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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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    From space and from the ground: determining forest dynamics in settlement projects in the Brazilian Amazon
    Diniz, F.H. ; Kok, K. ; Hott, H.C. ; Hoogstra-Klein, M.A. ; Arts, B.J.M. - \ 2013
    International Forestry Review 15 (2013)3. - ISSN 1465-5489 - p. 442 - 455.
    land-use change - secondary forests - ecuadorian amazon - transition theory - deforestation - cover - reforestation - colonization - biodiversity - expansion
    Deforestation in the Brazilian Amazon has been partially attributed to the establishment of settlement projects. Acknowledging the difficulties in quantifying the rate and patterns of deforestation, the objective of this paper is to determine forest dynamics (deforestation and reforestation) in areas where settlement projects have been established, at multiple levels and using different methods. Using satellite images from 1985 to 2010, a study was conducted in five settlement projects in Pará State, aiming to determine forest dynamics at municipal and settlement levels. At property level, participatory maps were constructed to understand settlers’ perception of forest/non-forest areas. The results show that reforestation is the current process in the municipality and in some settlements. Settlers, however, perceive areas with secondary regrowth as potentially fertile cropland and might deforest again in the future. More research is needed to elucidate whether the observed reforestation will lead to a forest transition or is merely a temporary trend.
    Pontoscolex corethrurus (Annelida: Oligochaeta) indicador de la calidad del suelo en sitios de Eucalyptus grandis (Myrtacea) con manejo tumba y quema
    Uribe, S. ; Huerta, E. ; Geissen, V. ; Mendoza, M.I. ; Godoy, R. ; Jarquin, A. - \ 2012
    Revista biologia tropical = International Journal of Tropical Ecology and Conservation 60 (2012)4. - ISSN 0034-7744 - p. 1543 - 1552.
    tropical tree plantations - organic-matter - ecosystem engineers - secondary forests - nitrogen pools - fire - earthworm - carbon - mexico - water
    La presencia de oligoquetos en los ecosistemas puede indicar fertilidad del suelo, ya que estos organismos transportan, mezclan y entierran los residuos vegetales de la superficie al interior del suelo. Se caracterizó la comunidad de oligoquetos bajo sitios con diferentes periodos de establecimiento y manejo de plantaciones de Eucalyptus grandis, sin vegetación (SV), con cinco años en producción (Euc) y vegetación secundaria con 15 años (Acah) que han pasado por el proceso de tumba y quema en suelos de Acri- sol en Huimanguillo, Tabasco; y se analizaron las propiedades físicoquímicas del suelo (D.A., humedad, textura, pH, Ntot, MO, P, K, CIC). La recolecta de lombrices se realizó al finalizar las lluvias (agosto-octubre 2007). Se muestreó en tres parcelas con seis réplicas en cada una. Se encontró que los suelos tenían pH de 3.0-4.5 en los primeros 30cm de profundidad. Los contenidos de materia orgánica (MO) y nitrógeno total (Ntot) fueron significativamente menores en los sitios SV (6-8% y 0.19-0.22% respectivamente) que en Euc y Acah (MO=9-11%; el Ntot=0.27-0.33%). La especie Pontoscolex corethrurus domino en toda el área, presentando mayores densidades y biomasas en Euc (164.4ind/m2 y 36.8g/m2 respectivamente) y Acah (138.7ind/m2 y 19.1g/m2 respectivamente), mientras que en SV sus poblaciones fueron reducidas en un 80%. Se encontró que el sistema Acah sigue presentando rasgos de un sistema perturbado, al no recuperar fácilmente la diver- sidad de oligoquetos y las concentraciones de nutrientes disponibles en el suelo
    Tree height integrated into pantropical forest biomass estimates
    Feldpausch, T.R. ; Lloyd, J. ; Lewis, S.L. ; Brienen, R.J.W. ; Gloor, M. ; Montegudo Mendoza, A. ; Arets, E.J.M.M. - \ 2012
    Biogeosciences 9 (2012). - ISSN 1726-4170 - p. 3381 - 3403.
    tropical rain-forest - aboveground live biomass - net primary production - land-use change - wood density - amazonian forests - carbon stocks - allometric equations - neotropical forest - secondary forests
    Aboveground tropical tree biomass and carbon storage estimates commonly ignore tree height (H). We estimate the effect of incorporating H on tropics-wide forest biomass estimates in 327 plots across four continents using 42 656 H and diameter measurements and harvested trees from 20 sites to answer the following questions: 1. What is the best H-model form and geographic unit to include in biomass models to minimise site-level uncertainty in estimates of destructive biomass? 2. To what extent does including H estimates derived in (1) reduce uncertainty in biomass estimates across all 327 plots? 3. What effect does accounting for H have on plot- and continental-scale forest biomass estimates? The mean relative error in biomass estimates of destructively harvested trees when including H (mean 0.06), was half that when excluding H (mean 0.13). Power- and Weibull-H models provided the greatest reduction in uncertainty, with regional Weibull-H models preferred because they reduce uncertainty in smaller-diameter classes (=40 cm D) that store about one-third of biomass per hectare in most forests. Propagating the relationships from destructively harvested tree biomass to each of the 327 plots from across the tropics shows that including H reduces errors from 41.8 Mg ha-1 (range 6.6 to 112.4) to 8.0 Mg ha-1 (-2.5 to 23.0). For all plots, aboveground live biomass was -52.2 Mg ha-1 (-82.0 to -20.3 bootstrapped 95% CI), or 13%, lower when including H estimates, with the greatest relative reductions in estimated biomass in forests of the Brazilian Shield, east Africa, and Australia, and relatively little change in the Guiana Shield, central Africa and southeast Asia. Appreciably different stand structure was observed among regions across the tropical continents, with some storing significantly more biomass in small diameter stems, which affects selection of the best height models to reduce uncertainty and biomass reductions due to H. After accounting for variation in H, total biomass per hectare is greatest in Australia, the Guiana Shield, Asia, central and east Africa, and lowest in east-central Amazonia, W. Africa, W. Amazonia, and the Brazilian Shield (descending order). Thus, if tropical forests span 1668 million km2 and store 285 Pg C (estimate including H), then applying our regional relationships implies that carbon storage is overestimated by 35 Pg C (31–39 bootstrapped 95% CI) if H is ignored, assuming that the sampled plots are an unbiased statistical representation of all tropical forest in terms of biomass and height factors. Our results show that tree H is an important allometric factor that needs to be included in future forest biomass estimates to reduce error in estimates of tropical carbon stocks and emissions due to deforestation.
    Soil organic carbon stocks and changes upon forest regeneration in East Kalimantan- Indonesia
    Yassir, I. - \ 2012
    Wageningen University. Promotor(en): Pavel Kabat, co-promotor(en): Peter Buurman; Bram van Putten. - S.l. : s.n. - ISBN 9789064645761 - 175
    natuurlijke verjonging - tropische bossen - imperata cylindrica - secundaire bossen - koolstofvastlegging in de bodem - organisch bodemmateriaal - bodemeigenschappen - vegetatie - plantensuccessie - kalimantan - indonesië - natural regeneration - tropical forests - imperata cylindrica - secondary forests - soil carbon sequestration - soil organic matter - soil properties - vegetation - ecological succession - kalimantan - indonesia

