Foliar nutrient resorption constrains soil nutrient transformations under two native oak species in a temperate deciduous forest in Mexico

Abstract

Foliar nutrient resorption (FNR) is a key pro- cess in the dynamics of nutrients in a forest ecosystem. Along with other factors, FNR regulates the chemical composition of the forest floor and, consequently, the rates of organic matter decomposition and soil nutrient avail- ability. The main objective of the present study was to examine the effect of FNR of two deciduous oak species (Quercus castanea and Q. deserticola) in the litter and soil nutrient dynamics, in addition to analyze whether the interaction between two species was positive (synergistic) or negative (antagonistic) through the mixed litter from two species. For this purpose, the nutrient concentration of green leaves, litterfall, litter and soil was measured, as well as soil microbial activity. These measurements were taken in isolated stands with the presence of one of the oak species and stands with the two oak species mixed. Quer- cus deserticola, with lower FNR, produced litter with a higher N concentration, which apparently enhancing microbial activity in the forest floor litter and increased nutrient transformations and soil fertility. In contrast, Q. castanea has a higher FNR and produced litter with a lower nutrient concentration. The microbial soil community associated with Q. castanea must therefore invest more energy in metabolic processes at the expense of biomass growth. However, forest floor nutrient transformations were more intense and soil fertility increased in areas where both species intermix; in this case, the latter species received the rich-nutrient litterfall of Q. deserticola. These results suggest a strong footprint of species traits on microbial activities and soil nutrient transformations.