中国全球变化样带的设置与研究

ALLOCATION AND STUDY ON GLOBAL CHANGE TRANSECTS IN CHINA

为研究中国全球变化与陆地生态系统（ＧＣＴＥ）关系及过去全球变化（ＰＡＧＥＳ）需要，我国全球变化样带（ＣＥＮＴ）将分别按经向（Ｅ１１０—１２０°）和纬向（Ｎ４０°）设置。第一样带（ＣＥＮＴＩ）系中国东部森林生态系统样带，是沿着热量梯度，在东亚季风控制下的各个森林地带的生态系列。第二样带（ＣＥＮＴＺ）系中国北温带森林－草原－荒漠生态系统样带，是沿着湿度梯度，由大陆性气候向海洋性气候过渡的生态系列。在样带上进行生物地球化学过程、能量交换、植被结构与动态、气候－植被关系、土地利用格局、模型测试和遥感校验等研究。

The ecological transect is considered as an effcient approach for studying the 'interaction between global change and terrestrial ecosystems. It could be used as a linkage between site observation and integrated regional studies, or a medium for transferring and coupling between models of time and space on different scales or levels. In the core projects of IGBP such as 'Global Change and Terrestrial Ecosystems(GCTE)' and 'Past Global Changes(PAGES)', the research on transects has been highly emphasized. The Northeast China's Forest--Steppe Transect(NECT) that we proposed at the GCTE International Symposium of Transects, Marshall, CA, USA in 1993 has been accepted as one of four international IGBP transects. A global change;transect is comprised of a set of coherent research sites along the gradient of a major global change driving force, e.g., temperature, precipitation, the intensity of land use, etc. The main items are to study biogeochemical processes including trace gas emissions, carbon and nitrogen cycles. etc., to study energy exchange of ecosystems', to study vegetation structure and dynamics, climirate-vegetation interaction' and changes in biodiversities, to study the characteristics and patterns of land use; to debuge 'models on different scales; and to test remote sensing data. On the basis of these considerations, China's global oh.ange transects can be allocated longitudinally and latitudinally in the eastern and northern parts of the country, called CENT (Eastern and Northern Transects of China) for short. The Eastern Forest Biomles Transect (CENTI) extends frolm the northern point of Great Xin'an Mountains, through Northeast China mountain regions, North China Plain, Chang Jiang-Hui River Plain, and South China Hilly area to the southern end of Hainan Island. The longitudinal range is E109°30'-128°, the latitudinal range N 18°44'-53°, and the altitudinal range 0-.1 300m. The vegetation/soil zonation of the transect is in order from north to south: cold temperate (boreal) coniferous forest/podozolic soil; cool temperate mixed coniferous-deciduous broadleaf forest/dark brown forest soil; warm temperate deciduous broadleaf forest/brown earth and cinnamon soil; subtropical evergreen broadleaf forest/red and yellow earth; and tropical seasonal forest/laterite. The whole transect, except its boreal coniferous forest zone, is a forest zonal series controlled by the East Asian Monsoon System, a latitudinal zonal system driven by thermal gradient, and also the most complete and continuous forest biome series on the Earth. The climatological indexes of the transect are as follows: the mean annual temperature--4-24℃, the mean annual precipitation -420-1 750mm, the potential evapotranspiration rate (PER)-0.4,.4, and the net primary productivity (NPP)-4.5-20t. a-1. ha-1. The land use pattern is in order from north to south: boreal forestry; semiforestry-semiagriculture (one cropping in one year); three croppings in two years and temperate deciduous broadleaf fruit orchard; two croppings in one year, subtropical evergreen fruit orchard and economic tree plantation; and two croppings in one year, tropical fruit orchard an economic tree plantation.The Northern Temperate Desert-Steppe-Forest Biome Transect(CENT2) extends along N40' from the Tarim Basin on the west, through Hexi Corridor, Alasan Sand Desert and North China's Plain to Southern Liaoning Hilly area on the east. The elevation ranges between 0-2 555m. The vegetation/soil zonation of the transect is from west to east: extreme-arid desert; primitive brown desert soil and drift sand; temperate steppe/castanozem; secondary deciduous broadleaf forest and farmland/cinnamon soil and cultivated soil; and secondary deciduous broadleaf forest/brown earth. This transect is a biome series driven by moisture or precipitation gradient. Themain climatological indexes are: the mean annual temperature-4-11℃, the mean annual precipitation-25--800mm, the potential evapotranspiration rate(PER)-0.9-29.2, and the net primary productivity-0-10.2t. a-1. ha-1. The land u