    Imperata grassland is a common vegetation type in Kalimantan (Indonesia), and other parts of South-East Asia. It indicates a high degree of degradation of the vegetation, and mostly occurs after slashing and burning of primary forest. Through secondary succession Imperata grassland is converted into new secondary forest and much of the original biodiversity is restored. The overall objective of the thesis was to study the regeneration of Imperata grasslands in East Kalimantan, and to measure the effects of regeneration on soil properties, with emphasis on the organic fraction. The research strategy was to compare plots of different regeneration stages, characterized by the period elapsed since the vegetation was last burned.
    Results show that during regeneration of Imperata grasslands, both vegetation composition and soil properties change, including chemistry of soil organic matter. Soil carbon stocks are higher under Imperata grasslands than under primary forest, and increase further upon natural regeneration of grassland to secondary forest. Highest carbon stocks are found in the later regeneration phases. Lower carbon stocks under primary forests are due to extremely low fertility, combined with shallow soils and low root mass in the topsoil. Root density as observed in the field is much higher under the grass vegetation. Results show as well that soil organic matter decomposition is most advanced under forest, as indicated by lower amounts of plant derived compounds and higher contribution of microbial matter. The results indicate that decomposition efficiency is related to soil organic matter chemistry, but more to abundance of N-compounds than to that of potentially recalcitrant compounds.
    In our case study, soil texture appears an important factor in the vegetation succession. On sandy soils, there is a strong increase with time of Pteridium aquilinum L., while the number of other species is lower. This slows down the development towards secondary forest. Canonical correspondence analysis (CCA) of environmental factors and vegetation show that pH, bulk density, sand and clay are the factors related to the distribution of species. The rapid secondary succession indicates that Imperata grasslands are not a final and stable stage of land degradation, but that frequent fires are necessary to maintain Imperata grasslands. If protected from fire and other intrusions such as shifting cultivation, Imperata grassland will readily develop into secondary forest. Imperata grasslands seem to be permanent because of human interference, especially through burning, and because so far few attempts have been made to sustainable rehabilitation.

