TITLE:
Effect of Land Use Change on Carbon Content and CO2 Flux of Cloud Forest Soils, Santa Elena, Costa Rica
AUTHORS:
Lawrence H. Tanner, David L. Smith, Jessica Curry, Justin Twist
KEYWORDS:
Cloud Forest; Secondary Succession; Soil Carbon; Soil Nitrogen; Soil CO2 Flux
JOURNAL NAME:
Open Journal of Soil Science,
Vol.4 No.2,
February
15,
2014
ABSTRACT: We investigated the effects of land-use changes on
soil carbon storage and soil CO2 flux by comparing soils from mature
cloud forest and 31-year-old secondary forest, both in the Santa Elena Forest
Reserve, a municipallyowned reserve at an elevation of 1600 to 1700 m near
the town of Monteverde, and a clear-cut pasture near the reserve. Soils in the
mature forest exhibit only weak horizonation but typically thick A horizons;
they also consistently yield the highest carbon contents in the upper 30 cm.
Soil CO2 flux was the highest in these soils, but also displayed the
highest spatial variability. Secondary forest soils contain substantially less
soil carbon than mature forest soils, but more than pasture soils. CO2 flux in the secondary forest soils was more similar to that of the mature
forest, but displayed lower spatial variability. The pasture soils contain less
soil carbon and produced lower CO2 flux levels than either of the
forest soils. The pasture soils typically contain a well-defined coarse sandy
layer 10 to 20 cm below the surface that we interpret as a sediment layer
deposited across much of the landscape following a widespread erosion event,
likely a consequence of the clear-cutting. Soil nitrogen concentrations are
more than an order of magnitude lower than soil carbon concentrations, and
display no trends between the different landscapes examined. Our preliminary
results suggest that reforestation does restore soil carbon to clear-cut
landscapes, but returning soil carbon levels to pre-land use levels occurs at a
time scale of centuries, rather than decades.