荒漠草原植物群落根系和土壤氮素对不同放牧处理的响应

发布时间：2018-05-01 11:01

本文选题：荒漠草原 + 混合放牧　；参考：《内蒙古农业大学》2017年硕士论文

【摘要】：放牧是天然草原最主要的利用方式。牛和羊是内蒙古草原最主要的放牧畜种。不同家畜具有不同的采食行为,进而对草地植物种群的生长和种间竞争产生影响,因此,研究牛羊混合放牧与单独放牧对于草地的影响,具有重要的理论和实际意义。根系是植物与土壤的主要连接点,它决定着土壤环境与草地植被之间的作用界面,也是土壤生态系统功能的重要参与者,是支持植物地上部分和固定植物体的重要器官,草地植物根系对草地植物整个生态功能的有效发挥具有非常重要的作用。对草地生产力而言氮素的影响很大,氮素是一个很重要的营养元素,植物生长中有较多的限制因子,氮素是其中重要的限制因子之一,氮素在草地生产力、生态系统结构和功能及草地植物群落多样性等方面有重要影响。本研究在内蒙古包头市达茂旗希拉穆仁荒漠草原设置不同放牧处理:羊单牧、牛单牧、牛羊混合放牧和不放牧,研究土壤氮素、植物地下净初级生产力及根系周转速率和植物根系构型对不同放牧方式的响应。结果表明:1.放牧14个月后(约2个生长季),牛单牧和牛羊混合放牧显著提高了 10～20 emm土层土壤全氮含量,其中牛单牧提高了硝态氮含量,而牛羊混合放牧则以提高有机氮为主;2.无牧区植物群落地上生物量显著高于羊单牧、牛单牧和混合放牧区。地下生物量在各处理间差异不显著;3.牛羊混合放牧使根系周转加速,根系地下净初级生产力增高;羊单牧和牛单牧下根系周转缓慢;4.在不同放牧处理下植物群落根系长度、直径、表面积和体积等根系构型均没有显著差异,但总体来看单牧羊会使植被根系长度、直径、表面积和体积指数减小,而牛羊混合放牧会使植被根系构型指数增大;5.在不同放牧处理下建群种克氏针茅根系构型也没有显著差异,通过直径级分级发现,无牧区根系直径在2.5～3.5及4～4.5 mm区间的克氏针茅根系长度、体积和表面积显著高于其他放牧区,说明无牧区克氏针茅拥有较多的粗根;整体上看,放牧处理时间还比较短,土壤和植物的根系生产力及根系构型参数变化还不明显,有待于继续观测。
[Abstract]:Grazing is the most important use of natural grassland. Cattle and sheep are the main grazing livestock species in Inner Mongolia grassland. Different livestock have different feeding behaviors, which will affect the growth of grassland plant population and the competition between species. Therefore, it is of great theoretical and practical significance to study the effects of mixed grazing of cattle and sheep and individual grazing on grassland. Root system is the main junction point between plant and soil, it determines the interface between soil environment and grassland vegetation, it is also an important participant in the function of soil ecosystem, and it is an important organ to support the aboveground part of plant and fixed plant. The root system of grassland plants plays an important role in the effective exertion of the whole ecological function of grassland plants. Nitrogen is a very important nutrient element, and there are many limiting factors in plant growth. Nitrogen is one of the important limiting factors, and nitrogen is one of the important limiting factors in grassland productivity. The structure and function of ecosystem and the diversity of grassland plant community play an important role. In this study, different grazing treatments were established in Xilamuren desert steppe of Damao Banner, Baotou City, Inner Mongolia: sheep single grazing, cattle single grazing, cattle and sheep mixed grazing and non-grazing. Responses of net primary productivity, root turnover rate and plant root configuration to different grazing patterns. The result shows that 1: 1. After 14 months of grazing (about 2 growing seasons), mixed grazing of cattle and sheep significantly increased soil total nitrogen content of 10 ~ 20 emm soil layer, in which cattle single grazing increased nitrate nitrogen content, while cattle and sheep mixed grazing mainly increased organic nitrogen content. The aboveground biomass of plant community in no-grazing area was significantly higher than that in sheep, cattle and mixed herding area. There was no significant difference in underground biomass among treatments. Mixed grazing of cattle and sheep accelerated root turnover, increased net primary productivity of root system, and slow turnover of root system under sheep single grazing and cattle single grazing. There was no significant difference in root system length, diameter, surface area and volume of plant community under different grazing treatments, but the root length, diameter, surface area and volume index of vegetation were decreased by single herding sheep as a whole. However, mixed grazing of cattle and sheep increased the vegetation root configuration index by 5. 5%. Under different grazing treatments, there was no significant difference in the configuration of Roots of Stipa krjabini. It was found that the length, volume and surface area of Roots in the range of 2.5 ~ 3. 5 mm and 4 ~ 4. 5 mm were significantly higher than those in other grazing areas. The results showed that Stipa krjabini had more thick roots in the no-pasturing area, the grazing time was relatively short, and the changes of root productivity and root configuration parameters of soil and plants were not obvious, which needed to be further observed.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812

【参考文献】