Decomposition of tall fescue (Festuca elatior var. arundinacea) and cellulose litter on surface mines and a tallgrass prairie in central Missouri, U.S.A.
Decomposition of 14C-labelled and unlabelled fescue, and of pure cellulose litter in non-vegetated and vegetated coal surface mine spoils and on a tallgrass prairie soil in central Missouri, U.S.A. was examined. Losses of ash-free mass, 14C, nitrogen, and phosphorus from decomposing fescue litter were better described by double exponential decay equations than by single exponential decay equations. Compared to other studies of litter decomposition in temperate grasslands, losses of ash-fire mass from fescue litter were rapid. In addition, 14C-labelled fescue litter (initial C:N = 14.2) decomposed more rapidly than unlabelled fescue litter (initial C:N = 25.9), reflecting the influence of initial nitrogen content on decomposition. Decomposition of fescue and cellulose litter on non-vegetated mine sites was slow, probably because of low exogenous nitrogen inputs and harsh environmental conditions that characterize barren spoil. Regression models of remaining ash-free mass as a function of C:N, C:P, and N:P ratios increased progressively in complexity from non-vegetated mine to vegetated mine to tallgrass prairie sites, reflecting differences in the structure and function of the decomposer communities among the three sites. Significantly less ash-free mass, 14C, and nitrogen was lost from fescue situated over very acidic (pH ≤ 4.5) spoil than from fescue situated over moderately acidic (pH ≥ 5.0) spoil. However, the transfer of 14C from decomposing litter to the spoil directly below was unaffected by either spoil pH or by the presence or absence of vegetation, and its magnitude was comparable to similar studies conducted on unmined soils. newline˜These results suggest that current reclamation practices, such as liming, fertilization, and mulching, could have conflicting effects on organic matter accumulation and nitrogen and phosphorus dynamics in surface mine spoils.