关键词: 白桦, 种源试验, 地理变异, 优良种源选择

Abstract: [Objective] The study was to analyze patterns of geographical variation and to identify provenance regions or seed zones, based on observations on a 16-year-old Betula platyphylla provenance trial, in order to provide a scientific basis for selection of superior provenances with high productivity and strong adaptability for each provenance region or seed zone. [Method] Eighteen provenances of B. platyphylla planted in Maoershan Experimental Forest Farm of Shangzhi City, Heilongjiang Province, Shancheng Experimental Forest Farm of Benxi, Liaoning Province and Jinhe Forestry Bureau of Inner Mongolia, were used to study height(H), diameter at breast height (DBH),volume(V) by analysis of variance and multiple comparisons for single site and multiple sites.Then correlation analysis and cluster analysis was conducted between growth traits and their geographical and climatic factors. Superior provenances were selected and provenance regions or seed zones were identified. [Result] The results showed that there were statistically significant (P<0.01) differences in H,DBH,and V among different sites and provenances,and also significant in site×provenance interaction.Superior provenances were selected based on average volume of individual trees. At Maoershan site, the top provenances were Qingyuan, Caohekou, Maoershan, Huinan, Xiaobeihu and Dongfanghong. These six superior provenances had a volume 23.23% higher than the average of all provenances. At Caohekou site, the top provenances were Caohekou, Qingyuan and Tianshui. These three superior provenances were 22.14% higher in volume than the average of all provenances. At Jinhe site, the top provenances were Moerdaoga,Wuyiling and Chaoer,105.00% higher in volume than the average of all provenances. For provenances at Maoershan and Caohekou sites, geographical variation analysis showed negative correlation between growth and latitude, and significant correlation between growth and the average annual temperature. Provenances located in low latitudes and high average annual temperatures, performed better in growth traits at Maoershan and Caohekou sites. However, for provenances at Jinhe site, significant correlation was found between growth and latitudes, and negative correlation between growth and the average annual temperature. Provenances located in high latitudes and low average annual temperatures, displayed better growth traits at Jinhe site, and provenances from low latitudes and high average annual temperatures displayed inferior traits because of weak adaptation. The above results indicated that the growth of B. platyphylla was mainly regulated by temperature and latitude, belonging to the type of "cold-warm" geographic variation trend, which conforms to the main pattern of geographical variation of tree species in north China, under the main effects of temperature together with effects of water and heat, and in a clinal variation with latitudes. Correlation analysis and cluster analysis showed that the 18 provenances were divided into 5 provenance regions, of which 3 regions distributed in the northeast and 2 regions in the northwest.[Conclusion] Superior provenances were selected respectively for the three trial sites, including 6 provenances for Maoershan site, 3 for Caohekou site and 3 for Jinhe site. Correlation analysis showed that the 18 tested provenances displayed a "cold-warm" geographic variation pattern. Considering results from the correlation analysis and the clustering analysis, 5 provenance regions or seed zones were identified.

Key words: Betula platyphylla, provenance test, geographic variation, selection of superior provenance