SCHAEFER, DOUGLAS. A.; McDOWELL, WILLIAM H.; SCATENA, FREDRICK N.; ASBURY,CLYDE E. 2000. Effects of hurricane disturbance on stream water concentrations and fluxes in eight tropical forest watersheds of the Luquillo Experimental Forest, Puerto Rico. . Journal of Tropical Ecology 16:189-207
Abstract:
Stream water chemistry responds substantially to watershed disturbances,
but hurricane effects have not been extensively investigated in tropical
regions. This study presents a long-term (2.5-1 1 y) weekly record of stream water
chemistry on eight forested watersheds (catchment basins) in the Luquillo Mountains
of Puerto Rico. This includes a period before and at least 2 y after the
disturbance caused by the 1989 Hurricane Hugo. Nitrate, potassium and ammonium
concentrations increased after the hurricane and remained elevated for up
to 2 y. Sulphate, chloride, sodium, magnesium and calcium showed smaller relative
significant changes. Average stream water exports of potassium, nitrate and
ammonium increased by 13.1, 3.6 and 0.54 kg ha-' y-' in the first post-hurricane
year across all watersheds. These represent increases of 119, 182 and 102%
respectively, compared to the other years of record. The increased stream outputs
of potassium and nitrogen in the first 2 y post-hurricane are equivalent to 3%
(potassium) and 1% (nitrogen) of the hurricanederived plant litter. Effects of
hurricanes on tropical stream water potassium and nitrogen can be greater than
those caused by canopy gaps or limited forest cutting, but less than those following
large-scale deforestation or fire.