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水源圈内植物群落和土壤种子库变化特征
连仲民
学位类型硕士
导师杨维康
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词水源圈 放牧 植物群落 土壤种子库 相似性
摘要在干旱区牧场,由于饮水需求导致牲畜经常性地集中在水源点周围,从而使草地生态系统形成以水源点为中心的梯度退化,形成“水源圈”。作者在新疆准噶尔盆地东部荒漠草原上选择典型水源点,以水源点为中心,在8个方向上设置50 m、100 m、200 m、400 m、800 m和1200 m距离分别设置6个采样距离进行调查取样。记录了水源圈内植物群落功能群组成、数量特征、物种重要值、地上生物量、物种多样性变化特征和土壤种子库组成、密度以及多样性的变化特征,在此基础上分析了土壤种子库与地上植物群落的关系。结果表明: 1)水源圈内,随着距水源点距离的增加,荒漠草原植物群落特征呈现明显梯度变化。 2014年5月和10月分别记录到8科20种植物和6科13种植物。多年生草本植物、特别是博洛塔绢蒿(Seriphidium borotalensis)优势度逐渐增加,一年生草本植物优势度逐渐下降;植物群落、多年生草本植物和一年生草本植物的物种丰富度逐渐降低;群落总盖度逐渐增加,与建群植物博洛塔绢蒿的盖度显著正相关。由于有毒植物骆驼蓬盖度和高度随着与水源点距离的减小而增加,导致群落地上生物量在不同距离间没有出现梯度变化。一年生和多年生杂草在水源点附近优势度的提高,表明随放牧强度升高,水源点附近植物群落趋于退化。 2)放牧改变了水源圈内土壤种子库物种组成和空间分布。 从土壤种子库共鉴定出17种植物种子,分属于8科,即菊科、藜科、禾本科、十字花科、豆科、莎草科、蒺藜科和蓼科,其中藜科和菊科居多。其中一年生植物10种,多年生草本植物7种。水源圈内土壤种子库密度在211.5~362.5粒﹒m-2之间,距水源点50 m处土壤种子库密度最低,距水源点1200 m处最高。距离水源点越近,土壤种子库的物种数量显著增加(Spearman相关分析,R=-0.74,P<0.01),一年生草本植物种数所占比例减小,多年生草本植物种数所占比例增大。相邻采样点,土壤种子库物种组成相似性指数较高,为0.70~0.84,显示出较小的空间异质性。距离水源点越近,土壤种子库密度显著减小(ANOVA,df=5,F=15.47,P<0.05),多样性指数、丰富度指数和均匀度指数增大。水源圈效应增加了土壤种子库物种数量,导致主要建群植物种子的减少,短命、类短命草本植物种子的增加。 3)水源圈内植物群落和土壤种子库物种组成上有较高的相关性,地上植物群落与土壤种子库相似性系数变化范围为0.36~0.81,且距水源点越近,相似性越高,在距水源点50 m处达到最高值0.81。
其他摘要On the grassland of arid regions, due to the demand of water livestock often round-trip between water point and pasture, thus generates the formation of piosphere. To study the piosphere effects, sampling was carried out based on 6 sampling distance (50m, 100m, 200m, 400m, 800m and 1200m) with eight orientations radiating outward from an artificial water point in desert steppe, Eastern Junggar Basin, Xinjiang. In piosphere, not only the variation characteristics of the plant species composition, quantitative features, value importance, above-ground biomass and diversity, but also the variation characteristics of the species composition, density and diversity of the soil seed bank were studied. Based on these, this study was aimed to determine the relationship between soil seed bank and standing plant. The main results are as follows: 1) With the increase of distance from the water point, the community characteristics varied significantly, suggesting the grazing gradient around the watering point in piosphere. 20 species belonging to 8 families and 13 species belonging to 6 families were recorded in May and October 2014 respectively. With the increase of distance from the watering point, the dominance value of perennials significantly increased, especially for the Seriphidium borotalense, but the dominance value of annuals decreased; the species richness of the community including perennials and annuals decreased; and the vegetation coverage increased, which showed a significant positive correlation with the Seriphidium borotalense. The cover and height of the noxious plant Peganum harmala increased with a declinein the distance from the watering point, which was the reason why there were no gradient changes for the aboveground biomass of the community along with the distances. The improvement of abundance of ruderal annuals and perennials in the vicinity of the watering point indicate that the plant community tends to deterioration with the increase of grazing intensity. 2) In piosphere, the species composition and spatial distribution of soil seed bank were affected by grazing. There were 17 species belonging to 8 families in soil seed bank. The 8 families are Compositae, Chenopodiaceae, Gramineae, Cruciferae, Leguminosae, Cyperaceae, Zygophyllaceae and Polygonaceae. The species mainly were Compositae and Chenopodiaceae. The number of annual herbs and perennial herbs was 10 and 7 separately. The variation range of the soil seed bank density was 211.5~362.5 seeds﹒m-2, and the lowest density of soil seed bank was found in the closest vicinity of the water point (50m), while the highest was observed in farthest areas (1200m). The species number of the soil seed bank significantly decreased (Spearman correlation analysis, R=-0.74, p<0.01) with distance from water point. Along the same vector, the percentage of the annual herbs increased, while the percentage of the perennial herbs decreased. Since the variation range of the similarity of the soil seed bank coefficient between every two adjacent sampling points was 0.70~0.84, the spatial heterogeneity seemed to be small. The density of soil seed bank significantly increased (ANOVA, df=5, F=15.47, P<0.05) with distance from the water point. The Shannon-Wiener, Margalef and Pielow index of soil seed bank decreased with distance from water point. These results suggested that the number of plant species in soil seed bank was increasing by piosphere effect. This leads the number of ephemeral and ephemeroid plant seeds increasing, while the number of constructive species seeds was decreasing. 3) The similarity between standing vegetation and soil seed bank was high. The nearer to water point was, the higher the similarity was. The variation range of the similarity index between standing vegetation and soil seed bank was 0.36~0.81. The largest number was 0.81 of 50m from water point.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14650
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
连仲民. 水源圈内植物群落和土壤种子库变化特征[D]. 北京. 中国科学院大学,2015.
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