城市生态系统中丛枝菌根真菌侵染状况及群落特征

作者采集了北京、青岛、济南、南京、武汉和贵阳6个城市中部分大学校园高羊茅Festuca elata、城内公园大叶黄杨Euonymus japonicus及郊区公园连翘Forsythia suspensa根区土样,测定菌根着生状况和丛枝菌根（arbuscular mycorrhizal,AM）AM真菌孢子密度,形态鉴定AM真菌种类,测定AM真菌种丰度、多样性指数及群落结构等。除从北京中国人民大学校园草坪和南京下马坊公园的大叶黄杨根系上未见丛枝结构外,其他根系样品均观测到典型的丛枝和泡囊结构,丛枝着生率较低,且多为A-型。各城市大多数样品的菌根总侵染率、丛枝着生率和泡囊数分别低于40%、5%和1/mm。北京中国人民大学草坪根系菌根总侵染率显著低于其他城市校区的。除北京香山的连翘和济南山东大学的高羊茅上的种丰度、Shannon指数、以及北京紫竹院公园大叶黄杨上的孢子密度之外,青岛市的3种植物上AM真菌的孢子密度、种丰度和Shannon指数均高于其他城市的。各校园草坪中相同的AM真菌种类较少,但放射球囊霉Glomus radiatum分布频率100%,为校园草坪中的优势种。城市公园以青岛中山公园的AM真菌的孢子密度和种丰度最高;郊区公园以贵阳黔灵山的孢子密度、种丰度和Shannon指数最高,武汉狮子山的种丰度和Shannon指数最低。土壤氮沉降与泡囊数量呈显著负相关,土壤压实程度与泡囊数量呈显著正相关。大叶黄杨根区土壤中AM真菌种丰度与土壤有机质含量呈显著正相关,Shannon指数与土壤pH呈显著正相关。结论认为,中国不同城市生态系统中AM真菌群落结构差异较大,氮沉降和土壤压实程度对根内泡囊数量具有不同的影响。

Colonization and community structure of arbuscular mycorrhizal fungi in urbanising landscapes of China

Samples of root zone soil and roots of Festuca elata grown in university campuses, Euonymus japonicus in urban parks, and Forsythia suspensa in suburb parks in Beijing, Qingdao, Jinan, Nanjing, Wuhan, and Guiyang of China were collected to determine AM fungus colonization and community structure. Typical arbuscules and vesicles were observed, and most of the arbuscules were Arum-type, while no arbuscule was observed on roots of F. elata in the campus of Renmin University of China in Beijing and on E. japonicus in Xiamafang Park, Nanjing. Total mycorrhizal colonization, arbuscule colonization, and number of vesicles per mm length of root was generally under 40%, 5% and 1, respectively, regardless of sampling sites. Total mycorrhizal colonization of F. elata in the campus of Renmin University of China was significantly lower than that in campuses of other cities. The spore density, species richness and Shannon index of AM fungi on the three plants in Qingdao were higher than those in the other cities, except for species richness on F. suspensa, and spore density on E. japonicus in Beijing, and species richness and Shannon index on F. elata in Jinan. There were few of common AM fungal species in different grass lawns, while frequency of Glomus radiatum was 100% in all the grass lawn sampled, which was also the dominant species. Compared with the other urban parks, Qingdao Zhongshan Park showed the highest spore density and species richness of AM fungi on E. japonicus. Among of suburb parks, Qianling Mountain at Guiyang had the highest spore density, species richness and Shannon index of AM fungi on F. suspensa; while Shizi Hill in Wuhan showed the lowest of species richness and Shannon index. There was a negative correlation between N deposition and vesicle density, while a positive correlation between soil compaction and the vesicle density. The present investigation showed that species richness of AM fungi was significantly positively correlated with the organic matter content in the root zone soil of E. japonicus, while Shannon index was significantly positively correlated with soil pH value. It is suggested that community structure of AM fungi in urban lands in China be quite different, and the nitrogen deposition and soil compaction degree have different effects on the number of vesicles in roots.