[Influence of mulching management on the relationships between foliar non-structural carbohydrates and N, P concentrations in Phyllostachys violascens stand].

To understand the physiological adaptive mechanism of Phyllostachys violascens to intensive mulching management, the effect of mulching management (CK, 1, 3 and 6 years) on the concentrations and ratios of non-structural carbohydrates (NSC), nitrogen (N) and phosphorus (P) in bamboo foliage, and their stoichiometry was investigated. The results showed the concentrations of NSC and soluble sugar increased, while the starch content and N/P decreased markedly in bamboo stand with 1-year mulching, compared to CK stand, which suggested the N limitation to bamboo growth was strengthened. Foliar soluble sugar content decreased significantly, while the starch content increased dramatically, and the NSC content by per unit mass of N and P reached the maximum in the bamboo stand with 3-year mulching, compared to all other treatments. Foliar NSC and soluble sugar contents decreased significantly, while foliar starch content and N/P increased dramatically in the stand with 6-year mulching, which suggested the P limitation to bamboo growth was strengthened. Foliar NSC content was positively correlated with N and P concentrations in a short-term mulching management stand (≤ 3 years), while showed negative relationship with N/P. The foliar starch content in the stand with 6-year mulching was negatively correlated with N and P contents, while was positively correlated with N/P. The results indicated that short-term mulching management accelerated the accumulation of soluble sugar and decomposition of starch in foliage, thus the growth and activity of Ph. violascens was enhanced greatly. Long-term mulching management promoted the starch accumulation, which led to the transition from N limitation to P limitation for bamboo growth. In summary, long-term (6 years) mulching management caused the decrease of growth and activity of Ph. violascens dramatically, thus enhancing the bamboo stand degradation. The utilization efficiency of N and P reached the highest in the stand with 3-year mulching, which implied 3-year was the best suitable period for intensive mulching management for maintaining bamboo stand quality.