Austin A.T.,University of Buenos Aires |
Bustamante M.M.C.,University of Brasilia |
Nardoto G.B.,University of Brasilia |
Mitre S.K.,University of Brasilia |
And 8 more authors.
Science | Year: 2013
Human impacts on the N cycle require sustainable ecological solutions to preserve ecosystem and human health.
Kitajima K.,University of Florida |
Kitajima K.,Smithsonian Tropical Research Institute |
Poorter L.,Wageningen University |
Poorter L.,Instituto Boliviano Of Investigacion Forestal
New Phytologist | Year: 2010
•Leaf toughness is thought to enhance physical defense and leaf lifespan. Here, we evaluated the relative importance of tissue-level leaf traits vs lamina thickness, as well as their ontogenetic changes, for structure-level leaf toughness and regeneration ecology of 19 tropical tree species.•We measured the fracture toughness of the laminas and veins of sapling leaves with shearing tests, and used principal component analysis and structural equation modeling to evaluate the multivariate relationships among traits that contribute to leaf toughness and their links to ecological performance traits.•Tissue traits (density and fracture toughness of lamina and vein) were correlated positively with each other, but independent of lamina thickness. The tissue traits and lamina thickness contributed additively to the structure-level toughness (leaf mass per area and work-to-shear). Species with dense and tough leaves as saplings also had dense and tough leaves as seedlings and adults. The patterns of ontogenetic change in trait values differed between the seedling-to-sapling and sapling-to-adult transitions.•The fracture toughness and tissue density of laminas and veins, but not the lamina thickness, were correlated positively with leaf lifespan and sapling survival, and negatively with herbivory rate and sapling regeneration light requirements, indicating the importance of tissue-level leaf traits. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).
Veldman J.W.,Instituto Boliviano Of Investigacion Forestal |
Putz F.E.,University of Florida
Biotropica | Year: 2010
Predicting responses of vegetation to environmental factors in human-altered tropical ecosystems requires an understanding of the controls on plant population expansion across landscapes (i.e., long-distance dispersal) as well as of factors affecting recruitment at local scales (i.e., microsite conditions). We studied the roles of light availability, habitat type, soil disturbance, and seed dispersal in a selectively logged forest in lowland Bolivia where the exotic forage grass Urochloa (Panicum) maxima is abundant on roads and log landings but does not invade felling gaps or unlogged forest. Shade-house trials and seed addition experiments with U. maxima revealed that this C4 grass thrives in high light but also grows in partial shade (10% full sun, but not 1% full sun), and that felling gaps, but not undisturbed forest, are suitable for grass establishment. To determine if seed dispersal by logging vehicles explains the discrepancy between actual and potential grass recruitment sites, we collected grass seeds that fell from trucks onto log landings located long distances (>500m) from established grass populations. Trucks dispersed an estimated 1800 alien grass seeds per log landing during the early dry season; automobiles also transported seeds of grass (135 seeds/vehicle). The seeds collected (and relative abundances) were the exotics U. (Panicum) maxima (97%) and Urochloa (Brachiaria) brizantha (2%), and the pan-tropical weeds Sorghum halapense (1%) and Rottboellia cochinchinensis (0.2%). Grasses invade this forest where disturbance coincides with seed dispersal by motor vehicles, while dispersal limitation apparently prevents invasion of many sites otherwise suitable for grass recruitment (i.e., felling and natural gaps). © 2010 The Author(s). Journal compilation © 2010 by The Association for Tropical Biology and Conservation.
Toledo M.,Wageningen University |
Toledo M.,Instituto Boliviano Of Investigacion Forestal |
Toledo M.,Instituto Boliviano Of Investigacion Forestal Ibif |
Pena-Claros M.,Wageningen University |
And 9 more authors.
