[Effects of stand density on Oligostachyum lubricum leaf carbon, nitrogen, and phosphorus stoichiometry and nutrient resorption].

Taking pure Oligostachyum lubricum forest as test object, this paper studied the matured and withered leaves carbon (C), nitrogen (N), and phosphorus (P) stoichiometry and N and P resorption patterns of 1-3 years old stands at the densities of 24600-29800 stem hm-2 (D, ), 37500-42600 stem hm-2 (D2 ), 46500 - 52800 stem hm-2 (D3), and 76500 - 85500 stem hm-2 (D4). With increasing stand density, the matured leaves C, N, and P contents and withered leaves C and P contents had an overall decrease, the withered leaves N content decreased after an initial increase, and the matured leaves C content at density )4 decreased dramatically. The leaf C/N and C/P ratio increased with increasing stand density, whereas the leaf N/P ratio increased first but decreased then. At stand densities D3 and D4, the leaf N and P utilization efficiencies were significantly higher than those at D, and D2. With increasing stand density, the leaf N resorption capacity increased after an initial decrease, while the leaf P resorption capacity increased steadily. At stand densities D,-D3, the matured leaves N/P ratio was 16.24-19.37, suggesting that the P limitation occurred, leaf establishment increased, and population increase and expansion enhanced. At density D4, the matured leaves N/P ratio was 13.42-15.74, implying that the N limitation strengthened, leaf withering and defoliation increased, and population increase inhibited. All the results indicated that O. lubricum could regulate its leaf C, N and P contents and stoichiometry and enhance the leaf N and P utilization efficiency and resorption capacity to adapt to the severe competition of environment resources at high stand density. In our experimental condition, 46500-52800 stem hm-2 could be the appropriate stand density for O. lubricum management.