    A multi-criterion index for the evaluation of local tropical forest conditions in Mexico
    Ochoa-Gaona, S. ; Kampichler, C. ; Jong, B.H.J. de; Hernandez, S. ; Geissen, V. ; Huerta, E. - \ 2010
    Forest Ecology and Management 260 (2010)5. - ISSN 0378-1127 - p. 618 - 627.
    tree diversity - rain-forest - secondary forests - delphi technique - fuzzy-logic - indicators - conservation - regeneration - biodiversity - management
    Despite the ecological and economical importance of tropical forests they are currently affected by human activities, mainly through deforestation and selective extraction. With the aim of making an opportune diagnosis of the condition of forests, we developed an ecological index based on qualitative and semi-quantitative data, allowing a quick diagnosis in order to manage and conserve tropical forests. We evaluated 44 plots of tree vegetation, measuring canopy height, number of strata, tree cover, dominant trees, number of tree species, as well as the management of and damage to the forest. The data of each parameter was classified in categories of 3, 4 or 5, which were normalized between 0 and 1 for the worst and best characteristics, respectively. For the purpose of analysis, the average, a set of IF–THEN rules, and fuzzy logic were applied and as a result we obtained a model that measures the ecological condition of the tropical forests. The model has the advantages of having an ecological basis, allows data to be gathered quickly and is clear and easy to manage and interpret. When running the model, the value of each intermediate variable is displayed, thus allowing the detection of where necessary action is required to improve the ecological condition of the forest. We expect this index to contribute in evaluating the effectiveness of forest management and possibly offer advice for the short-term management and conservation of the remnants of tropical forests
    Pathways, mechanisms and predictability of vegetation change during tropical dry forest succession
    Lebrija Trejos, E.E. ; Meave, J. ; Poorter, L. ; Pérez- García, E.A. ; Bongers, F. - \ 2010
    Perspectives in plant ecology, evolution and systematics 12 (2010)4. - ISSN 1433-8319 - p. 267 - 275.
    intermediate disturbance hypothesis - rain-forests - secondary forests - species composition - plant-communities - central amazonia - dynamics - competition - diversity - chronosequence
    The development of forest succession theory has been based on studies in temperate and tropical wet forests. As rates and pathways of succession vary with the environment, advances in successional theory and study approaches are challenged by controversies derived from such variation and by the scarcity of studies in other ecosystems. During five years, we studied development pathways and dynamics in a chronosequence spanning from very early to late successional stages (ca. 1–60 years) in a tropical dry forest of Mexico. We (1) contrasted dynamic pathways of change in structure, diversity, and species composition with static, chronosequence-based trends, (2) examined how structure and successional dynamics of guilds of trees shape community change, and (3) assessed the predictability of succession in this system. Forest diversity and structure increased with time but tree density stabilized early in succession. Dynamic pathways matched chronosequence trends. Succession consisted of two tree-dominated phases characterized by the development and dynamics of a pioneer and a mature forest species guild, respectively. Pioneer species dominated early recruitment (until ca. 10 years after abandonment), and declined before slower growing mature-forest species became dominant or reached maximum development rates (after 40–45 years). Pioneers promoted their replacement early in succession, while mature-forest species recruited and grew constantly throughout the process, with their lowest mortality coinciding with the peak of pioneer abundance. In contrast to prevailing stochastic views, we observed an orderly, community driven series of changes in this dry forest secondary succession. Chronosequences thus represent a valuable approach for revealing system-specific successional pathways, formulating hypotheses on causes and mechanisms and, in combination with repeated sampling, evaluating the effects of vegetation dynamics in pathway variation.
    Dynamics of secondary forests
    Breugel, M. van - \ 2007
    Wageningen University. Promotor(en): Frans Bongers, co-promotor(en): M. Ramos. - [S.l.] : S.n. - ISBN 9789085046936 - 240
    secundaire bossen - bossen - plantensuccessie - populatiedynamica - bosecologie - vegetatie - landbouwgronden - verlaten grond - tropen - mexico - secondary forests - forests - plant succession - population dynamics - forest ecology - vegetation - agricultural soils - abandoned land - tropics - mexico
    The succession of tropical secondary forests on abandoned agricultural fields has been studied since long, most often by comparing stands of different age since abandonment. These so-called chronosequence studies have yielded much insight in general patterns of succession and the constraints and conditions that affect the course of succession (shortly reviewed in chapter 1). Successional dynamics, however, are inferred rather than directly monitored in such studies; i.e. direction and rates of change of community structure and composition are deduced indirectly on the assumption that similar successional processes take place in any one stand. Only very few studies followed successional dynamics through repeated measurements in permanent sample plots, hence our current understanding of the variation in successional dynamics across secondary forest stands, the underlying processes of growth, mortality and recruitment, and the processes and mechanism that steer them, is still poor.

