Knowledge Resource Center for Ecological Environment in Arid Area
| 浑善达克退化生态系统恢复研究-自然力在沙地草地恢复中的应用 | |
| 其他题名 | Submitted to Graduate School, Chinese Academy of Sciences (GSCAS), in partial fulfillment of the requiement for the Degree of Doctor of Philosophy |
| 刘美珍 | |
| 出版年 | 2004 |
| 学位类型 | 博士 |
| 导师 | 蒋高明 |
| 学位授予单位 | 中国科学院植物研究所 |
| 中文摘要 | 浑善达克沙地是我国四大沙地之一，地处北方干旱半干旱区，为草原区向荒漠区过渡的地带。长期以来，由于人类不合理的生产活动，加上这里脆弱的生态环境，已引起了严重的土地退化问题：流动沙丘面积由19505年占沙地总面积的2％增加到19905的近50％。因此浑善达克沙地成为我国研究土地退化、防治沙尘暴的重点地区，本文从自然科学和人文科学相结合的角度出发，对浑善达克沙地草地退化原因、自然恢复潜力、恢复过程、适宜物种选择，以及社区生存、生产等方面进行了综合研究，得出以下主要结论：1）浑善达克沙地土壤种子库中含有大量的种子，在退化草地自然恢复中表现出极大的潜力。这些种子在摆脱人和牲畜干扰的前提下，可以萌发、定居并形成植物群落，使退化草地恢复；当地表达到一定程度的植被覆盖，可有效减少沙尘暴的危害。土壤种子库中的植物种类与地上植被有极显著的相似性（P＜0.05），这是地上植被形成稳定群落的基础。种子库中的物种组成影响植被恢复演替的进程；反之，恢复演替也制约着种子库组成和幼苗建立。2）退化沙地草地围封后，对不同恢复阶段草地的群落学调查表明，该地区自然恢复过程大致分为3个阶段：围封2年的恢复早期，流动沙丘向半固定沙丘转变；围封3一5年的恢复中期，半固定沙丘向固定沙丘转变；围封6年后的恢复后期，为固定沙丘稳定发展阶段。根据生活型及植物种类随恢复演替的变化规律，浑善达克沙地植被演替的总体趋势可归纳为：沙米（Agriophyllumsquarrosum）＋雾冰黎（Bassiadasyphylla）群落咔黄柳（Salixgordejevii）＋冰草（Agropyroncrista翔m）群落一褐沙篙（Artemisiaintramongolica）＋冰草群落一沙地榆（Ulmuspumilavar．sablosa）疏林十冰草群落。在围封禁牧下，浑善达克退化沙地草地在较短时间内实现自然恢复，因此制约退化草地恢复演替的关键因素主要是人为和牲畜的干扰，只要排除了这种干扰因素，浑善达克大面积的退化沙地草地完全能够借助自然力实现生态恢复。3）浑善达克沙地3种生境下84种植物叶片渗透势值和含水量，表现出不同功能型上的差异。总体变化趋势为：深根系＞浅根系；灌木＞乔木＞草本；分布在湿地和丘间低地的植物牙卜片渗透势和含水量较高，而生长在沙丘上的植物叶片渗透势较低，需要有发达的根系吸收土壤深层的水。不同植物具有独特的水分利用特性，使它们能共存于同一生态系统中。这些不同植物功能型表现出的植物水分生理生态特性，表明浑善达克天然分布的植物群落发育有完善的利用水资源的能力，能够保证在很大降水波动条件下分布有丰富的植物群落和较高的生物生产力，构成该特殊类型生态系统很强的恢复潜力。另外，浑善达克沙地沙丘的存在是该类生态系统恢复弹性较高的另一重要原因。4）本地种与引入种在生理生态上表现出不同的适应能力。在相似的太阳辐射和汗卜片温度下，引入种旱柳的叶片水势较高，而净光合速率、气孔导度、水分利用效率则较低。这表明它的光合潜能在改变环境中没有正常发挥。同时，引入种较低的最大光化学效率进一步表明它抵抗环境胁迫的能力较低。当土壤水分可利用程度降低而导致水分竞争时，引入种很可能在竞争中被淘汰。因此，在生态恢复中，应尽量避免引入外来种，大量使用本地种。5）生态恢复不仅是自然科学问题，更重要的是社会经济问题‘为了充分认识当地社区的参与对生态恢复的作用，在实验过程中，调查了当地居民自本实验开展以来的思想观念、经济收入和生产效益等变化。在生态恢复中当地社区的积极参与是保证恢复成功与否的关键因素。从发挥“自然力”和“以人为本”的指导思想出发，在生态恢复中应注重充分利用自然的力量；在管理方面，要以解决社区居民的生产生活实际需求为目标。只有这样，才能保证生态、社会和经济可持续发展。 |
| 英文摘要 | Locating in an arid and semi-arid area, Hunshandak Sandland is a transition area from typical grassland to desert grassland. It had ever been the flourish grassland, however, has been greatly degraded because of the unmanaged human activities exerting on a frail ecological environment. For example, the percent of shifting sand dunes had increased from 2% in 1950s to almost 50% in 1990s. Now Hunshandak has been blamed as an important sand storm source'to Beijing and Tianjin regions, so it becomes one of the vital regions in land degradation research and also sandstorm controls. From a point of both natural and social science views, we here report the restoration potentials through natural process. The restoration stage, the species option for re-vegetation, the production and live of local people have been also studied, with main conclusions being achieved as follows: (1) The soil seed banks included numerous seeds which play potential roles in the restoration of degraded ecosystem in Hunshandak Sandland. Those seeds would germinate into seedlings and settle to form certain coverage if the disturbance of human and livestock were avoided. The degraded grassland can be correspondingly restored then the harms of sandstorms be reduced. There are significantly similar compositions both in soil seed banks and aboveground vegetations, which forms the base of plant community stability. Therefore, the soil seed banks may affect the restoration succession, in reverse, the restoration succession could also restrict the development of soil seed banks.