Liu Jian-Kang, Feng Xiang, Zhang Ke-Bin, Liu Shu-Qin, Liu Xin-Yue
Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China/Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Ningxia University, Yinchuan 750021, China.
Key Laboratory of State Forestry Administration on Soil and Water Conservation/Ministry of Education Engineering Research Center of Forestry Ecological Engineering, Beijing Forestry University, Beijing 100083, China.
Ying Yong Sheng Tai Xue Bao. 2022 Mar;33(3):720-726. doi: 10.13287/j.1001-9332.202203.005.
Shrubs play an important role in maintaining biodiversity, stability and ecological service in grassland. Exploring the effects of enclosure on dominant shrub population can provide scientific guidance for grassland restoration and tending management. In this study, we investigated main growth characteristics and spatial distribution pattern of population in four enclosed grasslands with duration of 0, 5, 15, and 25 years. The results showed that population density increased first and then decreased with time extension, and peaked after enclosed for 15 years, which was 3.7 times that of unenclosed plot. The crown and projected area showed opposite responses trend to that of density, which decreased by 31.7% and 52.3% after enclosed 15 years, respectively. The height decreased by 25.3% after 5 years of enclosure, and then increased gradually. Semi-variance function analysis showed that population distribution in all grasslands conformed to Gaussian model. The spatial variation decreased gradually in the early stage of enclosure, and then increased after enclosed for 15 years. Structure ratio in each plot was higher than 0.75, but nugget was relatively small, indicating that spatial autocorrelation of population was mainly affected by structural factors rather than random factors. Spatial distribution of population was patchy and striped. Enclosure reduced spatial variation of population at small scale. However, spatial heterogeneity and scale dependence of population enhanced after enclosed 25 years as plaque dissociating. Our findings suggest that enclosure duration is the key factor affecting plant growth and spatial distribution of dominant population in desert steppe. Long-term fencing enhances the spatial heterogeneity of dominant population. Appropriate human intervention should be carried out after 15 years of enclosure.
灌木在维持草原生物多样性、稳定性及生态服务功能方面发挥着重要作用。探究围栏封育对优势灌木种群的影响可为草原恢复及抚育管理提供科学指导。本研究调查了围栏封育年限分别为0年、5年、15年和25年的四块围栏草地中优势灌木种群的主要生长特征及空间分布格局。结果表明，种群密度随时间延长先增加后降低，在封育15年后达到峰值，是未封育样地的3.7倍。冠幅和投影面积与密度呈现相反的响应趋势，封育15年后分别下降了31.7%和52.3%。株高在封育5年后下降了25.3%，之后逐渐增加。半方差函数分析表明，所有草地中优势灌木种群的分布均符合高斯模型。在封育初期空间变异逐渐减小，封育15年后又增大。各样地的结构比均高于0.75，但块金值相对较小，表明优势灌木种群的空间自相关主要受结构因素而非随机因素影响。优势灌木种群的空间分布呈斑块状和条带状。围栏封育降低了小尺度下优势灌木种群的空间变异。然而，封育25年后，随着斑块解体，优势灌木种群的空间异质性和尺度依赖性增强。我们的研究结果表明，封育年限是影响荒漠草原优势种群植物生长和空间分布的关键因素。长期围栏封育增强了优势种群的空间异质性。封育15年后应进行适当的人为干预。
