A Analysis On Community Characteristics And Benefits Comparison Of Urban Landscape Woods In Hefei City

Urban landscape woods, one type of Urban forest, provide an important role forcity environment in both of ecological effects and landscape aesthetics, such as purifythe atmosphere, block dust, alleviate heat-island effect, conserve water, fixate carbonand release oxygen, beautify the city and so on. In this paper, based on field surveyfor urban landscape woods in Hefei city area, author distinguished community typesof landscape woods, meanwhile the species composition, community structure andstand characteristic, community characteristic value was accounted, and using I-treetools the ecological effects and carbon storage function were estimated as well. Thenconstruction cost and annual benefit for different community types of landscapewoods were compared. The writer generalized community types of high value andproposed advices for the constructions of urban landscape woods.The results can provide theoretical reference for sustainable development ofurban landscape woods and prompt healthy development of the city greening. Thechief results were as follows:(1) Based on survey for typical communities in different function areas, such asparks, residential areas, college campus and roads, total111tree species wereidentified, which belonged to45families and81genus. The major dominant wereCinnamomum camphora, Pterocarya stenoptera, Metasequoia glyptostroboides,Bischofia polycarpa, Populus canadensis, Osmanthus fragrans, Photinia serrulataetc.Species richness index of the named landscape woods in the study area wascollege campus> residential areas> roads> parks in order; Simpson diversity indexand Shannon-wiener diversity index were parks> college campus> residentialareas> roads. Evenness index was parks>residential areas> college campus> roads,so was health index. The result was relatively representative.The DBH, tree height and crown width of trees of landscape woods showednormal distribution. The tree with10～20cm at DBH,5～10m in tree height and2～4m in crown width occupied the highest proportion based on tree number in that ofparks, residential areas and roads. And the tree with20～30cm at DBH,10～15m inheight and4～6m in crown width occupied the highest proportion at college campus.(2) The system of vegetation classification type-formation-association was builtfor identify of community type. Then there are5vegetation types,21formations,45associations in Parks;6vegetation types,20formations,29associations at College campus; and5vegetation types,11formations,19associations in residential areas;3vegetation types,3formations,4associations in roadside. Main types were the both ofdeciduous broad-leaved woods and evergreen and deciduous broad-leaved mixedforest in different function areas. It tallied with the zonal vegetation characteristics.The community vertical structure of landscape woods in different function areasis relatively simple in the mass. It is mainly2layers which is arbor-shrub orarbor-inferior arbor. Some landscape woods are only arbor layer, most of themlocated at college campus, which remains to be improved.(3)The average biomass of landscape woods in different function areas showedthat: college campus (163.96t/hm~2)>roads (119.05t/hm~2)>parks (63.9t/hm~2)>residential areas (51.48t/hm~2). The average ecological effects of landscape woods indifferent function areas showed that: roads (138.40million Yuan/hm~2)> collegecampus (134.91million Yuan/hm~2)> parks (64.87million Yuan/hm~2)> residentialareas (55.35million Yuan/hm~2). Due to mainly small and medium-sized trees inresidential areas, both of carbon storage and ecological function were less than that ofthe other three function areas. Although the community types were rich in parks, theirecological function was finite.(4) In the general, for both of the carbon storage and ecological effects, thebroad-leaved forest is better than that of coniferous forest, coniferous andbroad-leaved mixed forest. So Coniferous and deciduous broad-leaved mixed forest,warm temperate coniferous forest and evergreen broad-leaved forest in carbon storagefunction and ecological function were dominant. And coniferous evergreenbroad-leaved forest is worthy of popularization.(5) The cumulative investments cost for all types of landscape w oods in thestudy area was from8.44million Yuan/hm~2to129million Yuan/hm~2, average45.08million Yuan/hm~2; and the monetary value of ecological effects for all landscapewoods types in the investigation year was accounted as from1.29million Yuan/hm~2to90.7million Yuan/hm~2, average39.64million Yuan/hm~2. The ratio between thebenefit value and total investment cost (written as benefit/investment as follows) forwoods in parks was from0.08to2.14, which showed a more fluctuations pattern. Thereason involved the selection of tree species and tree size for planting using. That oflandscape wood community having the ratio of benefit/investment>1accounted forabout50%of the total. This showed that almost half of communities of landscapewoods in the study area had a limited benefit returned although under the high investment cost. The situation should be avoided in the future.(6)Based on survey of3typical associations, the investments cost and ecologicaleffects were increasing year by year. The investments cost only contained annualmaintenance fees for trees besides builting year cost. But ecological effects value oftrees will be visibly increasing for years. Some community investments cost may behigher than the value of ecological effects for previous years, but ecological effectsvalue will be higher than investments cost because of trees growth. BCR ofassociations is gradually increasing year after year. The trend is that increasing forBCR was relatively stable in the first5years, then faster after10years. Coniferousand deciduous broad-leaved mixed forest advantaged over deciduous broad-leavedforest and evergreen and deciduous broad-leaved mixed forest about dynamicvariation.Based on the comprehensive view, coniferous and deciduous broad-leaved mixedforest, evergreen and deciduous broad-leaved mixed forest and warm temperateconiferous forest is advantageous in carbon storage function, ecological function,investments cost and benefit/investment. Some associations having relative lowerinvestment cost and higher benefit value should be popularized in Hefei city area,which are: Koelreuteria paniculata+Pistacia chinensis-Punica granatum+Trachycarpus fortunei association, Populus canadensis association, Castaneamollissima+Liriodendron chinense-Prunus cerasifera Ehrh.’Atropurpurea’+Punica granatum-Distylium racemosum association, prunus armeniaca+Cinnamomum camphora-Camellia japonica association, Metasequoiaglyptostroboides+Salix babylonica-Lagerstroemia indica association,Camptotheca acuminate+Cinnamomum camphora-Acer palmatum-Pittosporumtobira association, Liquidambar formosana-Loropetalum chinense Oliv.var.rubrumassociation, Ligustrum lucidum+Platanus acerifolia association, Sapium sebiferum-Sabina komarovil association, Camptotheca acuminate+Ligustrum lucidumassociation and so on.