不同草地利用方式对暖性(灌)草丛类草地固碳能力的影响

Effects of utilization patterns on the carbon sequestration capacity of warm-temperate tussock and shrub-tussock grasslands

利用方式差异对草地生态系统碳循环影响不同,评价不同利用方式下各类型草地生态系统固碳能力有助于制定相应生态管理策略,对减缓草地温室气体排放具有现实意义。采用野外调查和室内试验相结合的方法,对河南不同利用方式下(围封未利用、零散放牧+割草、季节性放牧和全年放牧)两种典型草地(暖性草丛和暖性灌草丛)固碳能力进行研究。结果表明,暖性草丛植被生物量在不同利用方式上表现为围封未利用>零散放牧+割草>季节性放牧>全年放牧,但差异不显著(P>0.05);而暖性灌草丛植被生物量在零散放牧+割草条件下显著大于围封未利用和全年放牧方式(P<0.05)。在围封未利用条件下,暖性草丛植被生物量显著大于暖性灌草丛(P<0.05)。两种草地地上碳密度和根系碳密度在不同利用方式下差异均不显著(P>0.05)。从植被碳密度来看,暖性草丛在不同利用方式下表现为围封未利用>零散放牧+割草>全年放牧>季节性放牧,暖性灌草丛为零散放牧+割草>围封未利用>季节性放牧>全年放牧。季节性放牧条件下暖性草丛土壤碳密度(13369.07g C·m^(-2))显著大于围封未利用方式(2544.25g C·m^(-2))(P<0.05);暖性灌草丛土壤碳密度在不同利用方式下表现为零散放牧+割草>围封未利用>季节性放牧>全年放牧,但差异不显著(P>0.05)。不论在何种利用方式下,两种类型草地的植被碳密度均主要由根系所贡献,分别达到87.42%与81.52%;而生态系统碳密度均主要由土壤所贡献,分别达到91.72%与84.98%。双因素方差分析表明,土壤碳密度是决定河南两种类型草地固碳能力的根本因素,而与利用方式无关。本研究可为河南草地资源合理利用提供科学依据,为精确评估河南草地固碳能力提供数据支撑。

Differences in utilization patterns affect the carbon cycle of grassland ecosystems.Evaluating the carbon sequestration capacity of grassland ecosystems under different utilization patterns will help to establish relevant ecological management strategies,and so have practical significance for mitigating greenhouse gas emissions from grasslands.Based on a field survey and laboratory tests,the carbon sequestration capacity of two typical grassland types(WT:warm temperate tussock,and WS:warm temperate shrub-tussock)under four utilization patterns(FUG:fenced and unexploited grassland,SMG:scattered grazin g+mown grassland,SGG:seasonally grazed grassland and AGG:all-year-grazed grassland)in Henan Province were studied.The results indicated that no difference was found in the vegetation biomass of WT(P>0.05).However,the vegetation biomass of WS under SMG was significantly greater than that of FUG and AGG(P<0.05).Under FUG,the vegetation biomass of WT was significantly greater than that of WS(P<0.05).No significant difference existed in the underground and root carbon density between WT and WS(P>0.05).With respect to the carbon density of vegetation(shoot+root),the management regimes ranked:FUG>SMG>AGG>SGG(2187.93-4211.56 g C·m-2)in WT.However,the soil carbon density of WT under SGG(13369.07 g C·m-2)was significantly greater than that of FUG(2544.25 g C·m-2)(P<0.05).For WS,the root carbon storage was no significant difference among them(P>0.05).For all utilization patterns,the root system was the major contributor to vegetation carbon density in both WT(87.42%)and WS(81.52%).With respect to the carbon density of the total grassland ecosystem,soil C(excluding roots),accounted for 91.72%and 84.98%of total C in WT and WS,respectively.Hence,soil carbon density was the major factor determining carbon sequestration capacity of both types of grassland,under all utilization patterns.This study provides scientific data to assist with rational allocation of grassland resources and for accurate assessment of carbon sequestration capacity of Henan grasslands.