退化草地甘肃臭草和冷蒿种群空间格局及关联性

Spatial pattern and spatial association of Melica przewalskyi and Artemisia frigida in degraded grassland

空间格局和空间关联性是研究种群扩散、群落演替及生物与环境间相互作用的重要手段。在石羊河上游高寒退化草地,运用点格局分析法,对不同演替阶段甘肃臭草和冷蒿的地上生物量、高度、空间格局及关联性进行了研究。结果表明:甘肃臭草在斑块没有形成阶段(CK)和斑块形成阶段(A),所有尺度上为聚集分布,在斑块扩散(B)、稳定(C)和衰退阶段(D),从聚集向随机过渡,随着聚集尺度减少、聚集强度下降,植株高度和地上生物量先增加后减少;冷蒿在各阶段均从聚集分布向随机分布过渡,随着聚集尺度增加,聚集强度增强,植株高度和地上生物量先减少后增加。CK、A、D阶段甘肃臭草和冷蒿之间表现为显著正关联,在B阶段从显著负关联过渡到关联性不显著。在放牧干扰影响下,地上生物量和高度的变化与种群空间格局及关联尺度转换的对应关系反映了退化草地植物种群竞争与生态适应性策略。

Spatial pattern and spatial association are the important means xor me stuay of population diffusion, community succession, and interactions between organisms and environment. In this paper, point pattern method was applied to study the plant height, aboveground biomass, spatial pattern, and spatial association of Melica przewalskyi and Artemisiafrigida at their different succession stages in the upper reaches of Shiyang River in Sunan County, Gansu Province of Northwest China. At the stages of no patch formation （CK） and patch formation （ A）, the M. przewalskyi population showed a clumped pattern at all scales; while at diffusion stage （B）, stable stage （C）, and degradation stage （D）, the clumped pattern transferred to random, and, with the decreases of clumped scale and clumped intensity, the plant height and aboveground bio- mass of M. przewalskyi decreased after an initial increase. The spatial distribution pattern of A. frigida at its different succession stages all presented a transition from clumped to random, and, with the increase of clumped scale, the clumped intensity increased, and the plant height and aboveground biomass decreased after an initial increase. At the stages CK, A, and D, the spatial association between M. przewalskyi and A. frigida was significantly positive; at stage B, the spatial association transferred from significantly negative to not significantly. The correspond- ing relationships of the changes in plant height and aboveground biomass with the populations＇ spatial pattern and spatial association scale transformation under the interference of grazing reflec- ted the populations＇ competition and ecological adaptable strategies in degraded grassland.