不同放牧方式下的草场植被群落特征及其与土壤因子的关系——以新巴尔虎左旗为例

Characteristics of Grassland Vegetation Community under Different Grazing Management and Its Relationship with Soil Factors: A Case Study of Xin Barag Zuoqi

探究干旱半干旱草原不同放牧方式对退化草地生态系统恢复的影响,对退化草地植被恢复与重建及生态畜牧业可持续经营管理体系建设具有重要的科学意义。以呼伦贝尔市新巴尔虎左旗"七个一"生态家庭牧场为研究对象,对禁牧、休牧、轮牧和连续放牧4种放牧方式下的植被群落特征及与土壤因子间的关系进行研究。结果表明,(1)植被以多年生旱生、中旱生植物为主,轮牧区(45)和休牧区的物种数(42)大于禁牧区(37)和连续放牧区(34),禁牧区植被盖度(88.07%)和生物量(3 714.37 kg·hm^-2)最高,连续放牧区植被盖度(61.33%)及生物量(1 029.83 kg·hm^-2)最低。(2)4种放牧方式区的植被都以莎草科(Cyperaceae)和禾本科(Gramineae)植物为主,以寸草苔(Carex duriuscula)的重要值为最高,其中禁牧区最高(IV=38.30)。(3)休牧区和轮牧区的群落多样性指数较高,禁牧区的群落多样性指数最低(Ma=4.02,H=2.05,C=0.76,Jsw=0.72),且禁牧区与其他放牧方式区的物种分布及多样性指数均存在显著差异(P<0.05)。(4)物种CCA排序结果显示,土壤容重、含水量和全磷是影响左旗植被分布的主要土壤因子。此外,群落多样性指数变化与容重、速效磷和含水量显著相关(P<0.05)。研究认为,轮牧和休牧方式有利于保护草地生物多样性,禁牧对退化草地生态系统恢复有显著促进作用,但长期禁牧会导致群落多样性下降,连续放牧会降低草地生产力。建议减少连续放牧区放牧频率,在长期禁牧的牧场实施休牧、轮牧或适当的割草利用。

Exploring the effects of different grazing management on the restoration of degraded grassland ecosystems in arid and semi-arid grasslands had important scientific significance for the restoration and reconstruction of degraded grassland vegetation and construction of sustainable ecological animal husbandry management system. This study assessed the “Seven-one” ecological family ranch in Xin Barag Zuoqi, Hulunbuir City of Inner Mongolia, China. The vegetation community characteristics and its relationship with soil factors were analyzed under four grazing management including grazing-prohibited, rest grazing, rotational grazing and continuous grazing. The results showed that:(1) Vegetation was mainly perennial xerophytes and mesoxerophytes. Species number of rest grazing (45) and rotational grazing area (42) was higher compared to grazing-prohibited (37) and continuous grazing area (34). The vegetation coverage (88.07%) and biomass (3 714.37 kg·hm^-2) of grazing-prohibited area were the highest and the vegetation coverage (61.33%) and biomass (1 029.83 kg·hm^-2) of continuous grazing area were the lowest (1 029.83 kg·hm^-2).(2) The main vegetation under the four kind of grazing management was dominated by Cyperaceae and Gramineous family, and the important value of Carex duriuscula was the highest, with the highest in the grazing-prohibited area (IV=38.30).(3) The community diversity index of rest grazing and rotational grazing area were relatively high. In the grazing-prohibited area, the community diversity index was lowest (Ma=4.02, H=2.05, C=0.76, Jsw=0.72) and there were significant differences in species distribution and diversity between the grazing-prohibited and other grazing management (P<0.05). And (4) results of CCA ordination showed that soil bulk density, water content and total phosphorus were the main soil drivers of the spatial distribution of vegetation in Xin Barag Zuoqi. Besides, the bulk density, water content and available phosphorus were significantly correlated with vegetation diversity index (P<0.05). It had been also found that rotational grazing and rest grazing were conducive to protecting grassland biodiversity while grazing-prohibited could significantly promote the restoration of degraded grassland ecosystems, but long-term grazing-prohibited could lead to a decline in vegetation diversity. Continuous grazing reduced grassland productivity. It is suggested that grazing frequency in continuous grazing area should be reduced and rest grazing, rotational grazing or mowing should be promoted in grassland where grazing-prohibited has been implemented for a long period.