    This thesis presents data from one of the very few studies on secondary tropical forest succession in multiple permanent sample plots. The focus of this work is on the first years of secondary forest succession, and on the role of competition on the level of individuals, populations and communities. The main aims of this work were: 1) To evaluate the dynamics of young secondary forests on abandoned agricultural fields in terms of rates and direction of community changes, how these dynamics vary across sites and how they change with time since abandonment; 2) To evaluate the dynamics of young secondary forests in terms of growth, mortality and recruitment, and how community changes are related to these processes; and 3) To examine the degree to which competition for light can account for variation in growth and mortality of saplings within a population and for variation in population dynamics across distinct sites.

    The study was carried out in three villages in theMarquésdeComillas(MdC) region, part of theSelvaLacandonain easternChiapas,Mexico. The climate of theMdCregion is humid tropical, with an average annual temperature of 24 ºC, mean annual rainfall of ~3000 mm and a short dry period in February-April. The original vegetation consists mainly of tropical evergreen and semi-deciduous forests. Colonization of the region started in the late 1960s, and since then a large part of the landscape has been converted to a mosaic of temporary and permanent grazing pastures, cultivated land, young secondary forest and old-growth remnants. The prevailing land use types in the three villages are slash-and-burn shifting cultivation practices (mainly maize) with short fallow periods and semi-permanent cattle ranging.

    Data for this study were collected in secondary forests on abandoned agricultural fields and pastures with time since abandonment (age) ranging from 0.5 to 18 years. A first dataset consisted of a chronosequence of 72 stands, widely distributed over an area of roughly 60 km2 and encompassing differentgeomorphologicalunits (low hills vs. alluvial planes) and former land-use types (abandoned agricultural fields vs. pastures). In each stand, three 2 x 25 m transects were randomly located in which all woody stems with diameter at 1.3-m above ground (dbh) ≥ 1 cm identified to lowest possibletaxonand their dbh and height were measured. A second dataset consists of permanent sample plots in twelve secondary forests with similar former land-use (maize fields) and geomorphology (low hills with sandy acidic and unfertile soils). Initial stand age ranged from 1-17 y. In each stand a 10 x 50-m permanent sample plot is established, and all trees with height ≥ 1.5-m are recorded, and tagged. Location of each tree was determined using a 1 x 1-m grid system. Every year dead trees and new recruits are recorded and dbh and height of all living trees is (re-)measured. The first dataset is used in chapter 2, and in chapters 3-7 data are used from the first three years of permanent plot study.

