引用本文:张露洋,雷国平,郭一洋,路中.三江平原耕地归一化植被指数对气候因子的时滞响应[J].土壤学报,2021,58(2):526-536. DOI:10.11766/trxb201910240413
ZHANG Luyang,LEI Guoping,GUO Yiyang,LU Zhong.Delayed Responses of Normalized Difference Vegetation Index of Cultivated Land to Climatic Factors in Sanjiang Plain[J].Acta Pedologica Sinica,2021,58(2):526-536. DOI:10.11766/trxb201910240413
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三江平原耕地归一化植被指数对气候因子的时滞响应
张露洋, 雷国平, 郭一洋, 路中
东北大学土地管理研究所, 沈阳 110169
摘要:
三江平原位于我国中温带北段,近年来气候变暖和耕地利用变化较为显著。基于2000-2015年三江平原耕作期(5-9月)耕地利用数据、旬气候数据、旬归一化植被指数(NDVI)数据,利用变异系数、趋势系数以及时滞互相关的研究方法在分析气候因子时间变化特征和耕地NDVI空间变化差异的基础上,分析区域旬气候因子对耕地旬NDVI的时滞影响情况。研究发现:(1)三江平原耕作期气温年际变化较降水量变化更加稳定,在月际变化上更显规律性。(2)耕地NDVI年际稳定,9月植被覆盖度最大;16年的变化在空间差异上呈现以西部区域为代表的低值-不稳定-增加趋势区域以及东部为代表的高值-稳定-减少趋势区域的二元模式。(3)区域气温对耕地NDVI的影响程度大于降水对其的影响,大多数县域耕地NDVI对气温的响应时间大于对降水的响应时间。(4)气温对区域水田NDVI的影响较大;旱地NDVI对区域气候因子的响应时间大于水田的响应时间。研究结果可为指导区域应对气候变化的耕作生产、保障粮食安全等提供依据。
关键词:  NDVI  降水量  气温  时滞相关  耕作期  三江平原
基金项目:国家自然科学基金项目(41671520)资助
Delayed Responses of Normalized Difference Vegetation Index of Cultivated Land to Climatic Factors in Sanjiang Plain
ZHANG Luyang, LEI Guoping, GUO Yiyang, LU Zhong
Land Management Institute, Northeastern University, Shenyang 110169, China
Abstract:
The Sanjiang Plain is located in the northern part of the mid-temperate zone of China. In recent years, climate warming and cultivated land use have been changing significantly. So it is of great significance in protecting food security and stability to analyze responses of cultivated land use to regional climate change. As cultivated land is a kind of artificial vegetation, its NDVI value reflects certain crop information, like growth and yield. Therefore, by analyzing impacts of climate factors on cultivated land NDVI, information relevant to response of regional cultivated land use to climate change can be obtained.[Objective] Based on the data of cultivated land use, ten-day climatic data, and ten-day normalized difference vegetation indexes (NDVI) of the Sanjiang Plain during the farming period (May~September) of the years from 2000 to 2015, temporal changes in climatic factors and spatial variation of NDVI of the cultivated land were obtained through analysis and furthermore, information about delayed response of cultivated land NDVI to regional climate change was acquired.[Method] In this research, methods, like variation coefficient analysis, trend coefficient analysis and time-delay cross correlation analysis were adopted.[Result] Results show:(1)The interannual variability of temperature was more stable than that of precipitation during the farming period of the Sanjiang Plain, while the intermonthly variabilities of the two tended to be more regular; (2)The cultivated land NDVI did vary much between years, with the vegetation coverage being the highest in September; spatial variation of the cultivated land NDVI during the 16 years exhibited a trend of being low-unstable-increasing in value, representative in the western part of the region and being high-stable-decreasing in value, representative in the eastern part; (3)Maximum unbiased correlation coefficients of the ten-day NDVIs and ten-day mean temperatures of the cultivated land varied mostly in the range between 0.931 and 0.992, and delayed response was observed for 2 ten-day periods. Maximum unbiased correlation coefficients of the ten-day NDVI and ten-day precipitation of the cultivated land varied in the range between 0.778 and 0.927, and delayed response was observed for 1 ten-day period only. The cultivated land NDVI of the Sanjiang Plain, except for Fuyuan County, Raohe County and Tongjiang City, responded more slowly to air temperature than to precipitation. The cultivated land NDVI responded quite slowly to regional climate change in Jiamusi City and Shuangyashan City, while it did rather quickly in Mishan City, Baoqing County, and Hulin City. Moreover, it responded faster to change in air temperature and slower to change in precipitation in Fuyuan County and Muling City; and (4) The maximum unbiased correlation coefficients of dry land ten-day NDVI and ten-day mean temperature were both 0.942, and that of the paddy field's was 0.962. Delayed response of NDVI to mean temperature in dry land was observed for 2.026 ten-day periods, and that in paddy field for 1.633 ten-day period. The mean maximum unbiased correlation coefficient between ten-day NDVI and ten-day precipitation was 0.809 in dry land, and 0.765 in paddy field, and the mean time lag of NDVI to precipitation was 1.323 ten-day period in dry land, and 1.045 ten-day periods in paddy field.[Conclusion] Change in regional temperature impacts cultivated land NDVI more than change in precipitation does. The lag of NDVI responding to air temperature of cultivated land is longer than that to precipitation in most counties. Temperature is a major factor affecting regional paddy field NDVI; the lag of dry land NDVI responding to regional climate change is longer than that of paddy field's. The findings in the research may provide a scientific basis for guiding farming production of the region to cope with climate change and ensure food security.
Key words:  Normalized Difference Vegetation Index  Precipitation  Air temperature  Time-delay correlation  Farming period  Sanjiang Plain