Nitrogen Addition Exacerbates the Negative Effect of Throughfall Reduction on Soil Respiration in a Bamboo Forest

Yi Wang,Chunju Cai,Junwei Luan,Fan Zhou,Chen Chen,Yaping Di,Shirong Liu,Xiaomin Gao

doi:10.3390/f12060724

Abstract

Impacts of drought events and nitrogen (N) deposition on forests are increasingly concerning in the context of global climate change, but their effects, in particular, their interactive effects on soil respiration and its components remain unclear. A two-factor random block field experiment was conducted at a subtropical Moso bamboo forest in Southwest China to explore the response of soil respiration (Rs), autotrophic respiration (Ra), and heterotrophic respiration (Rh) to throughfall re-duction and N addition. Our results showed that throughfall reduction significantly decreased Rs, which is mainly attributed to the decrease in Ra as a result of the decline in fine roots biomass. The N addition led to microbial carbon limitation hence significantly decreased Rh, and thus Rs. We also observed the negative effect of throughfall reduction on Rs was exacerbated by N addition, which is attributed to the significant reduction in Ra under the interaction between throughfall reduction N addition. Our findings suggest that Ra tended to respond more sensitively to potential drought, while Rh responds more sensitively to N deposition, and consequently, increased soil N availability caused by N deposition might aggravate the negative effect of expected drought on soil carbon cycling.

Highlights

As the second-largest fluxes in the global terrestrial carbon (C) cycle, soil respiration (Rs ) exerts a strong influence on the feedbacks between soil C pools and atmospheric CO2 concentration [1]
A two-factorial field manipulation experiment was conducted in a subtropical Moso bamboo forest, we aim to investigate the effects of throughfall reduction, N addition, and their interaction on soil respiration and its components
Our observations found that N addition or throughfall reduction slightly decreased Q10 values of Rs, but what is interesting is that the combined effect of N

Summary

Introduction

As the second-largest fluxes in the global terrestrial carbon (C) cycle, soil respiration (Rs ) exerts a strong influence on the feedbacks between soil C pools and atmospheric CO2 concentration [1]. The global change characterized by the concurrence of multiple environmental factors, like N deposition and drought events, and leading to large uncertainties in predicting impacts of the combined factors [9], because both N deposition and drought will be very likely to affect soil N availability and soil water availability and further impact on ecological process in future [5,10] Their combined effects have inadequately been addressed from the perspective of coupled relationships between N and water, which often interact together to alter the direction and magnitudes of the response of the ecological process [11,12]

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