Response of stomatal characteristics and its plasticity to different light intensities in leaves of seven tropical woody seedlings
七种热带雨林树苗叶片气孔特征及其可塑性对不同光照强度的响应

Stomatal characteristics and its plasticity in leaves of four canopy species, Shorea chinensis, Pometia tomentosa, Anthocephalus chinensis, Calophyllun polyanthum and three middle-layer species, Barringtonia pendula, Garcinia hanburyi, Horsfieldia tetratepala acclimated to different light conditions (8%, 25%, 50% and 100% of full sunlight) for more than one year were surveyed. All plant's stomata were distributed on the abaxial of leaves. Pometia tomentosa and Barringtonia pendula had higher stomatal density, and the guard cell length of Anthocephalus chinensis and Calophyllun polyanthum were much greater than others'. Stomatal density and stomatal index (ratio of stomatal numbers to epidermal cell number) were increased with growth irradiance increased, while numbers of stomata per leaf were higher in the low than the high relative PFD, and stomatal conductance of leaves was the highest in the 50% of sunlight except for Anthocephalus chinensis. The relative PFD had little effects on the guard cell length of all seven plants. There was a significant negative correlation between stomatal density and leaf area, but the stomatal conductance was not significantly positive with the stomatal conductance in some degree. The analysis of phenotypic plasticity of stomatal characteristics showed that plasticity index for stomatal index and numbers of stomatal per leaf were similar for canopy and middle-layer species, while the plasticity index of stomatal density and stomatal conductance were significantly greater for canopy species than middle-layer species. The high plasticity of canopy species was consistent with the hypothesis that specialization in a more favorable environment increases plasticity.