Economic strategies of plant absorptive roots vary with root diameter

[摘要] Plant roots typically vary along a dominant ecological axis, the rooteconomics spectrum, depicting a tradeoff between resource acquisition andconservation. For absorptive roots, which are mainly responsible forresource acquisition, we hypothesized that root economic strategies differwith increasing root diameter. To test this hypothesis, we used seven plantspecies (a fern, a conifer, and five angiosperms from south China) for whichwe separated absorptive roots into two categories: thin roots (thickness ofroot cortex plus epidermis < 247 µm) and thick roots. Foreach category, we analyzed a range of root traits related to resourceacquisition and conservation, including root tissue density, differentcarbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, andacid-insoluble fractions) as well as root anatomical traits. The resultsshowed significant relationships among root traits indicating anacquisition-conservation tradeoff for thin absorptive roots while no suchtrait relationships were found for thick absorptive roots. Similar resultswere found when reanalyzing data of a previous study including 96 plantspecies. The contrasting economic strategies between thin and thickabsorptive roots, as revealed here, may provide a new perspective on ourunderstanding of the root economics spectrum.

[学科分类] 地球化学与岩石