Forest ecosystem responses to edge effects and secondary forest development in northeastern Costa Rica :implications for conservation


Schedlbauer, Jessica L.. (2007). Forest ecosystem responses to edge effects and secondary forest development in northeastern Costa Rica :implications for conservation. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Forest ecosystem responses to edge effects and secondary forest development in northeastern Costa Rica :implications for conservation
Schedlbauer, Jessica L.
Forest ecology--Costa Rica Forest conservation--Costa Rica Forests and forestry--Costa Rica--Water-supply
Natural Resources
The landscape of northeastern Costa Rica is characterized by fragmented forests interspersed with pasture and agricultural land. Knowledge of ecosystem responses to forest edge effects and the recruitment of new secondary forests is critical to regional conservation planning directed at increasing forest cover.;Forest structure was examined at 20+ year old forest-pasture edges to assess edge effects. Stem density was significantly higher at forest edges than interiors due to an increase in small diameter trees close to edges. These data show that forest edges seal with dense vegetation in the 20+ years following edge creation, suggesting that edges are robust and likely to promote high-value environmental services in these forests.;Measures of water-use efficiency (WUE) and stable carbon isotopes ([delta]{esc}p13{esc}sC) were used to evaluate changes in forest function at edges. No changes in foliar [delta]{esc}p13{esc}sC and thus WUE were detected in Pentaclethra macroloba, consistent with the theory that these forests develop resilient edges. A significant depletion in the [delta]{esc}p13{esc}sC of soil respired CO{esc}b2{esc}s was found at forest edges, and may be linked to changes in species composition.;Forest recruitment and carbon dynamics were examined in a chronosequence of secondary forests. Though aboveground carbon storage increased with site age, soil carbon storage did not vary. [delta]{esc}p13{esc}sC data showed that soil carbon turned over within 10 years of pasture abandonment. Rapid recovery of aboveground carbon storage and soil carbon cycling highlights the conservation value of these secondary forests.;To evaluate Costa Rica's 1996 Forestry Law initiating environmental service payments (pago por servicios ambientales, PSA) and prohibiting deforestation, landowner data were used to compare forest change before and after 1996. A decline in natural forest loss was observed after 1996. This indicated that PSA helped to retain forest, a finding corroborated by landowner data. Increased forest connectivity over time was related to recruitment of tree plantations and secondary forests. Secondary forest carbon storage approached primary forest levels after 25-30 years, but few landowners retained natural regeneration. As a result, secondary forests will persist as minor landscape components without incentives. This case study provides evidence that PSA can be effective in retaining natural forest.
Thesis (Ph. D., Natural Resources with a concentration in Tropical Forestry)--University of Idaho and Centro Agronómico Tropical de Investigación y Enseñanza, January 2007.
Major Professor:
Kathleen Kavanagh and Bryan Finegan.
Defense Date:
January 2007.
Format Original:
xiv, 94 leaves :ill., maps (some col.) ;29 cm.

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