荒漠草原优势种群油蒿空间分布格局对封育恢复的响应

灌木对维持草原生物多样性、稳定性及生态服务功能等具有重要作用,探究封育措施对优势灌木种群的影响,可为草原恢复和抚育管理提供科学指导.本研究对荒漠草原4个封育时间(封育0、5、15、25年)的优势种群油蒿个体特征及种群空间分布格局进行研究.结果表明:油蒿种群密度随着封育时间延长先增加后降低,封育15年时最高,为未封育样地...

Responses of spatial distribution pattern of the dominant population Artemisia ordosica to enclosure restoration in desert steppe.

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 Artemisia ordosica 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 A. ordosica 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.