珙桐的天然分布和人工引种分析

珙桐（Ｄａｖｉｄｉａｉｎｖｏｌｕｃｒａｔａ）是我国特有单型植物，世界著名观赏树种，其天然分布只在我国西南山地，北纬２７°１＇～３１°７＇，东经９８°６＇～１１１°１＇的范围内。我国西南诸省地形复杂，气候多样，珙桐在这一地区从７００ｍ以下的低山沟谷到２０００～３０００多米的云贵高原都有分布，但其分布方式是不连续和零星状的，珙桐分布区的环境条件差异大，很多地区与郑州和北京气候土壤条件也有相似之处，所以被广泛地引种栽培。国内外引种最北部达北纬３９°５４＇（北京）和５５°以北（哥本哈根），分布高度从南部山地的７００～１４００ｍ降至５０ｍ以下（郑州、北京和哥本哈根），土壤条件也从原产地的酸性土壤（ｐＨ４．５～６。５）到碱性土镶（ｐＨ６．５～８．４）．所以珙桐是一个适应性强、生态幅度宽的树种，在园林绿化中有巨大的应用潜力。

Natural Distribution of Davidia involucrata and Introduction Andysis

The Chinese dovetree(Davidia involucrata)is an endemic unitary species ofthis country and a famous ornamental species of the world. Its natural distribution is limitedwithin the area of 27°1'～31°7'N; 98°6'～111°1'E. The provinces in southwest China havecomplicated topography and diversified climate. The Chinese dovetrees distributed in this re-gion are from the lower vally with altitude below 700m to the Yunnan-Guizhou plateau of2000～3000m in altitude, However, the distribution patterns are discontinuous and scat-tered. The environmental conditions where the Chinese dovetree are distributed vary signifi-cantly, some of the places having similar climate conditions as to Zhengzhou and Beijng. Sothere exist possibilities for the Chinese dovetrees to be widely introduced with success. Untilnow, the northern limit is 39°54'(Beijng) in China and over 55°(Copenhagen)in the world.The distribution heights have changed from the southern mountains of 700～1400m in alti-tude to north China plain of 100m in altitude,and the soil condition has changed from the acidtype(pH 4.5～6.5)to the alkaline soil type(pH 6.4～8. 4).So the Chinese devetree is stillaspecies with high adaptability and broad ecological niche,having great potentials,to be ap-plied in gardens and forests.