    Chapter 2 demonstrates that patterns of species diversity, frequency and dominance are highly variable across secondary forests of an agricultural landscape, even when they are of similar age. Diversity varied widely between the plots, which could only partly be explained by differences in time since abandonment and geomorphology while the influence of former land use was even more ambiguous. Species richness changed with age, but dominance levels remained similar over the first 18 year of succession. Similarly, species richness, but not dominance, differed between secondary forests on low hills and alluvial plains. Across-stand frequency and abundance patterns varied strongly among tree species, and most among pioneer species. Despite the high species richness (almost 200 species identified across all plots), only a very small sub-set of the regional species pool dominated secondary forests in terms of frequency of occurrence and abundance, all of them pioneer species. Most pioneer species, however, and nearly all shade tolerant species, occurred in less than 15% of the plots and always in low densities. Only two species (Cecropia peltata and Trichospermum mexicanum) occurred in ≥ 50% of the plots and they were also the only species that were relatively dominant (> 10 stems / > 10% of stand basal area) in ≥ 20% of the plots. Other species were dominant (> 10% basal area) in the plots were they occurred, but never abundant (e.g.Ochromapyramidale); frequent but never abundant (e.g.Vernoniapatens); or locally abundant but with low relative basal area (e.g.Acalyphadiversifolia).

    The "Initial Floristic Composition" hypothesis predicts that, on abandoned agricultural fields with light previous land-use and close to seed sources, both pioneer and shade-tolerant species colonize a site directly after abandonment and that the recruitment of pioneers sharply declines while the recruitment of shade-tolerant species continues as soon as the canopy closes. It also predicts higher mortality among pioneers. Consequently, recruited and dead trees are expected to differ in species composition, with highest species richness for the recruits. To evaluate these predictions, recruitment and mortality was examined in eight permanent sample plots with initial fallow age of 1 to 5 y (chapter 3). Shade-tolerant species established in the first years of succession, albeit in low numbers. As predicted, recruited and dead trees differed in species richness and composition, and in shade-tolerant frequency. In contrast to expected, over 50% of recruits were from pioneer species. Results suggested that high stand-level mortality opened new opportunities for continued pioneer colonization. Results demonstrate that species turnover starts very early in succession but is not always a gradual and continuous process, complicating prevailing succession models.

    In chapter 4, stand structure dynamics (i.e, rate and direction of stand structure changes) were related to mortality, growth, and recruitment rates over a two-year period, and the dependence of these demographic processes on fallow age and initial stand structure attributes was evaluated. Changes in stand structure were especially fast in the first 5 y of succession, and decreased rapidly afterwards, which resulted from similar stand-level changes in relative mortality, growth, and recruitment rates. Changes in most stand structure attributes (e.g. basal area, canopy height) were closely correlated, and more linked with tree growth rates than with net changes in tree density due to recruitment and mortality. Demographic processes were negatively related with initial stand basal area, but independent of initial tree density. Results suggest that asymmetric competition and resulting patterns of size and density dependent mortality and growth are major driving forces determining secondary forest successional pathways. Sudden mass mortality among dominant species in some stands showed that early secondary forest succession is not always a gradual and unidirectional process.

    The strong spatial and temporal variability of successional dynamics emphasizes the need to monitor these dynamics in permanent plots across a range of initial stand ages, with multiple plots in a given age class. In chapter 5, case studies inCosta RicaandMexicoshow that the actual rates of change in tree communities often deviate from chronosequence trends. With respect to tree species composition, sites of different agesdiffermore than a single site followed over time through the same age range. While changes in stem density have little to do with chronosequence trends, changes in basal area within stands generally followed chronosequence trends. Stem turnover rates were poor predictors of species turnover rates, particularly at longer time-intervals. Effects of the surrounding landscape on tree community dynamics within individual plots were not specifically included in this or in any of the other chapters, but results suggest that they are likely to be important determinants of species accumulation rates and relative abundance patterns.

    Competition for light is often considered to be one of the main mechanisms that regulate successional vegetation dynamics. Competition for light is largely asymmetric, as larger trees shade smaller trees and not the other way around. Consequently, within-site variation in growth and survival of tree saplings can be expected to relate to variation in the degree of neighborhood competition, especially from the larger neighbors. In chapter 6, these hypotheses were tested for Cecropia peltata and Trichospermum mexicanum saplings in two adjacent 1-2 year old secondary forest stands. The degree of competition was estimated by neighborhood basal area (NBA). Both diameter and height growth were strongly negatively related to NBA of the larger neighbors. Only a small proportion of variation in survival, on the other hand, could be accounted for by variation in NBA, suggesting that other factors are more important. The effect of NBA of smaller neighbors on growth and survival was very weak or non-significant, indicating that competition between neighbors, indeed, is largely asymmetric.

