基于i-Tree模型的城市绿道生态服务效益研究

为了量化分析城市绿道中树木的各类生态服务效益价值,为未来绿道树种筛选和种植规划提供参考。以宁波市“三江六岸核心区”绿道树种为研究对象,对其树木群落结构组成、胸径分布、树高结构和生长类型进行分析;并运用i-Tree模型进行生态效益评估,将节能效益、固碳效益、改善空气质量效益、截留雨水效益和美学效益值量化为经济价值。结果表明:绿道树种类型丰富(37科54属71种),生长类型多为阔叶落叶型乔木,绿道树木的胸径和高度多数介于15.2~30.5 cm和5.0~10.0 m,处于稳定生长阶段,季相变化较丰富且景观效果较强。通过i-Tree模型评估“三江六岸核心区”绿道年总生态效益值为4 287 024.54元,其中,美学效益(64.62%)>固碳效益(17.25%)>截留雨水效益(9.79%)>节约能源效益(8.32%)>改善空气质量效益(0.02%)。树种优势度与绿道总生态效益贡献率相关性较强,樟树、银杏、柳树、鸡爪槭的总生态效益贡献率最高,但与单株年生态效益之间没有较强相关性;泡桐(2 494.70元·株^-1)、二球悬铃木(1 994.49元·株^-1)、枫杨(1 824.93元·株^-1)、喜树(1 542.23元·株^-1)的单株年生态效益较高,但其数量在绿道中不占优势。建议在选择树种时,将植物挥发性有机物(BVOC)纳入改善空气质量价值评估体系中,推广单株生态效益价值较高的树种应用于绿道中。

Study on ecological service benefits of urban greenway based on i-Tree model

In order to quantitatively analyze the value of various ecological services of trees in urban greenways, and provide reference for tree species selection and planting planning in the future. By taking the greenway tree species in “The River Junction Area” of Ningbo City as the research object, the composition of tree community structure, diameter at breast height (DBH) distribution, tree height structure, and growth type were analyzed. The ecological benefits were evaluated by using i-Tree model, and energy-saving benefit, carbon sequestration benefit, air quality improvement benefit, rainwater interception benefit and aesthetic benefit were quantified as economic values. The results showed that there were abundant tree species in the greenway (71 species, 54 genera and 37 families), and the growth types were mostly broad-leaved deciduous trees. The DBH and height of greenway trees were mostly between 15.2-30.5 cm and 5.0-10.0 m, which were in stable growth stage, with abundant seasonal changes and strong landscape effect. According to i-Tree model, the annual total ecological benefit of greenway in “The River Junction Area” is 4 287 024.54 yuan, including aesthetic benefit (64.62%)>carbon sequestration benefit (17.25%)>rainwater interception benefit (9.79%)>energy saving benefit (8.32%)>air quality improvement benefit (0.02%). There was a strong correlation between the dominance of tree species and the total ecological benefit contribution rate of greenway. The contribution rate of Cinnamomum camphora, Ginkgo biloba, Salix babylonica and Acer palmatum were the highest, but there were no strong correlation with the annual ecological benefit of individual tree; Paulownia fortune(2 494.70 yuan per tree) , Platanus acerifolia(1 994.49 yuan per tree), Pterocarya stenoptera(1 824.93 yuan per tree) and Camptotheca acuminata(1 542.23 yuan per tree) had higher ecological benefits per plant, but the numbers of them were not dominant in the greenway. It was suggested that plant volatile organic compounds (BVOC) should be included in the evaluation system of air quality improvement, and tree species with higher ecological benefit value should be applied to greenway.