干旱区城市防护林景观化更新提升策略研究

Study on Transformation Strategies of Protection Forest in Arid Area

随着城市的不断发展,原本处于干旱区城市边缘的城防林带变成了城中林,其防护隔离作用也逐渐弱化,将其改造成为集游憩、景观、生态多功能为一体的公园绿地成为必然趋势。针对如何最大限度的保护和利用现状植被、实现功能与形象的更新与提升的问题,本文通过对城防林现状的研究分析,并依托二连浩特和石河子两个防护林改造项目作为实践案例,初步总结若干条干旱区城市普遍适用的更新策略,包括保障林地生态功能、低干预地打造满足多种户外活动需求的游憩廊道、植入主题展示宣传城市文化、适当增加节水型水景、补植林下植被形成"乔—灌—草"复层种植模式、注重带状公园城市界面的处理,以及其他气候适应性设计手法等。

China started large-scale construction of urban defense forest in northwest and the north China in the 1950s.The shelter forest surrounding the city can not only improve urban greening rate,adjust the urban microclimate,reduce the urban heat island effect,purify air and increase the humidity of the air,but also can be used as a city’s biological corridor,connecting various ecological matrix and plaques.It is the most important city green infrastructure in arid areas,and plays a key role in maintaining urban soil and water conservation,protecting agricultural production,improving the environment and maintaining ecological balance.With the continuous development of the city,the urban forest protection belt,which used to be on the edge of the arid area,has become a forest in the city,and its protection and isolation function are gradually weakened.It has become an inevitable trend to transform it into a park green space integrating multi-functions of recreation,landscape and ecological.For arid areas cities that urgently need park green space,the current vegetation of urban forest protection is a scarce resource in the city,so the current vegetation should be protected and utilized to maximize extent,and the function and image should be updated and improved.Based on the analysis of the current situation and common characteristics of urban forest protection,this paper summarizes four core issues of urban forest protection in the renovation and promotion of ecological security,citizen demand,climate adaptability and characteristic design.Based on the current situation of relevant studies at home and abroad,six renewal and upgrading strategies are proposed for cities in arid regions:not removing tree,not transplanting,not affecting the status of any tree in the renewal process;improving the current vegetation level,enriching the vegetation types,making the urban forest more healthy;meeting the diverse recreational needs of the public with low disturbance facilities;according to the climatic characteristics of arid region,suitable structures,irrigation methods and waterscape design were adopted.Implant urban culture and memory,strengthen the spiritual connection between urban forest protection and the city and residents,becoming the exhibition platform of urban culture;the interface of the outer edge of the forest is processed to improve the openness and attraction of the park.In the end,the author takes Erenhot and Shihezi,two cities in arid areas,as practical cases to explain the above strategies in detail.The former one is located in the northern part of the Inner Mongolia Autonomous Region.Based on the principle of retaining vegetation to the maximum extent in the design,a landscape corridor with both recreational and cultural displays was created,consisting of two juxtaposed 1-meter-wide recreational trails and a 2.5-meter-wide rocky beach landscape zone in the middle.This corridor not only shows the landscape of the arid desert steppes around Erenhot,but also provides a series of activities and recreation facilities for the citizens.It is the carrier of Erenhot’s urban spirit and culture.The forest vegetation system on both sides of the linear corridor was improved,and a series of small,point-type layout water features were arranged.Finally,the port culture of Erenhot was reflected through sculptures,paving and facilities details,which became a city window to promote economic and trade exchanges and cultural exchanges between the port of Europe and Asia.After the completion of the project,the woodland,which has once been inaccessible with no recreational value at all,now is transformed into an important outdoor activity space for local citizens and tourists.The second one is located in the middle part of the north foot of Tianshan Mountain.This shelterbelt has more than 70 years’history and used to be the protective separation zone between Shihezi Old City and the west factory area.With the transformation of urban industrial function,its function changes from“protective separation”to“integrated link”.In the design,according to the current vegetation,road and site,a slow-moving system was established under the forest with minimal intervention.Replanting native shade tolerant ground can improve the diversity and ornamental value of the plant community,improve the interspecies relationship and enhance the stability of this kind of woodland while protecting the roots of trees and protecting the soil against wind.The container module is used as a functional structure to provide citizens with a variety of recreational spaces,and to increase the structure and landscape water system to improve the local microclimate.After all,for the cities in the arid regions,the huge forest reserves are a fortune left by their predecessors.Whether it can be updated and upgraded in a reasonable way not only affects cities in arid areas to achieve major strategic objectives of ecological protection and sustainable development,but also affects ordinary citizens to enjoy a better life.It is hoped that this research can contribute to the construction of ecological civilization and living environment in arid cities.