英语作文介绍一下美国(2)

　　英语作文介绍一下美国2

　　Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized.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 es- timated 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 (AD 1700–1998) is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined by 0.95×108 hm2 (or 9.2% of the coverage rate) in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated de- scending. The forest area was reduced by 1.66×108 hm2 (or 17% of the coverage rate) in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×108 hm2 (or 8% of the 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 de- creasing in western China are both smaller than the ones in eastern China. During the rapid declining period from 1700 to 1949, the most serious decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20%. In Heilongjiang Province, the coverage rate dropped by 50%. In Jilin Province, it dropped by 36%. In Sichuan Province and Chongqing Municipality, it dropped by 42%. In Yunnan Prov- ince, it dropped by 35%. During the recovery period 1949–1998, the western provinces, mu- nicipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Si- chuan–Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc, the increase rates are all below 5%, while the eastern provinces, municipality and autonomous regions (except Heilongjiang, Hubei, Jiangsu–Shanghai) have achieved an increase over 5%, among which the Guang- dong–Hainan, Guangxi, Anhui, Beijing–Tianjin–Hebei, Shandong, Henan, Zhejiang, and Fu- jian have an increase over 10%.

　　根据历史文献、现代调查和统计,以及前人研究的结果,这一趋势和主要森林动态识别的过程。每个省的森林面积、森林覆盖率从1700年到1949年中国的es - timated向后每50年。连接结果与现代国家森林库存数据,中国森林的时空动力学在最近300年(公元1700年- 1700年)是定量分析。研究表明,在最近的300年,森林面积在当前中国境内已经下降了0.95×108款hm2(或9.2%的覆盖率),减少和恢复的趋势。在1960年代之前,有一个趋势,加速de -左右摇晃。森林面积减少1.66×108款hm2(或17%的覆盖率)在260年。在1960年代后,迅速增加。森林面积增加了0.7×108款hm2(或8%的覆盖率)在40年。研究还表明,存在着显著的空间差异的动态的森林。的振幅增加,de -压痕在中国西部都是低于中国东部的。快速下降的时期从1700年到1949年,最严重的减少出现在东北,西南和东南,大部分省份的覆盖率下降超过20%。在黑龙江省,覆盖率下降了50%。在吉林省,下降了36%。在四川省和重庆市,下降了42%。云南箴言——因斯,下降了35%。复苏期间1949 - 1998年,西部省份,μ- nicipality和自治区,包括宁夏、甘肃、内蒙古、Si - chuan-Chongqing,云南、西藏、新疆和青海、等,增加率都低于5%,东部省份,直辖市、自治区(除黑龙江、湖北、Jiangsu-Shanghai)实现了增加超过5%,其中光——dong-Hainan、广西、安徽、京津冀、山东、河南、浙江、和傅——剑已经增加超过10%。