Journal of Ecology | Year: 2012
1. The analysis of species distribution patterns along environmental gradients is important for understanding the diversity and ecology of plants and species responses to climate change, but detailed data are surprisingly scarce for the tropics. 2. Here, we analyse the distribution of 100 woody species over 220 1-ha forest plots distributed over an area of c. 160000km 2, across large environmental gradients in lowland Bolivia and evaluate the relative importance of climate and soils in shaping species distribution addressing four multivariate environmental axes (rainfall amount and distribution, temperature, soil fertility and soil texture). 3. Although species abundance was positively related to species frequency (the number of plots in which the species is found), this relationship was rather weak, which challenges the view that most tropical forests are dominated at large scales by a few common species. 4. Species responded clearly to environmental gradients, and for most of the species (65%), climatic and soil conditions could explain most of the variation in occurrence (R 2>0.50), which challenges the idea that most tropical tree species are habitat generalists. 5. Climate was a stronger driver of species distribution than soils; 91% of the species were affected by rainfall (distribution), 72% by temperature, 47% by soil fertility and 44% by soil texture. In contrast to our expectation, few species showed a typical unimodal response to the environmental gradients. 6. Synthesis. Tropical tree species specialize for different parts of the environmental gradients, and climate is a stronger driver of species distribution than soils. Because climate change scenarios predict increases in annual temperature and a stronger dry season for tropical forests, we may expect potentially large shifts in the distribution of tropical trees. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.
Veldman J.W.,Instituto Boliviano Of Investigacion Forestal |
Veldman J.W.,University of Florida |
Putz F.E.,Instituto Boliviano Of Investigacion Forestal |
Putz F.E.,University of Florida
Biological Conservation | Year: 2011
Changes in land-uses, fire regimes, and climate are expected to promote savanna expansion in the Amazon Basin, but most studies that come to this conclusion fail to define " savanna" clearly or imply that natural savannas of native species will spread at the expense of forest. Given their different conservation values, we sought to differentiate between species-diverse natural savannas and other types of fire-maintained grass-dominated vegetation that replaced tropical forests between 1986 and 2005 in 22,500km2 of eastern lowland Bolivia. Analysis of Landsat TM and CBERS-2 satellite imagery revealed that, in addition to 1200km2 (7.1%) of deforestation for agriculture and planted pastures, 1420km2 (8.4%) of forest was replaced by derived savannas. Sampling in 2008 showed that natural savannas differed from forest-replacing derived savannas floristically, in soil fertility, and in fuel loads. Natural savannas typically occurred on sandy, acidic, nutrient-poor soils whereas most derived savannas were on comparatively fertile soils. Fuel loads in derived savannas were twice those of natural savannas. Natural savannas supported a diversity of grass species, whereas derived savannas were usually dominated by Guadua paniculata (native bamboo), Urochloa spp. (exotic forages), Imperata brasiliensis (native invasive), Digitaria insularis (native ruderal), or the native fire-adapted herb Hyptis suaveolens (Lamiaceae). Trees in derived savannas were forest species (e.g., Anadenanthera colubrina) and fire-tolerant palms (Attalea spp.), not thick-barked species characteristic of savanna environments (e.g., Curatella americana). In addressing tropical vegetation transitions it is clearly important to distinguish between native species-diverse ecosystems and novel derived vegetation of similar structure. © 2011 Elsevier Ltd.