    Population dynamics of a species vary much from one secondary forest to another. In chapter 7 we examined if such between-site differences in demographic behavior can be related to variation in asymmetric competition that result from differences in stand and population size structures. Specifically, we tested if differences in mean growth and mortality of the biggest and of the smallest trees of a population (growth and survival asymmetry) were related to differences in the average level of asymmetric neighborhood competition in both size groups (competition asymmetry). We used 24 populations of four pioneer tree species in nine early (1-5 y) secondary forest stands. For each population, we compared average neighborhood basal area, growth and survival of the twenty percent smallest and twenty percent largest trees. The between-plot variation in competition asymmetry explained a significant part of the between-plot variation in growth asymmetry, with smallest trees growing faster in populations with low competition asymmetry, and largest trees growing fastest in populations with high competition asymmetry. Survival was size-related, with lowest survival rates among the smallest plants, as expected. However, survival asymmetry was significantly related to competition asymmetry in just one species. The differences in

    theeffects of asymmetric competition on the mortality and survival of the four species show that susceptibility to competition for, presumably, light, varies considerably between early successional pioneer species. Results of chapter 6 and 7 support the prediction that in young secondary forests, asymmetric competition for light is one of the main mechanisms that govern secondary forest dynamics.

    Essays on the economics of forestry-based carbon mitigation
    Benítez-Ponce, P.C. - \ 2005
    Wageningen University. Promotor(en): Henk Folmer, co-promotor(en): R. Olschewski. - s.l. : S.n. - ISBN 9789085041375 - 187
    milieu - economie - klimaatverandering - kosten - koolstof - bebossing - risico - secundaire bossen - conservering - ecosystemen - natuurlijke verjonging - opwarming van de aarde - milieubeleid - ecuador - latijns-amerika - ecosysteemdiensten - environment - economics - climatic change - costs - carbon - afforestation - risk - secondary forests - conservation - ecosystems - natural regeneration - global warming - environmental policy - ecuador - latin america - ecosystem services
    Keywords:climate change, carbon costs, afforestation, risk, secondary forests, conservation payments, ecosystem services

    This thesis is a collection of articles that deal with the economics of carbon sequestration in forests. It pays special attention to the comparison of forestry alternatives for carbon sequestration, carbon supply curves at regional and global levels and the impact of risk on payments for ecosystem services. Case-studies inEcuadorandLatin Americacontribute to a better understanding of these issues. Policy implications of this research are: (1) Natural regeneration of secondary forests is a cost-efficient activity for carbon sequestration in the humid tropics and should be included as part of the Clean Development Mechanism of the Kyoto Protocol. (2) Country-risk is a relevant factor to be considered in climate change mitigation assessments. When accounting for country riskassociated with political, economic and financial risks ― the potential carbon sequestration at a global level is reduced by more than half. (3)Potential carbon sequestration through afforestation ranges from 5% to 25% of the emission reduction targets of different policy scenariosfor stabilization of atmospheric greenhouse gas concentrations, andtherefore is relevant in a global context. (4) Farm-level decisions are influenced by risks associated to price and yield volatility of land-use alternatives. Efficient conservation policies that aim at enhancing carbon sequestration, biodiversity and other environmental services should look at both net revenues and risks. Combining payments for conservation with risk-hedging strategies is a policy option to be considered by conservation agencies worldwide.

    Chinantec shifting cultivation : InTERAcTIVE landuse : a case-study in the Chinantla, Mexico, on secondary vegetation, soils and crop performance under indigenous shifting cultivation
    Wal, H. van der - \ 1999
    Agricultural University. Promotor(en): R.A.A. Oldeman. - S.l. : s.n. - ISBN 9789058081315 - 162
    zwerflandbouw - vegetatietypen - bosbouw - agroforestry - landgebruik - vegetatie - herbegroeiing - vegetatiebeheer - secundaire bossen - mexico - shifting cultivation - vegetation types - forestry - agroforestry - land use - vegetation - revegetation - vegetation management - secondary forests - mexico - cum laude

    The development of secondary vegetation, soils and crop performance was studied in local variants of shifting cultivation in two villages in the Chinantla, Mexico. In Chapter 1, the institutional, social and political context of the research are presented and the reader is advertised that the scope of the study is limited to the interaction between ecological-productive aspects and the landuse pattern as practiced by the farmers.

