不同生态系统CO_2通量和浓度特征分析研究

本文利用1993～1994年日本国家农业环境研究所与中国科学院沙漠研究所合作在内蒙古奈曼地区实测的7种不同生态系统（沙丘、轻度放牧草原、中度放牧草原、重度放牧草原、无放牧草原、玉米田和大豆田）的净辐射、土壤热通量、两个高度的CO2浓度、温度、湿度和风速等资料，采用空气动力学方法，计算了CO2通量及其与环境和人为干扰因子的关系，并分析了不同下垫面的光合作用特征．结果表明：各种下垫面CO2通量的共同特点是：在白天，CO2通量和梯度的输送方向是从大气向植被，在中午（11-13时）输送达到负的最大值；在夜间，CO2通量和梯度输送方向与白天相反，是从植被向大气，在早晨（3～5时）达到正的最大值．植被覆盖率及生物量不同的下垫面光合作用强度有明显差异，天气状况对光合作用也有一定影响．

不同生态环境系统下野生蒲公英化学成分的研究

本项目拟以长白山生态系统为依托,研究森林,农田和草地生态系统环境下蒲公英的化学成分(绿原酸,叶绿素,甾醇),结果表明蒲公英中绿原酸和叶绿素含量为农田生态系统最多,甾醇含量则草地生态系统最多。

白云岩喀斯特地区土壤养分及生态化学计量特征

针对白云岩喀斯特地区存在的脆弱生境与土地资源利用不合理的问题,在贵州省施秉县白垛乡典型白云岩喀斯特地区,选取水田、旱地、灌木林、草坡和有林地等5种生态系统为研究样地,测定各生态系统0~30 cm土层土壤的有机碳(SOC)、全氮(TN)、全磷(TP)和全钾(TK)平均含量。通过生态化学计量学方法,分析4种土壤养分的质量比特征。分析结果表明:研究区内5种生态系统土壤中的SOC、TN、TP和TK平均含量分别为9.27~51.23 g/kg、1.40~6.00 g/kg、0.13~0.78 g/kg和15.64~31.73 g/kg。m(C)∶m(N)、m(C)∶m(P)、m(C)∶m(K)、m(N)∶m(P)、m(N)∶m(K)和m(P)∶m(K)的值分别为6.36~10.01、21.68~337.83、0.41~3.28、3.42~46.13、0.06~0.33和0.01~0.05。SOC平均含量与各生态化学计量比间均呈正相关,TN平均含量与m(P)∶m(K)呈不显著负相关,与其他生态化学计量比呈显著或极显著正相关;TP平均含量与m(C)∶m(N)、m(C)∶m(K)、m(N)∶m(K)相关性不显著;TK平均含量与m(C)∶m(N)、m(C)∶m(P)、m(N)∶m(P)相关性不显著。

Analysis on Genetic Diversity and Isolation Mechanism by Distance of Different Ecological Type Sheep Breeds in Mon-golia Sheep Group

In the present study with Tan sheep, small-tailed Han sheep, Hu sheep, Tong sheep, and Wadi sheep, we detected the distribution of gene frequency of several microsatellite sites in different chromosomes, the result showed that： 1） Hu sheep was in the status of Hardy-Weinberg extreme disequilibrium （P 〈 0.01）, while populations including Tong sheep, small-tailed Han sheep, Tan sheep, and Wadi sheep were in Hardy-Weinberg equilibrium （P 〉 0.05）. 2） Variance analysis of the heterozygosity and poly- morphic information content at rnicrosatellite makers showed that there were not significant differences among populations as to heterozygosity and PIC （P 〉 0.05）, as to effective number of alleles there were not significant differences both among Tan sheep, Hu sheep, Tong sheep, and Wadi sheep, and between Wadi sheep and small-tailed sheep （P 〉 0.05）, but between the former three populations and the latter two populations, there were significant differences （0.01〈 P 〈0.05）. The variation levels of small-tailed Han sheep was the highest in the five populations based on microsatellite maker data, subsequently followed by Wadi sheep, Tong sheep, Tan sheep, and then Hu sheep. 3） The phylogenetic relationships of the five sheep populations in this study did not meet the mechanism of isolation by distance, and the genetic differentiation relationships among five sheep populations were not closely linearly correlative with their geography distribution. Our findings supported related records in literature： The five populations originated on different time stage from the primogenitor population and communicated genetically with each other thereafter in the process of natural and artificial selection and on different ecological environment.

桂北喀斯特峰丛洼地植物群落特征及其与土壤的耦合关系

基于喀斯特峰丛洼地草丛、灌丛、次生林、原生林4个生态系统24个样地(20m×20m)的系统取样调查,研究了喀斯特峰丛洼地不同生态系统群落的结构组成与生物多样性特征,选取代表植物群落和土壤性质的35个指标,对不同生态系统及整个喀斯特脆弱生态系统植物群落与土壤主要养分、土壤矿质养分和土壤微生物间的相互关系进行了主成分分析与典范相关分析。结果表明:沿草丛、灌丛、次生林、原生林的顺向演替发展,重要值(importance value,IV)>10.00的科、属、种及物种多样性最大值出现在次生林,群落结构最佳值出现在顶级群落原生林;喀斯特峰丛洼地景观异质性高,各生态系统影响因子不同,土壤微生物在喀斯特脆弱生态系统处于主导地位,其次为灌丛;不同集团因子的典范相关分析表明,植物多样性指标与土壤氮素、Al2O3、Fe2O3、土壤微生物生物量碳(Cmic)、真菌和细菌关系密切。因此,在喀斯特脆弱生态系统恢复与重建过程中,应针对不同生态系统制定相应的培育管理措施。