Soriano M.,Instituto Boliviano Of Investigacion Forestal |
Soriano M.,University of Florida |
Kainer K.A.,University of Florida |
Staudhammer C.L.,University of Florida |
Soriano E.,Gabriel René Moreno Autonomous University
Forest Ecology and Management | Year: 2012
The encroachment of the logging frontier into Western Amazonia, where non-timber extraction has historically driven regional economies, provides an opportunity to explore the practice of multiple-use forest management. Families are now harvesting timber in their Brazil nut (. Bertholletia excelsa)-rich community-titled forests, and we examined effects of formal and informal logging (with and without government-approved management plans, respectively) on forest disturbance and natural regeneration (individuals ≤10. cm. dbh) of B. excelsa and 10 timber species in Northern Bolivia. B. excelsa regeneration densities 2-5. years after timber harvests did not differ between unlogged or logged (formally nor informally) sites; densities were, however, greater in larger logging disturbances (i.e., log landings vs skid trails), corroborating our model in which canopy openness explained regeneration densities. Regeneration of the two most valuable timber species, Swietenia macrophylla and Amburana cearensis, rarely occurred, and only where conspecific trees were felled, implying that population recovery of selected species may need post-harvest silvicultural interventions. In contrast, two other high-value timber species (. Cedrela odorata and Dipteryx odorata) responded favorably to disturbances. Contrary to our expectations and reported industrial-scale findings, formal logging resulted in a larger percentage, but still acceptable level, of disturbed area than informal logging (10.6%. ±. 0.65 SE vs 6.9%. ±. 1.26 SE; p=. 0.047).Our overall finding that Brazil nut regeneration was unaffected by low logging intensities suggests that combined Brazil nut and timber harvests are compatible under certain circumstances. Still, adhering to legal requirements has been challenging for individual landholders. Preparing legally-required management plans without assistance is difficult, and individual landholders seek to harvest timber over multiple years, which is discouraged by formal logging that indirectly entails one-time extraction of nearly all commercial stems from the approximately 200. ha of forest landholders dedicate to timber production. Thus, reconciliation of legal requirements with community conditions is fundamental to long-term success of multiple-use forest management. © 2012 Elsevier B.V..
Bakker M.A.,Wageningen University |
Bakker M.A.,Instituto Boliviano Of Investigacion Forestal |
Carreno-Rocabado G.,Wageningen University |
Carreno-Rocabado G.,Instituto Boliviano Of Investigacion Forestal |
And 2 more authors.
Functional Ecology | Year: 2011
Decomposition is a key ecosystem process that determines nutrient and carbon cycling. Individual leaf and litter characteristics are good predictors of decomposition rates within biomes worldwide, but knowledge of which traits are the best predictors for tropical species remains scarce. Also, the effect of a species' position on the leaf economics spectrum (LES) and regeneration light requirements on decomposition rate are, until now, unknown. In addition, land use change is the most immediate and widespread global change driver, with potentially significant consequences for decomposition. Here we evaluate 14 leaf and litter traits, and litter decomposition rates of 23 plant species from three different land use types (mature forest, secondary forest and agricultural field) in the moist tropics of lowland Bolivia. Leaf and litter traits were closely associated and showed, in line with the LES, a slow-fast continuum ranging from species with tough, well-protected leaves (high leaf density, leaf dry matter content, force to punch and litter C:N ratio) to species with cheap, productive leaves [high specific leaf area (SLA) and nutrient concentrations in leaves and litter]. Fresh green leaf traits were better predictors of decomposition rate than litter traits, and leaf nitrogen concentration (LNC) was a better predictor of decomposition than leaf phosphorus concentration, despite the widely held belief that tropical forests are P-limited. Multiple regression analysis showed that LNC, SLA and chlorophyll content per unit leaf area had positive effects on decomposition, explaining together 65-69% of the variation. Species position on the LES and regeneration light requirements were also positively related to decomposition. Plant communities from agricultural fields had significantly higher LNC and SLA than communities from mature forest and secondary forest. Species from agricultural fields had higher average decomposition rates than species from other ecosystems and tended to be at the fast end of the LES. 7.Both individual traits of living leaves and species' position on the LES persist in litter, so that leaves lead influential afterlifes, affecting decomposition, nutrient and carbon cycling. © 2010 The Authors. Functional Ecology © 2010 British Ecological Society.
Van Der Sleen P.,Wageningen University |
Van Der Sleen P.,Instituto Boliviano Of Investigacion Forestal |
Groenendijk P.,Wageningen University |
Vlam M.,Wageningen University |
And 9 more authors.
