北部湾沿海地区植被覆盖对气温和降水的旬响应特征

The NDVI Characteristics of Vegetation and Its Ten-day Response to Temperature and Precipitation in Beibu Gulf Coastal Region

论文分析北部湾沿海地区植被覆盖对气候变化的响应,为该区域植被恢复和植被生产力研究提供依据。基于研究区2000—2011年423景SPOT-VEGETATION逐旬NDVI数据及逐日气温和降水数据,利用像元二分模型、相关分析、偏相关分析和时滞偏相关分析等数理统计方法,对研究区植被覆盖时空变化特征及与旬降水和旬均温的相关性及滞后性进行分析。结果表明：1）近12 a来,北部湾沿海地区植被覆盖度平均值呈增长趋势,由2000年的65.23%增加到2011年的72.02%,增加了6.79%;2）研究区植被生长季旬NDVI均值介于0.21~0.67之间,在不同时期变化是不同的,其值呈现出＂降低—增长—降低＂3种变化过程;3）各种植被类型与温度具有显著的相关关系,全部通过了0.01的显著性水平,且NDVI与温度的显著性水平高于NDVI与降水的显著性水平,说明北部湾沿海地区植被覆盖NDVI对气象因子中的温度更为敏感;4）NDVI与气温的时滞偏相关系数显著高于NDVI与降水的时滞偏相关系数,旬NDVI与旬降水的滞后时间多集中于6~9旬之间,而旬NDVI与旬气温的滞后时间多以0~5旬为主;5）不同类型植被的生长对气温和降水的响应时间不一致,但与水热条件时滞偏相关系数越高的植被类型响应时间越短。上述研究结果表明,近12 a来北部湾沿海地区植被处于恢复状态,且植被对降水和气温具有明显的阈值和滞后性。

By analyzing the response of vegetation coverage climate change in Beibu Gulf coastal region, this paper aims to provide references for studies on regional vegetation restoration and vegetation productivity. Based on 10- day SPOT- VEGETATION NDVI data and 10-day temperature and precipitation datasets during the period of 2000-2011, this study uses the mathematical-statistic methods, such as dimidiate pixel model, correlation analysis, partial correlation analysis and time-lag partial correlation analysis to explore the quantitative characteristics of temporal- spatial change of vegetation coverage and their correlation with the climatic factors in Beibu Gulf coastal region. The results indicate： 1） In recent 12 years, the vegetation coverage in the Beibu Gulf coastal region increased by 6.79%, from 65.23% in 2000 to 72.02%in 2011. 2） The ten- day average NDVI in growing season ranged from 0.21 to 0.67, showing the tendency of a little reduce at the beginning, then going up steadily and finally going down again. 3） The NDVI of all kinds of vegetations had significant relationship with temperature,all passing the test at significant level of 0.01, and the significance level of correlation between NDVI and temperature is higher than correlation between NDVI and precipitation, which showed that the vegetation coverage of NDVI is more sensitive to temperature. 4） The time-lag partial correlation coefficient of NDVI and temperature was significantly higher than that of NDVI and precipitation, the lag time of NDVI and precipitation being 6-9 ten-day periods, that of NDVI and temperature being 0-5 ten-day periods. 5） The growth of different types of vegetations responded to temperature and precipitation differently, and the vegetations whose NDVI have higher time-lag partial correlation coefficient with water and heat conditions have short response time. In conclusion, the vegetation in Beibu Gulf coastal region is in recovery in past 12 years, and its response to precipitation and temperature has obvious threshold and is lag in time.