不同刈割制度对谢尔塔拉草原羊草群落特征及水分利用的影响

发布时间：2018-04-23 20:43

本文选题：刈割 + 羊草群落　；参考：《内蒙古大学》2017年硕士论文

【摘要】：本文以呼伦贝尔谢尔塔拉草原羊草群落为研究对象,设置3个割草梯度样地,分别为一年割草一次的样地简称一年一割(用1G表示)、两年割草一次的样地简称两年一割(用2G表示)和常年不割草的围封羊草样地简称围封(用Y表示)。以常年不割的围封样地为对照,分析在整个生长季节内(6月、7月、8月),不同刈割频度下对羊草草原的植被、土壤水分和土壤理化性质的影响及其水分利用特征的影响及变化规律,为草甸草原的合理割草、合理利用水提供理论依据。研究结果如下:(1)相比常年不割草的植物群落,刈割使群落高度和群落生物量下降,使群落密度增加;不同植物种群高度羊草、贝加尔针茅较占优势;相对于不刈割,种群密度羊草的最高,贝加尔针茅的种群密度最低,种群生物量羊草的最高;刈割使群落中苔草、裂叶蒿等植物的重要值下降,使羊草的重要值增高。(2)不同刈割频度下,土壤含水量的月变化趋势不同,6月土壤含水量高于7、8月的土壤含水量,在土壤表层含水量降低。两年一割使土壤含水量相对于年一割有所增加,并且土壤下层的含水量刈割高于围封。割草对土壤含水量空间分布无显著影响。(3)刈割使群落蒸散值下降,随着刈割频度升高,群落蒸散值逐渐下降,在整个生长季节内,群落蒸散值从6月至8月逐渐升高。在割草利用条件下,割一年休一年(两年一割)有利于水分利用效率的提高,而一年一割的高频刈割对草场的群落水分利用效率影响较大。(4)不同刈割频度对光合特征的影响:刈割使得净光合速率(Pn)、蒸腾速率(Tr)、胞间C02浓度(Ci)、气孔导度(Gs)以及水分利用效率(WUE)都高于对照的围封样地,且两年一割的光和参数均高于一年一割。(5)不同刈割频度下叶绿素荧光的影响:在自然条件下,测定了羊草以及贝加尔针茅在不同刈割频度下的叶绿素荧光参数并且进行比较,不同割草方式对植物叶绿素荧光有显著影响,在割草条件下,割草处理的初始荧光(F0)、最大荧光(Fm),PS II最大光化学量子产量(Fv/Fm),化学碎灭系数(qP)和非光化学猝灭系数(qN)均较对照常年不割样地显著增加;刈割条件下的羊草及贝加尔针茅叶片叶绿素荧光参数F0、Fm、Fv/Fm、qP、qN均高于不刈割处理,且两年一割的叶绿素荧光参数均高于一年一割。(6)不同刈割频度下对稳定碳同位素的影响:通过研究不同刈割频度下的稳定碳同位素组成变化特征,结果显示羊草的δ 13C的值在(-25.79±0.05)～(-27.08±0.05);贝加尔针茅的 δ 13 C 的值在(-26.76±0.05)～(-28.15±0.05),6 13 C值两年一割大于一年一割大于围封不割。
[Abstract]:In this paper, the Leymus chinensis community in Hulunbeir Sheertara grassland was studied, and three gradients of mowing plots were set up. The sample plots, which are mowed once a year, are mowed once a year (expressed as 1G), biennial mowers (2G) and enclosed plots without annual mowing (Y) for short. The vegetation of Leymus chinensis steppe during the whole growing season (June, July, August, and different cutting frequency) was analyzed by comparing with the enclosed sample plots. The effects of soil moisture and soil physical and chemical properties, the effects of water use characteristics and their changing rules provide theoretical basis for rational mowing and water utilization of meadow grassland. The results are as follows: (1) compared with the perennial non-mowing plant communities, cutting decreased the community height and community biomass and increased the community density; the height of Leymus chinensis was dominant in different plant populations, and the Stipa bajalensis was more dominant than non-cutting. The population density of Leymus chinensis was the highest, the population density of Stipa baicalensis was the lowest, and the population biomass of Leymus chinensis was the highest, and cutting decreased the important value of Carex and Artemisia chinensis in the community, increased the important value of Leymus chinensis, increased the important value of Leymus chinensis under different cutting frequency. The monthly variation trend of soil water content was different. In June, the soil moisture content was higher than that in July and August, but the soil water content in surface layer decreased. The water content of soil was increased in two years, and the water content in the lower layer was higher than that in the enclosure. Mowing had no significant effect on the spatial distribution of soil water content. Cutting decreased the evapotranspiration value of the community. With the increase of cutting frequency, the evapotranspiration value of the community decreased gradually, and the evapotranspiration value of the community gradually increased from June to August in the whole growing season. Under the condition of mowing, cutting for one year (once every two years) is beneficial to the improvement of water use efficiency. The effects of different cutting frequency on photosynthetic characteristics were as follows: net photosynthetic rate (PnN), transpiration rate (Tran), intercellular C02 concentration (C02), stomatal conductance (Gs), and The water use efficiency (Wue) was higher than that in the enclosed sample plots of the control. And the light and parameters of two years cutting were higher than that of one cutting per year. (5) the effect of different cutting frequency on chlorophyll fluorescence: under natural conditions, the chlorophyll fluorescence parameters of Leymus chinensis and Stipa Baikal were measured and compared under different cutting frequency. The chlorophyll fluorescence of plants was significantly affected by different mowing methods, under the condition of cutting grass, The initial fluorescence (F0), the maximum photochemical quantum yield (FV / Fm), the chemical crushing coefficient (QP) and the non-photochemical quenching coefficient (QN) of the grass mowing treatment were significantly higher than those of the control. The chlorophyll fluorescence parameters of Leymus chinensis and Stipa baicalensis leaves under cutting conditions were higher than those of unmowing treatments. The chlorophyll fluorescence parameters of two years cutting were higher than that of one cutting per year. (6) the effects of different cutting frequency on stable carbon isotopes were studied, and the change characteristics of stable carbon isotopic composition were studied under different cutting frequency. The results showed that the values of 未 13 C of Leymus chinensis were 25.79 卤0.05, 27.08 卤0.05, and those of Stipa baicalensis were -26.76 卤0.05 and -28.15 卤0.05, respectively. The values of 未 13 C of Leymus chinensis were greater than that of enclosure.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812

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