We have focused on studying the interactions between plants and their environment. The objectives are to understand (1) the factors responsible for the distribution pattern of plants in Taiwan, and (2) the underlying acclimation and adaptation process that increase the fitness of individual phenotypes under different environment. In addition, we have applied stable isotope techniques to study functions, energy flow and nutrients cycling, of ecosystems.

Following subjects have been studied in the past five years.

1. Ecophysiological study of mangrove species in Taiwan. We have investigated the adaptation mechanisms of Kandelia candel to salinity and factors affecting the distribution pattern of mangrove species in Taiwan. We found that sensitivity to low winter temperatures is a primary limiting factor in the distribution of the mangrove species Avicennia marina along the western coast of Taiwan.

2. Ecophysiological study of wild soybeans in Taiwan. The wild soybeans in Taiwan have differentiated in their photosynthetic susceptibility to water availability and salinity. Different mechanisms are attributed to the inhibition effect of salinity on photosynthesis of the three species.

3. Photosynthetic characteristics of endemic plant species. ƒÔ13C ratio of endemic plant species are currently analyzed to identify photosynthetic pathways and to compare their long-term photosynthetic water use efficiency. The long-term goal of this study is to understand the photosynthetic characteristics of these endemic plants, especially those distributing at high elevations.

4. Carbon flux and nutrient dynamics in Yuanyang Lake Nature Preserve. Currently, we focus on investigating N acquisition mechanisms adapted by dominant plants species in this naturally acidified, nutrients limited forest.

5. Stable Isotopes Analyses and Trophic Linkages. Stable isotope ratios of carbon and nitrogen of biologically important components were analyzed to identify carbon sources that support the aquatic systems and to defining trophic positions of major components in different habitats of Lanyang River.

Kao, W.-Y. and H.-C. Tsai. 1999. Photosynthesis and chlorophyll a fluorescence in seedlings of Kandelia candel (L.) Druce grown under different nitrogen and NaCl controls. Photosynthetica 37, 405-412.

Kao, W.-Y., Y.-S. Chiu and W.-H. Chen. 2000. Vertical profiles of CO2 concentration and 13C values in a subalpine forest of Taiwan. Bot. Bull. Acad. Sin. 41, 213-218.

Kao, C.-P. Chen and P.-J. Liu. 2000. Detrital flows through the feeding pathway of the oyster (Crassostrea gigas) in a tropical shallow lagoon: ƒÔ13C signals. Marine Biology 136: 677-684.

Kao, W.-Y., C.-N. Shih, T.-T. Tsai, and L.L. Handley. 2002. Changes in d13C, d15N and nutrient contents in a mangrove species, Kandelia candel (L.) Druce, during leaf senescence. Bot. Bull. Acad. Sin. 43:277-282.

Kao, W.-Y., T.-T. Tsai and C.-N. Shih. 2003. Photosynthetic gas exchange and chlorophyll a fluorescence of three wild soybean species in response to NaCl treatments. Photosynthetica 41, 415-419.

Kao, W.-Y., C.-S. Lu and Y.-C. Chang. 2004. Foliar nutrient dynamics of five dominant plant species in Yuangyang Lake Nature Preserve, Taiwan. Taiwania 49: 49-56.

Kao, W.-Y., C.-N. Shih and T.-T. Tsai. 2004. Sensitivity to chilling temperatures and distribution differ in two mangrove species, Kandelia candel and Avicennia marina. Tree Physiology 24:859-864.