosbedrijfsvoering - ethiopië - forest policy - governance - forest dynamics - history - forest management - ethiopia

    This thesis deals with forest governance in Ethiopia. Forest governance is an important subject to study both as an emerging field of scientific analysis and as a means to understand and tackle the practical challenges facing forest resource management and conservation. Forests are one of the vital renewable resources that support the livelihoods of millions of people in Ethiopia. Despite their significance, Ethiopia is fast losing its forest resources due to intense and unsustainable human uses coupled with institutional and policy deficiencies. This study aims to provide a better understanding of how forest governance has developed and been practiced in Ethiopia over the past five decades. It analyses forest governance dynamics over several years, at multiple political-administrative levels, from multi-actor perspectives, and the effect of the new governance system on local forest management practices. The thesis thereby contributes to the scientific analysis of governance from the perspective of a country for which there is a dearth of relevant research. It also comprehensively explains the establishment process and performance of forest governance reforms in Ethiopia. It is hoped that the results will assist people who design and implement forest and related natural resource policies.

    From landless to forestless? : settlers, livelihoods and forest dynamics in the Brazilian Amazon
    Homero Diniz, F. - \ 2013
    Wageningen University. Promotor(en): Bas Arts, co-promotor(en): Kasper Kok; Marjanke Hoogstra-Klein. - [S.l.] : s.n. - ISBN 9789461735836 - 184
    ontbossing - landloosheid - bossen - bosdynamiek - bosecologie - middelen van bestaan - strategieën voor levensonderhoud - bosbedrijfsvoering - brazilië - deforestation - landlessness - forests - forest dynamics - forest ecology - livelihoods - livelihood strategies - forest management - brazil

    Keywords: deforestation; remote sensing; mental models; stakeholders’ perceptions; agrarian reform

    Over the last decades, hundreds of thousands of families have settled in projects in the Brazilian Amazon within the Agrarian Reform Program (ARP) framework, the rationale being to enable settlers to earn their living by small-scale farming and produce an agricultural surplus for sale. Further, the Brazilian Forestry Code requires settlers not to deforest more than 20% of forest on their properties, but in many projects settlers have deforested larger areas than this. However, specific questions about whether the settlers’ activities are, at the very least, providing their livelihoods, and about the effects of these choices on deforestation over time, have hardly been addressed. Located in five settlement projects in Eldorado do Carajás, southeast Pará State, this research investigated how settlers make their living; how their activities and practices affect forest cover changes; and how future prospects for both, i.e. people and forest, are envisioned. Within the framework of the sustainable livelihoods approach, the results indicated that settlers rely on three livelihood strategies (livestock-, diversified-, and off-farm-oriented), with dairy cattle as the main agricultural activity. These strategies are shaped by several factors, such as agrarian reform policies (e.g. credit) and settlers’ background. Forest dynamics analysis showed a clear recent increase in forest (2005–2010) at municipal level, suggesting that the first steps towards forest transition are taking place. However, settlers do not perceive secondary regrowth as ‘real’ forest, implying a high risk of future deforestation in these areas; but these areas can also be seen as having a high potential of remaining forested if technological innovations in agricultural activities and practices become available in the (near) future. The research findings also indicated the necessity to analyse livelihoods and forest cover changes as dynamic processes. It was not possible to determine one-to-one relationships and general patterns of effects of livelihood trajectories on forest dynamics due to the complexities involved, although analysis of individual household- and property-level cases offered insights into factors driving both. Fuzzy cognitive mapping was used to capture current settlers’ perceptions about their realities. The results indicated that settlers have similar perceptions of the factors that affect their livelihood security and environmental sustainability, independent of livelihood strategy adopted. However, differences were found in the relationships among factors and the weight attributed to each relationship, creating fundamentally different system dynamics for each livelihood strategy. Consequently, strong trade-offs exist between livelihood security and environmental sustainability independent of livelihood strategy and in (nearly) all future scenario analyses. The research produced five key messages: 1) small farmers within the studied ARP projects are less poor than often assumed; they achieve livelihood security through on- and off-farm income; 2) there is a strong trade-off between livelihood security and environmental sustainability; hence primary forest deforestation continues, although the first signs of secondary forest transitions have been observed; 3) the settlers’ contribution to deforestation is less than often assumed because they contribute to emerging forest transitions and because local deforestation peaked before the projects; 4) policies strongly affect the settlers’ realities; hence their views are crucial for effective policymaking, including both the Forestry Code and agrarian reform policies; and 5) livelihood trajectories and forest dynamics models are more appropriate to capture the realities of the human–environment systems in the Brazilian Amazon than livelihoods as snapshots and unidirectional deforestation models.

