近300年来中国森林的变迁

Quantitative Analysis on Forest Dynamics of China in Recent 300 Years

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。

Based on historical documents, modem survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized.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 modem 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 × 10^8 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 × 10^8 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 ×10^8 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 eastem 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 westem 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 eastem 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.