松嫩草原羊草草地的碳储量现状及其碳通量对刈割和氮添加的响应
发布时间：2019-05-21 08:19
【摘要】：最近30年来,碳循环作为陆地生态系统的重要生态功能受到前所未有的关注。草地是全球面积最大的陆地生态系统类型,割草和放牧是我国草地的最主要利用方式,同时氮沉降是草地生态系统面临的重要全球变化因子,然而它们对草地生态系统碳储量和碳通量的影响尚未有一致的结论。松嫩平原羊草草地作为全球气候变化响应的敏感区和生态系统脆弱区域,极易受到人类活动的干扰和全球气候变暖的影响。2013年和2014年连续2年采用野外观测、控制实验和室内分析结合的方法,对试验区羊草草地的植物地上部分、根系、凋落物和土壤的碳含量、生态系统气体交换特征等进行了研究,阐明了松嫩平原羊草草地碳储量现状以及刈割和氮沉降对松嫩平原羊草草地碳通量的影响。我们的研究结果表明,2013年和2014年羊草草地碳储量分别为321.1t/hm2、939.1t/hm2。松嫩平原2014年羊草草地地上地下生物量和草原碳储量是受2013年降雨量的影响,导致草地理化性质发生改变。2013年形成内涝,导致地上地下生物量下降,所以草地碳储量也相应减少,而2014年由于雨量充沛,温度增高,草地生长状况良好,地上地下生物量较往年明显增高,草地碳储量也明显增加。本研究在松嫩平原羊草草地通过同化箱法观测并对比了刈割和模拟氮沉降条件下生态系统碳通量的变化。结果表明,无论从季节动态还是日动态来看,氮添加处理的净生态系统气体交换量(NEE)、总生态系统呼吸(TER)和总生产系统生产力(GEP)总体上均高于对照,而刈割处理的NEE、TER和GEP均低于对照。就土壤呼吸而言,各处理间无显著差异。整个生长季中对照、刈割和氮添加处理累计碳释放量分别为107.78g·m-2·year-1、285.20 g·m-2·year-1 和 102.92 g·m-2·year-1。由此看来,整个实验区域是碳源,氮素添加可以在一定程度上减弱草地的碳源作用,且有向碳汇转变的趋势,而高频次和高强度刈割加重了草地的碳源作用。在生产实践上建议对草地实行轻度合理放牧和施肥管理,既能加强草地生态系统的生产功能,也能增加以碳固持为主的生态功能,从而实现草地生态系统的可持续利用。
[Abstract]:In the past 30 years, carbon cycle, as an important ecological function of terrestrial ecosystem, has received unprecedented attention. Grassland is the largest terrestrial ecosystem type in the world. Mowing and grazing are the most important ways of grassland utilization in China, and nitrogen deposition is an important global change factor faced by grassland ecosystem. However, there is no consistent conclusion on their effects on carbon reserves and carbon fluxes in grassland ecosystems. Leymus chinensis grassland in Songnen Plain, as a sensitive area of global climate change response and fragile area of ecosystem, is highly vulnerable to human activities and global warming. Field observations were used for two consecutive years in 2013 and 2014. The above ground part, root system, litter and soil carbon content and ecosystem gas exchange characteristics of Leymus chinensis grassland in the experimental area were studied by means of control experiment and laboratory analysis. The present situation of carbon storage in Leymus chinensis field in Songnen Plain and the effects of cutting and nitrogen deposition on carbon flux of Leymus chinensis grassland in Songnen Plain were expounded. The results of our study show that the carbon storage of Leymus chinensis grassland in 2013 and 2014 is 321.1 t / hm ~ 2939.1t / hm ~ 2. The above-ground and underground biomass and grassland carbon storage of Leymus chinensis grassland in Songnen Plain in 2014 were affected by rainfall in 2013, resulting in changes in physical and chemical properties of grassland. Waterlogging occurred in 2013, resulting in a decrease in above-ground and underground biomass. Therefore, the carbon reserves of grassland also decreased accordingly, but in 2014, due to abundant rainfall and higher temperature, the growth of grassland was good, the above-ground and underground biomass was significantly higher than in previous years, and the carbon storage of grassland was also significantly increased. In this study, the changes of carbon fluxes in ecosystems under cutting and simulated nitrogen deposition were observed and compared by assimilation box method in Songnen Plain Leymus chinensis grassland. The results showed that the net ecosystem gas exchange capacity (NEE), total ecosystem respiration (TER) and total production system productivity (GEP) were higher than those of the control in terms of seasonal and diurnal dynamics. The NEE,TER and GEP of cutting treatment were lower than those of the control. As far as soil respiration was concerned, there was no significant difference among the treatments. In the whole growing season, the cumulative carbon release of cutting and nitrogen addition treatments was 107.78 g 路m-2 路year-1285.20 g 路m-2 路year-1 and 102.92 g 路m-2 路year-1, respectively. Therefore, the whole experimental area is carbon source, nitrogen addition can weaken the carbon source effect of grassland to a certain extent, and there is a tendency to change to carbon sink, while high frequency and high intensity cutting aggravate the carbon source effect of grassland. In production practice, it is suggested that mild and reasonable grazing and fertilizer management of grassland can not only strengthen the production function of grassland ecosystem, but also increase the ecological function of carbon sequestration, so as to realize the sustainable utilization of grassland ecosystem.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812
