Large-scale wind disturbances promote tree diversity in a Central Amazon forest

PLoS One. 2014 Aug 6;9(8):e103711. doi: 10.1371/journal.pone.0103711. eCollection 2014.

Abstract

Canopy gaps created by wind-throw events, or blowdowns, create a complex mosaic of forest patches varying in disturbance intensity and recovery in the Central Amazon. Using field and remote sensing data, we investigated the short-term (four-year) effects of large (>2000 m(2)) blowdown gaps created during a single storm event in January 2005 near Manaus, Brazil, to study (i) how forest structure and composition vary with disturbance gradients and (ii) whether tree diversity is promoted by niche differentiation related to wind-throw events at the landscape scale. In the forest area affected by the blowdown, tree mortality ranged from 0 to 70%, and was highest on plateaus and slopes. Less impacted areas in the region affected by the blowdown had overlapping characteristics with a nearby unaffected forest in tree density (583 ± 46 trees ha(-1)) (mean ± 99% Confidence Interval) and basal area (26.7 ± 2.4 m(2) ha(-1)). Highly impacted areas had tree density and basal area as low as 120 trees ha(-1) and 14.9 m(2) ha(-1), respectively. In general, these structural measures correlated negatively with an index of tree mortality intensity derived from satellite imagery. Four years after the blowdown event, differences in size-distribution, fraction of resprouters, floristic composition and species diversity still correlated with disturbance measures such as tree mortality and gap size. Our results suggest that the gradients of wind disturbance intensity encompassed in large blowdown gaps (>2000 m(2)) promote tree diversity. Specialists for particular disturbance intensities existed along the entire gradient. The existence of species or genera taking an intermediate position between undisturbed and gap specialists led to a peak of rarefied richness and diversity at intermediate disturbance levels. A diverse set of species differing widely in requirements and recruitment strategies forms the initial post-disturbance cohort, thus lending a high resilience towards wind disturbances at the community level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biodiversity*
  • Brazil
  • Forests*
  • Spacecraft*
  • Trees / physiology*
  • Wind*

Grants and funding

This study was financed by the Brazilian Council for Scientific and Technological Development (CNPq) [Projeto SAWI (Chamada Universal MCTI/N° 14/2012, Proc. 473357/2012-7) and INCT - Madeiras da Amazônia], by the National Aeronautics and Space Administration’s Biodiversity Program (Project 08-BIODIV-10), and by the Max-Planck-Institute for Biogeochemistry (BGC-Processes, Jena). The presented results are part of the first author’s PhD thesis, which incorporate data from his Master thesis, undertaken at the INPA/CFT, with fellowship funded by the Coordination for the Improvement of Higher Level Personal (CAPES). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.