La Santisima Trinidad, Bolivia

Autonomous University of Beni
La Santisima Trinidad, Bolivia
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Hablutzel P.I.,Autonomous University of Beni | Hablutzel P.I.,Catholic University of Leuven | Pantel J.H.,CNRS Center of Evolutionary and Functional Ecology
Hydrobiologia | Year: 2016

In freshwater ecosystems, spatial turnover in fish assemblages is often attributed to dispersal limitation imposed by fragmentation of water bodies. Other factors like environmental properties or biotic interactions have often been assumed to be minute relative to dispersal limitation when hydrogeological barriers are abundant. This study aims to describe the spatial differentiation of cichlid fish assemblages in the upper río Madera in Bolivia, Brazil and Perú, a large drainage system characterized by the absence of significant hydrogeological barriers. We assessed the relative importance of spatial, climatic and geological predictors in the observed biogeographic structure using an integrative combination of cluster analyses, elements of metacommunity structure analysis, variation partitioning, and network analysis. Our results show that distinct assemblages of cichlid fish species replace each other across the landscape and that this turnover is partially determined by climate and geological gradients. A considerable fraction of the cichlid assembly structure could not be assigned to either space, climate or geology and might be explained by unmeasured parameters such as habitat structure or biotic interactions. Incorporating knowledge on spatial turnover of species assemblages into conservation strategies will be essential for the biodiversity management of the diverse aquatic fauna of the upper río Madera. © 2016 Springer International Publishing Switzerland

PubMed | Institute Investigaciones Of La Amazonia Peruana, James Cook University, University of Nottingham, Herbario Universitario and 39 more.
Type: Journal Article | Journal: Global change biology | Year: 2016

Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs.

PubMed | CIFOR, Jardin Botanico Joaquin Antonio Uribe, Red para la Mitigacion y Adaptacion al Cambio Climatico de la UNAD, Herbario Universitario and 63 more.
Type: | Journal: Scientific reports | Year: 2017

Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity.

Soliz-Gamboa C.C.,University Utrecht | Soliz-Gamboa C.C.,Autonomous University of Beni | Rozendaal D.M.A.,University Utrecht | Rozendaal D.M.A.,Autonomous University of Beni | And 4 more authors.
Trees - Structure and Function | Year: 2011

Knowledge on juvenile tree growth is crucial to understand how trees reach the canopy in tropical forests. However, long-term data on juvenile tree growth are usually unavailable. Annual tree rings provide growth information for the entire life of trees and their analysis has become more popular in tropical forest regions over the past decades. Nonetheless, tree ring studies mainly deal with adult rings as the annual character of juvenile rings has been questioned. We evaluated whether juvenile tree rings can be used for three Bolivian rainforest species. First, we characterized the rings of juvenile and adult trees anatomically. We then evaluated the annual nature of tree rings by a combination of three indirect methods: evaluation of synchronous growth patterns in the tree-ring series, 14C bomb peak dating and correlations with rainfall. Our results indicate that rings of juvenile and adult trees are defined by similar ring-boundary elements. We built juvenile tree-ring chronologies and verified the ring age of several samples using 14C bomb peak dating. We found that ring width was correlated with rainfall in all species, but in different ways. In all, the chronology, rainfall correlations and 14C dating suggest that rings in our study species are formed annually. © 2010 The Author(s).

Rozendaal D.M.A.,Netherlands Institute of Ecology | Rozendaal D.M.A.,Autonomous University of Beni | Soliz-Gamboa C.C.,Netherlands Institute of Ecology | Soliz-Gamboa C.C.,Autonomous University of Beni | And 2 more authors.
Forest Ecology and Management | Year: 2010

Most growth and yield models for tropical tree species use diameter growth data obtained from permanent sample plots. A potential disadvantage of this data source is that slow-growing, suppressed juvenile trees are included of which only a small fraction will attain harvestable size. If this is the case, the average growth rate of extant juvenile trees will be lower than the historical, juvenile growth rate of trees of harvestable size. Thus, if juvenile growth rates are obtained from permanent plots, future timber yield may be underestimated. To determine the magnitude of this effect we simulated tree growth based on two types of diameter growth data: long-term tree-ring data from harvestable trees ('lifetime growth data') and growth data of the last 10 years from trees of all sizes ('plot-type growth data'). The latter data type is a proxy for growth data from permanent sample plots. Second, we evaluated which percentage of harvestable timber volume at initial harvest is available at second harvest using lifetime growth data. We obtained tree-ring data from 89 to 98 individuals of three Bolivian timber species over their entire size range. Based on these data tree growth simulations were performed for two scenarios: a second harvest in 20, and in 40 years. A realistic degree of growth autocorrelation was incorporated in the growth projections, for both the lifetime and the plot-type growth data. Observed ages at the minimum cutting diameter in tree-ring data of harvestable trees were high: average ages varied from 63 to 179 years among species. Commercial ingrowth was 23-46% larger when using lifetime growth data than for plot-type growth data for two of the three species. Thus, the faster juvenile growth of trees that reached harvestable size indeed resulted in higher projected timber yield. In spite of the positive effect of higher juvenile growth on projected timber yield, our simulations showed that the recuperation of timber volume was low. Only 18-33% of the timber volume logged at first harvest could be obtained at second harvest after 20 years. For a second harvest after 40 years this was 26-49%. Based on our results we recommend the use of above-average growth rates in timber yield projections that apply permanent plot data. To determine which percentage of faster growers should be used in such simulations, it is important that similar analyses are conducted for more species. © 2010 Elsevier B.V. All rights reserved.

Rozendaal D.M.A.,University Utrecht | Rozendaal D.M.A.,Autonomous University of Beni | Rozendaal D.M.A.,Instituto Boliviano Of Investigacion Forestal Ibif | Brienen R.J.W.,University Utrecht | And 6 more authors.
New Phytologist | Year: 2010

Long-term juvenile growth patterns of tropical trees were studied to test two hypotheses: fast-growing juvenile trees have a higher chance of reaching the canopy ('juvenile selection effect'); and tree growth has increased over time ('historical growth increase'). Tree-ring analysis was applied to test these hypotheses for five tree species from three moist forest sites in Bolivia, using samples from 459 individuals. Basal area increment was calculated from ring widths, for trees < 30 cm in diameter. For three out of five species, a juvenile selection effect was found in rings formed by small juveniles. Thus, extant adult trees in these species have had higher juvenile growth rates than extant juvenile trees. By contrast, rings formed by somewhat larger juveniles in four species showed the opposite pattern: a historical growth increase. For most size classes of > 10 cm diameter none of the patterns was found. Fast juvenile growth may be essential to enable tropical trees to reach the forest canopy, especially for small juvenile trees in the dark forest understorey. The historical growth increase requires cautious interpretation, but may be partially attributable to CO2 fertilization. © 2009 New Phytologist.

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