[Abstract]:In the past 30 years, carbon cycle, as an important ecological function of terrestrial ecosystem, has received unprecedented attention. Grassland is the largest terrestrial ecosystem type in the world. Mowing and grazing are the most important ways of grassland utilization in China, and nitrogen deposition is an important global change factor faced by grassland ecosystem. However, there is no consistent conclusion on their effects on carbon reserves and carbon fluxes in grassland ecosystems. Leymus chinensis grassland in Songnen Plain, as a sensitive area of global climate change response and fragile area of ecosystem, is highly vulnerable to human activities and global warming. Field observations were used for two consecutive years in 2013 and 2014. The above ground part, root system, litter and soil carbon content and ecosystem gas exchange characteristics of Leymus chinensis grassland in the experimental area were studied by means of control experiment and laboratory analysis. The present situation of carbon storage in Leymus chinensis field in Songnen Plain and the effects of cutting and nitrogen deposition on carbon flux of Leymus chinensis grassland in Songnen Plain were expounded. The results of our study show that the carbon storage of Leymus chinensis grassland in 2013 and 2014 is 321.1 t / hm ~ 2939.1t / hm ~ 2. The above-ground and underground biomass and grassland carbon storage of Leymus chinensis grassland in Songnen Plain in 2014 were affected by rainfall in 2013, resulting in changes in physical and chemical properties of grassland. Waterlogging occurred in 2013, resulting in a decrease in above-ground and underground biomass. Therefore, the carbon reserves of grassland also decreased accordingly, but in 2014, due to abundant rainfall and higher temperature, the growth of grassland was good, the above-ground and underground biomass was significantly higher than in previous years, and the carbon storage of grassland was also significantly increased. In this study, the changes of carbon fluxes in ecosystems under cutting and simulated nitrogen deposition were observed and compared by assimilation box method in Songnen Plain Leymus chinensis grassland. The results showed that the net ecosystem gas exchange capacity (NEE), total ecosystem respiration (TER) and total production system productivity (GEP) were higher than those of the control in terms of seasonal and diurnal dynamics. The NEE,TER and GEP of cutting treatment were lower than those of the control. As far as soil respiration was concerned, there was no significant difference among the treatments. In the whole growing season, the cumulative carbon release of cutting and nitrogen addition treatments was 107.78 g 路m-2 路year-1285.20 g 路m-2 路year-1 and 102.92 g 路m-2 路year-1, respectively. Therefore, the whole experimental area is carbon source, nitrogen addition can weaken the carbon source effect of grassland to a certain extent, and there is a tendency to change to carbon sink, while high frequency and high intensity cutting aggravate the carbon source effect of grassland. In production practice, it is suggested that mild and reasonable grazing and fertilizer management of grassland can not only strengthen the production function of grassland ecosystem, but also increase the ecological function of carbon sequestration, so as to realize the sustainable utilization of grassland ecosystem.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812
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