生态因子对云贵水韭濒危的影响

Effects of Ecological Factors on the Endangerment of Isoetes yunguiensis

[目的]研究水质、放牧等生态因子对云贵水韭种群生长状况的影响。[方法]用便携式pH计（HI98107，HANNACo．Italy）和便携式电导率仪（HI983004，HANNACo．，Italy）分别实地测定水体pH值和电导率。根据云贵水韭种群较小和分隔成2个宽块生长的特点，研究2个宽块云贵水韭与放牧的关系。[结果]云贵水韭种群为小种群，每种群200-240株，星散混生于杂草丛中。有水之处的云贵水韭比湿润和半湿润处的长势好，植株健壮，叶数多且丛生。云贵水韭在斑块1和斑块2的频度分别为64．5％和75．0％，植株数分别为150～180和50～60株，密度分别为1．5—1．8和0．84～1．00株／矗。在所有的样方中都有放牧干扰，牛脚印的面积分别占斑块1和斑块2样方总面积的22％和50％左右。水体pH值和电导率的平均值分别为6．81和0．08mS／cm[结论]pH值、电导率和放牧可能是导致云贵水韭濒危的重要原因。

[Objective] The purpose was to study the effects of ecological factors such as water quality and grazing on the growth status of Isoetes yunguiensis population. [Method] The pH value and conductivity of water body were measured under field condition by portable pH meter （HI 98107, HANNA Co. ,Italy） and portable conductivity meter （E983004, HANNA Co. ,fraly） resp.. The correlation between I. ywzguiensis and grazing in the 2 patches was studied on the basis of character that the I. yunguiensis population was relatively small and grew in 2 separated batches. [Result] The I. yunguiensis population was small population and there were 200 ？240 plants mixed-growing among weeds sporadically and dispersedly in each small population. The growth potential of 1. yunguiensis in the place with water was well, the plants were strong and healthy and had many clustered leaves. The frequencies, plant numbers and densities of I. priguiensis in batches 1 and 2 were 64.5% and 75.0%,150 -180 and 50 - 60 plants,1 .5 ？1.8 and 0.84 -1.00 plants/m^2 resp.. There was grazing disturbance in all the quadrats and the areas of cattle footprints accounted for about 22% and 50% in the total quadrat area in hatches 1 and 2 resp.. The average pH value and conductivity of water body were 6.81 and 0.08 mS/cm resp.. [Conclusion] The pH value, conductivity and grazing may be important causes for the endangerment of I. yunguiensis