放牧对西天山野果林下物种多样性及土壤的影响

探究不同强度放牧干扰下西天山野果林下植物群落物种多样性和土壤因子间的关系,为后期野果林的恢复和保护提供理论依据。以西天山野果林下植物为研究对象,依照放牧强度的划分方法,采用典型样地法,选择12个典型样地布置草本样方。以林下植物群落物种重要值指数、物种多样性指数和土壤因子作为评价指标,对比研究轻度（距离牧民居住点2~3 km）、中度（距离牧民居住点1~2 km）、重度（距离牧民居住点0~1 km）3种放牧干扰强度下群落结构、物种多样性和土壤因子的变化,进而分析植物群落物种多样性和土壤因子间的关系。结果表明,随着放牧强度的增加,群落植物组成发生明显变化,植物群落中优势种禾本科狗牙根和豆科车轴草逐渐被菊科蒲公英所取代;西天山野果林林下植物群落物种多样性水平呈逐渐下降的趋势;群落土壤理化性质差异明显,其中有机质、全氮含量表现出先降低后升高的趋势,全钾含量则表现出逐渐升高的趋势。研究认为,土壤中全钾含量和N/K是限制野果林群落多样性的主要土壤因子,这很可能与家畜排泄物的归还作用有关。

The Influence of Grazing on Species Diversity and Soil of Wild Fruit Forest in Western Tianshan Mountain

To provide theoretical evidence for ecological recovery and protection on wild fruit forest, the relationship between plant community species diversity and soil factors under different intensities of grazing disturbance were explored in wild fruit forest of western Tianshan Mountain. Taking the undergrowth plants in the wild fruit forest as research object, according to the division method of grazing intensity and the typical plot method, 12 typical herbal samples were arranged. Using the plant species important value, species diversity and soil factor as the evaluation indexes, mild type (2-3 km from the herdsmen’s settlement), moderate type (1-2 km from the herdsmen’s settlement), and severe type (0-1 km from the herdsmen’s settlement) were compared to study the change of community structure, species diversity and soil factors. The relationship between plant community species diversity and soil factors was analyzed. The results showed that with the increase of grazing intensity, the plant composition of the community changed significantly, the plant community dominant species Cynodon dactylon and Trifolium spp. were gradually replaced by Taraxacum mongolicum. The species diversity of understory plant communities showed a gradual decline, the soil physical and chemical properties had obvious differences in the wild fruit forest of the western Tianshan Mountain. The soil organic matter and total nitrogen content showed a trend of first decrease and then increase but the total potassium content showed a gradually increasing trend. The preliminary conclusion shows that total potassium content and N/K in soil are the main soil limiting factors on the diversity of wild fruit forest communities, which is most probably caused by nutrient-restitution of livestock excrement.