Studies on forest ecosystem physiology: marginal water-use efficiency of a tropical, seasonal, evergreen forest in Thailand
- 132 Downloads
Marginal water-use efficiency plays a critical role in plant carbon–water coupling relationships. We investigated the ecosystem marginal water-use efficiency (λ) of a tropical seasonal evergreen forest to (1) determine the general pattern of λ across time, (2) compare different models for calculating λ, and (3) address how λ varies with soil water content during different seasons. There was a U-shaped diurnal pattern in λ, which was higher in the early morning and late afternoon. At other times of the day, λ was lower and remained constant. Ecosystem λ was higher in the wet season than in the dry season. All three models successfully captured the diurnal and seasonal patterns of λ but differed in the calculated absolute values. The idea that λ is constant on a subdaily scale was partly supported by our study, while a constant λ was only true when data from the early morning and late afternoon were not included. The λ increases with soil water content on a seasonal scale, possibly because early morning λ remained low in dry conditions when the soil water content was low.
KeywordsCanopy conductance Stomatal optimization Soil moisture Photosynthesis model
We acknowledge AsiaFLUX for providing the data set and Emeritus Professor Minoru Gamo for data sharing. This study was supported by National Natural Science Foundation of China (NSFC Nos. 31660142 and 41771099).
- Beerling DJ (2007) The emerald planet: how plants changed Earth’s history. Oxford University Press, Oxford, pp 9–34Google Scholar
- Cowan IR (1977) Stomatal behaviour and environment. Adv Ecol Res 4:117–228Google Scholar
- Cowan I (1982) Regulation of water use in relation to carbon gain in higher plants. In: Lange OL et al (eds) Physiological plant ecology II. Water relations and carbon assimilation. Springer, Berlin, pp 589–614Google Scholar
- Cowan IR, Farquhar GD (1977) Stomatal function in relation to leaf metabolism and environment. In: Jennings DH (ed) Integration of activity in the high plant. Cambridge University Press, London, pp 471–505Google Scholar
- Darwin F (1898) Observations on stomata. Proc R Soc Lond 63:413–417Google Scholar
- Farquhar GD, O’Leary MH, Berry JA (1982) On the relationship between carbon isotope discrimination and the intercellular carbon dioxide concentration in leaves. Aust J Plant Physiol 9(2):281–292Google Scholar
- Givnish TJ (1986) Optimal stomatal conductance, allocation of energy between leaves and roots, and the marginal cost of transpiration. In: Givnish TJ (ed) On the economy of plant from and function, vol 115, no 4. Bull. Torrey Bot. Club, New York, p 319Google Scholar
- Tan ZH, Zhang YP, Yu GR et al (2008) Spatial and temporal dynamics of CO2 concentration and its causes in Xishuangbanna tropical seasonal rain forest, China. Chin J Plant Ecol 32:555–567Google Scholar
- Willmer C, Fricker M (1996) Stomata, 2nd edn. Springer, New York, pp 92–106, 126–177Google Scholar
- Yamakura T (1987) An empirical approach to the analysis of forest stratification: I. Proposed graphical method derived by using an empirical distribution function. J Plant Res 100:109–128Google Scholar