Department of Life Sciences, Whitelands College, University of Roehampton, London, SW15 4JD, UK.
Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecosystem Research, Müggelseedamm 301, 12587, Berlin, Germany.
Nat Commun. 2019 Jan 16;10(1):255. doi: 10.1038/s41467-018-08039-3.
The size structure of autotroph communities - the relative abundance of small vs. large individuals - shapes the functioning of ecosystems. Whether common mechanisms underpin the size structure of unicellular and multicellular autotrophs is, however, unknown. Using a global data compilation, we show that individual body masses in tree and phytoplankton communities follow power-law distributions and that the average exponents of these individual size distributions (ISD) differ. Phytoplankton communities are characterized by an average ISD exponent consistent with three-quarter-power scaling of metabolism with body mass and equivalence in energy use among mass classes. Tree communities deviate from this pattern in a manner consistent with equivalence in energy use among diameter size classes. Our findings suggest that whilst universal metabolic constraints ultimately underlie the emergent size structure of autotroph communities, divergent aspects of body size (volumetric vs. linear dimensions) shape the ecological outcome of metabolic scaling in forest vs. pelagic ecosystems.
自养生物群落的大小结构——小个体与大个体的相对丰度——塑造了生态系统的功能。然而，普遍的机制是否支持单细胞和多细胞自养生物的大小结构尚不清楚。利用全球数据汇编，我们表明树木和浮游植物群落中的个体体重遵循幂律分布，并且这些个体大小分布（ISD）的平均指数不同。浮游植物群落的平均 ISD 指数与新陈代谢与体重的四分之三幂律缩放以及质量等级之间的能量使用等效相一致。树木群落偏离了这种模式，其方式与直径大小等级之间的能量使用等效相一致。我们的研究结果表明，虽然普遍的代谢限制最终是自养生物群落大小结构的基础，但身体大小的不同方面（体积与线性尺寸）塑造了森林与浮游生态系统中代谢缩放的生态结果。
