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 (D₁), 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 D₄ 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 D₁ and D₂. With increasing stand density, theleaf N resorption capacity increased after an initial decrease, while the leaf P resorption capacity increased steadily. At stand densities D₁ -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. [ABSTRACT FROM AUTHOR]