近300 年来中国森林的变迁

以清代以来史料为依据, 在现代清查统计资料和前人研究成果的基础上, 通过对森林变迁大体趋势及主要过程的客观把握, 重新校订了1949 年和1700 年前人的估算数据, 回溯估算了1750~1900 年中国各省区每50 年森林面积与森林覆被率值, 并与现代森林清查资料衔接, 分析1700~1998 年近300 年来中国森林变迁的时空特征。结果表明: 近300 年来中国现境内共减少森林面积约0.95×10⁸ ha, 森林覆被率减少9.2 个百分点, 变化曲线呈先抑后仰; 以1960s 为界, 此前呈加速递减态势, 260 年间减少森林面积达1.66×10⁸ hm², 覆被率下降约17 个百分点；1960s 以后呈逐步增长态势, 近40 年间增加森林面积约0.7×10⁸ hm², 覆被 率提高了约8 个百分点。结果还表明: 近300 年来中国森林消长, 西部地区均小于东部地区; 在1700~1949 年的锐减期中, 东北、西南和东南三区是森林面积缩减最为严重的地方, 大部分省区覆被率下降超过20 个百分点, 其中黑龙江达50 个百分点, 吉林达36 个百分点, 川渝地区达42 个百分点, 云南达35 个百分点；在1949~1998 年的恢复期中, 西部各省区森林覆 被率增加均小于5 个百分点, 东部地区(除黑龙江、湖北和沪宁外) 均超过5 个百分点; 其中 粤琼、广西、安徽、京津冀、山东、河南、浙江、福建等省区高达10 个百分点以上。

Quantitative Analysis on For est Dynamics of China in Recent 300 Years

Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized. The forest area and forest coverage rates for each province of China from 1700 to 1949 are estimated backward by every 50 years. Linking the result with modern National Forest Inventory data, the spatial-temporal dynamics of Chinese forest in recent 300 years (A.D.1700-1998) is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined 0.95 ×10⁸ ha (or 9.2 percentage points of coverage rate) in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated descending. The forest area was reduced 1.66×10⁸ ha (or 17 percentage points of coverage rate) in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×10⁸ ha (or 8 percentage points of coverage rate) in 40 years. The study also shows that there is a significant spatial difference in the dynamics of forest. The amplitudes of increasing and decreasing in western China are both smaller than the ones in eastern China. During the rapid declining period 1700-1949, the most decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20 percentage points. In Heilongjiang Province, the coverage rate dropped 50 points. In Jilin Province, it dropped 36 points. In Sichuan Province and Chongqing Municipality, it dropped 42 points. In Yunnan Province, it dropped 35 points. During the recovery period 1949-1998, the western provinces, municipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Sichuan-Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc., the increase rates of the coverage are all below 5 percentage points, while the eastern provinces, municipality and autonomous regions (except Heilongjiang, Hubei and Jiangsu-Shanghai) have achieved an increase over 5 percentage points, among which the Guangdong-Hainan, Guangxi, Anhui, Beijing-Tianjin-Hebei, Shandong, Henan, Zhejiang and Fujian have an increase over 10 points.