Papers by Hernan Castellanos
Global Ecology and Biogeography
AimTo investigate the geographic patterns and ecological correlates in the geographic distributio... more AimTo investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser‐availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource‐availability hypothesis).Time periodTree‐inventory plots established between 1934 and 2019.Major taxa studiedTrees with a diameter at breast height (DBH) ≥ 9.55 cm.LocationAmazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield.MethodsWe assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree‐inventory plots across terra‐firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We ...
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Science (New York, N.Y.), Mar 3, 2017
The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We per... more The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are five times more likely than nondomesticated species to be hyperdominant. Across the basin, the relative abundance and richness of domesticated species increase in forests on and around archaeological sites. In southwestern and eastern Amazonia, distance to archaeological sites strongly influences the relative abundance and richness of domesticated species. Our analyses indicate that modern tree communities in Amazonia are structured to an important extent by a long history of plant domestication by Amazonian peoples.
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Scientific Reports, 2019
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics ... more Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such “monodominant” forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree specie...
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Science, 2002
The high alpha-diversity of tropical forests has been amply documented, but beta-diversity—how sp... more The high alpha-diversity of tropical forests has been amply documented, but beta-diversity—how species composition changes with distance—has seldom been studied. We present quantitative estimates of beta-diversity for tropical trees by comparing species composition of plots in lowland terra firme forest in Panama, Ecuador, and Peru. We compare observations with predictions derived from a neutral model in which habitat is uniform and only dispersal and speciation influence species turnover. We find that beta-diversity is higher in Panama than in western Amazonia and that patterns in both areas are inconsistent with the neutral model. In Panama, habitat variation appears to increase species turnover relative to Amazonia, where unexpectedly low turnover over great distances suggests that population densities of some species are bounded by as yet unidentified processes. At intermediate scales in both regions, observations can be matched by theory, suggesting that dispersal limitation, w...
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PLoS Biology, 2008
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Biodiversity and Conservation, 2003
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Scientific Reports
Despite increasing attention for relationships between species richness and ecosystem services, f... more Despite increasing attention for relationships between species richness and ecosystem services, for tropical forests such relationships are still under discussion. Contradicting relationships have been reported concerning carbon stock, while little is known about relationships concerning timber stock and the abundance of non-timber forest product producing plant species (NTFP abundance). Using 151 1-ha plots, we related tree and arborescent palm species richness to carbon stock, timber stock and NTFP abundance across the Guiana Shield, and using 283 1-ha plots, to carbon stock across all of Amazonia. We analysed how environmental heterogeneity influenced these relationships, assessing differences across and within multiple forest types, biogeographic regions and subregions. Species richness showed significant relationships with all three ecosystem services, but relationships differed between forest types and among biogeographical strata. We found that species richness was positively...
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bioRxiv, 2021
In a time of rapid global change, the question of what determines patterns in species abundance d... more In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain almost ten times more of local relative abundances then constraints based on either directional or stabilizing selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale dat...
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Scientific reports, Jan 17, 2018
Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDM... more Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and MaxEnt predictions relates to a spatial abundance model, based on a large plot dataset for Amazonian tree species, using inverse distance weighting (IDW). We also propose a new pipeline to deal with inconsistencies in NHCs and to limit the area of occupancy of the species. We found a significant but weak positive relationship between the distribution of NHCs and IDW for 66% of the species. The relationship between SDMs and IDW was also significant but weakly positive for 95% of the species, and sensitivity for both analyses was high. Furthermore, the pipeline removed half of the NHCs records. Presence-only SDM applications should consider th...
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Emu, 2003
Large-scale patterns of Amazonian biodiversity have until now been obscured by a sparse and scatt... more Large-scale patterns of Amazonian biodiversity have until now been obscured by a sparse and scattered inventory record. Here we present the first comprehensive spatial model of tree a-diversity and tree density in Amazonian rainforests, based on the largest-yet compilation of forest inventories and bolstered by a spatial interpolation technique that allows us to estimate diversity and density in areas that have never been inventoried. These data were then compared to continent-wide patterns of rainfall seasonality.We find that dry season length, while only weakly correlated with average tree a-diversity, is a strong predictor of tree density and of maximum tree a-diversity. The most diverse forests for any given DSL are concentrated in a narrow latitudinal band just south of the equator, while the least diverse forests for any given DSL are found in the Guayana Shield and Amazonian Bolivia. Denser forests are more diverse than sparser forests, even when we used a measure of diversity that corrects for sample size. We propose that rainfall seasonality regulates tree a-diversity and tree density by affecting shade tolerance and subsequently the number of different functional types of trees that can persist in an area.
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Revista de Biología Tropical, 2012
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copernico.uneg.edu.ve
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Simposio Investigación y …
... A esta amenaza, se suma ahora la de minería (Castellanos, 2008). ... satanas Ateles belzebuth... more ... A esta amenaza, se suma ahora la de minería (Castellanos, 2008). ... satanas Ateles belzebuth Tayassu pecari Psophia crepitans Pecaritajacu Crax alector Cebus olivaceus M itu tom entosa Tinamus major Aburria cumanensis Dasyprocta leporina M azama americana Penelope ...
