上海地区几种杂草的生态位分析

采用Levins公式和王刚生态位重叠计测方法,分别从群落梯度和土壤水分维、土壤盐分维、土壤酸碱度维、有机质维等4个单一生态因子对上海地区7种杂草生态位分化进行了定量分析。结果表明：（1）在群落梯度上,生态位大小依次为牛繁缕〉齿果酸模〉蛇莓〉香附子〉狗牙根〉马兰〉蒲公英。（2）牛繁缕在土壤水分、土壤盐分、土壤酸碱度、有机质维上的生态位分别为0．5274、0．6039、0．3620和0．7325,齿果酸模在这4维上分别为0．3320、0．3083、0．5103和0．5353。生态位宽度研究表明：牛繁缕和齿果酸模处于优势种地位,其余属于伴生种。（3）每个物种在群落梯度上的生态位宽度基本大于在上述4个资源轴上的平均生态位。（4）牛繁缕与齿果酸模在土壤盐分维上的生态位重叠最大（0．4203）．表明这2个优势种在利用土壤盐分方面有相似的特性。

Analysis on the niches of several weeds in Shanghai area

The niche differentiations of 7 weed species in Shanghai area were quantitatiVely analyzed in terms of community gradient and 4 simple ecological factors(soil moisture,soil salinity,soil acidity and soil organic matter)by the Levins formula and the Wang Gang method of measuring niche overlaps.The results were as follows:(1)The descending order of niche breadths in community gradient was Malachium aquaticum(0.7010),Rumex dentatus(0.6434),Duchesnea indica(0.4774),Cyperus glomeratus(0.3745),Cynodon dactylon(0.3541),Kalimeris indica(0.3354)and Taraxacum mongolicum(0.2769).(2)In dimensions of soil moisture,soil salinity,soil acidity and soil organic matter,the niche breadths of Malachium aquaticum were 0.5274,0.6039,0.3620 and 0.7325 respectively,and those of Rumex dentatus were 0.3320,0.3083,0.5103 and 0.5353 respectively,indicating that both Malachium aquaticum and Rumex dentatus were dominant species and the rest were companion species.(3)Each weed species,except Taraxacum mongolicum.was greater in the niche breadth of community gradient than in its average niche breadth of the above 4 dimensions.(4)The niche overlap in soil salinity dimension was the greatest between Malachium aquaticum and Rumex dentatus,showing both species had similar characteristics in absorbing soil salt.