Ningal Tine, Hartemink A E, Bregt A K
ISRIC-World Soil Information, PO Box 353, 6700 AJ Wageningen, The Netherlands.
J Environ Manage. 2008 Apr;87(1):117-24. doi: 10.1016/j.jenvman.2007.01.006. Epub 2007 Mar 13.
The relation between human population growth and land use change is much debated. Here we present a case study from Papua New Guinea where the population has increased from 2.3 million in 1975 to 5.2 million in 2000. Since 85% of the population relies on subsistence agriculture, population growth affects agricultural land use. We assessed land use change in the Morobe province (33,933 km2) using topographic maps of 1975 and Landsat TM images of 1990 and 2000. Between 1975 and 2000, agricultural land use increased by 58% and population grew by 99%. Most new agricultural land was taken from primary forest and the forest area decreased from 9.8 ha person(-1) in 1975 to 4.4 ha person(-1) in 2000. Total population change and total land use change were strongly correlated. Most of the agricultural land use change occurred on Inceptisols in areas with high rainfall (>2500 mm year(-1)) on moderate to very steep slopes (10-56%). Agricultural land use changes in logged-over areas were in the vicinity of populated places (villages), and in close proximity to road access. There was considerable variation between the districts but districts with higher population growth also had larger increases in agricultural areas. It is concluded that in the absence of improved farming systems the current trend of increased agriculture with rapid population growth is likely to continue.
人口增长与土地利用变化之间的关系备受争议。在此，我们呈现一个来自巴布亚新几内亚的案例研究，该国人口已从1975年的230万增长至2000年的520万。由于85%的人口依赖自给农业，人口增长影响着农业土地利用。我们利用1975年的地形图以及1990年和2000年的陆地卫星专题绘图仪图像，评估了莫罗贝省（33,933平方公里）的土地利用变化。1975年至2000年间，农业土地利用增加了58%，人口增长了99%。大部分新的农业用地来自原始森林，森林面积从1975年的人均9.8公顷降至2000年的人均4.4公顷。总人口变化与土地利用总变化密切相关。大部分农业土地利用变化发生在年降雨量超过2500毫米、坡度为中度至非常陡峭（10 - 56%）的始成土地区。伐木地区的农业土地利用变化发生在人口聚居地（村庄）附近，且靠近道路。各地区之间存在相当大的差异，但人口增长较高的地区农业面积增加也较大。得出的结论是，在缺乏改良耕作制度的情况下，当前随着人口快速增长农业不断增加的趋势可能会持续下去。
