三峡库区扩种龙眼荔枝的适宜性分析

荔枝与龙眼系亚热带水果，集中分布于闽粤两省，三峡库区上段河谷两侧也有零星分布，是该类水果分布的最北界。这类水果在训区栽培始于汉唐时代，并被列为贡品荔枝与龙眼系喜温性水果，库区栽培间冻害发生，成为限制扩大栽培的主要因素，故多分布于万县－重庆江段两海拔２００ｍ上下地段，水库蓄水后，原栽培区部分被淹没，但水体有增温作用，为扩大栽培提供了有利的条件。研究了万县－重庆沿江两岸河谷地段与非河谷地段适宜载种范围

ANALYSIS OF THE SUITABILITY OF EXPANDING THE CULTIVATION OF LONGAN AND LITCHI IN THE THREE GORGE RESERVOIR AREA

Logan (Dimocarpus longan lour)and litchi (Litchi chinensis) are subtropic fruits,distributed largely in Fujian and Guangdong provinces.Their northern limits of distribution are located in the upper section of the Three Gorge Reservoir Area,where longan and litchi occur sporadically along the valley.Since Han and Tang dynasties,longan and litchi have been cultivated in this area,and at that time,they were well known in the capital and were selected as tributes to the emperors.Longan and litchi are thermophilic plants.They suffer occasionally from cold injury,which is the major factor that restricts the extension of their cultivation.So,they are distributed largely in Wanxian to the Chongqing Valleys around the elevation of 200 m above sea level.When the reservoir is filled with water,some original growing area will be submerged.Howerver,local temperature will be slightly increased,which is favorable to the enlargement of cultivating area.This paper studied the scope of the valleys and non valleys in that area suitable for cultivating longan and litchi.The results shows that the elevation limit of growing is higher in valleys than in non valleys.Besides,the elevation limit of growing is higher in open slopes than in shaded slopes.Finally,the elevation limit of growing in Chongqing area is higher than that in Wanxian area.