title: [Spatiotemporal change characteristics of agricultural climate resources in middle and lower reaches of Yangtze River].
abstract: The period 1961-2007 was divided into two by the time node of year 1981, and the change characteristics of the agricultural climate resources both in period I (1961-1980) and in period II (1981-2007) were analyzed and compared. The results showed that under the background of global warming, the average climatic trend rate of > or = 10 degrees C accumulated temperature in the middle and lower reaches of Yangtze River in temperature-defined growth season during 1961-2007 was 74 degrees C x d x 10 a(-1), and the > or =10 degrees C accumulated temperature in period II was 124 d higher than that in period I. Comparing with that in period I, the safe planting boundary of double cropping rice in period II moved 0.79 degrees northward. In 1961-2007, the precipitation in temperature-defined growth season had an overall increasing trend. Comparing with those in period I, the precipitation and the area of > or = 767 mm precipitation (water requirement for normal growth of double cropping rice) in period II were increased by 1.6% and 1.13 x 10(4) km2, respectively. The average sunshine hour in temperature-defined growth season in period II was reduced by 8.1%, comparing with that in period I. In recent 47 years, about 91.1% stations in the reaches showed a decreasing trend in sunshine hours. Comparing with that in period I, the reference crop evapotranspiration in temperature-defined growth season in period II showed a slightly decreasing trend, and its low value region expanded while its high value region narrowed. The beginning date of daily temperature over 10 degrees C was averagely 2 days earlier in period II than that in period I, while the ending date was in reverse. The ending date of daily temperature over 22 degrees C was almost the same in periods I and II.
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. zyn-jw@cau.edu.cn
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Xiao-guang
authors.initials: XG
authors.lastname: Yang
authors.forename: Shu-wei
authors.initials: SW
authors.lastname: Dai
authors.forename: Wen-feng
authors.initials: WF
authors.lastname: Wang
mesh_terms: D002681:China; D057231:Climate Change / Q000706:statistics & numerical data*; D018556:Crops, Agricultural / Q000254:growth & development*; D004463:Ecology / Q000379:methods; D017753:Ecosystem; D004784:Environmental Monitoring; D057232:Global Warming; D011891:Rain; D045483:Rivers; D013472:Sunlight; D013696:Temperature