不同放牧退化程度典型草原植被—土壤系统的有机碳储量

以典型草原大针茅+羊草群落为研究目标,以1979年围封样地为参照(CK),选择轻度(GL)、中度(GM)、重度(GH)放牧退化样地开展植被—土壤系统有机碳分布与储量的研究,结果表明,1)不同放牧退化典型草原植被地上碳储量为42.63～203.16 g/m²,植被地下(0～40 cm)碳储量为664.14～1 199.53 g/m²,且大小顺序均为CK>GL>GM>GH,植被总碳储量CK和GL显著高于GM和GH;植被地上、地下碳储量存在显著相关关系。2)不同放牧退化典型草原土壤0～100 cm有机碳储量均存在显著性差异,碳储量为9.85～13.33 kg/m²,且GM>GL>GH>CK;土壤有机碳随土层深度增加而减少,有机碳储量与深度具有显著相关性。3)放牧退化典型草原植被—土壤系统的碳储量为11.26～14.07 kg/m²,且GM>GL>GH>CK,各类型间亦均存在显著性差异;有机碳主要储存于土壤当中,占比约88%～95%,土壤有机碳储量与植被无显著相关性。4)适度放牧利用有利于发挥草原生态系统的碳汇功能。

Organic carbon storage in vegetation-soil systems of typical grazing degraded steppes

Stipa grandis+Leymus chinensis grassland was analyzed for organic carbon storage and distribution in vegetation-soil systems under four different grazing degraded plots (CK:exclosed in 1979, GL:grazed lightly, GM:grazed moderately, GH:grazed heavily). The carbon storage in aboveground biomass was 42.63-203.16 g/m², in belowground biomass (0-40 cm) was 664.14-1 199.53 g/m², and the order in both was CK>GL>GM>GH. The total plant carbon storage in CK and GL were significantly higher (P<0.05) than in GM and GH. There was a significant positive correlation between the carbon storage in aboveground and belowground biomass. The carbon storage in the 0-100 cm soil depth among the different grazing degraded grasslands was 9.85-13.33 kg/m² and they were significantly different from each other in the order GM>GL>GH>CK. The carbon storage was significantly correlated with soil depth and was reduced with an increase of soil depth. The total carbon storage in the vegetation-soil system was 11.26-14.07 kg/m² and was significantly (P<0.05) different between the different grazing degraded grasslands in the order GM>GL>GH>CK. Grassland organic carbon was mostly stored in soil, which accounted for 88%-95% of the storage. There was no significant correlation between soil organic carbon and plant carbon. Moderate grazing can benefit the carbon sequestration function of grassland ecosystems.