1.1 Main Agro-ecological Features of China
China located in East Asia, with a land area of about 9.6 million km2, ranks the third largest country in the world, next only to Russia and Canada. From north to south, the territory of China measures some 5,500km from latitude 53°30′N to 4°N. From west to east, the country extends about 5,200km from longitude 73°40′E to 135°05′E, with a time difference of over four hours. China has land borders of 22,800km long, with 15 contiguous countries: Korea, Mongolia, Russia, Kazakhstan, Kirghizstan, Tajikistan, Afghanistan, Pakistan, India, Nepal, Sikkim, Bhutan, Vietnam, Laos and Myanmar (http://www.china.org.cn/e-china/geography/index.htm).
China’s topography is diverse and complicated, with towering mountains, basins of different sizes, undulating plateaus and hills, and flat and fertile plains. The altitude ranges from -154m (Turpan Basin in Xinjiang Province) to 8,848m (Mt Qomolangma or Mt Everest, the world’s highest peak and the main peak of the Himalayas).
China has a marked continental monsoonal climate characterized by great variety. Northerly winds prevail in winter, while southerly winds reign in summer. The four seasons are quite distinct. The rainy season coincides with the hot season. From September to April the following year, the dry and cold winter monsoons from Siberia and Mongolia in the north gradually become weak as they reach the southern part of the country, resulting in cold and dry winters and great differences in temperature. The summer monsoons last from April to September.
The warm and moist summer monsoons from the oceans bring abundant rainfall and high temperatures. China’s complex and varied climate results in a great variety of temperature belts, and dry and moist zones. In terms of temperature, the nation from south to north can be divided into equatorial, tropical, sub-tropical, warm-temperate, temperate, and cold-temperate zones; in terms of moisture, from southeast to northwest it can be divided into humid (32% of land area), semi-humid (15%), semi-arid (22%) and arid zones (31%).
The temperature difference between north and south is quite large in winter, the coldest month in the whole year is January, in which the average temperature ranges from -30.9℃ to 22.9℃. The warmest month is July, in which the average temperature ranges from 5.4℃ to 35℃. Annually rain fall ranges from 50mm to 1600mm (http://www.china.org.cn/e-china/geography/index.htm).
China has been identified as one of the 17 mega-diverse countries in the world (Mittermeier, 1988), also the most biodiversity-rich country in the Northern Hemisphere, with an ancient creatures origin and plentiful germplasm of cultivated plants and domestic animals. Especially South Central China, including Eastern Himalaya and the Mountain of Southwest China, is one of the 25 biodiversity hotspots globally (Myers et al., 2000).