不同轮牧时间对荒漠草原植被空间异质性的影响
The Influence of Different Rotation Time to Spatial Heterogeneity of Vegetation in Desert Steppe

空间异质性是指变量在空间分布的不均匀性和复杂程度,综合反应了变量的空间缀块性和梯度性。空间异质性是草地生态系统的基本特征之一,研究放牧干扰对草地空间异质性的影响,对草地科学放牧有重要意义。以宁夏荒漠草原为研究对象,在前期四区轮牧研究基础上,对封育、延迟开始轮牧、延迟开始提前结束轮牧下植物群落特征,植物群落和蒙古冰草、短花针茅、牛枝子和远志4种主要种群的空间异质性,草群可食牧草和主要种群营养成分的空间变化规律进行了研究。(1)不同轮牧时间对草地主要物种重要值改变不明显;各处理下群落盖度、密度、高度、生物量差异性不显著。(2)各处理下物种均匀度和优势度指数接近,轮牧处理下物种丰富度和多样性指数显著高于封育处理。(3)植被密度与速效氮成极显著正相关、与土壤容重呈显著负相关;地上生物量与土壤有机质、速效氮成显著正相关。(4)封育和延迟开始处理植物群落的盖度以及各处理下植被的密度、生物量空间自相关性较强。(5)4种主要种群的盖度、密度、生物量的空间异质性不同。总体看,延迟开始轮牧空间异质性较小。异质性的差异除了与植物自身生物学特性有关外,轮牧时间的差异是种群空间异质性不同的主要因素。(6)草群可食牧草粗蛋白、粗脂肪、ADF的差异性不显著;4种主要植物的营养成分在不同处理下的空间特征表现不同;各处理下蒙古冰草和短花针茅粗蛋白的含量为中等程度变异。而牛枝子和远志的粗蛋白在封育小区为中等程度变异。从群落和种群空间分布来看,研究初步认为,延迟开始轮牧是较为合理轮牧时间。

Spatial heterogeneity refers to the inhomogeneity and complexity of the spatial distribution of variables,which comprehensively reflects the spatial fragmentation and gradient of variables.Spatial heterogeneity is one of the basic characteristics of grassland ecosystem.It is of great significance to study the effect of grazing disturbance on grassland spatial heterogeneity.Taking Ningxia desert grassland as the research object,on the basis of the four-paddock rotational grazing in the early stage,was used CK,YT and YG measurements made include the plant community characteristics,plant community,the spatial heterogeneity of four main populations.The main results showed:(1)the important value of different rotational grazing time on the main species of grassland did not change obviously.There was no significant difference in community coverage,density,height and biomass under each treatment.(2)the Pielou E and Simpson C index of each treatment were close,and the Margalef R and Shannon-Wiener H index of rotational grazing treatments were significantly higher than those of CK.(3)vegetation density was positively correlated with available nitrogen and negatively correlated with soil bulk density,while aboveground biomass was positively correlated with soil organic matter and available nitrogen.(4)the coverage of plant community and the density of vegetation under each treatment were strongly correlated with the spatial autocorrelation of biomass.(5)the spatial heterogeneity of coverage,density and biomass of the four main populations was different.On the whole,the spatial heterogeneity of YG was small.The difference of heterogeneity is not only related to the biological characteristics of plants,but also the difference of rotation grazing time is the main factor of different spatial heterogeneity of population.(6)there was no significant difference in Cp,EE and ADF among edible herbage,but the spatial characteristics of nutritional components of the four main plants were different under different treatments.The content of crude protein in Agropyron mongolicum and Stipa breviflora varied moderately under each treatment However,the crude protein of Lespedeza potaninii and polygala tenuifolia varied moderately in the closed plot.From the point of view of the spatial distribution of community and population,it is considered that YG is more reasonable.

荒漠草原; 轮牧时间; 群落特征; 植被空间异质性;

desert grassland; rotational grazing time; community characteristics; spatial heterogeneity of vegetation;

国家重点研发计划课题(2016YFC0500505); 中国科学院“西部之光”人才培养引进计划项目(XAB2015A10); 宁夏科技创新领军人才培养项目(KJT2018003); 宁夏高等学校一流学科建设(草学学科)资助项目(NXYLXK2017A01);

马红彬;

S812

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