不同利用方式对天山北坡中段山地草甸草地植物生物量分布的影响

【目的】研究游牧放牧与定居放牧不同利用方式下山地草甸草地植物群落地上生物量与地下生物量的变化规律,为提高山地草甸草地生产力及确定合理的放牧方式提供依据。【方法】采用野外实地调查取样的方法,以天山北坡山地草甸草地为对象,分别在游牧放牧区和定居放牧区设置轻度放牧(Light grazing,LG)和重度放牧(Heavy grazing,HG)2种放牧强度,围栏打草场(未放牧区)为对照(Check test),分析2种放牧方式下植物群落地上生物量与地下生物量的分布。【结果】(1)在LG和HG下,不同利用方式下植物群落地上总生物量有显著差异(P<0.05)。游牧放牧和定居放牧在不同放牧强度下植物群落地上总生物量大小均为CK>LG>HG;除杂类草外,多年生禾草、多年生豆科草、多年生莎草地上生物量随放牧强度增加呈逐渐减少趋势。游牧放牧区与定居放牧区多年生莎草和杂类草地上生物量在LG下有显著差异(P<0.05),多年生豆科草地上生物量在HG下具有显著差异(P<0.05)。(2)在CK和LG下,不同放牧方式下土层0~10、10~20、20~30 cm的植物群落地下生物量有显著差异(P<0.05),且定居放牧区植物群落地下生物量比游牧放牧区分别高出36.79%、31.55%、27.38%。游牧放牧区植物群落地下生物量范围在743.99~1 229.83 g/m²;定居放牧区植物群落地下生物量分布范围在864.33~1 550.95 g/m²。(3)在LG和HG下,不同利用方式下植物根冠比有显著差异(P<0.05),定居放牧区植物群落根冠比游牧放牧区分别高出19.38%、9.91%。在不同放牧强度下,游牧放牧区和定居放牧区植物群落根冠比由大到小依次为HG>CK>LG。【结论】山地草甸草地的不同利用方式改变了植物群落地上、地下生物量的分布,定居放牧方式下植物群落地上、地下总生物量显著高于游牧放牧方式(P<0.05)。

Effects of different utilization methods on the biomass distribution of mountain meadows in the middle of northern slope of Tianshan Mountain

【Objective】To study the changes law of above-ground biomass and underground biomass of mountain meadow grassland in different utilization modes of nomadic grazing and settlement grazing in the hope of providing the basis for improving the productivity of mountain meadow grassland and determining the reasonable grazing methods.【Methods】Using the method of field survey and sampling, taking the mountain meadow grassland on the northern slope of Tianshan Mountain as the research object, two types of grazing intensities, light grazing and heavy grazing were set in the nomadic grazing and residential grazing areas respectively, and the no grazing area (fenced grazing field) was used as the control (Check test) to analyze the distribution of above-ground biomass and underground biomass of plant communities under two grazing methods.【Results】(1) Under LG and HG, there was a significant difference in the total biomass of plant communities under different utilization methods (P<0.05). Under Nomadic grazing and residential grazing of different grazing intensities, the total biomass of the plant community on the landing was CK>LG>HG; in addition to forbs, the aboveground biomass of functional groups of perennial grasses, perennial legumes and perennial sedges showed a gradual decrease with the increase of grazing intensity. The aboveground biomass of functional groups of perennial sedges and forbs in nomadic and settled grazing areas was significantly different under LG (P<0.05), the aboveground biomass of perennial legumes had significant differences under HG (P<0.05). (2) Under CK and LG, there were significant differences in the biomass of plant communities in the soil layer of 0~10, 10-20, and 20-30 cm under different grazing modes (P<0.05). In addition, the below-ground biomass of the flora in the settled grazing area was 36.79%, 31.55%, and 27.38% higher than that of the nomadic grazing area, respectively. The below-ground biomass of nomadic grazing area plants ranged between 743.99-1,229.83 g/m²; the distribution range of below-ground biomass of the flora in the settled grazing area was between 864.33-1,550.95 g/m². (3) Under LG and HG, there was a significant difference in plant root-to-shoot ratio under different utilization modes (P<0.05); the roots and shoots of plant communities in settled grazing areas were 19.38% and 9.91% higher than those in nomadic grazing areas, respectively. Under different grazing intensities, the root-to-shoot ratio of plant communities in nomadic grazing and settled grazing areas was HG>CK>LG in descending order.【Conclusion】The different utilization methods of mountain meadow grass change the distribution of the above-ground and underground biomass of the flora, the total biomass of the above-ground and underground plant communities under the settled grazing method is significantly higher than that of the nomadic grazing method (P<0.05).