\n(2) The natural restoration successions could be marked as three stages based on plant community analysis in different fenced locations. First, the early stage exists in 2 years after fenced, characterized by changes from shifting sand dunes to semi-fixed dunes. Second, the intermediate stage is within 3-5 years of closure, the semi-fixed sand dunes being gradually stabilized. Third, the later stage of restoration can be found after 6 years of community stabilization, during which the fixed sand dunes have been gradually developed. Considering the way of changes in growth forms and species components with restoration succession, the series of vegetation succession can be summed up as: Agriophyllum squarrosum + Bassia dasyphylla Salix gordejevii + Agropyron cristatum Artemisia intramongolica+ Agropyron cristatum Ulmus pumila var. sabulosa+ Agropyron cristatum. Thus, the degraded grassland may be mostly restored within a short period time'under fenced conditions. To achieve this, the disturbances of human activities and grazing are the keys in restricting the succession of restoration, which should be seriously considered. The leaf water traits varied among both in species and habtitats. Those species\nwith deeper rooting depths and lower leaf water contents showed the lower leaf osmotic potentials. Among the different growth forms, the shrubs had the lowest leaf osmotic potential, with a series of shrubs > trees > grass; deep rooting depth > shallow rooting depth (P< 0.05). In addition, species distributing in the wetland and lowland appeared\nthe higher leaf osmotic potentials and leaf water contents, while those growing on the sand dunes performed the lower values. Such indicates that plants with different growth\nforms possessed differential water use patterns enabling them coexist in the same ecosystem. Compared with the native species, the introduced species presented a lower\nvalue of net photosynthetic rate, stomatal conductance and water use efficiency, a higher value of leaf water potential under the similar photosynthetic photon flux density\nand leaf temperature. So the introduced species might be eliminated afterwards by the natives through water competition when the soils became acutely drought. |
| 中文关键词 | 浑善达克沙地 ; 退化沙地草地 ; 水分生理生态 ; 自然力 ; 植被演替 ; 社会经济 |
| 英文关键词 | Hunshandak Sandland degraded sandy grassland natural process leaf osmotic potential vegetation succession social economy |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286392 |
| 推荐引用方式 GB/T 7714 | 刘美珍. 浑善达克退化生态系统恢复研究-自然力在沙地草地恢复中的应用[D]. 中国科学院植物研究所,2004. |
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