Nature Geoscience | Year: 2014
The biomass of undisturbed tropical forests has likely increased in the past few decades, probably as a result of accelerated tree growth. Higher CO2 levels are expected to raise plant photosynthetic rates and enhance water-use efficiency, that is, the ratio of carbon assimilation through photosynthesis to water loss through transpiration. However, there is no evidence that these physiological responses do indeed stimulate tree growth in tropical forests. Here we present measurements of stable carbon isotopes and growth rings in the wood of 1,100 trees from Bolivia, Cameroon and Thailand. Measurements of carbon isotope fractions in the wood indicate that intrinsic water-use efficiency in both understorey and canopy trees increased by 30-35% over the past 150 years as atmospheric CO2 concentrations increased. However, we found no evidence for the suggested concurrent acceleration of individual tree growth when analysing the width of growth rings. We conclude that the widespread assumption of a CO2-induced stimulation of tropical tree growth may not be valid. © 2014 Macmillan Publishers Limited. All rights reserved.
de Jong W.,Kyoto University |
Cano W.,Tropenbos International |
Cano W.,Center for International Forestry Research |
Zenteno M.,Tropenbos International |
Soriano M.,Instituto Boliviano Of Investigacion Forestal
Forest Policy and Economics | Year: 2014
We analyze legality in the forest sector in Bolivia, focusing particularly on the domestic timber value chain in the northern Bolivian Amazon. Bolivia adopted wide-reaching forest, land and democratic regulatory changes since the mid-1990s that were partly intended to reduce illegal logging and related practices. The new forest regulations, in turn, led to new illegal practices because implementation and sanctioning were poor, but also because new forest and land regulations were inadequate and often contradictory. In response, the government and various forest agencies adopted new measures to address the new illegal practices. These forest regulatory and forest policy renovations and modifications of the last two decades are, for instance, reflected in the domestic timber market of the northern Bolivian Amazon, a region that relies heavily on the forest sector. The paper analyzes Bolivia's regulatory changes that were relevant for legality in the forest sector and the multiple modifications that were made to address shortcomings of these reforms. It also analyses legality in the domestic timber value chain in northern Bolivia. The new actors involved in especially the domestic timber value chain have moved away from formal and legal mechanisms to benefit from timber that grows on their land and forests to practices that were not considered or actually shunned in the law and that appear difficult to regulate. Unless these new practices are recognized adequately in a new forestry law, some of the production and trade of the timber value chain will likely continue to operate at the margin of legality. © 2014 Elsevier B.V.
van der Sande M.T.,Wageningen University |
van der Sande M.T.,Instituto Boliviano Of Investigacion Forestal |
Zuidema P.A.,Wageningen University |
Sterck F.,Wageningen University
Oecologia | Year: 2015
Tropical forests are important in worldwide carbon (C) storage and sequestration. C sequestration of these forests may especially be determined by the growth of canopy trees. However, the factors driving variation in growth among such large individuals remain largely unclear. We evaluate how crown traits [total leaf area, specific leaf area and leaf nitrogen (N) concentration] and stem traits [sapwood area (SA) and sapwood N concentration] measured for individual trees affect absolute biomass growth for 43 tropical canopy trees belonging to four species, in a moist forest in Bolivia. Biomass growth varied strongly among trees, between 17.3 and 367.3 kg year−1, with an average of 105.4 kg year−1. We found that variation in biomass growth was chiefly explained by a positive effect of SA, and not by tree size or other traits examined. SA itself was positively associated with sapwood growth, sapwood lifespan and basal area. We speculate that SA positively affects the growth of individual trees mainly by increasing water storage, thus securing water supply to the crown. These positive roles of sapwood on growth apparently offset the increased respiration costs incurred by more sapwood. This is one of the first individual-based studies to show that variation in sapwood traits—and not crown traits—explains variation in growth among tropical canopy trees. Accurate predictions of C dynamics in tropical forests require similar studies on biomass growth of individual trees as well as studies evaluating the dual effect of sapwood (water provision vs. respiratory costs) on tropical tree growth. © 2015, The Author(s).