| Acer tutcheriis a typical native tree which distributed in the hilly region of Pan Pearl River Delta.Due to the colorfulleaves in spring,autumn,and winterhave,itcan be widely used in urban greening of lingnan area.The natural communities of A.tutcheri Guangdong Nanling National Nature Reserve,Heishiding Nature Reserve,and Shenzhen Dapeng Peninsula National Geopark Qiniangshan had been chosen and community characteristics,leaf color,and best viewing period were determined to explorer the key fators of leaves color change.The SBE method had been used to evaluate the variation of leaves colorsand to establish evaluation modelfor each regions.The results showed:(1)The number of species in different communities of A.tutcheri rich,and Nanling community had the highest speciesrichness with 214 vascular plants,followed by Heishiding and Qiniangshan.The DBH size-class structure of all species in the plot generally fitted a "reverse J" distribution,indicating good regeneration across the community.The Heishiding community had the highest proportion in DBH size-class structure under 4 cm which reach 57.14%.Besides,the average tree height of A.tutcheri in Heishiding community reach to 15.1m which showed the best red leaf landscape.Species diversity index in Nanling is higher than in Heishiding and Qiniangshan which indicated communities of A.tutcheri isstable in Nanling.A significant positive correlation(P<0.05)was found in interspecific associations of main woody plants in three regions,and communities of A.tutcheri inHeishiding had better associativity.Therefore,seedling should be replantingand Heishiding community is the best sample to improve the species diversity and landscape in Pan Pearl River Delta urban greening.(2)The color leaf periods of A.tutcheri were lasted from September to the following year in January.The longest color leaf period was found in Heishiding with 81-111 days,followed by Qiniangshan.From the leaf color characteristics,the chromatic aberration between leaves and environment was increased from early October,and the highest chromatic aberration of Heishiding and Nanling was found in early December,which reach to 17.92 NBS and 26.20 NBS,respectively.But chromatic aberration of Qiniangshan was the highest in later December with 24.71 NBS.Annual chromatic aberration was the highest in Nanling which had the best leaf color landscape.(3)From the chromatic aberration,the best viewing periods of Nanling was November,Heishiding was from early November to early December,and Qiniangshan was from later November to later December.Viewing periods in high altitude areas were half month shorter than in low altitude areas.A.tutcheri best viewing periods in Qiniangshan were longer and later than other areas which had a better landscape of color leave in winter.(4)A.tutcheri leaf color characteristics and soil physical and chemical properties were significantly different among these areas(P<0.05).TheA.tutcheri red leaves beginning,longitude,soil available K content were significantly positive correlation.The maximum color difference values was positively correlated with the available K content.The best viewing duration was significantly negatively correlated with available Cu.The maximum color difference value of best viewing period was significantly negatively correlated with latitude.The duration of red leaves was negatively correlated with total K,and it also showed a significant negative correlation with available P and Cucontent.A.tutcheriredleaves best ornamental period delay gradually from north to south.Lower altitude,longitude,latitude,soil total K,valid P,valid Cu content and higher available K content is beneficial to the expression of red leaves in A.tutcheri.(5)Thescores of the landscape beauty in three regions from high to low were Heishiding,Qiniangshan,Nanling.Heishiding with the ratio of bright red,more than 2/3 red leaf,the significant different of leaf color,and the clearer trunk which had higher scores than other areas.The leaf color,leaf color difference,leaf density,crown shape and background are the main factors influencing the A tutcheri beauty.The model Analysis shows that people prefer the A tutcheri beauty with bright color,the significant different color with the surrounding,flourishing trees,non-spindle-shaped crown shape. |
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