木荷稳定碳同位素分辨率的种源差异

Provenance difference in stable carbon isotope discrimination of Schima superba

利用设置在福建建瓯、浙江淳安和浙江庆元3个区试点的5年生木荷种源试验林,选取18个代表性种源测定叶片的稳定碳同位素分辨率(Δ值),研究其在种源间的差异和地理变异模式,以及造林立地环境和种源生长对其的影响.结果表明:木荷种源叶片稳定碳同位素分辨率存在很大差异,福建建瓯、浙江淳安和庆元3个区试点的叶片Δ值最高和最低种源分别相差6.9%、3.0%和3.7%.种源叶片Δ值与其产地纬度呈显著负相关,而与产地经度的相关性较小,表现为典型的纬向渐变模式,来自木荷分布区南部的种源叶片Δ值较大,说明其长期水分利用效率较低.随着造林立地环境的改善和年降雨量的增多,木荷叶片Δ值显著增加.种源叶片Δ值与其树高、胸径、一级侧枝总数和最大侧枝长等皆呈显著正相关,树冠浓密的速生种源具有较高的Δ值.此外,在木荷中心产区(福建建瓯)和边缘产区(浙江淳安)分别初选出2个和4个水分利用效率高的速生优良种源,供推广应用.

The difference in leaf stable carbon isotope discrimination （Δ） of 18 representative Schima superba provenances was investigated based on three provenance trails located at Jian＇ ou of Fujian Province and Chun＇ an and Qingyuan of Zhejiang Province, and the geographic variation pattern and the effects of trial site and provenances growth rate were studied. Significant differences in leaf Δ were observed among the provenaces, and the differences in leaf Δ value between the highest and lowest provenances reached 6.9% , 3.0%, and 3.7% in 3 experimental sites, respectively. Δ classic latitudinal clinal variation pattern was found, because there were significant correlations between the leaf A value and the latitude of seed sources in all the 3 sites while no significant correlations were observed between the leaf Δ value and the longitude of the seed sources. The southern provenances showed higher leaf Δ value than the northern provenances, indicating that the water use efficiency （WUE） was lower in southern provenances. The leaf Δ value of different provenances was demonstrated to be greatly affected by the environment of trial sites. The leaf Δ value increased significantly with the improvement of site environment and with the increase of annual rainfall. Significant positive correlations were observed between the leaf Δ value and the growth traits including tree height, DBH, total number of lateral branches, and length of the strongest lateral branch, which indicated that the provenances with higher growth rate and denser crown had larger leaf Δ value. Two and four superior provenances with high were selected for Jian＇ ou of Fujian and Chun＇ an growth rate and low leaf Δ value （ or high WUE） of Zhejiang, respectively.