Knowledge Resource Center for Ecological Environment in Arid Area
| 不同干扰对沙坡头地区生物结皮覆盖区域土壤种子库的影响 | |
| 其他题名 | Impacts of different disturbance on seed banks of soil covered by biocrusts in the Shapotou Region |
| 陈孟晨 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 张景光 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 生物结皮是荒漠生态系统最主要的地表覆被类型之一，其在土壤表层形成了一道致密的结皮层，进而改变了荒漠地区种子的传播过程。生物结皮的结构和功能决定了其易受到自然和人为因素的干扰。目前，关于生物结皮对土壤种子库影响的研究多集中在其对土壤种子库组成及数量特征影响等方面，而关于生物结皮覆盖区域土壤种子库的垂直分布特征及不同干扰下生物结皮对土壤种子库影响的研究较少。本文以沙坡头人工植被区的藓类结皮、地衣结皮覆盖土壤和裸沙为研究对象，采用野外调查取样和室内萌发试验相结合的方法，研究了藓类结皮、地衣结皮和裸沙覆盖区域土壤种子库组成及垂直分布特征，以及不同类型干扰(移除或破碎生物结皮)发生3年后(长期)和半年后(短期)，生物结皮覆盖区域土壤种子库的基本特征。探讨了不同干扰发生后，生物结皮覆盖区域土壤种子库对未来植被格局的影响，旨在加深对生物结皮与维管束植物的关系以及荒漠地区生态恢复与植被演替规律的认识，并为该区域生物多样性保护及生态系统管理提供理论依据。主要结论如下：(1)人工植被区土壤种子库的物种组成简单，以一年生草本为主，相较于裸沙，两种生物结皮的存在显著增加了土壤种子库的密度(p < 0.01)，但降低了土壤种子库的物种丰富度、多样性及其与地上植被的相似性；(2) 2种生物结皮覆盖区域土壤种子库的总密度虽无显著差异，但在0–2 cm土层中，地衣结皮土壤种子库的密度显著高于藓类结皮(p < 0.05)，而在2–5 cm和5–10 cm土层中，藓类结皮土壤种子库的密度高于地衣结皮，但差异不显著; (3)不同生物结皮覆盖区域土壤种子库的垂直分布特征存在差异，藓类结皮覆盖土壤中有活力的种子主要分布在0–5 cm土层中，而地衣结皮和裸沙覆盖土壤中有活力的种子主要分布在0–2 cm土层中，且随着深度的增加，土壤中有活力的种子急剧减少。(4)不同干扰处理增加了2种生物结皮覆盖区域土壤种子库的物种数，且随着干扰后恢复年限的增加，土壤种子库的物种数也随之增加。不同干扰处理虽然增加了土壤种子库的物种数和丰富度，但是降低了土壤种子库的物种多样性及其与地上植被的相似性。 (5)相较于完整的藓类结皮和地衣结皮，对生物结皮进行长期破碎和长期移除处理显著增加了土壤种子库的密度(p < 0.01)，短期破碎处理略微增加了土壤种子库的密度，但是差异不显著，而短期移除生物结皮层则显著降低了土壤种子库的密度(p < 0.05)。(6)不同干扰处理均增加了一年生草本在土壤种子库中所占的比例，土壤种子库中的各物种对干扰的响应不同，几种干扰处理显著增加了小画眉草的土壤种子库密度，却降低了油蒿、沙鞭土壤种子库的密度。 |
| 英文摘要 | Biocrusts are important land covers in desert ecosystem; they form a compact layer at the desert soil surface and change the spread of seeds. The structure and function of biocrusts are sensitive to many disturbances. The current researches mainly focus on the effects of biocrusts on the composition of soil seed banks and quantitative features, little is known about their effects on vertical distribution of soil seed banks and the effects after disturbances.Based on random sampling in the field and observing the emergence of seedlings, we studied the structure, density and vertical distribution of soil seed banks, in moss crusts, lichen crusts, and bare sands, as well as the impacts of disturbances of different types (remove and destroy) and different durations (three years and half years) on features of soil seed banks in the artificially re-vegetated region of Shapotou. The study discusses the potential effects of seed banks of soil covered by biocrusts on vegetation pattern in desert areas, aiming at deepening the understanding of relationships between biocrusts and vascular plants and providing theoretical basis for biodiversity conservation and ecosystem management of this region.The main results are as follows: (1) The soil seed banks of this region had simple species compositions that were mainly composed of annual herbs. The existence of biocrusts significantly increased the seed density in soil (p < 0.01), but decreased the species diversity of soil seed banks and the similarity of soil seed banks with corresponding ground vegetation.(2) No significant differences in the total density of soil seeds between the two biocrusts were observed, but the seeds distributions in various soil layers were markedly different. Specifically, the soil seed density in the 0–2 cm soil layer of lichen crusts was significantly higher than in the corresponding layer in moss crusts (p < 0.05), while that of moss crusts was higher in the 2–5 cm and 5–10 cm soil layers.(3) The effects of biocrusts on vertical distribution of soil seed banks varied with biocrusts types. For example, germinative seeds were primarily distributed in the 0–5 cm soil layer for moss crusts and in the 0–2 cm soil layer for lichen crusts and bare sands, and their abundance decreased with soil depths. (4) The species richness of seed banks were increased with the years of restoration after disturbances. While the diversity, evenness and the similarity of soil seed banks with corresponding ground vegetation were decreased after disturbance.(5) Compared with intact biocrusts, the long-term disturbances increased the soil seed banks density (p < 0.01), the seed banks density were slightly increased after the short-term destroy and decreased after short-term remove (p < 0.05).(6) The annual herbs made up a larger proportion of the soil seed banks after disturbance and the herbs responded to disturbance differently. The seed banks density of Eragrostis poaeoides increased, while those of Artemisia ordosica and Psammochloa viollosa decreased after disturbance. |
| 中文关键词 | 生物结皮 ; 土壤种子库 ; 垂直分布 ; 干扰 ; 物种多样性 |
| 英文关键词 | biocrusts soil seed banks vertical distribution disturbance diversity of species |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287961 |
| 推荐引用方式 GB/T 7714 | 陈孟晨. 不同干扰对沙坡头地区生物结皮覆盖区域土壤种子库的影响[D]. 中国科学院大学,2017. |
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