Knowledge Resource Center for Ecological Environment in Arid Area
| 荒漠化生态系统格局变化及其生态效应-以陕西省榆林市为例 | |
| 其他题名 | Study on Pattern Dynamics and Ecological Effects of Desertification Rebuilding Ecosystem-A case study in Yulin County, Shannxi Province |
| 程淑兰 | |
| 出版年 | 2004 |
| 学位类型 | 博士 |
| 导师 | 欧阳华 |
| 学位授予单位 | 中国科学院地理科学与资源研究所 |
| 中文摘要 | 本研究以陕西省榆林市这一典型的荒漠化生态系统为例，分别从景观格局、土壤有机碳、河川径流和地下水埋深的角度研究荒漠化生态系统格局变化及其生态效应，以期为荒漠化生态系统重建提供科学依据。基于1986、1996和2000年TM影像和1982～2000年NOAA/AVHRR影像的生态系统格局变化研究表明：（1）沙地、草地和耕地为该地区最主要的景观类型，在19S6～2000年间大面积沙地转化成为草地，沙地景观的破碎度和草地景观的连接度均显著增加，从而促进了荒漠化生态系统的稳定性；（2）1950～2000年间，气候呈暖干化趋势，但是草地面积和NDVI指数呈增加趋势，这表明气候变化的环境影响己经被人类活动的生态效应所掩盖，植树造林种草。退耕还林还草等荒漠化重建措施是该荒漠化生态系统格局变化的主要驱动力。基于1982年土壤普查和2003年重复采样的土壤有机碳研究表明：（1）在1982～2003年间，耕层（0～20cm）、1m深（0～100cm）和全剖面（母质层以上整个土体）土壤有机碳含量（SOCC）、有机碳密度（SOCD）和有机碳储量（SOCS）均呈增加趋势；其中对人类活动最敏感的耕层土壤变化最显著。（2）在不同的土壤类型和区域范围，土壤有机碳差异十分显著。20年来风沙土类耕层、lin深和全剖面SOCC分别增加0.55g·kg-1、0.20g.kg-1和0.219.kg-1，SOCD分别增加0.15kg·m-2、0.28kg.m-2和0.31kg·m-2，SOCS分别增加10.07Gg、18.99Gg和20．19Gg。以风沙土为主的西北部风沙草滩区SOCC和SOCD普遍低于以黄绵土为主的东南部丘陵沟壑区。这表明植树造林种草、退耕还林还草、水土流失治理等荒漠化防治措施能显著提高土壤固碳潜力。基于景观格局一水源距离。1957～2000年河Jll径流和1991～2000年地下水埋深研究表明：（1）1986～2000年间，在不同水源距离缓冲区范围内，草地面积显著增加、沙地面积显著减少，其中距离水源1000～10000m变化最为剧烈，这表明在距离水源10000m水源距离缓冲区内，水分条件不是该荒漠化生态系统治局变化的控制因子。（2）1991～2000年间，西北部风沙草滩区NDVI、地下水埋渝地下水埋深／降水比值呈增加趋势，这一方面表明植被恢复提高了土壤持水性，另一方面表明植被蒸腾增加造成地下水资源亏损；（3）1957～2000年间，西北部风沙草滩区海流兔河的径流系数M-K突变检验表明在1972年径流系数发生突变，以1957～1972年降水～径流数据建立近似天然的径流～降水线性拟合方程，1972～2000年天然径流量（模拟径流量）和实测径流量差异显著，这表明荒漠化生态系统重建过程显著减少地表径流量，从而降低无效水分损失和土壤侵蚀风险。 |
| 英文摘要 | A case study was conducted to study the pattern changes and ecological effects of desertification ecosystem in Yulin County, Shannxi Province. Landscape change, soil organic carbon, surface runoff and groundwater embedment in the study area were studied in this paper because landscape changes were apparent characteristics of desertification ecosystems' pattern change, soil organic carbon and hydrological change (such as surface water and ground water) were its potential characteristic and ecological responses. Main conclusions were as follows: 1. Based on database of TM images (1986, 1996 and 2000), NOAA/AVHRR images (1982-2000), and long-term climate data (precipitation, temperature, moisture between 1951~2000), the processes and driving forces of landscape change in the study area were concluded below. (1) sandy land, grass land and arable land were the main landscape in this area, part of slope arable land were turned into woodland and grassland, and large area of sandy land were changed into grassland, so landscape indices such as fragment index of sandy land and connectivity index of grassland increased greatly during the past 20 years, which demonstrated that the stability and function of the ecosystem were improved. (2) In spite of the aridity tendency of climate system since 1950, the area of grassland and NDVI index increased greatly, which, indicated that climatic impact was covered up by the anthropogenic influences, and landscape pattern change was the main driving force of desertification ecosystem reversion. 