Open Access

ARTICLE

Effects of Forest Types on Soil Available Nutrients and Carbon Contents in Coastal Areas, China

Zirui Chen^1,2, Jiale Liu^1,2, Haijun Sun^1,2,*

1 Co-Innovation Center for Sustainable Forestry in Southern China, College of Soil and Water Conservation, Nanjing Forestry University, Nanjing, 210037, China
2 National Positioning Observation and Research Station of Forest Ecosystem in Changjiang River Delta, Nanjing, 210037, China

* Corresponding Author: Haijun Sun. Email:

Phyton-International Journal of Experimental Botany 2024, 93(10), 2557-2569. https://doi.org/10.32604/phyton.2024.056868

Received 01 August 2024; Accepted 14 September 2024; Issue published 30 October 2024

Abstract

Clarifying the soil nutrient dynamics caused by forest type variations in the coastal region helps scientifically to apply fertilizer to forest plantations and enhance the carbon (C) sink capacity. Pure forests of Ligustrum and Metasequoia, as well as their mixed forests, in a coastal region of China were investigated by collecting 0–20 and 20–40 cm soil samples and analyzing their differences in bulk density, water content, pH, soil organic matter (SOM), ammonium (NH₄⁺–N), nitrate (NO₃^––N) and total nitrogen (TN), available phosphorus (AP) and potassium (AK), microbial biomass C (MBC) and N (MBN), and enzyme activity. The results demonstrated that different forest types had no significant (p ≥ 0.05) effect on 0–20 cm soil bulk density, water content, pH, NH₄⁺–N, and SOM. However, the surface soil NO₃^––N, TN, AP, and AK contents as well as enzyme activity changed significantly (p < 0.05), in which the soil AK content of the ligustrum × metasequoia mixed forest was 47.5% and 65.5% higher than that of the ligustrum and metasequoia pure forest, respectively. The mixed forest soil had the highest MBN content, which was significantly (p < 0.05) 25.1% higher than that in the pure metasequoia forest. Meanwhile, soil phosphatase activities in ligustrum and metasequoia pure forests were significantly (p < 0.05) lower than those in the mixed forests by 17.4% and 43.1%, respectively. However, soil NO₃^––N and AP contents in the metasequoia pure forest were significantly (p < 0.05) higher than those in the ligustrum pure forest and mixed forests. Soil MBC content and reductase NO₃^––N activity were significantly (p < 0.05) higher in ligustrum pure forest than in metasequoia pure forest and mixed forests. In addition, the results of two-way ANOVA showed that there were no significant (p ≥ 0.05) differences in nutrient contents (e.g., NH₄⁺–N, AP, AK, and SOM) in different soil layers (0–20 and 20–40 cm) within the same forest type, except for NO₃^––N. However, forest types had a significant (p < 0.05) impact on NO₃^––N and AP contents in 20–40 cm soil layer. Combining the two factors of forest stand and soil layer, there was a significant (p < 0.05) interaction effect for their soil NH₄⁺–N, NO₃^––N, AP, and AK contents. In conclusion, significant (p < 0.05) differences were observed in nutrient contents in 0–20 cm soil layer from different forest types, with soil fertility indices inmixed forests generally higher than in pure forests. Therefore, establishing mixed forests in coastal saline region is recommended to retain soil fertility and to enhance the C sink capacity of forestry.

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Keywords

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