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天祝高寒草地植被、土壤及土壤微生物时间动态的比较
引用本文:姚拓,王刚,张德罡,龙瑞军.天祝高寒草地植被、土壤及土壤微生物时间动态的比较[J].生态学报,2006,26(6):1926-1932.
作者姓名:姚拓  王刚  张德罡  龙瑞军
作者单位:1. 甘肃农业大学草业学院,兰州,730070;兰州大学干旱农业生态国家重点实验室,兰州,730000
2. 兰州大学干旱农业生态国家重点实验室,兰州,730000
3. 甘肃农业大学草业学院,兰州,730070
基金项目:中国博士后科学基金;甘肃省科技攻关项目;国家科技攻关项目
摘    要:对天祝高寒草地21a前(1982年)、后(2003年)植被状况、土壤理化性质、土壤三大类微生物(细菌、放线菌和真菌)和各生理群微生物(硝化细菌、好气性固氮菌和好气性纤维素分解菌)及不同退化程度(围栏内、围栏外和鼠丘地)草地土壤微生物数量变化特点进行了对比研究。结果表明:(1)与1982年相比,目前该区天然草地植被总盖度、主要优良牧草种类、产草量等显著下降,草地植被退化明显;(2)草地土壤pH升高,土壤含水量、有机质、氮、磷含量均下降,草地土壤理化性质劣于1982年;(3)目前该区天然草地土壤三大类微生物数量及各生理群微生物数量变化十分明显,1982年土壤细菌、放线菌和真菌及微生物总数分别是2003年的153.6、5.5、4.1倍和151.2倍;土壤硝化细菌、好气性固氮菌和好气性纤维素分解菌数量分别是2003年的5.7、43.3倍和94.4倍;(4)轻度退化草地(围栏内)土壤各类微生物数量明显高于严重退化草地(围栏外、鼠丘地),其数量前者一般为后者的1.5—4.5倍。

关 键 词:高寒草地  植被  土壤  微生物数量  时间动态  天祝
文章编号:1000-0933(2006)06-1926-07
收稿时间:2005-04-11
修稿时间:2005-04-112005-11-21

Temporal changes of grassland vegetation, soil and soil microbial population in the Tianzhu alpine region
YAO Tuo,WANG Gang,ZHANG Degang and LONG Ruijun.Temporal changes of grassland vegetation, soil and soil microbial population in the Tianzhu alpine region[J].Acta Ecologica Sinica,2006,26(6):1926-1932.
Authors:YAO Tuo  WANG Gang  ZHANG Degang and LONG Ruijun
Institution:1. Pratacaltural College, Gansu Agricultural University, Lanzhou, 730070, China ; 2. State Key Laboratory of Arid Agroecology , l, anzhou University, Lanzhou , 730000, China
Abstract:Sustained overgrazing and rodent's destruction are responsible for the degradation of more than 50% of grassland in north-western China.In fact these persistent adverse effects caused a reduction in the number of high quality forage species and grassland productivity,accompanied with an increase in the incidence of weed and poisonous plants.The degradation of the grassland ecosystem causes serious social and economical problems in the region.To prevent and control grassland degradation,intensive multidisciplinary research projects have been performed in this area.However information on the microbial population changes in the grassland is scarce.Soil microbial activity plays an important and vital role in grassland ecosystem because it affect soil physical properties like the stability of aggregates,soil aeration and water holding capacity,and it is responsible of the mineralization and recycling of several important nutrients like carbon,nitrogen and phosphorus.Soil organic matter is also significantly affected by microbial activity.Thus,grassland soil microbial importance and diversity can be used as an index of grassland health and soil fertility.The present work was performed in the alpine region of Tianzhu,eastern part of the Qinghai-Tibetan Plateau,which is characterized by high altitude,important daily temperature variations with sparse air,strong radiation and low temperature.We studied the temporal changes in vegetation and soil properties,the different physiological groups of soil microorganisms and the effect of the degree of grassland deterioration on soil microbes,by comparing measurements made in 1982 with those made in 2003.In general,the vegetation condition as well as soil physical and chemical characteristics were obviously in better condition in 1982 as compared to 2003.In 2003,the parameters showing important decreases as compared to 1982,included: the dominant plant species of the vegetation coverage,forage yield,soil water content,soil organic matter,N and P content.On the contrary an increase in soil pH was observed.The total microbial population in 1982 was higher than in 2003.Soil bacterial population decreased from log 8.97 cfu g~(-1) of dry soil in 1982 to log 6.79 in 2003.Similarly from 1982 to 2003,the observed population decreases in cfu g~(-1) of dry soil were as follows: actinomycetes from log 6.91 to log 6.17;fungi from log 3.89 to log 3.28;nitrifiers from log 4.29 to log 3.54;aerobic nitrogen fixing bacteria from log 5.54 to log 3.90 and cellulose degraders from log 5.65 to log 3.68.The number of physiological groups was also from 1.5 to 4.5 times higher in the moderately deteriorated grassland(fenced) than in the severely deteriorated grassland(unfenced and rodents hill).The results clearly illustrate the important decline of the soil microbial population associated with the deterioration of the grassland.
Keywords:alpine grassland  vegetation  soil  soil microbial population  Temporal changes  Tianzhu
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