不同降水条件下沙鞭种群非生殖株丛空间格局分析

植物空间分布格局是物种自身生物学特性与环境因素共同作用的结果，非生殖株丛空间分布格局能够揭示物种无性繁殖与种群扩张过程对异质生境的生态学适应机制。利用基于完全随机、泊松聚块和嵌套双聚块模型的点格局方法和群落学调查，分析了沙鞭(Psammochloa villosa)种群非生殖株丛空间分布格局，探讨了空间格局对降水梯度的响应和适应过程。结果表明：(1)聚集分布是沙鞭种群非生殖株丛的主要类型。在89 mm/a、107.8 mm/a、117.4 mm/a、186 mm/a、191.1 mm/a、363 mm/a降水梯度上聚集尺度分别为3—126 cm、9—200 cm、9—129 cm、6—77 cm、2—95 cm、2—96 cm;(2)基于完全随机模型的空间分布格局对降水的响应规律显著，整体表现为随干旱程度加剧，沙鞭种群非生殖株丛聚集尺度从2—96 cm下降至6—77 cm;(3)在107.8 mm/a、117.4 mm/a、191.1 mm/a、363 mm/a降水梯度上，基于泊松聚块模型的空间分布格局分别在15—19 cm、2—6 cm、2—4 cm、9—25 cm尺度正向偏离泊松聚...

Spatial pattern of Psammochloa villosa asexual cluster populations under different precipitation conditions

Population spatial pattern refers to the distribution state of population individuals in horizontal space. It is the result of interaction between biological characteristics of species and environmental factors. It has always been one of the hot spots and basic problems in ecological research. One of the most common reasons for the formation of population distribution patterns in plant populations is the difference in growth tradeoff strategies due to the difference in life history of species. Clonal plants have both sexual and asexual reproduction modes, among which the asexual reproduction mode is an important reproductive mode to ensure the conservation of plant population resources and the continuation of the population. Precipitation will greatly affect the material accumulation of asexual cluster and the resource acquisition of corresponding organs of plant population, and then change the resource acquisition methods and strategies of plants, finally adapt to the habitat conditions. The spatial distribution pattern of asexual cluster can reveal the ecological adaptation mechanism of clonal reproduction and population expansion to heterogeneous habitats. In this study, we analyzed the spatial distribution patterns of Psammochloa villosa asexual cluster using community investigation and point pattern method based on complete spatial randomness, poisson cluster process, nested double cluster process. And we discussed the response and adaptation mechanism of spatial pattern to precipitation gradient. The results showed that:(1) aggregation distribution was the main type of Psammochloa villosa asexual cluster. At the precipitation gradients of 89 mm/a, 107.8 mm/a, 117.4 mm/a, 186 mm/a, 191.1 mm/a and 363 mm/a, the aggregation scales were 3-126 cm, 9-200 cm, 9-129 cm, 6-77 cm, 2-95 cm, and 2-96 cm. (2) The spatial distribution pattern based on the complete spatial randomness had a significant response to precipitation, which showed that the aggregation scale of asexual cluster decreased from 2-96 cm to 6-77 cm with the intensification of drought. (3) At the precipitation gradients of 107.8 mm/a, 117.4 mm/a, 191.1 mm/a and 363 mm/a, the spatial distribution pattern based on the poisson cluster was deviating it at 15-19 cm, 2-6 cm, 2-4 cm and 9-25 cm, but conformed to the spatial distribution pattern based on nested double cluster process. With the increase of precipitation, Psammochloa villosa asexual cluster adopted an expansion strategy to take up more resources and space for the plant population, showing a trend of increasing aggregation scale in the spatial pattern. The competition of companion species would increase the fitness of Psammochloa villosa population in the community. With the increase of other species, the aggregation scale of Psammochloa villosa asexual cluster showed a trend of decreasing due to the fierce interspecific competition. Psammochloa villosa asexual cluster may form the spatial distribution characteristics of small clusters on a small scale, which may be related to its reproduction mode, but the underlying mechanism is not clear, and further research is needed.