西藏巴松错夏季浮游植物优势种生态位及其种间联结性

Niche and Interspecific Associations of Dominant Summer Phytoplankton Species in Basomtso Lake,Xizang,China

为了解青藏高原高寒湖泊不同空间维度浮游植物群落优势种的生态位及种间联结性,选取青藏高原东南部最大的高寒冰山堰塞湖之一的巴松错为研究地点,2020年7月进行了浮游植物定性和定量采集,共采集水平和垂直维度浮游植物水样275个,结合生态位宽度、生态位重叠值、生态响应速率、总体联结性、χ^(2)检验、联结系数(AC)、共同出现百分比(PC)以及点相关系数(φ)等方法,分析优势种的生态位及种间联结性。结果显示:(1)共鉴定出浮游植物优势种5属8种,均属于硅藻门;(2)生态位宽度值差异较大,可分为3大生态位类群,水平维度对二维生态位宽度影响较明显;(3)在水平维度上,生态位重叠度达到有意义的种对比例较高,具有明显的同质性;在垂直和水平-垂直维度上,生态位重叠度达到有意义的种对比例较低,具有明显的异质性;(4)夏季浮游植物群落优势种生态响应速率在水平维度上形成正反馈,在垂直和水平-垂直维度上形成负反馈,表明巴松错夏季浮游植物群落存在多稳态,垂直和水平-垂直维度群落较水平维度更稳定;(5)夏季浮游植物群落总体处于演替初期,有正向演替趋势,物种间联结性不强,种间关系较为松散。研究结果为进一步研究高寒湖泊优势种生态位和群落多稳态提供了基础资料。

In this study,we explored the niche and interspecific associations of dominant phytoplank-ton species in different spatial dimensions of an alpine lake on the Tibetan Plateau in Qinghai.Ba-somtso Lake,one of the largest alpine glacier lakes in southeast Xizang,was selected for research.In July 2020,275 water samples in both horizontal and vertical dimensions were collected in Basomtso Lake for qualitative and quantitative analysis of phytoplankton.The niche and interspecific associa-tion among the dominant species were analyzed using niche breadth,niche overlap,ecological re-sponse rate,overall interspecific connection,chi-square(χ^(2))test,association coefficient(AC),per-centage cooccurrence(PC)and percentage point correlation(φ).Results show:(1)A total of 8 domi-nant phytoplankton species were identified,belonging to 5 genera of diatoms.(2)There were signifi-cant differences in the niche width of dominant species that could be divided into three niche groups.The variation of the two dimensional horizontal-vertical niche width was significantly affected by horizontal niche width.(3)In the horizontal dimension,the proportion of species pairs with signifi-cant niche overlap was higher,clearly indicating homogeneity.In the vertical dimension and the hori-zontal-vertical dimension,the proportion of species pairs with significant niche overlap was low,indi-cating heterogeneity.(4)The ecological response rate of dominant summer phytoplankton species in Basomtso Lake developed positive feedback in the horizontal dimension,and negative feedback in the vertical and horizontal-vertical dimensions.This indicates an alternative state of the phytoplankton community during the summer in Basomtso Lake,a community that was more stable in the vertical and horizontal-vertical dimensions than in the horizontal dimension.(5)The phytoplankton communi-ty was in an early successional stage and trending toward positive succession.The association be-tween species was weak and the relationship between species was loose.In conclusion,our study re-vealed the ecological adaptability,functional status,and resource usage of the phytoplankton commu-nity in Basomtso Lake.The study provides basic information to guide further research on the niches of dominant phytoplankton species and alternative community states in alpine lakes.