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退耕还林后陕西省植被覆盖度变化及其对气候的响应

李登科*,王钊   

  1. (陕西省农业遥感与经济作物气象服务中心, 西安 710014)
  • 出版日期:2020-01-10 发布日期:2020-01-10

Changes of fractional vegetation coverage after returning farmland to forests and its response to climate in Shaanxi.

LI Deng-ke*, WANG Zhao   

  1. (Shaanxi Agricultural Remote Sensing and Economic Crops Meteorological Service Center, Xi’an 710014, China).
  • Online:2020-01-10 Published:2020-01-10

摘要: 1999年起,陕西省实施了大规模的退耕还林、封山禁牧等生态建设和保护工程,使植被覆盖得到迅速恢复和增加。为了进一步跟踪评估植被覆盖变化,为生态建设和规划提供依据,本文基于2000—2017年MOD13Q1数据、气象数据,利用像元二分法估算陕西省18年间的植被覆盖度,通过空间插值方法、空间相关分析、统计学方法分区对其时空变化特征和对气候变化的响应进行了分析。结果表明:2000—2017年陕西省植被覆盖度呈现波动增加趋势,但增速逐年减少,2012年达到最大值后在高位波动;全省植被覆盖度增加区域面积占国土面积的82.4%,降低的区域仅占17.6%;陕北地区植被覆盖度显著增加,部分地区植被覆盖度达到最大值后出现下降趋势;植被覆盖度变异系数大的区域主要分布陕北长城沿线风沙区和丘陵沟壑区以及城市周边;陕西省植被覆盖度与降水量、气温在年尺度上相关系数均呈不显著的正相关;占全省98.4%的区域植覆盖度与降水、气温的复相关空间也未通过0.05显著水平检验;说明退耕还林等生态建设工程的实施,对植被恢复和生长具有重要的促进作用,一定程度上降低了植被生长对气候因子的敏感性;未来陕西省随着退耕还林等生态建设工程的环境资源的限制、土地利用程度的提高和城市用地的扩展,陕西省植被覆盖度将出现下降趋势。如何减缓这种下降趋势,是未来陕西省生态建设和保护的重大问题。

关键词: 净初级生产力, 协同应用, 参数优化, BEPS模型, 总初级生产力

Abstract: Vegetation coverage of Shaanxi Province has been gradually increased since 1999 due to the implementation of largescale ecological construction and protection projects such as returning farmland to forest and grazing prohibition. To provide basis for ecological constructions and planning, we analyzed the spatiotemporal variations of vegetation coverage from 2000 to 2017 in Shaanxi using pixel dichotomy method and its response to climate change through spatial interpolation method, spatial correlation analysis and statistical methods based on MOD13Q1 data and meteorological data. The results showed that vegetation coverage in Shaanxi presented a fluctuational increase during 2000 to 2017 and peaked in 2012. The area with increased vegetation coverage and that with decreased coverage accounted for 82.4% and 17.6% of the total land area, respectively. The vegetation coverage in Northern Shaanxi increased obviously, while there was a decreasing trend in some areas when it reached the maximum value. The regions with large coefficient of variation of vegetation coverage mainly spread over the windblown and sandy areas, hilly and gully regions and surrounding cities along the Great Wall of Northern Shaanxi. There was no positive correlation between vegetation coverage and precipitation or air temperature in Shaanxi on an annual scale. The multiple correlation space between vegetation coverage and precipitation and temperature in the areas which accounted for 98.4% of the whole province failed to pass the 0.05 significance test. Our results indicated that ecological construction projects such as returning farmland to forest play an important role in promoting vegetation restoration and growth, and to a certain extent, reducing the sensitivity of vegetation growth to climatic factors. In the future, there will be a decreasing trend of the vegetation coverage in Shaanxi with the resources and environment constrains of ecological construction projects, and the expansion of urban land use. How to slow down such decreasing trend is an important issue for ecological construction and protection in Shaanxi Province.

Key words: parameter optimization, collaborative application, BEPS, gross primary productivity, net primary productivity.