国家自然科学基金委员会地球科学部 中国水利水电科学研究院 Land use transition and its implications for ecological conservation LI Xiubin ICSS-Asia, Bangkok

Trilemma in land use policy 2 Food security Ecological security Urban development Policy Trade-off Marginalization /abandonment of farmland

3 Land use transition and its implications for ecological conservation Land use transition and its theoretical basis Land use transition in China Possibility of reduction in ecological pressure OutlineOutline

Trends in global land changes ——IGBP/IHDP-LUCC 1. The second half of the 20th century ( ) sees a dramatic rise in cropping intensity:  Irrigation area increased over 100%;  Fertilizer increased by 450%;  Tractors increased by 240%, while farmland expansion has been moderated: Which increased by 15% only. Compared with its expanding speed of % during the past 300 years ( ). 4

Trends in global land changes ——IGBP/IHDP-LUCC 2. Land changes in the geographical disparity are significant:  In developing countries, especially in humid tropics the forest area continued to decrease,  while in Europe, North America, Japan and other developed countries in the 20th century has gone through the "land use transition" - that is steep farmland, barren land and other "marginal land" opt-out of production, and consequently, forest area increased. 5

Land use transition or forest transition ——A. Mather The passage, in modern times, from net deforestation to net reforestation in a defined area, usually a country. 6 France Forest transition started from 1800, e.g: Denmark——early 19 century ； France——mid 19 century ； Portugual——1870s ； Northeast US——early 20 century ； Japan——probably18 century ； South America——recently ；

Its theoretical basis: 7 Intensification of fertile lands Crowding- out effect Farmland marginalization or abandonment agricultural labor force drain out Technology Technology Urbanization

Reasons for farmland marginalization/abandonment: 8 Rise of labor wage in urban sectors Rise of opportunity labor cost in rural sectors Urbanization and slowing down pop. growth Decline in farmland rent Marginalization of remote sloping or arid farmland

9 Land use transition and its implications for ecological conservation Land use transition and its theoretical basis Land use transition in China Possibility of reduction in ecological pressure OutlineOutline

Forest and farmland transition in China 10 Forest coverageCultivated land in total

Slowing down population growth 11 Replacement level One-child policy Low fertility trap The peak of labor force (15-64) in China will reach in 2015 China has been a very low fertility society since 1990 It may be a global trend —— the Economist Family planning policy

Rapid urbanization (as projected with Northam’s S-curve) 12 Accelerating stage Data sources ： UNDESA ， World Urbanization Prospects: The 2007 Revision Now 45.7%

Agricultural labor force is shrinking 13 进入 1990 年代，乡村劳动力增长趋缓；农业劳动力出现拐点 Rural labor in total Agricultural labor

Rural labor drain out from agriculture 年底包括乡镇以内务工的农民工总量为 2.25 亿 占劳动年龄内劳动力总量的 43%

Abandonment of marginal farmlands 15 A household survey in hilly areas of Ningxia, west China: Number of samples：222； Time of survey: May-June, 2008; Farmland area in total： hm 2 (irrigated hm 2 ， rainfed hm 2, sloping hm 2 ) Abandonment: hm 2 (37.5％ of total farmland) 二分类logistic模型分析结果： 与撂荒正相关的变量：农户劳动力外出数量、外出时间、农户坡耕地面 积、地块数 与撂荒负相关的变量：从事农业劳动力数量、农户耕地总面积

16 Land use transition and its implications for ecological conservation Land use transition and its theoretical basis Land use transition in China Possibility of reduction in ecological pressure OutlineOutline

A reduced rely on primary land produce —— firewood 17 Data sources: National agricultural census 1996 and 2006 全国平均下降了 8 个百分点 南方红黄壤丘陵区 下降了 13 个百分点

Indication from forest coverage in soil erosion areas 18 Data sources: National forest inventory 南方红黄壤丘陵区 近 20 年提高迅速 南方红黄壤丘陵区黄河中上游地区长江上游地区 上游地区上游地区 上游地区上游地区

国家自然科学基金委员会地球科学部 中国水利水电科学研究院 Thanks! Li Xiubin