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Interciencia, 2006
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Adaptive Radiations of Neotropical Primates, 1996
... some tree species, and one liana species provided fruits with high caloric content, with a hi... more ... some tree species, and one liana species provided fruits with high caloric content, with a higher percentage of lipids than carbohydrates. This suggests that storing or accumulating fat by eating such fruits, when available, would provide an energetic reserve in long periods of ...
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Science, 2013
Introduction Recent decades have seen a major international effort to inventory tree communities ... more Introduction Recent decades have seen a major international effort to inventory tree communities in the Amazon Basin and Guiana Shield (Amazonia), but the vast extent and record diversity of these forests have hampered an understanding of basinwide patterns. To overcome this obstacle, we compiled and standardized species-level data on more than half a million trees in 1170 plots sampling all major lowland forest types to explore patterns of commonness, rarity, and richness. Methods The ~6-million-km 2 Amazonian lowlands were divided into 1° cells, and mean tree density was estimated for each cell by using a loess regression model that included no environmental data but had its basis exclusively in the geographic location of tree plots. A similar model, allied with a bootstrapping exercise to quantify sampling error, was used to generate estimated Amazon-wide abundances of the 4962 valid species in the data set. We estimated the total number of tree species in the Amazon by fitting t...
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Analise cladistica das sequencias dos genes Epsilon-globin a e IRBP fornece informacāe complement... more Analise cladistica das sequencias dos genes Epsilon-globin a e IRBP fornece informacāe complementar importante para urn esboco das principais linhas da filogenia dos macacos do Novo Mundo. As abordagens morfologicas e de genetica molecular sao razoavelmente consistentes com as evidencias disponiveis atraves do reg istro fossil , significando que as formas modernas fornecem uma boa base para o desenvolvimento de uma classificācao dos platirrineos, e que o entendimento das relacōes entre fosseis podem ser facil itados com a inclusao dos generos viventes nas analises. Os estudos moleculares e morfologicas fortalecem a ideia de tres grandes grupos modernos, possivelmente divergindo num intervalo de tempo relativamente curto . Considerando as discordâncias nos estudos da sistematica de platirrineos nas ultimas decadas - a correta localizacoo filogenetica de Cebus, Saimiri, Aotus e Callicebus - a cornbina#x00E7;oo das evidencias colocam Callicebus definitivamente como parente dos pitecineos. Elas reforcam tambem a ligacoo entre Saimiri e os calitriquineos, o elo entre Cebus e Saimiri, e sua associacoo com calitriquineos como uma linhagem monofiletica do grupo dos «cebideos». Os dados de DNA divergem, porem, com a colocacoo de Aotus como uma linhagem basal desse agrupamento, urn achado inconsistente com as evidencias morfologicas. A analise de DNA tambem aponta a necessidade de uma reconsideracoo da taxonomia do genero Callitrhix, que talvez noo seja monofiletica. Os dados confirmam parcialmente o padroo de ramificacoo do clade dos atelideos, posicionando Alouatta como a linhagem mais velha. Problemas que permanecem dentro dos calitriquineos e atelineos incluem: 1)os afinidades precisas entre os atelineos, Lagothrix, Ateles e Brachyt eles; e 2) a sequencia de ramificacoo dentre os calitriquineos, i.e., Callithrix/Cebuella, Leontopithecus , Saguinus e Callimico.
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The human role in the transformation of nature and the impacts of the significant changes that ha... more The human role in the transformation of nature and the impacts of the significant changes that have occurred over time have been accompanied by an increasing awareness of ecology and bioethics in human development. It is important to discuss the environment and its variability in several narratives from the perspective of human ecology. Human ecology examines anthropic relationship with the surrounding environment to describe and discuss complex problems, such as global warming, decreasing biodiversity, large-scale deforestation and human ethical bias. This study presents a reflexive analysis of the bioethical context from the human ecology perspective. The study’s purpose is to establish an eco-ethical conscience that enables us to rethink the future of our species and reaffirms the relevance of ethical, social and environmental values in pursuing the global common good.
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Scientific Reports
Amazonian forests are extraordinarily diverse, but the estimated species richness is very much de... more Amazonian forests are extraordinarily diverse, but the estimated species richness is very much debated. Here, we apply an ensemble of parametric estimators and a novel technique that includes conspecific spatial aggregation to an extended database of forest plots with up-to-date taxonomy. We show that the species abundance distribution of Amazonia is best approximated by a logseries with aggregated individuals, where aggregation increases with rarity. By averaging several methods to estimate total richness, we confirm that over 15,000 tree species are expected to occur in Amazonia. We also show that using ten times the number of plots would result in an increase to just ~50% of those 15,000 estimated species. To get a more complete sample of all tree species, rigorous field campaigns may be needed but the number of trees in Amazonia will remain an estimate for years to come.
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Papers by Hernan Castellanos