    Amerikaanse vogelkers
    Nyssen, B. ; Ouden, J. den; Verheyen, K. - \ 2013
    Zeist : KNNV - ISBN 9789050114523 - 160
    prunus serotina - bosecologie - geïntroduceerde soorten - invasieve soorten - bosbedrijfsvoering - nederland - forest ecology - introduced species - invasive species - forest management - netherlands
    Hij is de schrik van veel bosbeheerders: de Amerikaanse vogelkers. Maar het verhaal achter de boom is verrassend. Want zijn positieve eigenschappen wegen wellicht op tegen de nadelen. Dit boek belicht alle kanten en laat zien hoe we deze boom een plek kunnen geven in het Europese bosecosysteem. In dit boek wordt een nieuw perspectief geschetst op de Amerikaanse vogelkers. Zij blijkt in haar oorsprongsgebied een waardevolle boomsoort, en in onze bossen heeft vogelkers uiteindelijk ook gunstige effecten op het bosecosysteem. Bovendien worden lang niet al onze bossen massaal gekoloniseerd. De auteurs pleiten voor een genuanceerdere kijk op de vogelkers, waarbij handvatten worden gegeven voor een gedifferentieerd beheer. Het boek behandelt de introductie en bestrijding en de huidige problematiek rondom deze exoot. Ook haar invloed op bossuccessie, biodiversiteit, houtteelt en beheerstrategieën komen aan de orde. Dit boek laat zien hoe we deze exoot een plek kunnen geven in het Europese bosecosysteem, en tegelijk de bestrijdingskosten kunnen verminderen. Actuele kennis zorgvuldig en toegankelijk bijeengebracht voor specialisten in boomteelt, bosbeheerders, beleidsmakers en ecologen.
    Bosbeheer en klimaatverandering : resulaten van LANDCLIM-simulaties voor Zuidoost-Veluwe
    Clerkx, A.P.P.M. ; Didion, M.P. ; Hengeveld, G.M. ; Schelhaas, M. - \ 2013
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2438) - 84
    bosbedrijfsvoering - klimaatverandering - modellen - simulatiemodellen - biodiversiteit - natuurontwikkeling - ecologische successie - recreatie - habitatrichtlijn - veluwe - forest management - climatic change - models - simulation models - biodiversity - nature development - ecological succession - recreation - habitats directive - veluwe
    Binnen het EU-FP 7-project MOTIVE is voor Nederland het studiegebied Zuidoost-Veluwe met behulp van het model LANDCLIM de bosontwikkeling gesimuleerd voor een periode van 100 jaar, waarin combinaties van drie beheer- en klimaatscenario’s zijn doorgerekend. Voor de beheerscenario’s is een voortzetting van het huidige beheer afgezet tegen een scenario waarin ingespeeld wordt op een toename van de productie als gevolg van hogere temperaturen en CO2 in de atmosfeer en een beheer waarbij zoveel mogelijk de verwachte negatieve gevolgen van klimaatverandering (droogte, storm) preventief worden opgevangen. De beheerscenario’s zijn ingevuld in samenwerking met de bosbeheerders uit het studiegebied. De klimaatscenario’s gaan respectievelijk uit van een milde verandering en een forse klimaatverandering, afgezet tegen de ontwikkelingen bij een gelijkblijvend klimaat. Voor een aantal ecosysteemdiensten die belangrijk zijn voor het studiegebied is bekeken hoe de verwachte bosontwikkeling deze diensten beïnvloeden.
    Forest management and regeneration of tree species in the Eastern Amazon
    Schwartz, G. - \ 2013
    Wageningen University. Promotor(en): Frits Mohren; Bas Arts, co-promotor(en): Marielos Pena Claros; J.C.A. Lopes. - S.l. : s.n. - ISBN 9789461734662 - 132
    bosbedrijfsvoering - bomen - soorten - verjonging - houtkap - houtteelt - amazonia - forest management - trees - species - regeneration - logging - silviculture - amazonia

    Forest management for timber production applied in the Brazilian Amazon follows a polycyclic silvicultural system where harvesting is done through reduced-impact logging (RIL). In this study the short- and medium-term effects of RIL on the regeneration of commercial tree species were assessed in the Tapajós National Forest, Eastern Amazon, Brazil. Besides, post-harvesting silvicultural techniques such as enrichment planting using commercial tree species and tending naturally established individuals in gaps created by RIL were tested in Jari Valley, Eastern Amazon, Brazil in order to improve forest management for ensuring sustainable timber production. Finally the profitability of the tested post-harvesting silvicultural treatments was evaluated. Results showed that RIL did not have a destructive effect on the regeneration of the investigated species. In the short-term RIL caused unevenly spatially distributed disturbances over the forest, which tended to increase recruitment and growth rates of seedlings and saplings in the medium-term. The silvicultural techniques proved to be efficient to decrease mortality and increase growth rates of commercial tree species but are not profitable under the current timber prices and harvesting operation costs in the Brazilian Amazon. Although not profitable, enrichment planting in logging gaps showed to be an important tool for conserving rare species.

