The manipulation of aboveground litter input affects soil CO2 efflux in a subtropical liquidambar forest in China

Abstract

Abstract: Litters on the forest floor represent an important organic carbon (C) sources from aboveground plants to the soil, which therefore have a significant influence on belowground processes such as soil respiration. In this study, dynamic property of soil respiration was investigated under aboveground litter manipulation treatments in a liquidambar forest in subtropical China. The purpose of this study was to examine the impacts of changing aboveground litter inputs on soil CO2 emission in forests. The litter manipulation included litter addition (LA), litter removal (LR) and litter control (LC) treatments. Each litter treatment had six replications. Soil respiration rates were measured using an infrared gas analyzer system (LI-COR 8100) with soil chambers. The results showed that mean soil respiration rates increased significantly in LA plots (mean ± SE: 2.21 ± 0.44 μmol m-2 s-1; P<0.05) and decreased slightly in LR plots (1.17 ± 0.16 μmol m-2 s-1) when compared to control plots (1.42 ± 0.20 μmol m-2 s-1). On average, LA treatment significantly increased annual soil respiration by about 56% (837.5 ± 165 gC m-2 year-1), while LR treatment decreased soil respiration by approximately 17% (443.1 ± 61.7 gC m-2 year-1) compared with the control (535.5 ± 75.7 gC m-2 year-1). The “priming effect” was a primary contributor to the increase of soil respiration in LA treatments and the reduction of soil CO2 efflux was mainly ascribed to the elimination of organic C sources in LR treatments. Soil temperature was the main factor affecting seasonal variation in soil respiration. Up to the 90% to 95% seasonal variation in soil respiration is explained by soil temperature within each of the litter treatments. Our study indicated that changes in litter inputs due to climate change and human practices would significantly affected soil CO2 emission and would subsequently affect C balance in subtropical forests.