STARCH AND NUTRIENT CONTENTS ARE KEY FOR MOSSES ADAPTING TO DIFFERENT SUCCESSION STAGES ALONG A RECEDING GLACIER

摘要

Mosses are the pioneer and the first green land plants developed during the evolutionary process, they play an important role in the development of soil, biogeochemical cycling and facilitating plant colonization. Although species richness, composition, diversity and cover of moss communities vary, they grow well almost in all forests. Why mosses can grow in different conditions? What are the adaptive strategies of mosses in different forests along primary succession sequences? It is not still completely clear. In order to answer these questions, nutrient and carbohydrate accumulation in mosses were tested along the primary succession following deglaciation of Hailuogou glacier, Gongga Mountain, China. Nitrogen (N), phosphorus (P), potassium (K) content, total organic carbon (TOC), soluble sugar and starch accumulated in the dominant moss species were determined and compared. TOC increased insignificantly with forest age. N, P, K contents in mosses were significantly higher in forests with dense shrubs, where N content was seperately 1.69% in A. hookeri and 1.35% in P. schreberi in 30 yr aged forest, P content in 30 yr and 52 yr aged forest was seperately 0.022% and 0.020% in A. hookeri and 0.020% and 0.017% in P. schreberi, and K content in 30 yr and 52 yr aged forest was seperately 0.570% and 0.553% in A. hookeri and 0.490% and 0.493% in P. schreberi. Soluble sugar was higher in the early stage of succession, but the opposite was observed for starch and non-structure carbohydrate content, which was lower in early successional stage. Mosses adopted different adaptive strategies in different aged forests along receding glacier, in which starch and N, P, K contents were key for adaptiation. That is, mosses accumulated much more starch in the severe environment of early succession stage. In more favourable environment, N, P, K was found to be accumulated for plant growth.