基于时序植被指数的湖北省物候空间特征分析

Phenological Spatial Characteristics of Hubei Province Based on Time Series Vegetation Index

湖北省地貌类型多样,植被类型丰富,也是农业大省,物候信息监测对于自然生态和农业生产具有重要意义。使用MODIS MOD13Q1产品中的归一化植被指数数据集,运用时间序列谐波分析法重构NDVI时序曲线,并结合土地覆被数据,采用物候特征动态阈值法获取湖北省植被物候空间分布特征,分析不同土地覆被类型的物候指标。结果表明:(1)湖北省西部山区、东南部和东北部丘陵地区,多为自然植被覆盖,且植被状况良好,NDVI最大值达到0.75以上,大部分区域NDVI最小值在0.6以上。中部江汉平原和农作物区域NDVI变化受农业耕种方式影响较大,与自然植被NDVI变化特征有所差异。(2)不同土地覆被类型物候特征各异。湖北省大部分区域的植被在2月到3月进入生长季,11月到12月结束生长,襄阳地区呈现相反的特征。耕地、裸地、水体等受人类影响较大的土地覆被类型生长季长度较短,开始时间较晚,结束较早。森林、草地、灌丛等自然植被生长季长度较长,开始较早、结束较晚。(3)物候参数由于地形地貌、地表覆被类型、人类和自然因素的影响具有显著的差异,对区域植被生态状况、不同土地覆被类型物候空间分布特点的分析,结果对于植被生态保护、植被分类、农业区划等都具有参考意义。

Hubei Province is a large agricultural province with diverse landforms and abundant vegetation types. Phenological information monitoring is of great significance to natural ecology and agricultural production. In this study, based on the normalized vegetation index data set of MODIS MOD13 Q1 products, time series harmonic analysis method was used to reconstruct NDVI time series curve. Combining with land cover data, the spatial distribution characteristics of vegetation phenology in Hubei Province were obtained by the dynamic threshold method of phenological characteristics, and the phenological indexes of different land cover types were analyzed. The results show that:(1)Most of the western mountainous areas, southeastern and northeastern hilly areas of Hubei Province are covered by natural vegetation covering from NDVI change characteristic. The maximum NDVI value is above 0.75, and the minimum NDVI value is above 0.6 in most of these areas which indicate good vegetation condition. NDVI characteristic changes in central Jianghan plain and crop regions are greatly affected by agricultural cultivation, which are different from that of natural vegetation.(2)The phenological characteristics vary among different land cover types. The vegetation in most areas of Hubei Province enters the growing season from February to March, and ends growing from November to December. The contrary characteristics are found in Xiangyang area. Land cover types such as cultivated land, bare land, and water bodies that are greatly affected by humans have shorter growth seasons, and the start time is later, ending earlier. The growth season of natural vegetation such as forests, grasslands and shrubs are longer, starting earlier and ending later.(3)Phenological parameters have significant differences due to the influence of topography, land cover types, human and natural factors. The analysis of the regional vegetation ecological status and the spatial distribution characteristics of phenological characteristics of different land cover types had significance for vegetation ecological protection, vegetation classification and agricultural regionalization.