Geography Publications and Other Works

Source Publication (e.g., journal title)

Kappelle, M. and Horn, S.P. (Eds.), Páramos de Costa Rica. Santo Domingo de Heredia, Costa Rica: Instituto Nacional de Biodiversidad, INBio.

Document Type

Book Chapter

Publication Date

2005

Abstract

We examined pollen, pteridophyte (ferns and fern-allies) spores, and charcoal in a 5.6 m long sediment core from Lago de las Morrenas 1, and charcoal in a 1.1 m long sediment core from Lago Chirripó, to reconstruct postglacial vegetation and fire history in the Chirripó páramo. Lago de las Morrenas 1, the largest lake in the Valle de las Morrenas of Chirripó National Park, is presently surrounded by treeless páramo vegetation and has apparently been so since deglaciation approximately 10,000 radiocarbon years ago. Pollen spectra suggest no pronounced changes in vegetation since ice retreat. Pollen percentages for Gramineae and other páramo taxa decline upward, whereas percentages for certain subalpine, lower montane, and lowland forest taxa increase slightly; these changes may reflect the impact of prehistoric human activity as well as slight upslope migration of forest taxa owing to postglacial climatic warming. Cores from both lakes contain abundant microscopic charcoal (examined on microscope slides) as well as macroscopic charcoal (quantified by sieving), indicating that fires set by people or lightning have repeatedly burned the Chirripó páramo. The microscopic charcoal record from Lago Chirripó spans the last 4,000 radiocarbon years and shows peaks in fire activity that generally match peaks in the corresponding section of the Lago de las Morrenas 1 microscopic charcoal record. The uppermost sections of both sediment cores show lower charcoal influx rates than some deeper sections, suggesting that recent fire recurrence intervals in the Chirripó páramo are not unprecedented. A high-resolution analysis of macroscopic charcoal in contiguous 1-cm intervals of the Lago de las Morrenas 1 core confirms that fires burned within the lake watershed throughout the Holocene, and reveals variations in charcoal influx that may signal Holocene climate variability.

Submission Type

Publisher's Version

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