Long-Term Research in Environmental Biology: Costa Rica

Área de Conservación Guanacaste

The Área de Conservación (ACG) in northwestern Costa Rica is a large (113,000 terrestrial hectares or ~2% of Costa Rica, with an additional 43,000 marine hectares), permanently conserved, government-owned wildlands in northwestern Costa Rica that is climatically, hydrologically, ecologically, and taxonomically diverse. Its environments range from extensive dry forest in the lowlands and foothills near the Pacific Ocean to cloud forest atop the mountains and rain forest on the Caribbean foothills (view large map of ACG).

In 1999, the ACG was inscribed as a UNESCO World Heritage site representing the best dry forest habitats from Central America to northern Mexico. ACG is also the site of the largest forest restoration project in the tropics, with the ultimate goal of reestablishing a major tropical dry forest wildland from large remnants of pristine forest and reclaimed pasturelands.

ACG World Heritage site. View larger map.

Today, the ACG is a mosaic of successional stages — most mid-elevation (i.e., 200-500 m a.s.l.) hill slopes are still open grasslands/savannahs while other areas have already developed young forests. Extensive changes in species composition and productivity are expected as trees grow and early colonizing species are replaced by slow dispersing and shade tolerant species.

Forest regeneration will make the ACG watersheds not only invaluable biodiversity resources, but irreplaceable reference points for understanding the ecology of former dry forest landscapes that surround the  ACG and are being converted and managed as multi-purpose agroforests. At a time when tropical habitats are increasingly deforested and fragmented, this represents a unique research opportunity to study 100s of kilometers of streams flowing beneath a dry forest canopy.

Rivers and streams of the ACG View larger map.

With the backdrop of a natural and successional mosaic, we established the small to intermediate size streams of the ACG as a LTREB site in the Central American, tropical forest. We will address hypotheses regarding the response of stream ecosystems to large-scale, passive restoration of tropical forests, and to a steep moisture gradient (with spatial and temporal components). These hypotheses build upon the long-term database that Stroud Water Research Center has established for ACG streams, especially near Estación Biológica Maritza.

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