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NUTRIENT CONCENTRATIONS IN FINE ROOTS
Author(s) -
Gordon Wendy S.,
Jackson Robert B.
Publication year - 2000
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2000)081[0275:ncifr]2.0.co;2
Subject(s) - nutrient , biogeochemical cycle , biogeochemistry , sink (geography) , botany , ecophysiology , biology , horticulture , zoology , chemistry , ecology , photosynthesis , geography , cartography
Fine roots are an important source and sink for nutrients in terrestrial biogeochemistry. We examined the following hypotheses for fine root nutrients by analyzing data from 56 published studies: (1) that there is a general, inverse relationship of fine root nutrient concentrations with root diameter, and (2) that retranslocation of nutrients out of fine roots is minimal. We analyzed nutrient concentrations of roots ≤5 mm in diameter as a function of root diameter and root status (live, dead, and undifferentiated), including a comparison for coniferous and broad‐leaved trees. For fine roots <2 mm in diameter, average C:N and C:N:P ratios were 43:1 and 522:12:1, significantly narrower than for 2–5 mm roots (79:1 and 920:12:1). Live roots <2 mm in diameter contained significantly more N, P, and Mg and less C than did roots 2–5 mm in diameter, but no significant differences were observed for K or Ca. Mean N and P concentrations were 11.0 and 0.9 g/kg, respectively, for live roots <2 mm diameter, compared to 6.5 and 0.6 g/kg in roots 2–5 mm in diameter. Mean N concentrations in live and dead fine roots were identical and may imply little retranslocation of root N with senescence, but conflicting evidence from Ca:N ratios highlights the need for further research. These results have practical implications for various ecological methods and for the representation of roots in biogeochemical models.