| 李晓琳,刘晓娜,孙丹峰.民勤绿洲农业系统变化的协整分析[J].干旱地区农业研究,2016,34(1):279~287 |
| 民勤绿洲农业系统变化的协整分析 |
| Co-integration analysis of Minqin oasis agricultural systems |
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| DOI：10.7606/j.issn.1000-7601.2016.01.43 |
| 中文关键词: 农业系统 协整分析 向量误差修正模型（VECM） Grange因果检验 民勤绿洲 |
| 英文关键词:agricultural system johansen co-integration vector error correction model (VECM) Granger causality Minqin oasis |
| 基金项目:国家自然科学基金(41071146)；西南林业大学生态学优势特色重点学科开放基金 |
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| 中文摘要: |
| 采用协整分析的方法，基于1956—2008年长时间序列数据，分析了近50年内民勤农业生产系统（作物和牲畜）和环境系统在土地退化条件下的变化规律，并通过建立向量误差修正模型（VECM）和Granger因果检验方法，进一步探寻了民勤农业各子系统间的相互作用关系及系统长期均衡关系和短期波动状态。研究表明：（1）在土地退化的条件下，民勤农业生产系统和环境系统之间依然存在一个长期的均衡状态，虽未使民勤农业系统在土地退化的影响下崩溃，但却存在过度种植放牧、水资源短缺、土地退化之间的恶性循环；（2）民勤绿洲农业各子系统围绕长期均衡态还存在短期的波动，其中天气条件（沙尘暴次数）和地下水资源（机井数）开采调整回均衡态的贡献显著，向量误差修正模型前系数绝对值分别为0.9129和-1.2583，远远大于其他指标；在对荒漠化地区进行监测时，应当优先选择沙尘暴天气数和机井数等指标；（3）Granger因果检验结果表明，羊只存栏数和地下水资源（机井数）开采是沙尘暴次数的Granger原因。畜牧业的发展，超过草场的自然承载能力，风蚀现象加重。地下水严重超采，导致地下水位急剧下降，矿化度增加、地表植被大面积死亡，导致沙尘暴灾害加剧。因此，可以通过减少放牧和有效管理地下水资源来实现研究区的荒漠化防治。 |
| 英文摘要: |
| Based on long time series statistical data from 1956 to 2008, the general changes of agricultural production system (crop and livestock) and environmental system under the condition of land degradation in Minqin oasis were analyzed comprehensively using the method of the Johansen co-integration vectors model. Vector error correction model and Granger causality tests were adopted to examine the interactions among different systems. Through the analyses of the long-term equilibrium relationship and short-term fluctuation in agricultural system, the adjustment of agricultural structure and comprehensive management policies of the Shiyang river basin would be supported. The result showed that under the condition of land degradation, there was a long time co-integration relationship between agriculture production system and environmental system, which avoided agricultural system crash. Whereas, there was a vicious circle among extensive crop production expansions, groundwater overdraw, overgrazing and sever land and water resources degradation. Additionally, in light of short term fluctuations deviated from the long run equilibrium, the adjusting speed of weather (sand storms) and groundwater resources (motor-pumped well number) were the fastest, which were 0.9129 and -1.2583, respectively. Dust storms times and motor-pumped well were chosen to monitor desertification. Moreover, the result of Granger causality tests showed that sheep population and groundwater resources (motor-pumped well number) were the granger reason of sand and dust storms. With the development of animal husbandry, carrying capacity of nature was exhaust, and frequencies of dust storms were increased. Exploitation of groundwater caused degradation of local water resources, the deaths and the recession of vegetation. Thus, reducing grazing and effective management of groundwater resources could counteract desertification in arid western region. |
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