Comprehensive Evaluation Of City Landscape Ecological Forest And Its Application

City landscape ecological forest(CLEF)is an important part of city environment,and plays an irreplaceable role in improving city ecological environment.Along with the people demand unceasing enhancement to the city environmental quality,the city landscape ecological forest construction is getting more and more attention.Then what does the idea to construct the city landscape ecological forest,not only has the advantages of low cost and high aesthetic value,but ecological and environmental benefit is high.That is a problem to be solved now.According to species composition all investigated stands were classified to be as formation,and a vegetation classification was built as well,in Hefei city.Based on field survey,22 formatons in cluding commosition species were identified.In order to make the types 22 of CLEF comparable,the unified specification base on the gude for tree planting published by park administration office was employed to make calculation for construction cost.The top five types rated in expenditure of building in order are Cedrus+Distylium racemosum combination、Ginkgo biloba+Sabina komarovii+Koelreuteria integrifoliola-Loropetalum chinense combination、Bischofia polycarpa+Magnolia grandiflora+Ulmus pumila combination、Salix babylonica+Cinnamomum camphora-Prunus ceraifera combination and Cinnamomum camphora+Sapindus mukurossi-Osmanthus fragrans combination.The lower expenditure for communit building are Pinus thunbergii+Cinnamomum camphora+Sabina komarovii-Forsythia suspense combination,pinus elliottii combination,Cinnamomum camphora-Photinia serrulata combination,Taxodiumascendens+Cedrus+Bischofia polycarpa+Sapium sebiferum combination and Bischofia polycarpa+Liriodendron chinensis combination.Aesthetic evaluation to 22 formations of CLEF by using SBE method,results show that the overall scenic beauty quality of landscape ecological forest is not high in Hefei City.The scenic beauty for CLEF has great relevance to 5 landscape elements,that are broadleaf tree ratio,average DBH,average crown width,color trees proportion and Lawn coverage ratio.The effecting degree of these elements is lisited in order:the proportion of broad-leaved tree>average DBH>average crown>the proportion of color tree>Lawn coverage ratio.Based on field measure of net photosynthesis rate and transpiration rate,the water use efficiencies(WUE)for 12 major tree species of CLEF was calculated in spring.The water consumption is different for different species in spring.Koelreuteria integrifoliola is rated at the highes,then Acer buergerianum,Prunus cerasifera,Ligustrum lucidum,Cinnamomum camphora,Osmanthus fragrans werel also listed at higher water consumption level in order,meanwhile Koelreuteria integrifoliola showed low transpiration and high water use characteristics.Tree species for low water comsumption are Sapium sebiferum,Salix babylonica,Magnolia grandiflora,Ginkgo biloba,Bischofia polycarpa,Platanus acerifolia.The 3 of them,Ginkgo biloba,Bischofia polycarpa,Platanus acerifolia showed higher transpiration and lower water use characteristics.The characteristic of water consumption in spring for tree species could be employed as a basical guid for selection of water-saving tree species,the native species,Koelreuteria integrifoliola Sapium sebiferum and Acer buergerianum could be used as water-saving specis to build CLEF;But if consideration water saving,the species such as Ginkgo biloba,Bischofia polycarpa,Platanus acerifolia should not be selected.Referencing the calculation methods used in European and America author designed an improved in this paper formula:City tree value=Trunk basal area(at breast high 1.3 meters)× tree base price × Tree species coefficient × tree growth position coefficient x growth situation coefficient × ornamental characteristic coefficient × ecological benefit coefficient.Cinnamomum camphora trees were transplanted using different plant methods,one is big tree at dbh 25cm and cut back whole crown(described as cutback tree as following),another is small at dbh 8cm but with whole crown(described as whole crwon tree as following),then the growth comparison between them are analyzed dynamically for 25 years after transplanting.The results show that cut back tree stem diameter growth after planting slower than whole crown tree.On the whole,The whole crwon tree is greater than cutback tree always.Comparison Leaf area increasing between two trees,that of wole craow and cutback treeo,the leaf area of the former is always larger than that of the later one.Aothour make conclution that transplating small trees with whole crown is much beter than that of big tree with no crown at all for both economic and aethstic views.There is no obvious correlation about heavy metals content between soil content and branch of Magnolia grandiflora Two heavy metals content of Magnolia grandiflora branch collected from the same types of greenbelts but different locations are not identical,and the distribution of heavy metals are different.The analysis of annualring increasing for 110 years indicated that the relationship between annualring growth and annual average temperature showed a negatively relevant,but has a positively relevant with annual precipitation、annual sunshine hours and the average relative humidity of year.Based on the analysis and evaluation of the above put forward to imitate the natural plant community or nearly natural plant community to constructe resource-saving city landscape ecological forest.And put forward to landscape ecological forest restoration ideas in Hefei city.