Urban Ecological Restoration Starting from Our Neighborhoods

Prof.Dr.-Ing.WANG Xiangrong Chief Editor

Cities are the areas where humans have transformed the natural environment the most.As a highly artificial system,cities are bound to face enormous ecological pressure.Through urban ecological restoration,human beings can minimize the damage to nature in the process of urban construction and operation,and use corresponding methods to compensate for the degradation of the urban ecological environment,so as to maintain a benign and dynamic balance of the urban ecological system.

If trees are planted in suitable and possible places in the city,decaying trees are timely replaced and missing trees are filled up as soon as possible,not only can the urban green coverage rate be greatly improved,but also the urban heat island effect can be effectively alleviated.Because the unnatural space in the city is mostly composed of concrete,asphalt,glass,stone and metal,the specific heat capacity of these materials is smaller than that of plants,and as the external environment changes,their temperature rises and falls much more violently than plants.When more of the city's skin made of these materials is no longer facing the sun directly,shaded by plants instead,it will not heat up sharply with the sun's rays,which will help reduce the peak temperature of the city.

If the newly built urban green space can more simulate the local original environment to design plant community,and manage it in accordance with the law of natural growth of plants;and if the existing urban green space with simple structure and single species of plants can be optimized,adjusted and restructured into a community with local plants as the main body,nurture the community according to the law of natural succession,gradually increase the complexity of the community structure so that it has more characteristics close to the zonal plant community,urban green space will have more efficient ecological value.

If there is a certain area in the city that basically excludes human interference and control and the nature there can succeed according to its own laws;if some original spontaneous plants on the site can be preserved in the construction and management of the park and the germination and growth of spontaneous plants are allowed;and if human management can be reduced in the areas with very low use intensity in the existing urban parks,allowing natural growth to a certain extent,there will be more nature full of wildness in the city,and the stability and health of urban environment and the diversified bio-habitat have a stronger foundation.

If there are clear regulations stipulating that the rainwater of every compound in the city,including residential areas,campuses,government agencies,hospitals,enterprises,and even each plot,is allowed to be discharged into the city's rainwater pipe network only after paying the corresponding fee,then the landscape of these courtyards and plots will certainly be redesigned and transformed,and a surface rainwater management system will be established to store rainwater in the courtyard as much as possible through infiltration,collection,storage and utilization.In this way,the pressure on the urban rainwater pipe network will be greatly relieved,the groundwater level will rise,rain gardens or seasonal small wetlands will spread all over the city,the ecological service capacity of each unit plot in the city will be improved,the distribution of ecological space will be more even,the structure will be more diverse,and the landscape of the city will become more natural.

If,on the premise of ensuring flood control safety,and according to the land use conditions,naturalized ecological restoration can be carried out on the canalized urban river,and the cross-sectional shape of the natural river can even be restored if conditions permit,and conditions for the growth of waterfront plant communities can be created,so that river courses have certain natural attributes and complete ecological processes;and through restoration,the rigid embankment can be transformed into a resilient flood bank,the river will become the city's biological corridor and species habitat,and the water bank will also become a waterfront public space with comprehensive functions in the city -the scenic coastline full of natural flavor,the life coastline with the city atmosphere,and the artistic coastline with the cultural atmosphere.

If the roofs of urban buildings can be covered with a suitable soil layer and barren-resistant plants,stretches of meadows in the sky will appear in the city;if the walls of some buildings and structures can hold climbing plants,herbaceous plants can grow in areas other than railway tracks in the rail transit land,and expressways or rail transit in cities go under the ground,transforming the released surface space into urban green spaces,the skins of many buildings and gray infrastructure in cities have natural attributes and thus become a space with certain ecological value.Urban construction land is often realized by occupying natural space,so that the skin of buildings and infrastructure having certain natural attributes is to some extent an insitu compensation for the degradation of urban ecological functions and the occupation of natural space.It can be imagined that through the continuous ecological transformation of buildings and gray infrastructure,the area of urban ecological space can be close to or even larger than the projected area of the city.

If a qualified community can take out a piece of land,divide it into vegetable plots and rent them out to residents,or transform the roofs of some residential buildings into aerial agricultural gardens,and let everyone grow vegetables and fruits on the basis of standardized management measures,it will not only bring the production of food,but also increase the communication between neighbors in the community,so that residents living in the downtown can experience a leisurely life and share the joy of farming and the joy of harvest.If there is a vegetable garden in every kindergarten,primary and secondary school,children will have more opportunities to get in touch with farming and observe the nature.In this way,the city will have a more pastoral atmosphere,and there will be more types of urban habitats.

If urban green waste,such as plant litter,can be crushed and returned to the land,or green waste treatment stations can be established in large parks and botanical gardens in the city to collect waste adjacent to green land and carry out classified treatment,the recycling of resources can be realized,and the garden waste disposal station will also become an ecological education base and a distinctive scenic spot in a park or botanical garden.The fallen leaves and branches can be used as compost,and after returning to the land,they can enhance the air permeability and water retention capacity of the soil,adjust the pH of the soil,increase the content of organic matter and fertility of the soil,and continuously improve the physical and chemical properties of urban soil.Urban soil is an integral part of the urban ecological environment system,and fertile soil ensures the healthy survival and growth of plants and animals.

If urban green space has good accessibility,connectivity,permeability and sharing,and can meet the diverse and rich outdoor living needs of citizens for rest,communication,sports,sightseeing,education,entertainment,etc.,citizens will have a healthier life way and a higher standard of life;if green space can become a convenient slow-moving corridor for commuting to work or to public transportation stations and service facilities,and if more urban roads can become green streets with a comfortable slow-moving system covered by trees,then walking and cycling will become the first choice of most citizens for short-distance travel,and public transportation will also be the choice of more citizens for travel,which will effectively increase citizens' daily fitness opportunities and help reduce urban pollution and alleviate traffic congestion.

The main purpose of urban ecological restoration is to repair the damaged ecological environment of the city,expand the urban ecological space,and connect the ecological space into a system to improve the quality of the urban ecological infrastructure.The ecological restoration of every place around us can contribute to the area expansion,structural optimization,quality improvement and network connectivity of urban ecological space,and even the restoration and improvement of micro-scale ecological space will bring comprehensive ecological value to the city.