Seasonal and Spatial Variation of Nitrogen Distribution for Leaves of Phyllostachys Pubescens and Its Response to Precipitation Exclusion

Abstract

The leaf nitrogen content in different canopy position for different ages of individuals for Phyllostachys pubescens was studied systematically with the season change in the experiment of precipitation exclusion in the bamboo field. The results showed that under different treatments (natural growth and precipitation exclusion treatment), the leaf nitrogen content of bamboo varied with seasons and in the decreasing order of spring, autumn, summer and winter. The change of leaf nitrogen content with bamboo age was also affected by the growing season. Precipitation exclusion treatment changed the seasonal and age difference of leaf nitrogen content in bamboo. In spring, the age differences in leaf nitrogen content of bamboo were significant (p<0.05). The leaf nitrogen content of bamboo varied with the height of the canopy, and the vertical distribution gradient was affected by the growing season. It increased with the increase of canopy height in summer and autumn, which also proved the applicability of the “light-nitrogen” hypothesis to the bamboo. Under two treatments, the leaf nitrogen content was linearly positively correlated with bamboo age. It changed with the change of soil water content in different growing seasons under treatments. Under precipitation exclusion, it was more sensitive to soil water content. This study confirmed the existence of the vertical distribution gradient of nitrogen in the leaves of P. pubescens and its variation with the growing season.