松嫩草原典型群落植硅体碳汇

Phytolith-occluded organic carbon sequestration of typical communities in Songnen grassland

植硅体碳汇是草原碳汇的重要部分。本研究选取松嫩草原中禾本科群落、莎草科群落、菊科群落为对象,通过湿式灰化法提取植硅体,并通过碱溶分光光度法对植硅体碳量进行测定。根据植硅体含碳量估算了松嫩草原的植硅体碳封存速率,探讨了禾本科群落、莎草科群落、菊科群落植硅体碳封存能力的差异。结果表明:松嫩草原的植硅体碳封存速率为1.67 kg CO2·hm^-2·a^-1。群落植硅体含碳量与植硅体含量之间有显著的负相关关系(P<0.05,R^2=0.94)。不同群落植硅体碳封存能力存在显著的差异,群落植硅体碳封存速率分别为:莎草科群落(2.151 kg CO2·hm^-2·a^-1)、禾本科群落(1.716 kg CO2·hm^-2·a^-1)、菊科群落(1.218 kg CO2·hm^-2·a^-1)。群落植硅体碳封存能力受到群落组成、地上净初级生产力、植硅体形成过程的影响。以上结果可为完善草原碳循环研究提供依据。

Phytolith-occluded organic carbon(PhytOC)sink is an important component of grassland carbon sink.In this study,we extract phytoliths by Walkley-Black type,from Poaceae community,Asreraceae community and Cyperaceae community in Songnen grassland.PhytOC was measured by alkali dissolution-spectrophotometry.PhytOC content of phytoliths,PhytOC content of biomass and phytolith content were calculated.We estimated the rate of PhytOC sequestration based on the amount of PhytOC in Songnen grassland and analyzed the differences in capacity of PhytOC sequestration among those three communities.The results showed that the average rate of PhytOC sequestration in Songnen grassland was 1.67 t CO2·hm^-2·a^-1.There was a significant negative correlation between phytolith content and PhytOC content of phytoliths(P<0.05,R^2=0.94).The capacity of PhytOC sequestration varied among different communities,with 2.151 kg CO2·hm^-2·a^-1 for Cyperaceae community,1.716 kg CO2·hm^-2·a^-1 for Poaceae community,and 1.218 kg CO2·hm^-2·a^-1 for Asreraceae community.PhytOC sequestration was affected by community composition,aboveground net primary productivity,and the formation processes of phytoliths.Our results could enrich the basis for studying grassland carbon cycling.