AOBPreview originally published online on November 3, 2006
Annals of Botany 2007 99(1):95-102; doi:10.1093/aob/mcl206
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Above- and Below-ground Biomass Relationships Across 1534 Forested Communities
1 Key Laboratory of Arid and Grassland Agroecology, Lanzhou University, Ministry of Education, Lanzhou, Gansu Province 730000, China
2 Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA
* For correspondence. E-mail kjn2{at}cornell.edu
Received: 23 June 2006 Returned for revision: 24 July 2006 Accepted: 9 August 2006 Published electronically: 3 November 2006
BACKGROUND AND AIMS: Prior work has shown that above- and below-ground dry biomass across individual plants scale in a near isometric manner across phyletically and ecologically diverse species. Allometric theory predicts that a similar isometric scaling relationship should hold true across diverse forest-types, regardless of vegetational composition.
METHODS: To test this hypothesis, two compendia for forest-level above- and below-ground dry biomass per hectare (MA and MR, respectively) were examined to test the hypothesis that MA vs. MR scales isometrically and in the same manner as reported for data from individual plants. Model Type II regression protocols were used to compare the numerical values of MA vs. MR scaling exponents (i.e. slopes of log–log linear relationships) for the combined data sets (n =1534), each of the two data sets, and data sorted into a total of 17 data subsets for community- and biome-types as well as communities dominated by angiosperms or conifers.
KEY RESULTS: Among the 20 regressions examined, 15 had scaling exponents that were indistinguishable from that reported for MA vs. MR across individual plants. The isometric hypothesis could not be strictly rejected on statistical grounds; four of these 15 exponents had broad 95% confidence intervals resulting from small sample sizes. Significant variation was observed in the y-intercepts of the 20 regression curves, because of absolute differences in MA or MR.
CONCLUSIONS: The allometries of forest- and individual plant-level MA vs. MR relationships share strikingly similar scaling exponents, but differ because of considerable variation in y-intercepts. These results support prior allometric theory and provide boundary conditions for the scaling of MA and MR.
Key words: Allometry, isometric scaling, plant biomass partitioning patterns, leaf, stem and root biomass allocation, tree allometry