包头南海湖浮游植物优势种生态位及种间联结性季节分析

为了解寒旱区浮游植物群落年内结构变化和演替规律及其优势种的联结性，于2017年12月~2018年11月对包头市南海湖的浮游植物群落进行了调查分析.共鉴定出浮游植物7门66属151种，其中浮游植物优势种有4门15属15种，其种类和丰度随季节而变化.运用改进的Levins公式和Petraitis指数测定浮游植物优势种的生态位量度，发现不同季节各优势种的生态位宽度和生态位重叠不尽相同，各优势种对环境因子的适应能力也存在较大差异，在年内各种生境条件下，微小平裂藻生态位变化幅度最显著，依此认为微小平裂藻可作为南海湖水体污染状态指示种，且有可靠的生态学依据.生态位重叠值中ΔSO_ij值表示物种发展趋势，可第一时间反映南海湖水质是否受到外来因素干扰.群落物种相关性、种间联结性检验结果显示，南海湖浮游植物种间联结性总体上呈正关联关系，128对优势种对中仅有10对显现显著联结性，可见南海湖群落种间联结不紧密，群落结构不稳定，处于演替的初、中期阶段.

Seasonal variation analysis of the niche and interspecific association with respect to the dominant phytoplankton species in Nanhai Lake

In order to get a better understanding of the annual structural changes and succession rules of phytoplankton community and the interspecific association of the dominant species in lakes at arid-cold regions, the phytoplankton community in Nanhai Lake at Baotou, Inner Mongolia from Dec. 2017 to Nov. 2018 was investigated and analyzed. A total of 151 species of 66 genera of 7 phyla were identified, among which 15 species of 15 genera of 4 phyla were dominant phytoplankton species although those species and their abundance varied with seasons. The improved Levins formula and Petraitis were applied to determine the niche metrics of the phytoplankton dominant species. The results showed that the niche breadth and niche overlap of each dominant species varied seasonally, and the adaptability of each dominant species to the environmental factors also presented a great difference. Under various habitat conditions in the different seasons during the year, the niche of Merismopedia tenuissima had the most significant variation. It could be used as an indicator species of water body pollution status in Nanhai Lake based on a reliable basis of ecology. The niche overlap results showed that ΔSO_ij could represent the trend of species development, which would indicate immediately whether the lake water quality was affected by external factors or not. The test results of the community species correlation and interspecific association showed dominant species pairs showed a significant association, indicating that the interspecific association in the phytoplankton community was positive correlated in general. However, only 10 out of the 128 dominant species pairs showed a significant association, indicating that the phytoplankton community in Nanhai Lake was still in the early and intermediate stages of succession with a loose interspecific association and unstable community structure.