Choice of resolution by functional trait or taxonomy affects allometric scaling in soil food webs

Belowground organisms often display a shift in their mass-abundance scaling relationships due to environmental factors such as soil chemistry and atmospheric deposition. Here we present new empirical data that show strong differences in allometric scaling according to whether the resolution at the local scale is based on a taxonomic or a functional classification, while only slight differences arise according to soil environmental conditions. For the first time, isometry (an inverse 1∶1 proportion) is recognized in mass-abundance relationships, providing a functional signal for constant biomass distribution in soil biota regardless of discrete trophic levels. Our findings are in contrast to those from aquatic ecosystems, in that higher trophic levels in soil biota are not a direct function of increasing body mass.

地下生物的质量-多度缩放（mass-abundance scaling）关系常因土壤化学、大气沉降等环境因素发生偏移。本研究提供了全新的实测数据，结果显示：局域尺度的分辨率若基于分类学分类或功能分类，异速缩放（allometric scaling）关系会呈现显著差异；而仅依据土壤环境条件所产生的差异则较为微弱。本研究首次在质量-多度关系中发现了等速关系（isometry，即反比1:1比例），该关系为不依赖离散营养级的土壤生物群恒定生物量分布提供了功能指征。本研究结论与水生生态系统的相关发现相悖：土壤生物群的更高营养级并非体重增加的直接函数。