监测并掌握城市排洪沟水体中致病菌的污染现状,对强化城市排洪沟的修复整理和常规性管理工作,提升污染突发事件中的预见预警能力和保障人居地周围的环境安全有着重要意义。以粪大肠菌群数为致病菌检测指标,通过五管发酵法对兰州市区不同功能区的主要排洪沟水体中粪大肠菌群进行了检测和分析。结果显示:水体中致病菌的污染程度较高,粪大肠菌群平均含量1.61×107个/L,最小2.3×105个/L,最大2.34×107个/L;文教区排洪沟致病菌污染最重,混合区次之,工业区污染较轻;根据GB 3838—2002《地表水环境质量标准》,利用单因子污染指数公式Pi=Ci/Si计算,污染最轻的深沟桥排洪沟水体中的粪大肠菌群数也已达到地表水环境质量V类标准的5.75倍。

通过野外大量调查,选取小陇山华山松林55个样方中的20个常见物种,运用多物种复合关联VR,χ2检验,Pearson相关系数和Spearman秩相关系数和关联测度等测算和综合分析群落的种间联接关系,结果表明:(1)多物种关联性(VR)的分析表明华山松林主要组成成员间的关系以正关联为主,说明华山松群落主要种群对生存环境的需求是一致的;(2)20个常见种种对中以华山松-锐齿栎、华山松-栓皮栎、华山松-辽东栎等种对之间呈正关联;锐齿栎-栓皮栎、锐齿栎-盐肤木等呈现负关联;黑刺菝葜、多毛樱桃等为独立关系等,是群落内环境的体现,是群落内环境异质性的表征;(3)依据华山松林种间关系的不同性质把组成群落的20个常见种归纳为3个生态种组,即正关联组、负关联组和独立组;(4)种间关联的研究结果对华山松群落的生境监测、营林管理、林区道路景观再造中的树种选择和配置有一定的实际指导意义.

The Xiaolongshan Nature Reserve is one of the Pinus armandii distribution areas in China.Based on large number of field surveys,study was carried out on ecological niches of the eight major populations of the Pinus armandii community,which is located in Xiaolongshan,Gansu Province,using the indexes such as the Levins and Shannon-Wiener′s ecological niche breadth,niche overlap index,and niche proportional similarity.Results show that the ecological niche breadth of the 8 plant populations follow the order of Pinus armandiiQuercus aliena var.acuteserrataLonicera lanceolataRhus verniciflusCrataegus kansuensisCastanea mollissimaQuercus liaotungensisTilia paucicostata.The population of Pinus armandii is the highest in Shannon-Wiener niche breadth,being 0.988 8,that of Quercus aliena var.acuteserrata follows,being 0.877 6,and that of Tilia paucicostata the lowest,being 0.352 9 only.The values of niche overlap of the populations in the community are generally low,which demonstrates low competition between most populations,but the niche overlap values of the dominant population of Pinus armandii with the other populations are relatively high,ranging between 0.079 1 and 0.101 3,whereas those of the other populations with that of Pinus armandii are relatively low,being in the range between 0.015 4 and 0.069 0.The overlap value is the highest between Pinus armandii and Castanea mollissima,being 0.101 3 and the lowest between Pinus armandii and Tilia paucicostata,being 0.079 1.There are 4 pairs of populations that have niche proportional similarity higher than 0.5 in value,accounting for 14.28%.They are Pinus armandii and Quercus aliena var.acuteserrata,Pinus armandii and Lonicera lanceolata,Quercus aliena var.acuteserrata and Lonicera lanceolata,and Quercus aliena var.acuteserrata and Rhus verniciflus.And the remaining 24 pairs are lower than 0.5,accounting for 85.72%,which demonstrates that the populations are mostly low in similarity of resource utilization.As one of the most important distribution areas for Pinus armandii in China,Xiaolongshan,the western section of the Qinling Mountains,is characterized by the ecological niche of a warm temperate coniferous forest.

Quercus aliena var.acuteserata is the main vegetation type of Xiaolongshan national nature reserve and its distribution pattern is one of the indexes to judge if the forest type recovers or not.In this paper,v/m ratio,negative binomial parameter,clumping index,cassie index and patch index are used to analyze the spatial pattern of Quercus aliena var.acuteserata forest at Xiaolongshan.The results show that the age structure of Quercus aliena var.acuteserata population is unreasonable at present,which belongs to stable population.The distribution pattern of this population takes the aggregation distribution,and the aggregation intensity is high,but it decreases with the increase of the maturity of the stands.

Based on the implementation of Tianbao Project,the paper gave an investigation on the species diversity and stability of the quercus aliena var.acuteserrata community.The conclusions were as follows:(1) Patrick abundance index was R=10.6,Shannon-Wiener index was H′=1.4222,Pielou index was Jsw =0.5450,Simpson index was C=0.4134.These datas showed the southern warm temperate zone's biodiversity characteristic as well as the regional features,which was between subtropical evergreen broad-leaved forest and broad-leafed deciduous forest in the north of warm temperate zone.(2)There were two distributed patterns of species diversity on M t.Xiaolong's sunny slope and shade slope.There were bigger diversity,evenness and richness on shade slope than that on the sunny slope.(3)As the development of community,diversity and abundance index had the similar variation.Conversely,that of evenness and dominance was different.It showed the different significance on ecology.(4) The quercus aliena var.acuteserrata community was built with quercus aliena var.acuteserrata species,which belonged to was stable.Compared with the earlier studies,the results proved that the implementation of Tianbao Project was scientific and effective.