2. According to the second soil survey in 1982 and re-sampling in 2003, temporal and spatial dynamics of soil organic carbon were studied. (1) On average, soil organic carbon content (SOCC), soil organic carbon density (SOCD), soil organic carbon storage (SOCS) and their changes of twenty years were various between different soil groups, soil C pools and sub-areas. (2) During 1982 and 2003, SOCC for arable layer (0~20cm), lm depth (0~ 100cm) and whole profile (whole soil layer upper parent material horizon) increased 0.55 g o kg-1, 0.20 g o kg-1 and 0.21 g o kg-1 respectively, which meant an increment of SOCD of 0.15 kg o m-2, 0.28 kg o m-2 and 0.31 kg o m-2, and an increment of SOCS of 10.07 Gg, 18.99 Gg and 20.19 Gg, correspondingly. (3) From the point of soil C pools, arable layer is much more sensitive to climate change and ecosystem management than lm depth and whole profile. (4) As far as soil group and sub-area were concerned, the change of SOCC and SOCD of sandy soil distributed in the northwest was much less than that of loessal soil located in the southeast, thus SOCS per area in the northeast is lower than that in the southeast. Above analysis indicated that desertification reversion process improved soil C sequestration, which had great impact on C cycle in arid terrestrial ecosystems. 3. Based on the buffer distances of watershed to each landscape, surface runoff (1957-2000) and groundwater embedment (1991-2000), preliminarily results of hydrological pattern and process were as follows: (1) Between 1986-2000, the attributed area of grassland increased significantly, while sandy land decreased greatly. The buffer distance to water-head between 1000-10000m was the most intensive one, which indicated that water supply was not the control factor for landscape pattern and dynamics in the buffer distance below 10000m from waterhead. (2) During 1991-2000, NDVI, groundwater embedment, the ratio of groundwater embedment to precipitation were on the increase, which demonstrated that vegetation recovery improved soil water capacity during desertification rebuilding process, and the increase of transpiration resulted in groundwater loss to a certain extent. (3) Based on M-K test of precipitation and observed surface runoff (1957-2000) of Hainiuru river of the northwest, linear simulation equation of precipitation and observed surface runoff between 1957 and 1972 was constructed, by which natural surface runoff between 1972 and 2000 were simulated and the difference of natural surface runoff and observed surface runoff can be alleged as the hydrological effect of desertification ecosystem's pattern change. The result demonstrated that desertification ecosystem's rebuilding process could decrease surface runoff and soil erosion as well. |
| 中文关键词 | 荒漠化生态系统 ; 生态系统格局变化 ; 土壤有机碳 ; 地表径流 ; 地下水埋深 ; 榆林市 |
| 英文关键词 | NDVI desertification ecosystem Landscape change soil organic carbon (SOC) liydrological process groundwater embedment surface runoff Yulin county |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院地理科学与资源研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286336 |
| 推荐引用方式 GB/T 7714 | 程淑兰. 荒漠化生态系统格局变化及其生态效应-以陕西省榆林市为例[D]. 中国科学院地理科学与资源研究所,2004. |
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