PARENT SESSION
Oral Session # 56: Plant Ecology IV: Plant - Water Relations II.
Presiding: D Rosenthal
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Meeting Room 200.
Soil moisture release curves for two tropical forests having similar rainfall but distinct tree communities.
Kursar, Thomas*,1, Engelbrecht, Bettina1, Tyree, Melvin2, 1 Department of Biology, Salt Lake City, Utah2 USDA Forest Service, Burlington, Vermont
ABSTRACT- While primary productivity, plant distribution and plant diversity in tropical rainforests are correlated with water availability, the mechanisms that link plant productivity, distribution and diversity with differences among tropical rainforest soils in their ability to supply water to plants are not well understood. We compared two sites in Panama, BCI and Rio Paja, that have very similar rainfall but different plant communities. The Rio Paja site has plants that are typical of much wetter forest. Soil water release curves were obtained from about -0.1 MPa to -9 MPa. We found that the Rio Paja site actually has a much more porous soil than does the BCI soil. Soil moisture release data alone are not sufficient to explain the observed distribution and diversity patterns. Nevertheless differences among soils in their abilities to supply water to plants likely help determine distribution and abundance in tropical forests. A comparison of moisture release data with other commonly used measures of soil water availability such as gravimetric water content, indicate that moisture release data provide a better understanding of the capacity of these soils to supply water to plants.
Key words: water stress, diversity, plant distribution