Rate of litter decay and litter macroinvertebrates in limed and unlimed forests of the Adirondack Mountains, USA

Abstract

Acid deposition can reduce the rate of litter decay in forests by changing environmental and substrate quality for macroinvertebrates and microbes. Terrestrial application of lime can ameliorate many of the negative effects of acid deposition, but the effects of liming on forest litter decay and fauna are poorly understood. We used reciprocal transplants of litter bags to better understand the effects of substrate calcium content and incubation context (limed plots versus unlimed plots) on rate of litter decay and abundance of litter-dwelling macroinvertebrates. Our study took place in the Adirondack Mountains (Adirondacks) of New York State, USA, a region affected by chronic acid deposition. Lime was added to randomly-selected plots at a rate of 10Mgha−1; control plots were not limed. Leaves for high-calcium litter bags were collected under trees grown in limed plots, and leaves for low-calcium litter bags were collected in unlimed plots. High-calcium and low-calcium leaves differed in %Ca but not in %N or C:N at the beginning of our study. Leaf litter decay was faster for bags containing high-calcium leaves than for those litter bags containing low-calcium leaves, and decay was slower in limed than unlimed plots. Assemblages of litter-dwelling macroinvertebrates were markedly different between litter bags collected from limed and those collected from unlimed plots. Snails increased in abundance; whereas, millipedes and spiders decreased in abundance at limed plots following liming. Millipedes likely were important litter-eating macroinvertebrates at these sites, and the decline in millipedes may have contributed to the reduction in rate of litter decay. The liming of areas negatively affected by acid deposition may decrease rate of litter decay immediately following lime application. This was a short-term study. Understanding the long-term, as well as immediate, effects of liming is necessary to determine the advisability of lime application in regions affected by acid deposition.