The Hengduan Mountains from Yunnan are well-known for their richness in biodiversity, but there is ample concern for these ecologically sensitive areas. From my two field surveys to the hinterlands in 1987 and 1995, respectively, I was shocked by the facts that swidden agriculture still prevailed widely, and some of the villages faced serious soil erosion and water shortages arising from traditional practices. To clarify the problems, a correlation matrix analysis was conducted using published data on total population (PO), villager population (VP), cultivated land area (CLA), grain yield (GY), agriculture output value (AOV) in eight poverty stricken counties in the area in 1990, and their increments between 1985 and 1990. It can be shown that there were significant positive correlations between: a) the VP (90% of PO) and the PO; b)the CLA and the PO, GY, and AOV, respectively; and c) the increment of the CLA and that of the PO and AOV, respectively. Both personal observations and computer outputs give us an ecological warning—the natural cover, which remained too little to maintain a healthy ecosystem, would continue to reduce with the growth of population. Better vegetation cover (vs that seen in ordinary circumstances), however, did exist on the slopes behind better farmlands. Accordingly, I believe the social/economic development and the maintenance of biodiversity depend on the success of birth control and the improvement of production model. For the latter, it may be a good choice for development planners to arrange for food production within smaller areas with much improved water and fertility conditions (i.g. through the study and use of agroforestry), and thus to vacate lands for planting economic trees, or allowing vegetation to recover naturally.