Effect of precipitation condition on photosynthesis and biomass accumulation and referring to splash erosion status in five typical evergreen tree species in humid monsoon climatic region of subtropical hill-land

摘要

Negative effect of precipitation on plant photosynthesis was investigated in this work. Stomatal conductance, transpiration rate and net photosynthetic rate were measured before and after each precipitation event, respectively, and the corresponding precipitation was recorded as well. Moreover, plant dry matter accumulation was counted at the end of our entire experiment. The results show that precipitation fully demonstrates its negative effect on plant photosynthesis under the condition of without water shortage. Although it has not been proved, leaf shape seems to be associated with this effect. Broad-leaved species are less influenced than coniferous and lanceleaf species no matter on the length of variation time or changes in variation values. The different situation among three broad-leaved species seems to illustrate that the effect is also related to the size of single leaf area. The correlation between precipitation and photosynthetic rate variation is analogous to the relationship between precipitation and splash erosion, and in the view of the relationship between plant photosynthetic characteristics and dry mass accumulation, it can be thought that it can reflect the negative impact of precipitation on plant growth by making use of splash erosion. Therefore, a section was added in the traditional plant biomass estimation algorithms by using eco-physiological models, and this was proved to enhance the accuracy of traditional estimation from preliminary verifications.