Environmental control of canopy stomatal conductance in a tropical deciduous forest in northern Thailand

摘要: Abstract Tropical seasonal forests in Southeast Asia are among the most important biomes terms of global and local hydrologic carbon fluxes, their vulnerability to climate change. We conducted eddy flux measurements a teak ( Tectona grandis Linn. f.) plantation northern Thailand over 6-year period; this forest undergoes drastic change foliage with somewhat constant incident radiative energy. used combination actual evapotranspiration (ET) data an inversed version simple two-layer ET model for estimating mean canopy stomatal conductance g s ). The main novelty analysis is that can be extracted from total surface (including floor effects), thus environmental biological controls explicitly compared seasons years. relationship between variations leaf area index (LAI) revealed apparent effect age on gas exchange capacity: within year, peaked earlier than full-leaf expansion abruptly declined after peak LAI. result classify three stages: leaf-out, mid-growing, leaf-senescence seasons. Then, two ecophysiological parameters, reference value sref ), sensitivity atmospheric demand m as well proportion / were derived logarithmic response curve vapor pressure deficit (VPD) each season. showed variation follows: leaf-out season ≈ mid-growing season > leaf-senescence demonstrated little seasonality interannual was observed either parameter. This resulted almost 0.6 during season less mid-growing seasons, which suggests trees had strict regulation prevent excessive xylem cavitation (i.e., under drought conditions) moist when risk water stress-induced hydraulic failure would occur. In addition, we obtained linear soil moisture , powerful tool further research land–atmosphere interactions using vegetation dynamics models.