    In Chapter 2 a conceptual framework is presented. Indigenous shifting cultivation is defined as a general form of landuse, characterized by the continuous recontextualization of a many-sided relation between man and nature, the continuous recreation of knowledge and the making and use of dynamic fields according to a landuse pattern. A great specificity of indigenous shifting cultivation in response to local environmental and socio-economical factors is observed.

    The ecology of secondary vegetation is reviewed, paying attention to mountain areas such as the Chinantla. The development of forest eco-units is not a simple, unilinear process, but, on the contrary, a process that can take one of many possible courses, influenced by environmental factors and the use-history of the land. Soils develop as an integral part of eco-units, as has been observed by comparing the soil in hurricane tracts and eco-units of different ages. The development of secondary vegetation and soils, as related to the landuse pattern for shifting cultivation, leads to variation in the ecological conditions within the mosaic of fields. Consequently, the performance of crops may vary within the mosaic of fields.

    In the Chinantla region a large variation in climate occurs due to a wide altitudinal range (Chapter 3). As a consequence, several vegetation types occur. Soils in the area have developed from limestone or sandstone/metamorphic rocks. Chapter 4 describes the variants of shifting cultivation and the landuse pattern in the Chinantec communities Santa Cruz Tepetotutla and Santiago Tlatepusco. Three variants of shifting cultivation were distinguished: shifting cultivation in the area of 'selva alta perennifolia de montaña' (the most widely practised), shifting cultivation in the limestone area, and shifting cultivation in the Quercus -forests. In all variants maize is the principal crop.

    In Chapter 5 the development of secondary vegetation as related to the use-history of fields is studied, concentrating on secondary vegetation in the area of 'selva alta perennifolia de montaña'. Secondary regrowths were sampled in 28 fields. Ages of regrowths varied from 5 to 50 years, and orders of regrowths (first-order regrowths develop after cutting primary or old secondary vegetation; second-order regrowths after cutting a first-order regrowth) varied from 1 to 4. On each field, data on the trees and shrubs with a diameter at breast-height of more than 2 cm were recorded in four transects, each of 100 m 2surface area, which were all laid out on steep slopes.

    A total of 5691 trees and shrubs, belonging to 229 species, were found on the sampled area. Thirty-seven species comprised 90% of all sampled individuals. Cluster and ordination analysis showed variation of the species composition of secondary vegetation with age, altitude, geographic location, lithology and order of regrowth. Analysis of farmers' information on the relation between order of regrowth and species composition confirmed the results of sampling.

    Structural parameters, species composition, tree development and eco-unit development varied between orders of regrowth. Basal area, number of trees and crown area index were high in first- and second-order regrowths, but fell sharply in subsequent regrowths. First-order regrowths were dominated by one or two species. In several second-order regrowths, Hedyosmum mexicanum was the single dominant. In other second-order and in later-order regrowths polydominance was observed. Analysis of height-diameter relations in frequent species also indicated a relation between the order of regrowth and the development of the trees of a certain species, demonstrating the flexibility of trees in responding to a changing environment. Whereas first- and second-order regrowths were composed of few eco-units, third- and fourth-order regrowths showed fragmentation of eco-units from early phases of development onwards. The results indicate that the number of consecutive eco-units per time unit diminishes with increasing order of regrowth.

    Changes in soils during one cropping season were studied by comparing soil parameters in samples obtained after slashing the vegetation (May), after burning (June) and at harvest (October-November). No significant differences in bases, pH, nitrogen and carbon were found between May- and June-samples on limestone-derived soils. Between burning and harvest, pH and the sum of exchangeable bases increased slightly. In the area of 'selva alta perennifolia de montaña' pH and exchangeable bases increased significantly between May and June. During the cropping season (June to October-November), the sum of exchangeable bases declined slightly. No relation of these changes with the use-history of fields was found, possibly due to the small number of sampled fields and burns being partial and heterogenous in the year of sampling (1993).

