Divergent responses of soil carbon and nitrogen pools to short-term nitrogen addition between two plantations in Northeast China

Yedong Li,Sen Dou,Yameng Pei,Bo Wang,Liyong Mei,Yang Zhang,Haoye Ren,Yaya Zhang,Shimin Wu,Haoyue Shen,Ximing Zeng

doi:10.25165/j.ijabe.20191206.5266

Abstract

Nitrogen (N) deposition has a profound influence on forest soil carbon (C) and N pools, but there was no consensus on the responses of different C and N components in different forest types. In this study, a two-year simulated N deposition experiment with four levels of N (NH4NO3)-addition treatments (0, 50, 100, and 150 kg N/hm2·a) were conducted in Larix gmelinii (LG) and Quercus mongolica (QM) plantation in Northeast China, in order to investigate the C and N pool dynamics under continuously enhanced N deposition. Soil organic carbon (SOC), soil total N (STN) and their active components (readily oxidizable C, ROC; dissolved organic C, DOC; microbial biomass C, MBC, dissolved organic N, DON; microbial biomass N, MBN) of the forest soil were measured monthly from May to October 2017. C and N contents in LG were observed higher than in QM. N addition had no effect on SOC and STN of LG, but significantly increased SOC and STN of QM at low N addition level. Low N addition generally raised active C components (ROC, DOC, and MBC) in both plantations, whereas high N addition did not significantly affect these components, or even decreased ROC in LG soil. Low N addition also increased STN and MBN of QM, while no significant change in STN and MBN of LG was observed. DON was directly affected by N addition and increased significantly with elevated N addition levels. The results indicated that N addition, especially of low rate, might enhance the C sequestration capacity of the forest soils and mitigate climate change. Keywords: nitrogen deposition, forest soil, active carbon, active nitrogen DOI: 10.25165/j.ijabe.20191206.5266 Citation: Li Y D, Wang B, Dou S, Shen H Y, Mei L Y, Zhang Y, et al. Divergent responses of soil carbon and nitrogen pools to short-term nitrogen addition between two plantations in Northeast China. Int J Agric & Biol Eng, 2019; 12(6): 82–90.

Highlights

With the rapid agricultural, industrial and urban development, human activities have released a large amount of reactive nitrogen (N) into the atmosphere and led to a dramatic increase in global N deposition over the past century[1,2,3]
N addition had no effect on Soil organic carbon (SOC) and soil total N (STN) of Larix gmelinii (LG), but significantly increased SOC and STN of Quercus mongolica (QM) at low N addition level
Forest type caused a significant difference in all soil C components (p

Summary

Introduction

Industrial and urban development, human activities have released a large amount of reactive nitrogen (N) into the atmosphere and led to a dramatic increase in global N deposition over the past century[1,2,3]. The enhancement of N deposition has exerted a profound impact on forest ecosystems[4], which dominates the dynamics of the terrestrial carbon (C) cycle and are crucial for mitigating climate change[5]. Soil N pools have been studied and found less affected by N addition[12,14]. Numerous studies have documented that enhanced N deposition could affect the forest soil C and N pools by influencing terrestrial ecosystem processes including plant growth, litter decomposition, soil organic matter turnover and soil respiration[17,18]. Due to the complexities of soil chemical properties and their interactions with soil microorganisms[19], the corresponding mechanisms remain uncertain

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