凋落物的去除和添加对典型草原生态系统碳通量的影响

发布时间：2018-04-18 05:35

本文选题：凋落物 + 生态系统总初级生产力　；参考：《江西师范大学》2016年硕士论文

【摘要】：本文以中国科学院内蒙古草原生态系统定位站为平台,以内蒙古草地为研究对象,采用样地调查和生态系统CO_2净交换方法,探讨凋落物去除和添加对植物群落组成、地上生物量、土壤理化性质和碳通量的影响,我们连续两年(2013-2014年秋)分别在成熟群落中进行不同梯度的凋落物去除(对照、-50%、-100%)和退化群落中进行不同梯度的凋落物的添加实验(对照、+50%、+100%)。同时,开展了春秋对照实验,以揭示不同季节凋落物处理对草原生态系统碳通量影响的差异。在每年的生长旺季进行地上生物量,土壤水分含量,土壤温度的测定;利用静态箱法测定净生态系统碳通量(NEE)。取得的主要研究结果结论如下:1.不同梯度凋落物去除和添加处理对典型草原生态系统碳通量的影响结果表明:两种群落的生态系统净CO_2交换(NEE)有明显的季节性变化。凋落物连续去除对成熟群落的NEE和生态系统总初级生产力(GEP)变化规律一致,去除50%对GEP、NEE具有正效应,去除100%对GEP、NEE具有负效应;凋落物添加对退化群落的NEE和GEP均具有显著的影响,随着凋落物添加量的增加,GEP、NEE均显著增加。但凋落物的去除和添加除对生态系统总呼吸(ER)无显著影响。两类群落的GEP与10cm土壤温度呈显著正相关(P0.05),但GEP和NEE变化规律与土壤温度相反,与10cm土壤含水量相同。由此推断凋落物的去除和添加主要通过改变土壤含水量来影响GEP,从而影响生态系统的碳通量。2.不同季节凋落物去除和添加对典型草原生态系统碳通量的影响结果表明:在成熟群落中,凋落物的秋季去除对GEP和NEE的影响是正效应,对生态系统碳通量的影响显著大于春季去除凋落物的影响。秋季凋落物的去除通过影响土壤温度,进而影响GEP和NEE。凋落物过度积累会影响草地生产力,秋季凋落物的去除解除了凋落物过度积累对光的有效辐射和土壤温度的限制。在退化群落中,凋落物的春季添加对GEP和NEE的影响是正效应。春季凋落物添加显著于秋季凋落物的添加对GEP和NEE的影响。退化群落凋落物不能有效的积累,植物生长受到土壤养分和土壤水分等因素的限制,春季凋落物添加同时解除了以上限制,使植物能够快速生长。这对于理解凋落物的合理利用对改善草地生态系统管理,促进草地恢复,预测未来碳循环动态提供了理论依据。
[Abstract]:Based on the Inner Mongolia grassland ecosystem Positioning Station of the Chinese Academy of Sciences and the Inner Mongolia grassland as the research object, the plant community composition of litter removal and addition was studied by using the method of sample land investigation and ecosystem CO_2 net exchange.Effects of aboveground biomass, soil physical and chemical properties and carbon fluxes,For two consecutive years (autumn 2013-2014), we carried out litter removal with different gradients in mature communities (control -50-100) and litter addition experiments with different gradients in degraded communities (control, 50,100).At the same time, a control experiment was carried out in order to reveal the difference of carbon fluxes in grassland ecosystem by litter treatment in different seasons.The aboveground biomass, soil moisture content and soil temperature were measured in the growing season, and the net ecosystem carbon fluxes were measured by static box method.The main results obtained are as follows: 1. 1.The effects of different gradient litter removal and addition treatments on carbon fluxes of typical grassland ecosystems showed that the net CO_2 exchange between the two communities had obvious seasonal changes.The variation of NEE and total primary productivity of mature community was consistent with litter continuous removal, 50% of litter removal had positive effect on GEPNe and 100% of removal of 100% had negative effect on GEPNEE.Litter addition had a significant effect on NEE and GEP of degraded communities, and with the increase of litter addition, it also increased significantly.However, the removal and addition of litter had no significant effect on the total respiration of ecosystem.There was a significant positive correlation between the soil temperature of GEP and 10cm in the two communities, but the variation of GEP and NEE was contrary to the soil temperature and the soil water content of 10cm was the same.It is concluded that the removal and addition of litter mainly affect GEP by changing soil moisture content, thus affecting the carbon flux of ecosystem.The effects of litter removal and addition on carbon fluxes of typical grassland ecosystem in different seasons showed that the effects of litter removal on GEP and NEE were positive in mature communities.The effect on ecosystem carbon flux was significantly greater than that on litter removal in spring.The removal of litter in autumn affected GEP and NEE by affecting soil temperature.The excessive accumulation of litter will affect grassland productivity, and the removal of litter in autumn can relieve the effective radiation of the excessive accumulation of litter on light and the restriction of soil temperature.In degraded communities, the effects of litter addition on GEP and NEE in spring were positive.The effect of litter addition on GEP and NEE in spring was significantly higher than that in autumn.Litter accumulation was not effective in degraded communities, and plant growth was restricted by soil nutrients and soil moisture. The above restrictions were lifted simultaneously by litter addition in spring, so that plants could grow rapidly.This provides a theoretical basis for understanding the rational utilization of litter for improving grassland ecosystem management, promoting grassland restoration and predicting future carbon cycle dynamics.
【学位授予单位】：江西师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S812

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