生态学报Issue(19)：6496-6506,11.DOI:10.5846/stxb201402080223
5个温带树种冠层枝叶非结构性碳水化合物浓度的空间变异
Within-crown variation in concentrations of non-structural carbohydrates of five temperate tree species
摘要
Abstract
Non-structural carbohydrates ( NSC) are important carbon reserves, particularly in trees, because they represent a large pool of biomass. Diverse strategies for carbon use and allocation are closely connected to ecological and evolutionary theories of trade-offs and niche partitioning. Crown is not only the source of NSC in a tree, but also a key NSC storage pool. However, few studies investigated within-crown variation in NSC concentrations, although such variation may introduce uncertainties in estimating NSC allocation in trees. In this study, we measured NSC concentrations in foliage and branches of five temperate tree species in northeastern China. The species included one evergreen conifer (Pinus koraiensis), one deciduous conifer ( Larix gmelinii) , and three deciduous broadleaved species ( Quercus mongolica, Fraxinus mandshurica, and Betula platyphylla). The objectives were to (1) examine vertical differences in NSC concentrations among foliage and small branches of different ages (diameter ≤ 3 cm) within the crown, (2) examine axial variations in NSC in bark, sapwood and heartwood of coarse branches (i.e. first order branches), and (3) explore the relationship between NSC concentration and diameter in coarse branches. Branch samples were randomly taken from the upper-, mid-and lower-crown layers 3—7 times across the season. The samples were divided into foliage ( current-year, one-year-old, and older than one year) and small branches. In late October, one coarse branch from each of the three broadleaved species was sampled and separated into 1—2 m-long sections consisting of bark, sapwood, and heartwood. All samples were analyzed for NSC concentration (including soluble sugars and starch) with a modified phenol-sulfuric method. The results showed that:(1) There were no significant vertical variations in foliage NSC concentration for any species except L. gmelinii, for which the starch concentration in late May was significant higher in the mid-crown and soluble sugar concentration in mid-August was higher in the upper-crown. Needle-age significantly affected needle NSC concentration of P. koraiensis in the mid-growing season, but this effect was insignificant in the late growing season and dormant season. ( 2 ) There were no significant vertical variations in NSC concentration in small branches for any species except P. koraiensis, for which the concentration of soluble sugars in the upper-crown was significant higher than in the mid-crown in late May. (3) For the three deciduous species, the NSC concentrations in the bark, sapwood and heartwood of the coarse branches tended to increase with increasing distance from the branch base to the top, and they decreased with increasing branch diameter for all species except for starch in sapwood of F. mandshurica and starch in bark of B. platyphylla. This suggests a declining trend in branch NSC concentration with source distance or tissue age. The trend of NSC concentration in branch heartwood indicates that C reserves in old heartwood are still accessible or even physiologically available. Overall, NSC concentrations in foliage and small branches varied insignificantly within the crowns of these tree species, but the effects of needle-age and branch diameter on NSC concentrations varied among species, tissue, or season;these within-crown variations should be taken into account when making NSC pool estimates for the whole tree.关键词
非结构性碳水化合物( NSC)/叶/枝/空间变异/温带森林Key words
non-structural carbohydrates (NSC)/foliage/branch/spatial variation/temperate forest引用本文复制引用
张海燕,王传宽,王兴昌..5个温带树种冠层枝叶非结构性碳水化合物浓度的空间变异[J].生态学报,2015,(19):6496-6506,11.基金项目
国家“十二五”科技支撑项目(2011BAD37B01) （2011BAD37B01）
教育部长江学者和创新团队发展计划(IRT1054) （IRT1054）