    First National Report on Forest Genetic Resources for Food and Agriculture,The Netherlands : country report for the FAO first state of the world's forest genetic resources for food and agriculture, Ministry of Economic Affairs, The Hague, November 2012
    Buiteveld, J. - \ 2012
    Wageningen : CGN/DLO Foundation (CGN Rapport 23) - 64
    genetische bronnen - genetische bronnen van plantensoorten - bossen - in-situ conservering - ex-situ conservering - bosbedrijfsvoering - duurzaamheid (sustainability) - nederland - genetic resources - plant genetic resources - forests - in situ conservation - ex situ conservation - forest management - sustainability - netherlands
    The Dutch national report is designed to contribute to a regional and global sysnthesis of the state of forest genetic resources and in particular to examine trends over the past ten years. After a general introduction to the Dutch forest sector and the historical background of today's forests, it describes the current state of forest genetic diversity in the Netherlands and the main factors influencing it
    Transnational governance through private authority : the case of the Forest Stewardship Council certification in Russia
    Tysiachniouk, M.S. - \ 2012
    Wageningen University. Promotor(en): Arthur Mol; Gert Spaargaren. - S.l. : s.n. - ISBN 9789461734327 - 352
    bosbouw - certificering - kwaliteitsnormen - bosbeleid - bosbedrijfsvoering - governance - internationale samenwerking - rusland - forestry - certification - quality standards - forest policy - forest management - governance - international cooperation - russia - cum laude
    cum laude graduation (with distinction)
    Desire for greener land : options for sustainable land management in drylands
    Schwilch, G. ; Hessel, R. ; Verzandvoort, S.J.E. - \ 2012
    Bern [etc.] : University of Bern [etc.] - ISBN 9789461733290 - 282
    droge gebieden - grondbeheer - duurzaamheid (sustainability) - duurzaam bodemgebruik - woestijnvorming - bodembescherming - waterbeheer - teeltsystemen - begrazingsbeheer - bosbedrijfsvoering - arid lands - land management - sustainability - sustainable land use - desertification - soil conservation - water management - cropping systems - grazing management - forest management
    Desire for Greener Land compiles options for Sustainable Land Management (SLM) in drylands. It is a result of the integrated research project DESIRE (Desertification Mitigation and Remediation of Land - A Global Approach for Local Solutions). Lasting five years (2007–2012) and funded within the EU’s Sixth Framework Programme, DESIRE brought together the expertise of 26 international research institutes and non-governmental organisations. The DESIRE project aimed to establish promising alternative land use and management strategies in 17 degradation and desertification sites around the world, relying on close collaboration between scientists and local stakeholder groups. The study sites provided a global laboratory in which researchers could apply, test, and identify new and innovative approaches to combatting desertification. The resulting SLM strategies are local- to regional-scale interventions designed to increase productivity, preserve natural resource bases, and improve people’s livelihoods. These were documented and mapped using the internationally recognised WOCAT (World Overview of Conservation Approaches and Technologies) methodological framework, which formed an integral part of the DESIRE project. The DESIRE approach offers an integrated multidisciplinary way of working together from the beginning to the end of a project; it enables scientists, local stakeholders and policy makers to jointly find solutions to desertification. This book describes the DESIRE approach and WOCAT methodology for a range of audiences, from local agricultural advisors to scientists and policymakers. Links are provided to manuals and online materials, enabling application of the various tools and methods in similar projects. The book also includes an analysis of the current context of degradation and SLM in the study sites, in addition to analysis of the SLM technologies and approaches trialled in the DESIRE project. Thirty SLM technologies, eight SLM approaches, and several degradation and SLM maps from all the DESIRE study sites are compiled in a concise and well-illustrated format, following the style of this volume’s forerunner where the land is greener (WOCAT 2007). Finally, conclusions and policy points are presented on behalf of decision makers, the private sector, civil society, donors, and the research community. These are intended to support people’s efforts to invest wisely in the sustainable management of land – enabling greener drylands to become a reality, not just a desire.
    Randvoorwaarden biodiversiteit bij oogst van biomassa
    Jong, J.J. de; Bijlsma, R.J. ; Spijker, J.H. - \ 2012
    Wageningen : Alterra (Alterra-rapport 2305) - 30
    biomassa - bossen - bosbedrijfsvoering - biodiversiteit - bio-energie - duurzaamheid (sustainability) - biomassa productie - biobased economy - biomass - forests - forest management - biodiversity - bioenergy - sustainability - biomass production - biobased economy
    In 2008 heeft het Rijk met de sector Bos, Natuur, Landschap en Hout het Convenant Duurzame Agrosectoren afgesloten waarin is afgesproken dat deze sector in 2020 32 PJ per jaar gaat bijdragen aan duurzame energie. Extra oogst in natuurgebieden kan daarvoor gewenst zijn. Deze studie gaat in op de vraag in hoeverre voor verschillende beheertypen extra biomassa kan worden geoogst zonder dat dit schadelijk is voor de biodiversiteit. Het blijkt dat vooral productiebos potenties heeft om de oogst te vergroten.
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