Decomposition drives convergence of forest litter nutrient stoichiometry following phosphorus addition

Plant and Soil
By: , and 

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Abstract

Background and aims

Nutrient levels in decomposing detritus and soil can influence decomposition rates and detrital nutrient dynamics in differing ways among various detrital components of forests. We assessed whether increased phosphorus (P) levels in litter and soil influenced decomposition rates and litter nutrient dynamics of foliage, fine roots, and twigs in nitrogen (N)-rich Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests in the Oregon Coast Range.

Methods

We decomposed fresh foliage, fine root, and twig litter from Douglas-fir seedlings at three sites for two years. Half of the seedlings and half of the plots at each of the sites were fertilized with P resulting in a factorial design with the following treatments: control (no P fertilization), plant P (P-fertilized litter), soil P (P-fertilized soil), and plant P × soil P.

Results

Soil P fertilization slightly decreased foliage decomposition rates. Fertilization of seedlings increased litter P concentrations by an average of 250 % relative to controls, but did not alter litter decomposition rates. Litter fertilized with P mineralized P rapidly and early in the decomposition process compared to N. Litter P concentrations decreased over the 2 years for all treatments, whereas N concentrations increased. Decomposition rates and loss of N and P were strongly related to initial litter chemistry. Despite different initial litter C:N:P ratios in P fertilized seedlings, ratios of C:N, C:P and N:P converged to similar values across treatments within a given litter type over 2 years.

Conclusions

We conclude that litter P concentrations and to some extent soil P may influence litter nutrient dynamics during decomposition, resulting in a convergence of element ratios that reflect the balance of substrate decomposition and microbial nutrient stoichiometry.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Decomposition drives convergence of forest litter nutrient stoichiometry following phosphorus addition
Series title Plant and Soil
DOI 10.1007%2Fs11104-016-2857-6
Volume 406
Issue 1
Year Published 2016
Language English
Publisher Kluwer Academic Publishers
Publisher location Dordrecht
Contributing office(s) Forest and Rangeland Ecosystem Science Center
First page 1
Last page 14
Country United States
Other Geospatial Oregon Coast Range
Online Only (Y/N) N
Additional Online Files (Y/N) N