Study On Scenic Beauty Estimation Of Urban Forest In Shenzhen City

Based on the actuality of Shenzhen’s urban forest, the species composition, speciesdiversity, community structure and ornamental characters of plants were investigated, and thescenic beauty evaluation （SBE） was applied to estimate the in-forest landscape and out-forestlandscape of the plantation and secondary forest, screening out the communities with higherSBE values. The major factors afecting the forest landscape were also analyzed and the variouskinds of forest landscape models were established. Through exploring the relationship betweenthe main components of the landscape elements and the quality of urban forest landscape,provide the technical support for the urban forest planning layout, selection of tree species andartificial regulation provide. The main results were as follows:（1） There were417vascular plants in50plots （30m×40m） belonging to131families and292genera, which including28ferns belonging to14families and19genera and389seedplants belonging to117families and273genera. Plantations forest included282vascularplants belonging to98families and211genera., and the secondary forest included319vascularplants belonging to168families and231genera. The top5families in vascular plants wereEuphorbiaceae, Rubiaceae, Lauraceae, Papilionaceae, Moraceae, and the genera, and the top4species in above families were Ficus, Syzygium, Ilex, Elaeocarpus. The higher frequency ofoccurrences about arbor were Aporosa dioica, Litsea rotundifolia, Schefflera octophylla,Sapium discolar, Castanopsis fissa, Cratoxylum cochinchinense, Toxicodendron succedaneumand so on, and the Aporosa dioica was up to80%.（2） In accordance with the different stand origin, urban forest in Shenzhen city could bedivided into plantations and natural secondary forests；According to the relative importancevalue of tree layer, Urban forest in Shenzhen city could be divided into Castanopsis fissacommunities, Machilus chekiangensis communities, Cratoxylum cochinchinense communities,Acacia auriculaeformis communities, Acacia mangium communities, Eucalyptus citriodoracommunities and so on,31community types.（3） The diversity index order was that the shrub layer outnumbered tree layer, and the natural secondary forests outnumbered the plantation in Shen zhen’s urban forest. Thediversities of the tree layer and the shrub layer were different. The tree layer’s Shannon-wienerindexes of Cinnamomum burmami+Aporosa chinensis+Rhus succedanea communities,Schima superba+Cinnamomum camphora+Litsea cubeba communities, Cratoxylumcochinchinense communities, Castanopsis fissa+Castanopsis chinensis communities,Cryptocarya chinensis+Sinosideroxylon wightianum+Sterculia lanceolata communities, wererelatively higher, and the tree layer’s Shannon-wiener indexes of Rhodoleia championiicommunities, Acacia mangium communities, Eucalyptus citriodora communities wererelatively lower. The shrub layer’s Shannon-wiener indexes of Castanopsis fissa+Castanopsischinensis communities, Cryptocarya chinensis+Sinosideroxylon wightianum+Sterculialanceolata communities, Aporosa chinensis+Cunninghamia lanceolata communities werecomparatively higher, and Rhodoleia championii communities’ was lowest. The tree layer’sSimpson index of Rhodoleia championii communities was highest, and the shrub layer’sSimpson index of Machilus chekiangensis communitier was highest.（4） There were many ornamental plants in Shenzhen’ urban forest, including color-leafplants, ornamental flower plants, ornamental fruit plants, ornamental shape plants. Thecolor-leaf plants were77species in total which belonged to37families and52genera. Theornamental flower plants were171species in total, which belonged to60families and131genera. The ornamental fruit plants were111species in total, which belonged to44familiesand72genera. The ornamental shape plants were236species in total, which belonged to73families and158genera.The ornamental trunk plants were Eucalyptus citriodora andCratoxylon ligustrinum and so on.（5） Urban forest in Shenzhen city could be divided into3types of communities:ornamental flower plants’ communities, color-leaf plants’ communities and ornamental shapeplants’ communities. The SBE value of ornamental flower plants’ communities was highest（SBE=0.39）, color-leaf plants’ communities’ was-0.03, ornamental shape plants’ communities’was-0.25. The SBE value of Rhododendron moulmainense+Machilus chekiangensis+Ilexnitidissima communities in ornamental flower plants’ communities was highest（SBE＝1.071）,followed by the Castanopsis fissa communities, Castanopsis fissa+Castanopsis chinensis communities, Polyspora axillaries+Aporosa dioica+Cassia siamea communities, Rhodoleiachampionii communities, Acacia confuse communities. The SBE value of Syzygiumhancei+Machilus chekiangensis+Psychotria rubra communities in color-leaf plants’communities was highest（SBE＝0.37）, followed by the Cinnamomum burmannii+Aporosadioica+Toxicodendron succedaneum communities, Machilus chekiangensis communities. TheSBE value of ornamental shape plants’ communities was lower, Cratoxylum cochinchinensecommunities in ornamental shape plants’ communities was highest（SBE＝0.12）, and the SBEvalues of Eucalyptus citriodora communities, Castanopsis carlesii+Albizia falcatariacommunities and Acacia auriculaeformis communities were lower.（6） The scenic quality of the plantations in-forest landscapes in Shenzhen was higherthan the natural secondary forests, and SBE value of the plantation in-forest landscapes was0.092, while the natural secondary’s in-forest landscape landscapes was-0.187. The SBE valueof Acacia mangium communities was maximum, yet, Adina pilulifera+Psychotriayunnanensis+Acacia confusa communities was minimum. The model of the plantation’sin-forest landscape factors and SBE values was, SBE＝0.131+0.177X5-0.195X8+0.208X9-0.162X10-0.129X12-0.00008X17+0.113X21+0.007X23-0.571X25.The model showed that, the major landscape features which affected thescenic quality of the plantations in-forest landscapes were height of ground plants, abundanceof interstratum plants, arrangement of trunks, the amount of downed-woods, uniformity ofundergrowth, age of stand, branch height, coverage of undergrowth, and density and so on. Themodel of the natural secondary forest’s in-forest landscape features and perceived scenicbeauty was SBE＝-2.016+0.157x1+0.215x4+1.753x16-0.063x18+0.021x24.The main featureswhich affected the quality of the natural secondary forest’s in-forest were litter, crown density,viewable distance, bark’s color, abundance of arbor and so on.（7） The scenic quality of spring landscapes was maximum, and summer landscaps andautumn-winter landscapes were minimum about urban forest’s out-forest landscapes. The SBEvalue of Rhododendron moulmainense+Machilus chekiangensis+Ilex nitidissima communitieswas maximum （SBE=1.071）, and the SBE value of Eucalyptus citriodora communities wasminimum （SBE=-0.641）. The model of out-forest landscape factors and SBE values was SBE ＝-0.530-0.144X₅+0.208X₇+0.278X₈+0.088X₁₆.The model showed that the major featureswhich affected the scenic quality of out-forest landscapes were colour and lustre, abundance ofcolor, and distribution pattern of plaque. Generally, larger the plaque, the richer colour variety,the brighter colour variety, older the stand ages, the higher the scenic beauty.（8） On the issue of urban forest, it was suggested that we should put more emphasize oneco-conservation and forest protection in the natural reserve areas and fung shui woodland, andcarry out manual control, improve tree branches height, reduce the number of dead, fallen,weakly growing, pests and diseases infected trees in outdoor recreation areas, like city park andthe forest park, in order to ultimately promote the stand openness and foest scenic beauty. Weshould plant some ornamental flower trees and colour-leaf trees in visal landscape interchange,such as Rhododendron moulmainense, Cassia siamea, Machilus chekiangensis and Syzygiumhancei.