    Sampling of soils in a chronosequence of fields in the area of 'selva alta perennifolia de montaña' gave strong indications of an increase of pH and exchangeable bases in the course of several decades, from the cutting of primary or old secondary vegetation onwards. The strongest increase was observed in the quantity of exchangeable calcium. Correlations between use-history parameters and carbon, nitrogen and phosphorus were not significant. A mechanism of soil change based on a combination of physical and biological processes is proposed, wherein an initial increase in pH through the addition of bases triggers of an increased biological activity resulting in a more hospitable soil.

    The performance of maize crops in a chronosequence of fields was studied in 1994 by determining several parameters referring to the crops (Chapter 7). Crop performance varied strongly between fields, both in the limestone area and in the area of 'selva alta perennifolia de montaña'. In the limestone area, yield per square meter sloping surface diminished with increasing number of burns; there was no relation between yield and any of the measured soil parameters. In the area of 'selva alta perennifolia de montaña', yields were not significantly correlated with any of the parameters applied to characterize the use-history of fields. However, yields per square meter sloping surface were correlated with several soil parameters: CEC-BaCl 2 , exchangeable calcium, total phosphorus and the C/N-ratio. At values smaller than 3.9 also pH-KCl was positively correlated with yields. In fertilization experiments, the combined application of nitrogen and phosphorus improved yield on a field where without fertilization a low yield was obtained; fertilization had no effect where high yields were obtained without fertilization.

    The development of secondary vegetation, soils and crop performance in indigenous shifting cultivation in two villages in the Chinantla, Mexico, illustrates the interactive and iterative character of this form of agriculture. This character should be taken as the point of departure for its redesign in such a way that the production of a variety of goods is combined with the production of a variety of services in a complex mosaic of eco-units.

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    Stormschade, wind in de zeilen voor natuurontwikkeling in bossen.
    Koop, H. ; Berris, L. ; Wolf, R. - \ 1990
    Nederlands Bosbouwtijdschrift 62 (1990). - ISSN 0028-2057 - p. 318 - 324.
    biomassa - ontwikkeling - bosschade - bosbouw - lagenstructuur - nederland - periodiciteit - planning - plantensuccessie - secundaire bossen - stormen - bomen - vegetatie - invloeden - natuur - biomass - development - forest damage - forestry - layer structure - netherlands - periodicity - planning - plant succession - secondary forests - storms - trees - vegetation - influences - nature
    Suksessie in geexploiteerd drooglandbos : de vierde opname; Techniek natuurlijke verjonging drooglandbos : behandeling en opname 1972
    Vletter, J. de - \ 1972
    Paramaribo : [s.n.] (Celos rapporten no. 74) - 31
    bosbouw - meting - natuurlijke verjonging - periodiciteit - plantensuccessie - onderzoek - secundaire bossen - suriname - synecologie - vegetatie - forestry - measurement - natural regeneration - periodicity - plant succession - research - secondary forests - suriname - synecology - vegetation
    Groei en mortaliteit der waardehoutsoorten in geexploiteerd en natuurlijk verjongd drooglandbos; Successie in ontbost terrein; Kiemoecologie der houtige gewassen in drooglandbos en Kapoeweri
    Gieteling, C.J. - \ 1970
    Paramaribo : [s.n.] (Celos rapporten no. 38) - 48
    milieufactoren - bosbouw - bosbouwkundige handelingen - groei - periodiciteit - plantensuccessie - secundaire bossen - zaadkieming - groei van zaailingen - houtteelt - suriname - vegetatie - environmental factors - forestry - forestry practices - growth - periodicity - plant succession - secondary forests - seed germination - seedling growth - silviculture - suriname - vegetation
    Successie op ontbost terrein : terreinvoorbereiding en boomopname ten behoeve van inrichting proefperken Saraweg (Mapanegebied); Lianenpopulatie in ongerept drooglandbos en daarvan afgeleide vegetaties : het inzamelen van herbariummateriaal aan de Saraweg; Successie op ontbost terrein : inrichten en eerste en tweede opname proefperk Blakawatra
    Consen, J.R. ; Lavieren, L.P. van; Boerboom, J.H.A. - \ 1968
    Paramaribo : [s.n.] (CELOS rapporten no. 8) - 47
    klimplanten - bosbouw - periodiciteit - plantensuccessie - secundaire bossen - suriname - vegetatie - climbing plants - forestry - periodicity - plant succession - secondary forests - suriname - vegetation
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