Tuesday 6
Forest governance and trajectories
Claude Garcia, Chris Kettle, Helene Dessard
› 11:30 - 12:30 (1h)
› JOFFRE 1-3
Tree species diversity along a gradient of agricutural landscapes in a Neotropical rain forest region: balances between conservation and production
Miguel Martinez-Ramos  1, *@  , Aline Pingarroni  1@  
1 : Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México  (CIEco-UNAM)  -  Website
Antigua Carretera a Pátzcuaro # 8701, Col. Ex-Hacienda de San José de la Huerta, CP 58190, Morelia, Michoacán -  Mexique
* : Corresponding author

Deforestation and forest conversion to agriculture in tropical regions has molded landscapes where remnant forest fragments are intermingled with agricultural fields and secondary forests. Presence of forest remnants in these landscapes is critical for the conservation of native biodiversity. In this context, we approached following questions: What is the trajectory of loss of native tree species in agricultural landscapes with increasing levels of deforestation? Is this lost proportional to the reduction in the old-growth forest cover? To what extend secondary forests can buffer the loss of tree diversity within human-modified landscapes? Is there a tipping-point of forest remnant after which species diversity collapse? In the Marqués de Comillas region, southeastern México, we evaluated changes in tree species diversity across a gradient of twelve human-modified landscapes (3 x 3 km2 each), where the cover of old-growth forest remnants varied between 5% and 100%. We used high-resolution satellite images to select and delimit the landscapes. At each landscape, we quantified the extension of different patch types (pasture, cultivars, plantations, orchards, secondary forests, and old-growth forests). In the center of each landscape, within a rectangular area of 1 km2, we established at random 30 sampling points; at each point, a circular plot (15-m radius) was delimited, where all trees with DBH ≥ 10cm were recorded, measured in DBH and height, taxonomically identified and classified as pioneer or non-pioneer. We find that species diversity declines in a concave way as remnant forest cover reduce. There was a tipping-point of rapid diversity loss when remnant forest cover was less than 20%. We discuss the importance of life history attributes of the species, habitat heterogeneity, and forest remnants for the conservation of tree species diversity in human-modified landscapes. Based on our results and those emerging from literature we approach the dilemma between production and conservation and provide policies that can favors the maintenance of high levels of species diversity in agricultural landscapes.


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