2年生白桦种源的地理变异

在“八五”期间对白桦所做全分布区种源试验的基础上，又做了一次局部分布区的种源试验。试验选取来自7个省份的16个种源，在3个试验点定植。对16个种源的2年生幼树高进行方差分析，结果表明，各种源间的差异极显著；利用幼树高与种源的地理因子（经、纬度）、气候因子 （温度、积温、降水、湿度、日照、无霜期）作相关分析，研究白桦种源的地理变异，发现幼树高与纬度呈负相关，与经度呈正相关，温度与无霜期是影响地理变异的主要气候因子。初步判断，白桦的地理变异符合经纬向双重渐变的模式，反映了冷-暖的气候生态模式，但并未反映干-湿的气候生态模式。

The Geographic Variance of Provenance for Betula platyphylla in Two Years Old/

Provenance test of Betula platyphylla in partial distribution region was done on the base of the former test in full distribution area. This test included 16 provenances selected from 7 provinces, which were planted in 3 trials. The results from variance analysis indicated that it has significant difference among provenances. Correlation analyses between the height growth and geographic factors, and between growth and climatic factors have been made to study the geographic variance of this specie. A negative correlation was found between height growth and latitude and positive correlation for longitude. Temperature and frost-free growing period are the main factors that affected the provenance variation. A principal opinion is that the provenance variance of Betula platyphylla is influenced by both of latitude and longitude, which is a reflection of climate changes from cold to warm in the distribution area of this specie.