深圳市古树资源特征与分布格局

Resource characteristics and distribution pattern of ancient trees in Shenzhen City

在收集资料的基础上,采用实地调查和走访相结合的方法,对深圳市古树资源的种类组成、区系分布、结构特征和生长状况进行了分析;并采用网格法对古树资源空间分布状况进行了统计分析。结果表明：深圳市共有古树1 482株,隶属于35科63属78种,古树数量多且种类丰富;主要以桑科（Moraceae）、无患子科（Sapindaceae）、桃金娘科（Myrtaceae）、大戟科（Euphorbiaceae）、樟科（Lauraceae）和榆科（Ulmaceae）等优势科和榕树（Ficus microcarpa Linn.f.）、樟树〔Cinnamomum camphora（Linn.）Presl〕、龙眼（Dimocarpus longan Lour.）、荔枝（Litchi chinensis Sonn.）和朴树（Celtis sinensis Pers.）等乡土树种为主;深圳古树资源的科、属分布类型具有明显的热带性质和由热带向亚热带、温带过渡的特点。从深圳市古树资源的结构上看,树龄主要集中在100-200 a,平均树龄为145.2 a;树高主要集中在8.0-16.0 m,平均树高为12.4 m;胸径主要集中在0.5-1.5 m,平均胸径为1.1 m;冠幅主要集中在10.0-20.0 m,平均冠幅为15.8 m。从空间分布状况看,深圳市古树分布广泛,但不同区域古树的种数和株数差异显著,主要集中在深圳市的中南部和东南部。从生长状况看,生长良好（Ⅰ级）、一般（Ⅱ级）、较差（Ⅲ级）和濒死（Ⅳ级）的古树分别有729、616、100和37株,分别占古树总株数的49.19%、41.57%、6.75%和2.50%。相关性分析结果表明：深圳市古树的树高与胸径、树高与冠幅、胸径与冠幅间均极显著正相关;古树树种丰富度与古树数量和土地性质极显著正相关;古树生长状况与所处环境的近自然程度和树池的有无极显著正相关,与树龄则无显著相关性,表明区域土地利用性质是影响古树空间分布的关键因素。根据调查结果,对深圳市古树资源的保护提出了建议。

Based on collection data, species composition, flora distribution, structure characteristics and growth status of ancient tree resources in Shenzhen City were analyzed by combined methods of field investigation and interview, and spatial distribution status of ancient tree resources was also analyzed statistically by grid method. The results show that there are 1 482 ancient trees belonging to 78 species in 63 genera of 35 families in Shenzhen City, and these ancient trees are abundant in quantity and species. In which, the dominant families including Moraceae, Sapindaeeae, Myrtaceae, Euphorbiaceae, Lauraceae and Ulmaceae, and native tree species including Ficus microcarpa Linn. f., Cinnamomum camphora （Linn.） Presl, Dimocarpus longan Lour., Litchi chinensis Sonn. and Celtis sinensis Pers., etc. are main. Distribution type of family and genus of ancient tree resources in Shenzhen City possesses the tropical property and transition characteristics from tropical to subtropical and temperate zone. From structure of ancient tree resources in Shenzhen City, tree age is concentrated on 100-200 a with average tree age of 145.2 a, height is concentrated on 8.0-16.0 m with average height of 12.4 m, diameter at breast height （DBH） is concentrated on 0.5- 1.5 m with average DBH of 1. 1 m, crown width is concentrated on 10.0-20.0 m with average crown width of 15.8 m. From spatial distribution status, ancient trees in Shenzhen City distribute widely, but there are significant differences in numbers of species and individuals among different distribution regions and they are mainly distributed in south central and southeast of Shenzhen City. From growth status of ancient trees, there are four grades of growing well （Ⅰ）, generally （Ⅱ）, poorly （Ⅲ） and dying （Ⅳ）, each with 729, 616, 100 and 37 individuals, accounting for 49.19% , 41.57% , 6.75% and 2.50% of total number of ancient trees, respectively. The result of correlation analysis shows that there are extremely significantly positive correlations between height and DBH, height and crown width, DBH and crown width, ancient tree species richness are significantly positively correlated with ancient tree number and land property, and growth status of ancient trees is very significantly positively correlated with near natural degree of their planting environment and with or without tree pond, but is not significantly correlated with tree age, showing that utilization property of regional land is the key factor affecting spatial distribution of ancient trees. Based on investigation results, the suggestions on protection of ancient tree resources in Shenzhen City are proposed.