美国荒野风景河流的空间分布特征及其对中国的启示

Spatial characteristics of the national wild and scenic rivers system in the United States and its enlightenment to China

美国荒野风景河流体系是全球最早建立的河流保护地类型。经过50年发展,其完善的体系呈现出一定空间分布特征。将线状国家荒野风景河流(NWSR)抽象为点状单元,对208个NWSR单元进行空间计算,并与自然生态和社会经济等因素进行叠加分析。结果表明,美国已有40个州分布NWSR,其中以俄勒冈等3个州的数量分布最多,且集中分布于特定的区域:西部的太平洋海岸、落基山脉和山间高地3个自然地理区;极地、温湿润、干旱3个Ⅰ级生态区;太平洋西北部、加利福尼亚、阿拉斯加及五大湖4个流域。NWSR线密度与州域的人口密度、经济水平相关性不强,但与大坝建设密切相关。荒野思想影响了法案制定,法案指导了遴选标准,遴选标准又进一步影响了NWSR的空间分布。研究对中国的借鉴意义在于:应当明确保护地指导思想、关注价值突出区域、确定合适遴选标准、重视保护地系统规划等。

The Wild and Scenic Rivers System(NWSRS)of the United States designated the earliest protected river system in the world.After 50 years of existence,the system continues to grow and to fulfill the promise of the original legislation.National Wild and Scenic Rivers(NWSR)are linear,and cross boundaries,including federal,state and private lands,and represent a variety of ecosystems and serve a variety of human populations.This paper uses available NWSRS and other biophysical river data,US natural ecological and socio-economic data,GIS and other analysis softwares for development of graphical overlays and correlation analysis.There are currently 208 NWSRS units,unevenly distributed across the United States.Parameters of this system can be analyzed,based on a Kernel Density tool to calculate the density of selected features in a neighborhood around those line or point features.A linear density measure is the length of NWSRs in each state.Based on these analyses,this paper further discusses the relevance of this distribution to natural and socio-economic variables in the US.The results show that while the NWSRS units in 40 of 50 states,three states far exceed the others:Oregon,Alaska and California.There is only one unit of the NWSRS in each of 18 states in the United States,most of which are located in the eastern region.In addition,10 states,concentrated in the Great Plains,do not have NWSRS units.High density of NWSRS units occurs in three physical geographical regions:the Pacific Coast,the high mountains,and the Rocky Mountains.Low densities of NWSRS units are found in the Plains and the Atlantic Plain.NWSRS units are distributed in Polar,Humid Temperate,Dry,Humid Tropical Domains;and only one ecological Division of the US has no NWSRS units.NWSRS units are mainly concentrated in four major continental watersheds:the Pacific Northwest,California,Alaska and Great Lake.The correlation between line density of NWSRS units and population density and level of economic development is not strong,but it is closely related to high dams.There are many reasons for the current spatial distribution of the NWSRS,especially the ideology behind political motivations for legislative protection.A guiding ideology for river conservation is needed,river designation recommendations must pay attention to key areas which have unique societal values and threats to those values,and establishing protected area selection criteria.A national system plan is needed.