湖南省单、双季稻识别与生育期提取研究

本文基于MODIS数据,构建并分析了湖南省典型地物的植被指数及地表水分指数的时序曲线,利用分类回归树区分单、双季稻像元,并使用转折点法和最大变化斜率法提取双季稻的主要生育期。结果表明,湖南省内双季稻主要分布于洞庭湖区、湘江流域株洲以下、衡阳以上河段的干流及各级支流周边的平原区,以及永州、郴州境内阳明山和南岭山脉之间的狭长地带;单季稻主要分布在双季稻种植区外围,湘西州、怀化市等地的山间谷地也有种植。双季稻生育期在空间上保持了较好的相对一致性。洞庭湖以南平原区以及湘南山地丘陵区的各阶段生育期均早于省内其他地区,而洞庭湖区东北部、娄底、邵阳等地则相对滞后。湖南省大部分地区单、双季稻及生育期的分布都较为破碎,且空间镶嵌程度较高。上述结论可为后续开展湖南省水稻自然灾害与气候变化风险研究提供支持。

Identification of single/double-season paddy rice and retrieval of growth periods in Hunan Province

This study analyzed the time series curves of enhanced vegetation index (EVI), normalized difference vegetation index (NDVI), and land surface water index (LSWI) of paddy rice areas in Hunan Province based on MODIS data. Single and double-season paddy rice was distinguished with the classification and regression tree (CART) decision tree method. The inflection method and the dynamic threshold method were applied to retrieve the growth periods of double-season paddy rice. The result shows that double-season paddy rice of Hunan Province was mainly distributed in the Dongting Lake area, the plain area surrounding the main stream and tributaries of the section between Hengyang and Zhuzhou of the Xiangjiang River, and the panhandle between the Yangming Mountains and the Nanling Mountains in Yongzhou and Chenzhou. Single-season paddy rice was mainly distributed on the periphery of the zones planted with double-season paddy rice and the valleys in Xiangxi and Huaihua. The growth periods of double-season paddy rice planted in the southern part of the Dongting Lake area and the hilly areas in southern Hunan are earlier than other regions. The distribution of single/double-season paddy rice and their growth periods in the most part of Hunan Province were spatially un-contiguous and this pattern is relatively consistent across space. These findings can provide support for future study of the relationship between natural disasters that affect paddy rice and the risk of climate change in Hunan Province.