Earthworms neutralize the influence of components of particulate pollutants on soil extracellular enzymatic functions in subtropical forests

Junbo Yang; Jingzhong Lu; Yinghui Yang; Kai Tian; Xiangshi Kong; Xingjun Tian; Stefan Scheu

doi:10.7717/peerj.15720

Earthworms neutralize the influence of components of particulate pollutants on soil extracellular enzymatic functions in subtropical forests

PeerJ. 2023 Aug 3:11:e15720. doi: 10.7717/peerj.15720. eCollection 2023.

Authors

Junbo Yang^{1

2}, Jingzhong Lu², Yinghui Yang¹, Kai Tian³, Xiangshi Kong⁴, Xingjun Tian^{1

5}, Stefan Scheu^{2

6}

Affiliations

¹ State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu Province, China.
² Johann Friedrich Blumenbach Institute of Zoology and Anthropology, University of Göttingen, Göttingen, Lower Saxony, Germany.
³ College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, Henan Province, China.
⁴ Key Laboratory for Ecotourism of Hunan Province, School of Tourism and Management Engineering, Jishou University, Jishou, Hunan Province, China.
⁵ College of Eco-Environmental Engineering, Qinghai University, Xining, Qinghai Province, China.
⁶ Centre of Biodiversity and Sustainable Land Use, University of Göttingen, Göttingen, Lower Saxony, Germany.

Abstract

Human activities are increasing the input of atmospheric particulate pollutants to forests. The components of particulate pollutants include inorganic anions, base cations and hydrocarbons. Continuous input of particulate pollutants may affect soil functioning in forests, but their effects may be modified by soil fauna. However, studies investigating how soil fauna affects the effects of particulate pollutants on soil functioning are lacking. Here, we investigated how earthworms and the particulate components interact in affecting soil enzymatic functions in a deciduous (Quercus variabilis) and a coniferous (Pinus massoniana) forest in southeast China. We manipulated the addition of nitrogen (N, ammonium nitrate), sodium (Na, sodium chloride) and polycyclic aromatic hydrocarbons (PAHs, five mixed PAHs) in field mesocosms with and without Eisenia fetida, an earthworm species colonizing forests in eastern China. After one year, N and Na addition increased, whereas PAHs decreased soil enzymatic functions, based on average Z scores of extracellular enzyme activities. Earthworms generally stabilized soil enzymatic functions via neutralizing the effects of N, Na and PAHs addition in the deciduous but not in the coniferous forest. Specifically, earthworms neutralized the effects of N and Na addition on soil pH and the effects of the addition of PAHs on soil microbial biomass. Further, both particulate components and earthworms changed the correlations among soil enzymatic and other ecosystem functions in the deciduous forest, but the effects depended on the type of particulate components. Generally, the effects of particulate components and earthworms on soil enzymatic functions were weaker in the coniferous than the deciduous forest. Overall, the results indicate that earthworms stabilize soil enzymatic functions in the deciduous but not the coniferous forest irrespective of the type of particulate components. This suggests that earthworms may neutralize the influence of atmospheric particulate pollutants on ecosystem functions, but the neutralization may be restricted to deciduous forests.

Keywords: Ecosystem functions; Eisenia fetida; Human activity; Particulate pollutants; Subtropical forests.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Ecosystem
Environmental Pollutants*
Forests
Humans
Oligochaeta*
Polycyclic Aromatic Hydrocarbons*
Soil

Substances

Environmental Pollutants
Polycyclic Aromatic Hydrocarbons
Soil

Grants and funding

This work was supported by the National Natural Science Foundation of China (31870598, 32160356, 32001300); the Strategic Priority Research Program of the Chinese Academy of Sciences (A)(XDA19050400); the Jiangsu Forestry Science and Technology innovation and promotion project (LYKJ[2021]16); the Key Program of Scientific Research projects of Hunan Provincial Education Department (21A0334); the Key Specialized Research and Development breakthrough program in Henan Province (222102320289); the Scholarship of China Scholarship Council (202006190207), and the Open Access Publication funded by the University Göttingen. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.