Special Column:Celebration of the 70th Anniversary of IGSNRR, CAS
MANFRED DOMRS
According to the leading national classification of the climate of China, given by B. Huang (revised version 1986), Hainan falls into the tropical climatic realm, subdivided into a "peripheral tropical" type for the northern part and a "middle tropical" type for the southern part of the island. While all-year-round frost-free conditions define the tropics in general, the 20t-isotherm for the coldest month represents the boundary between the peripheral tropical and middle tropical types. Compared to the tropical climate in general, Hainan experiences distinctly lower winter temperatures which thus result in a larger annual temperature variation. In terms of precipitation, Hainan records a long rainy season through the southwest monsoon and typhoon seasons from May until October while winter precipitation is comparably lower. Representing two agroclimatic hazards, strong typhoon winds and cold waves seriously affect Hainan. Although to be defined as "marginal tropica-1", the climatic conditions on Hainan are favourable for perennial tropical crops of which rubber and tea rank highest. Out of 92 state farms on Hainan, until the end of 1989 a total of 30 had been transformed from monocultivated rubber or tea plantations to rubber-cum-tea farms which are called in China "manmade communities". As shown for Nanhai State Farm on Hainan, a great economic am! social as well as ecological success could be achieved, only through intercropping of rubber anil tea. This underlines the large economic potential and agroclimatic capability of Hainan for tropical crops; it also proves the 'tropicality' of the climate on Hainan.The observations reported in this paper are part of a research project on the agroe-cological conditions in tropical China, carried out in close cooperation with the South China Academy of Tropical Crops, Danxian, Hainan, and the Chinese Academy of Sciences, Beijing.
