灌丛斑块和草本斑块碳交换对季节性降水增加的响应——基于地上净初级生产力和叶面积指数标准化的比较分析  

Response of carbon exchange between shrub and grass patches to increased seasonal precipitation:a comparative analysis based on aboveground net primary productivity and leaf area index standardization

作　　者：张梦迪 向官海 文艺瑶 王欢 呼格吉勒 白永飞[2,4] 王忠武 郑淑霞 ZHANG Meng-Di;XIANG Guan-Hai;WEN Yi-Yao;WANG Huan;Hugejile;BAI Yong-Fei;WANG Zhong-Wu;ZHENG Shu-Xia(College of Grassland,Resources and Environment,Inner Mongolia Agricultural University,Hohhot 010018,China;State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China;College of Agriculture,Chifeng University,Chifeng,Nei Mongol 024000,China;China National Botanical Garden,Beijing 100093,China;College of Life Sciences,Jiangxi Normal University,Nanchang 330022,China;College of Life Sciences,Shandong Agricultural University,Tai’an,Shandong 271001,China;Grassland Workstation of Zhenglan Banner,Xilinhot,Nei Mongol 027200,China)

机构地区：[1]内蒙古农业大学草原与资源环境学院,呼和浩特010018 [2]中国科学院植物研究所植被与环境变化国家重点实验室,北京100093 [3]赤峰学院农学院,内蒙古赤峰024000 [4]国家植物园,北京100093 [5]江西师范大学生命科学学院,南昌330022 [6]山东农业大学生命科学学院,山东泰安271001 [7]正蓝旗草原工作站,锡林浩特027200

出　　处：《植物生态学报》2024年第8期1035-1049,共15页Chinese Journal of Plant Ecology

基　　金：国家重点研发计划(2023YFF1305301);国家自然科学基金(32371779)。

摘　　要：随着气候变化和人类活动干扰的加剧,干旱半干旱地区草地灌丛化现象普遍发生,严重影响了草地生态系统的碳汇功能。水分是内蒙古半干旱草原的主要限制因子,未来降水格局的变化对草原生态系统的碳交换具有重要影响。然而,目前关于降水变化对灌丛化草地生态系统,特别是异质斑块碳交换过程的影响研究较少,相关机制尚不清楚。为此,该研究利用内蒙古小叶锦鸡儿(Caragana microphylla)灌丛化草地季节性降水增加(冬季增雪、夏季增雨)实验平台,系统观测了灌丛斑块和草本斑块的碳交换参数,即净生态系统碳交换(NEE)、总生态系统生产力(GEP)、生态系统呼吸(ER),并结合基于地上净初级生产力(ANPP)和叶面积指数(LAI)标准化的参数比较分析,研究了季节性降水增加对灌丛化草地碳交换的影响以及异质斑块的响应差异。结果表明:1)夏季增雨显著提高了草本斑块|NEE|、GEP和ER值,而冬季增雪显著降低了草本斑块|NEE|ANPP、GEPANPP和ERANPP。夏季增雨显著增加了灌丛斑块GEP和ER值,但对NEE影响不明显,冬季增雪对灌丛斑块的碳交换过程有促进作用。总体而言,灌丛斑块的|NEE|、GEP、ER显著高于草本斑块。相较于湿润年份(2021年),干旱年份(2020年)的碳交换对降水增加的响应更为敏感。2)灌丛斑块碳交换(|NEE|、GEP和ER)与土壤水分含量、叶片生物量呈正相关关系,夏季增雨主要通过增加深层土壤(40-80 cm)水分含量、降低土壤温度来促进碳交换。草本斑块碳交换与浅层土壤(0-20 cm)水分含量、ANPP呈正相关关系,与土壤温度、根冠比呈负相关关系;夏季增雨主要通过增加浅层土壤水分含量、降低土壤温度促进碳交换,而冬季增雪则通过增加深层土壤水分含量和减少地下生物量来抑制草本斑块碳交换。3)基于ANPP标准化后的碳交换参数能更好地揭示灌丛斑块和草本斑块对降水变化的响应差�Aims With the intensification of climate change and human activities,the phenomenon of shrub encroachment in arid and semi-arid grasslands is widespread,significantly impacting the carbon sequestration function of grassland ecosystems.Water availability is the primary limiting factor in the semiarid grassland of Nei Mongol,and future changes in precipitation patterns have important implications for carbon exchange in grassland ecosystems.However,there is limited research on the effects of precipitation changes on shrub-encroached grassland ecosystems,particularly on the carbon exchange processes within heterogenous patches.The underlying mechanisms remain unclear.Methods In this study,we conducted a seasonal precipitation manipulation experiment by increasing snowfall in winter and rainfall in summer in shrub-encroached grassland dominated by Caragana microphylla in Nei Mongol.Carbon exchange parameters,such as net ecosystem carbon exchange(NEE),gross ecosystem productivity(GEP),and ecosystem respiration(ER)of shrub patches and grass patches,were measured and compared using standardized parameters based on aboveground net primary productivity(ANPP)and leaf area index(LAI).The study investigated the impact of increased seasonal precipitation on carbon exchange in shrub-encroached grassland and the differential responses of heterogeneous patches.Important findings 1)Increased summer rainfall significantly enhanced|NEE|,GEP and ER of the grass patches,while increased winter snowfall significantly reduced|NEE|ANPP,GEPANPP and ERANPP of the grass patches.Increased summer rainfall significantly enhanced the GEP and ER of the shrub patches,while the effect on|NEE|was not significant.Additionally,increased winter snowfall had a positive impact on carbon exchange processes in the shrub patches.Overall,|NEE|,GEP and ER of the shrub patches were significantly higher than those of the grass patches.In comparison to a wet year(2021),the carbon exchange in a dry year(2020)was more sensitive to increased precipitation.2)Carbon

关 键 词：净生态系统碳交换(NEE) 总生态系统生产力(GEP) 生态系统呼吸(ER) 灌丛斑块 草本斑块 冬季增雪 夏季增雨 灌丛化 

分 类 号：Q948[生物学—植物学]