Relationships among leaf functional traits, litter traits, and mass loss during early phases of leaf litter decomposition in 12 woody plant species

Litter ‘quality’ or decomposability has historically been estimated through measuring chemical attributes, such as concentrations of nitrogen or ‘lignin’. More recently, foliar functional traits, which may incorporate indications of the physical structures of tissues, have been found to correlate with litter mass loss rates. However, these traits may not be adequate to predict early rates of mass loss, in which two factors are crucial: the amount of material quickly lost through leaching, and the ease of access of decomposer organisms to the more labile tissues in the interior of the litter. We investigated relationships among physical and chemical traits in foliage and litter of 12 species native to British Columbia and then observed how these traits related to mass loss during the first 3 months (Phase I) and between 3 and 12 months (Phase II). Novel traits measured in this study include cuticle thickness, litter leaching loss, and litter water uptake. Foliar and litter traits both co-varied along spectra, but several chemical traits, such as nitrogen concentration, changed from foliage to litter, i.e., during senescence. Phase I mass loss was best predicted by leaching loss and traits relating to leaching, such as cuticle thickness and specific leaf area. Phase II mass loss was predicted by traits that may relate to decomposer access and activity, such as leaf dry matter content and foliar nitrogen. Physical traits predicted mass loss as well or better than chemical traits, suggesting that physical characteristics of litter are important in determining early rates of decomposition.