Leaf Nitrogen and Phosphorus Stoichiometry of Plants from Natural and Restorable Communities at Lands Used for Qinghai—ktibet Highway Construction, China

Abstract

Highway network construction is one of common factors contributing to alpine grassland degradation in the Qinghai-Tibet Plateau as well as other regions, resulting in big area land used for highway construction by abruptly removing the vegetation and topsoil on both sides of roadbed. Taking the Land Used for Qinghai-Tibet Highway Construction (LUQHC) produced in 1994 as an example, a field survey was conducted to investigate the leaf N, P stoichiometry of plants from natural communities and restorable communities by using all plants and same pairwise of species, because the natural vegetation restoration at LUQHC is driven by element availability to some extent. This study showed that plants were probably P-limited in study region and the variation of N:P ratio was closely related to leaf P concentration. Results of same pairwise of species showed that the leaf N, P and N:P ratio of plants from restorable communities were higher than those of adjacent natural communities, indicating that leaf N and P were simultaneously affected by the environment circumstance of LUQHC. However, results of all species showed that the environment factors only impacted on leaf N concentration. These showed that the plant in restorable communities suffered from more intense P-limited conditions than those in natural communities, and that the same pairwise of species sampling was better to acquire the N- or P-limitation status for plant in restorable communities than all species. This study also showed that phylogenetic variation (family and genus identity) was key factor affecting the variations of N, P stoichiometry.