丛枝霸王（Zygophyllum dumosum）根际AM真菌生态学研究

AM真菌是一类广泛分布的土壤真菌，与宿主植物形成共生结构后，对于植物生长和植被恢复有多种有益的生理学和生态学作用。1999年11月至2000年10月，通过每月分别从0－10cm和10－20cm土层采集根际土样，对以色列荒漠地区丛枝霸王（Zygophyllum dumosum Boiss）根际AM真菌进行了系统的生态学研究。AM真菌的分布和定殖与季节变化和采样浓度密切相关。菌根真菌的最高定殖率并不伴随有最大的孢子密度，最高的定殖率发生在1999年11月，而最大的孢子密度则出现在2000年9月。10－20cm土层中的菌根真菌定殖率和孢子密度明显高于0－10cm土层。土壤温度与所有菌根结构的定殖率呈正相关，土壤有机质含量与泡囊和丛枝定殖率呈正相关，而土壤总可溶性氮对泡囊和丛枝定殖有显著正效应，对孢子密度有显著负效应。结果建议，孢子密度、泡囊和丛枝定殖程度可作为检测荒漠土壤状况的生态指标。研究应用于我国特别是西部荒漠地区的植被建立和恢复，可望发挥重任作用：（1）AM真菌能与绝大多数高奶系形成共生联合体，促进根系对土壤矿质营养和水分的吸收，提高植物对干旱、高温、盐碱、根部病害等的抗性，提高逆境条件下植物的成活率，深入研究荒漠生态系统中AM真菌动态分布，以及筛选优势AM菌种和人工接种，进行菌根化育苗，为植被建立和恢复提供优质苗木；（2）菌根的丛枝定殖时间短，主要发生在幼根，泡囊定殖时间长，主要发生在老根，而AM真菌的生长发育和繁殖所需的碳水化合物来自植物根系的分泌活动，所以，通过检测不同时期菌根各种结构的定殖程度和孢子的丰富度，可以获得宿主植物根系的生长状况，进而对土壤环境作出科学的评估。

Ecological research of arbuscular mycorrhizal fungi from the rhizospere of Zygophyllum dumosum in the desert ecosystem

The temporal and spatial dynamics of arbuscular mycorrhizal (AM) fungi were investigated in a field study at the Avdat Research Farm,Israel.Soil samples from the 0~10 cm and 10~20 cm depths were collected monthly between November 1999 and October 2000,under the canopy of Zygophyllum dumosum .AM fungal colonization and spore density was used to assess and compare the responses of AM fungi to soil conditions.The mean percent colonization and spore density of AM fungi reached maximal values in November 1999 and September 2000,respectively.These were significantly higher at the 10~20 cm depth.Spore density had a significant negative correlation with total percent colonization.Significant temporal and spatial effect for AM fungal colonization and spore density was obtained along the study period.Soil moisture content exhibited a positive effect on the colonization of AM structure groups.Soil organic matter and total soluble N presented a positive effect on vesicular and arbuscular colonization and total soluble N also had a significant negative effect on spore density.Our results suggest that spore density,and the extent of vesicular and arbuscular colonization are useful indicators for evaluating changes in desert soil ecosystems.