Within-twig biomass allocation in subtropical evergreen broad-leaved species along an altitudinal gradient: allometric scaling analysis |
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Authors: | Shuang Xiang Ning Wu Shucun Sun |
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Institution: | (1) Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, China;(2) Department of Biology, Nanjing University, 22 Hankou Road, 210093 Nanjing, China |
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Abstract: | We studied the effects of twig size and altitude on biomass allocation within plant twigs (terminal branches of current-year
shoots), to determine whether species with large twigs/leaves or living at low altitude allocate a higher proportion of biomass
to laminas than their counterparts with small twigs/leaves or living at high altitude. Stem mass, lamina mass and area, and
petiole mass were measured for terminal branches of current-year shoots in 80 subtropical evergreen broad-leaved species belonging
to 38 genera from 24 families along an altitudinal gradient of Mt. Emei, Southwest China. The scaling relationships between
the biomass allocations of within-twig components were determined using model type II regression method. Isometric relationships
were found between leaf mass and twig mass and between lamina mass and twig mass, suggesting that the biomass allocation to
either leaves or laminas was independent of twig mass. Petiole mass disproportionally increased with both lamina mass and
twig mass, indicating the importance of leaf petioles to the within-twig biomass allocation. These cross-species correlations
were consistent with those among evolutionary divergences. In addition, species at low altitude tended to have a greater leaf
and lamina mass but a smaller stem mass at a given twig mass than at middle and high altitudes. This is possibly due to the
high requirement in physical support and the low efficiency of eco-physiological transport for the species living at high
altitude. In general, within-twig biomass allocation pattern was not significantly affected by twig size but was greatly modulated
by altitude. |
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Keywords: | Allometry Biomass allocation Leaf size Petiole Twig Subtropical evergreen broad-leaved forest |
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