苔藓新老组织及其根际土壤的碳氮元素含量和同位素组成(δ^(13)C和δ^(15)N)对比

CONTENTS AND ISOTOPIC COMPOSITION OF C AND N IN MOSS(HAPLOCLADIUM MICROPHYLLUM)TISSUES AND SOIL RHIZOSPHERE

对细叶小羽藓(Haplocladium microphyllum)新老组织及其根际土壤的碳氮含量和同位素组成进行了分析,探讨了苔藓衰老过程控制元素和同位素变化的机制以及苔藓对土壤的贡献。同种组织碳氮含量之间的相关性反映了苔藓固碳能力和氮需求的相互联系。新生组织碳氮含量明显高于衰老组织且存在相关性,反映了苔藓衰老过程体内碳氮物质向新生组织迁移的生理特征。两种组织之间同位素组成(δ13C和δ15N)没有明显差异,说明组织间的物质迁移没有产生明显的同位素分馏,其原因可能在于细叶小羽藓形态结构简单,体内物质迁移对碳氮同位素组成的影响较小。相反,苔藓组织与根际土壤之间的有机碳/氮信息没有相关性,这可能与苔藓植物长期滞留营养物质、缓慢的分解和成土速度有关,反映了该研究区苔藓层对土壤碳氮累积的贡献较小。

Aims We investigated the new and senescent tissues of moss and the soil rhizosphere to determine 1）the elemental and isotopic composition characteristics during senescence and 2）the final contribution to soil.Methods C and N contents and isotopic composition（δ^13Cand δ^15Nof Haplocladium microphyllum and its soil rhizosphere were analyzed at Guiyang,China.Important findings The C and N contents were higher in new growing tissues than in senescent tissues,and there were significant correlations between the two types of tissues,indicating physiological malfunction（e.g.,loss of photosynthesis）and internal element redistribution during moss senescence.No significant difference was found between new and senescent tissues in isotopic composition,but their δ^13Cvalues or δ^15Nvalues were correlated,suggesting special isotopic regulation in the simple and nonvascular structure of mosses.In contrast,there was no C or N correlation between the moss tissues and soil.This was attributed to long-term nutrient retention and slow deposition to form soil,indicating the moss layer in this area has a small contribution to soil carbon and nitrogen.