呼伦贝尔草地利用单元划分与生态系统健康评价
Classification of Range Site and Ecosystem Health Assessment in Hulunber Steppe

在内蒙古呼伦贝尔草原上,根据植被、土壤和地形特征划分了8个有代表性的草地利用单元。并从中选择波状高平原-暗栗钙土-羊草草甸草原利用单元类型的1个放牧梯度系列,在定量划分放牧强度的基础上,分析了轻度、中度和重度3个不同放牧强度对草地生态系统结构和功能的影响,并应用模糊数学法和CVOR法对草地生态系统健康进行了评价。主要研究结论如下:(1)不同的草地利用单元可以属于同一草地类型,但各草地利用单元的植物种类数量和生产力都有较大的差异,因此,确定合理利用强度的基础应首先划分合理的草地利用单元。(2)放牧强度对草地植被的盖度和生产力都有较大的影响。各放牧梯度之间的变化规律是:轻度放牧区>中度放牧区>重度放牧区。随放牧强度的变化草地植物根系量变化不大,表现为随放牧强度增加而减少的趋势。(3)不同放牧强度对草地生物多样性的影响显著(p<0.05),α多样性指数随放牧强度的增加有降低的趋势,其值都在轻度放牧区最大,支持了“中度干扰理论”;β多样性指数随放牧强度的增加而变大,说明放牧强度增加使得草地植物种类组成发生了较大的变化,草地出现了逆行演替。(4)随放牧强度的增加土壤容重变大、土壤变得紧实,随放牧强度的增加砂粒含量增加、粘粒含量降低;随土壤深度的增加砂粒含量增加、粉粒含量降低;随放牧强度的增加土壤pH值升高,而土壤有机质、土壤全氮和土壤全磷都显著降低(p<0.05),土壤全钾、速效氮、磷、钾随放牧强度的变化不显著(p>0.05)。(5)随放牧强度的增加,土壤微生物数量降低。土壤微生物的生物量随放牧强度的增加呈下降的趋势。(6)选择植物群落地上生物量、植物群落地下生物量、土壤有机质、土壤全磷、土壤全钾、土壤pH值、土壤砂粒含量7个指标,应用模糊数学方法与CVOR评价方法得到的各放牧强度草地生态系统健康指数。模糊数学法的评价结果为:轻度放牧草地健康指数为1、中度放牧草地为0.90、重度放牧草地为0.62;而CVOR评价法的评价结果为:轻度放牧草地为1、中度放牧草地为0.87、重度放牧草地为0.58。

According to the vegetation, soil and terrain characteristics of grassland, Hulunber Steppe was divided into eight representative range sites in this experiment. A grazing gradient series of wavy high plains-the dark chestnut soil-Leymus chinensis meadow steppe range site was selected, and based on the quantitative division of grazing intensity, the influence under different grazing intensity (light grazing (LG), moderate grazing (MG) and heavy grazing (HG)) on grassland ecosystem structure and function were analyzed, and the illegibility mathematical method and CVOR (Condition, Vigor, Organization, and Resilience) method were used to evaluate the healthy condition of grassland ecosystem. The main results were as follows:(1) The different range sites could belong to the same grassland type, but all range sites have great difference in the numbers of the plant and the grassland productivity. Therefore, the determination of the rational grazing intensity should be founded on the rational division of range site.(2) The grazing intensity has great influence on grassland vegetation cover and the productivity, the change trend in different grazing gradient is:LG>MG>HG. As the grazing intensity increased, the quantity of plant root has no significant change (p>0.05), but showed a decreasing trend.(3) Grazing intensity has a significant influence on grassland biodiversity, when the grazing intensity increased, a diversity index decreased, and the value was biggest in the LG treatment, which supported the "moderate interference theory";βdiversity index increased with the increased of grazing intensity, which indicated the plant species composition changed with the increasing of grazing intensity, and promoted the retrograde succession in this grassland ecosystem.(4) With the increasing of grazing intensity, soil bulk density increased, the soil became more compacted, the also increased, but the clay decreased; with the increasing of the soil depth, the small gravel increased, while silt particle decreased; soil pH increased whereas soil organic matter, soil nitrogen and soil phosphorus significant (P<0.05) decreased with the increasing of grazing intensity, but the soil total potassium, available nitrogen, available phosphorus and available potassium had no obvious changes occurred under different grazing intensities (p>0.05).(5) The number of soil microorganisms reduced with the increasing of grazing intensity. The soil microorganisms biomass showed a decreased trend, but the change was not significant (p>0.05).(6) Plant community above-ground biomass, under-ground biomass, soil organic matter, soil total phosphate, soil total potassium, soil pH and soil sandy particle were selected to calculated the grassland ecosystem healthy indexes under different grazing intensities by the illegibility mathematical method and CVOR evaluation method. The evaluation values using illegibility mathematical method were as follows:the evaluation index is 1 in the LG treatment, it is 0.90 in MG treatment, while it is 0.62 in HG treatment; whereas the results by CVOR evaluation method were as follows:the evaluation value is 1 in LG treatment, and 0.87 in MG treatment, while it is 0.58 in HG treatment.

草地利用单元; 草地健康评价; 生物多样性; 呼伦贝尔草原; 草地生产力;

Range site; Grassland health assessment; Biodiversity; Hulunber steppe; Grassland productivity;

韩国栋;

S812

563915877K