Effects Of Simulated Nitrogen Deposition On Leaf Functional Traits Of Common Species In Natural Pinus Tabulae Formis Forest In Taiyue Mountain,Shanxi,China

Aims Our objectives were to explore the effects of increased atmospheric nitrogen deposition on leaf traits and nutritional features of the common species in natural P. tabulaeformis forests.Methods We conducted a continuous control experiment of simulated nitrogen (N) deposition from 2009 to 2013 in Chinese-specific natural P. tabulaeformis forests in Taiyue Mountain, Shanxi, China. The fourlevels of N addition were 0,50,100 and 150 kg·hm-2·a-1 respectively, which were designated as control, low-N, medium-N and high-N treatment. We selected 11 common plant species in the plots,such asP. tabulaeformis,Quercus liaotungensis and Carex rigescens. A total of 11 leaf traits were measured to reveal the effects of atmospheic N deposition,including leaf thickness (LT) specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf phosphorus content (LPC) etc.Important findings Based on the data analysis, we found that: ①With increasing N deposition, the general trends of leaf traits of all species showed as:LT and SLA reduced, leaf area (LA) and LDMC have gone up, chlorophyll content (CC), LNC and LPC increased significantly,while leaf carbon content (LCC)remained. ②Species with different life forms and leaf age have different responses of leaf traits to simulated N deposition. The growth of P. Tabulaeformis (current year) and Swida bretchneideri were mainly restricted by N supply, P. Tabulaeformis (former year), Lonicera maackii and Carex rigescens were mainly restricted by phosphorus (P) supply, other 7 plants were unrestricted by N or P supply. After N addition, the restrictions of N and P were reduced. ③There were general correlations between leaf traits, butthey changed as N deposition. ④Compared with tree and shrub, leaves of herb tended to be thinner, growing faster, and shorter lifespan, belonging to "quick investment-return" species, while coniferous tree obviously tended to be "slow investment-return" species, which were consistent with the theory of Leaf Economic Spectrum (LES). Moreover, N deposition changed survival strategies, and propelled the position of plant species moving towards different directions. But the relative position of species and the location of community both stayed the same.