美国山核桃引种栽培区划研究 Ⅲ区划结果与分区描述

Cultural Regionalization for the Introduced Pecan Tree in China Ⅲ. Region Designation and Description

以林木遗传变异、生境地域分异和引种栽培生态经济等理论为指导 ,根据地域分异、生态因素为主、综合分析、整体协调和简单易行的原则 ,依据原产地现实气候生态位宽度与引种地的前期引种效果 ,采用林木引种气候预测分析法 ,将我国美国山核桃引种栽培区域划分为适宜区、次适宜区、边缘区和不适宜区 .适宜区位于亚热带东部和长江两岸北纬 2 5°～ 3 5°、东经 10 0°～ 12 2°之间的大部分地区 ,与我国现有的美国山核桃分布区基本相符 .将林木引种气候预测分析法结果与聚类分析所得结果比较可知 ,本区划结果更为合理 ,更符合实际情况 .

This article is concerned with a regionalization of the cultural ranges for the introduced pecan crop in China in terms of site suitability. Taken into account are ranges of the water and heat indices of the current ecological niche for the pecan crop in the Pecan Belt of USA, which are composed of 7 factors: the annual mean temperature of 13～20℃, January mean of 4～12℃, July mean of 25～30℃, extremely low of -30～-8℃, heat units based on 10℃ and above of 3 300～5 400℃, annual frost free season of 154～245 days, and annual precipitation of 224～1 626 mm. The growth and fruiting performance of the pecan tree previously introduced to China is also considered. Based on the above considerations, four types of cultural regions are designated, using the Dendro climate Predicative Analysis. These regions consist of the Suitable Region, the Northern and Southern Hypo Suitable Regions, the Northern and Southern Marginal Regions, and the Northern and Southern Unsuitable Regions. The Suitable Region is located in the subtropical east and along both sides of the Yangtze River in between 25°～35°N and 100°～122° E. Compared with the cultural division derived from the Cluster Analysis, which is in general agreement with the situation regarding the existing pecans found in China, this designation is more rational and realistic.