放牧和降水量对内蒙古草原生物多样性和生产力的影响

发布时间：2018-01-31 02:25

本文关键词： 草地生产力物种多样性放牧降雨地上部分干物质内蒙古自治区　出处：《中国农业大学》2015年博士论文　论文类型：学位论文

【摘要】：明确放牧扰动、气候变化和生物多样性对牧草产量形成的影响对于优化牧场管理以及牧草保持具有重要的意义。因此,在我们当前的研究中,目的在于分析放牧、生物多样性、气候变化对内蒙古半干旱草原牧草产量形成的影响。研究发现,在典型草原和草甸草原处理中,放牧区和非放牧区牧草地上部生物量存在显著的差异,其中,放牧的地方牧草地上部分干物质质量显著低于未放牧草地。我们还发现,在这些半干旱草原,生长季降雨与牧草地上部干物质质量存在显著的正相关关系。降水利用效率(RUE)是一个非常重要的指标,能够用于标识内蒙古半干旱草地生态系统降雨模式变化对牧草产量形成的响应。我们研究发现,在湿润的2012年,草地RUEADM出现最小值,而在干旱的2008年,它出现最大值。在典型大草原生态系统和沙漠大草原生态系统中,RUEADM和RUETDM间不存在显著相关性,而相比RUEADM, RUETDM与每年的降雨(AP)以及生长季节降雨(GSP)具有显著的相关性。因此, RUEADM不能被用于代替RUETDM。另外,RUEADM随着物种丰度增加而增加。在草甸草原生态系统,典型草原生态系统和荒漠草原生态系统中,RUEADM和物种丰度显著相关。而且,三种草原生态系统中C3和C4作物地上部分干物质质量比值显著不同。C4作物为主的区域地上部分干物质质量显著最高,而在C3作物为主的区域或者C3和C4混合区域,物种丰度指数和Simpson指数间存在显著的线性相关性。但是,在一些C4作物主控区,地上干物质质量与物种丰度和多样性间不存在显著的相关。因此,在内蒙古半干旱草地生态系统中C3作物主控区以及C3、C4作物混合区对于生物多样性保存具有非常重要的作用。其中,豆科作物是自然草地生态系统的重要组成部分,它对于草地生态系统可持性具有非常重要的意义。研究区豆科作物占68.8%,该区的主控作物为豆科属作物,比如,紫云英属、苜蓿属和锦鸡儿属。三年平均地上干物质为5.97g m-2,能够解释群体地上部分总干物质变化的5.02%。在内蒙古自治区,豆科作物地上部分干物质以及占地上部总干物质的比值降低。因此,我们认为,内蒙古半干旱草地生态系统,作物生育期内降雨少、温度高,严重影戏一年生豆科作物生长发育。总之,我们研究表明过度放牧以及有限的降雨是草地生态系统退化的主要原因,可持续放牧管理策略将有助于这些草原生态系统的保持。
[Abstract]:It is important to clarify the effects of grazing disturbance, climate change and biodiversity on forage yield formation for optimal rangeland management and forage conservation. The purpose of this study was to analyze the effects of grazing, biodiversity and climate change on forage yield in semi-arid grassland of Inner Mongolia. There were significant differences between herbage aboveground biomass in grazing area and non-grazing area, among which, dry matter quality of grazing area was significantly lower than that of ungrazed grassland. We also found that in these semi-arid grasslands, dry matter quality was significantly lower than that in ungrazed grassland. There is a significant positive correlation between rainfall and dry matter quality in the aboveground part of forage in growing season. Precipitation utilization efficiency (Rue) is a very important indicator. It can be used to identify the response of rainfall pattern changes in semi-arid grassland ecosystem to forage yield in Inner Mongolia. We found that grassland RUEADM appeared minimum on humid 2012. In 2008 of drought, it reached its maximum value. There was no significant correlation between RUEADM and RUETDM in typical steppe ecosystem and desert steppe ecosystem. Compared with RUEADM, RUETDM has a significant correlation with annual rainfall (APP) and growing season rainfall (GSPs). RUEADM cannot be used as a substitute for RUETDM. in addition, RUEADM increases with the increase of species abundance in meadow steppe ecosystems. RUEADM and species abundance in typical steppe ecosystem and desert steppe ecosystem were significantly correlated. Among the three grassland ecosystems, the dry matter ratios of the aboveground parts of C3 and C4 crops were significantly different. The dry matter ratios of the aboveground parts of the three steppe ecosystems were the highest in the regions dominated by C4 crops. However, there was a significant linear correlation between the species abundance index and Simpson index in the region dominated by C3 crops or in the mixed region of C3 and C4. However, there was a significant linear correlation between the species abundance index and the Simpson index in some C4 crop control areas. There was no significant correlation between aboveground dry matter quality and species abundance and diversity. The C _ 4 crop mixed area plays an important role in the conservation of biodiversity, in which legume is an important part of natural grassland ecosystem. It is of great significance for the sustainability of grassland ecosystem. In the study area, the legume crops account for 68.8%, and the main controlling crops in the study area are legumes, such as the genus Violet. The average aboveground dry matter of Alfalfa and Caragana in three years is 5.97g m-2, which can explain the total dry matter variation of the aboveground part of the population 5.02.It is in Inner Mongolia Autonomous region. The ratio of aboveground dry matter and total dry matter in the upper part of leguminous crops is decreased. Therefore, we think that in Inner Mongolia semi-arid grassland ecosystem, the rainfall is less and the temperature is high during the growing period of crops. In conclusion, our studies have shown that overgrazing and limited rainfall are the main causes of grassland ecosystem degradation. Sustainable grazing management strategies will contribute to the conservation of these grassland ecosystems.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：S812

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