Soil Nitrogen Transformation Process Influenced by Litterfall Manipulation in Two Subtropical Forest Types

Wende Yan; Taimoor Hassan Farooq; Yi Chen; Wancai Wang; Rubab Shabbir; Uttam Kumar; Muhammad Umair Riaz; Saqer S Alotaibi; Yuanying Peng; Xiaoyong Chen

doi:10.3389/fpls.2022.923410

Soil Nitrogen Transformation Process Influenced by Litterfall Manipulation in Two Subtropical Forest Types

Front Plant Sci. 2022 Jul 14:13:923410. doi: 10.3389/fpls.2022.923410. eCollection 2022.

Authors

Wende Yan^{1

2

3

4}, Taimoor Hassan Farooq^{1

5}, Yi Chen^{1

3}, Wancai Wang^{1

3}, Rubab Shabbir⁶, Uttam Kumar⁷, Muhammad Umair Riaz⁸, Saqer S Alotaibi⁹, Yuanying Peng¹⁰, Xiaoyong Chen^{1

11}

Affiliations

¹ National Engineering Laboratory for Applied Technology of Forestry and Ecology in South China, Changsha, China.
² Ecological Restoration Innovation Alliance for Southern Purple Shale Mountains, Changsha, China.
³ College of Life Science, Central South University of Forestry and Technology, Changsha, China.
⁴ National Observation Research Station of Forest Ecosystem of Lutou Forest Farm in Hunan Province, Yueyang, China.
⁵ Bangor College China, A Joint Unit of Bangor University and Central South University of Forestry and Technology, Changsha, China.
⁶ Department of Plant Breeding and Genetics, Seed Science and Technology, University of Agriculture, Faisalabad, Pakistan.
⁷ Faculty of Agriculture, Center for Molecular and Functional Ecology in Agroecosystems, University of Talca, Talca, Chile.
⁸ Department of Forestry, Range and Wildlife Management, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
⁹ Department of Biotechnology, College of Science, Taif University, Taif, Saudi Arabia.
¹⁰ College of Arts and Sciences, Lewis University, Romeoville, IL, United States.
¹¹ College of Arts and Sciences, Governors State University, University Park, IL, United States.

Abstract

Nitrogen (N) is often recognized as the primary limiting nutrient element for the growth and production of forests worldwide. Litterfall represents a significant pathway for returning nutrients from aboveground parts of trees to the soils and plays an essential role in N availability in different forest ecosystems. This study explores the N transformation processes under litterfall manipulation treatments in a Masson pine pure forest (MPPF), and Masson pine and Camphor tree mixed forest (MCMF) stands in subtropical southern China. The litterfall manipulation included litterfall addition (LA), litterfall removal (LR), and litterfall control (LC) treatments. The project aimed to examine how litterfall inputs affect the soil N process in different forest types in the study region. Results showed that soil ammonium N (NH₄ ⁺-N) and nitrate N (NO₃ ^--N) content increased under LA treatment and decreased under LR treatment compared to LC treatment. LA treatment significantly increased soil total inorganic N (TIN) content by 41.86 and 22.19% in MPPF and MCMF, respectively. In contrast, LR treatment decreased the TIN content by 10 and 24% in MPPF and MCMF compared to LC treatment. Overall, the soil net ammonification, nitrification, and N mineralization rates were higher in MCMF than in MPPF; however, values in both forests were not significantly different. LA treatment significantly increased annual net ammonification, nitrification, and mineralization in both forest types (p < 0.05) compared to LC treatment. LR treatment significantly decreased the values (p < 0.05), except for ammonification, where LR treatment did not differ substantially compared to LC treatment. Our results suggested that changes in litterfall inputs would significantly alter soil N dynamics in studied forests of sub-tropical region. Moreover, mixed forest stands have higher nutrient returns due to mixed litter and higher decomposition compared to pure forest stands.

Keywords: Masson pine forest; camphor tree forest; litterfall; nitrogen forms; subtropical region.