Browsing by Autor "Eben N. Broadbent"

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Biomass resilience of Neotropical secondary forests
(Nature Portfolio, 2016) Lourens Poorter; Frans Bongers; T. Mitchell Aide; Angélica M. Almeyda Zambrano; Patricia Balvanera; Justin M. Becknell; Vanessa Boukili; Pedro H. S. Brancalion; Eben N. Broadbent; Robin L. Chazdon
Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon
(Public Library of Science, 2014) Eben N. Broadbent; Angélica M. Almeyda Zambrano; Gregory P. Asner; Marlene Soriano; Christopher B. Field; Harrison Ramos de Souza; Marielos Peña‐Claros; Rachel I. Adams; Rodolfo Dirzo; Larry Giles
Secondary forests cover large areas of the tropics and play an important role in the global carbon cycle. During secondary forest succession, simultaneous changes occur among stand structural attributes, soil properties, and species composition. Most studies classify tree species into categories based on their regeneration requirements. We use a high-resolution secondary forest chronosequence to assign trees to a continuous gradient in species successional status assigned according to their distribution across the chronosequence. Species successional status, not stand age or differences in stand structure or soil properties, was found to be the best predictor of leaf trait variation. Foliar δ(13)C had a significant positive relationship with species successional status, indicating changes in foliar physiology related to growth and competitive strategy, but was not correlated with stand age, whereas soil δ(13)C dynamics were largely constrained by plant species composition. Foliar δ(15)N had a significant negative correlation with both stand age and species successional status, - most likely resulting from a large initial biomass-burning enrichment in soil (15)N and (13)C and not closure of the nitrogen cycle. Foliar %C was neither correlated with stand age nor species successional status but was found to display significant phylogenetic signal. Results from this study are relevant to understanding the dynamics of tree species growth and competition during forest succession and highlight possibilities of, and potentially confounding signals affecting, the utility of leaf traits to understand community and species dynamics during secondary forest succession.
Recovery Of Forest Structure And Spectral Properties After Selective Logging In Lowland Bolivia
(Wiley, 2006) Eben N. Broadbent; Daniel J. Zarin; Gregory P. Asner; Marielos Peña‐Claros; Amanda Cooper; Ramon C. Littell
Effective monitoring of selective logging from remotely sensed data requires an understanding of the spatial and temporal thresholds that constrain the utility of those data, as well as the structural and ecological characteristics of forest disturbances that are responsible for those constraints. Here we assess those thresholds and characteristics within the context of selective logging in the Bolivian Amazon. Our study combined field measurements of the spatial and temporal dynamics of felling gaps and skid trails ranging from <1 to 19 months following reduced-impact logging in a forest in lowland Bolivia with remote-sensing measurements from simultaneous monthly ASTER satellite overpasses. A probabilistic spectral mixture model (AutoMCU) was used to derive per-pixel fractional cover estimates of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), and soil. Results were compared with the normalized difference in vegetation index (NDVI). The forest studied had considerably lower basal area and harvest volumes than logged sites in the Brazilian Amazon where similar remote-sensing analyses have been performed. Nonetheless, individual felling-gap area was positively correlated with canopy openness, percentage liana coverage, rates of vegetation regrowth, and height of remnant NPV. Both liana growth and NPV occurred primarily in the crown zone of the felling gap, whereas exposed soil was limited to the trunk zone of the gap. In felling gaps >400 m2, NDVI, and the PV and NPV fractions, were distinguishable from unlogged forest values for up to six months after logging; felling gaps <400 m2 were distinguishable for up to three months after harvest, but we were entirely unable to distinguish skid trails from our analysis of the spectral data.
Spatial partitioning of biomass and diversity in a lowland Bolivian forest: Linking field and remote sensing measurements
(Elsevier BV, 2008) Eben N. Broadbent; Gregory P. Asner; Marielos Peña‐Claros; Michael Palace; Marlene Soriano