四川牡丹群落物种生态位及空间关联度分析

An Analysis on Niche and Degree of Spatial Association of Paeonia decomposita Community

四川牡丹(Paeonia decomposita)分布于大渡河上游两岸干旱河谷地带,为中国特有的珍稀濒危物种;由于自身和人为干扰的原因,该物种受到灭绝威胁。本文以群落样方为一维综合资源生态位,分析了四川牡丹灌丛灌木物种的生态位特征,在此基础上对四川牡丹与其伴生灌木物种的空间关联度进行了研究。结果表明,灌丛内四川牡丹、蚝猪刺、野花椒、橿子栎、散生栒子、野蔷薇、金花小檗、平枝栒子和小马鞍羊蹄甲种群的标准化生态位宽度依次为0.745、0.979、0.950、0.748、0.947、0.924、0.792、0.863和0.610,四川牡丹与优势种群蚝猪刺、野花椒、野蔷薇等生态位重叠较高,潜在竞争作用强。四川牡丹与金花小檗、小马鞍叶羊蹄甲、橿子栎在小于15 m的空间尺度上呈显著负相关;与平枝栒子、蚝猪刺、野花椒在0～5 m的空间尺度上呈负相关或接近负相关。本研究认为在四川牡丹群落内,四川牡丹受到蚝猪刺、野花椒、散生栒子等群落内优势物种的竞争排斥,加之自身种子萌发的特性和人为干扰等因素,造成四川牡丹自身生态位狭窄,位于濒临灭绝的境地。

Understanding endangering mechanisms of Paeonia decomposita, endemic to China, is very crucial to protect and utilize this valuable germplasm. However, little was known on the niche characteristics and relationships of Paeonia decomposita and associated shrubs species in dry valleys of Dadu River. We investigated niche breadths, niche overlaps and spatial associations of P. decomposita and associated shrub species in dry valley of Dadu River, south-western China. The standard niche breadth of P. decomposita, Berberis julianae, Zanthoxylum simullans, Quercus baronii, Cotoneaster divaricatus, Rosa spp. , Berberis wilsonae, Cotoneaster horizontalis, Bauhinia faberi vat. Microphylla was 0. 745,0. 979, 0. 950, 0. 748, 0. 947,0.924, 0. 792, 0. 863,0. 610, respectively. Niche overlapping values of P. decomposita and the dominate species B. julianae, Z. simullans, C. divaricatus, Rosa spp. were over 0.50, which were higher than those between P. decomposita and the other species. Combined with the analysis of spatial associations of P. decomposita and associated shrub species in dry valley of Dadu River, it was concluded that P. decomposita had weak ability to utilize resources because of its small niche breadth, and was in a disadvantaged position within species competition, which significantly contributed to understanding of endangereing mechanism P. decomposita.