Phosphorus addition regulates the growth of Chinese fir by changing needle nitrogen fractions in growing and dormant seasons

• Published in: The Science of the total environment 2022-12, Vol.852, p.158230-158230, Article 158230
• Main Authors: Wang, Fangchao, Chen, Fu-Sheng, Fang, Xiang-Min, Wang, Huimin, Hu, Xiaofei
• Format: Article
• Language: English
• Subjects: Carbohydrates; Needle age; Nitrogen fractions; Nutrient addition; Seasonal growth
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.158230

Forest productivity is generally limited by nutrient scarcity. This study aims to reveal seasonal interactions among leaf carbon (C), nitrogen (N) fractions and tree growth driven by nutrient addition in a subtropical forest. Here, a field nutrient addition experiment was conducted with six treatments, namely, +N5 (5 g N m−2 yr−1), +N10 (10 g N m−2 yr−1), +P5 (5 g P m−2 yr−1), +N5 + P5, +N10 + P5, and control (N0 + P0). C fractions (structural and non-structural carbohydrates) and N fractions (soluble N, nucleic N and protein N) in needles as well as tree growth indicated by basal area increment (BAI) were measured in growing and dormant seasons. Total N and protein N in old needles were significantly increased by P addition, while no significant differences of non-structural carbohydrates in young (1-year old) were detected among the treatments in both seasons. N and P addition increased the structural carbohydrates of old needles in dormant season. P addition decreased and increased tree growth in growing and dormant seasons, respectively. The variation of BAI was explained 18.3 % by total N and 17.8 % by protein N in growing season, and was explained 33.9 % by total N and 34.2 % by protein N in dormant season. Our study suggested that the P addition effect on Chinese fir growth mostly depends on needle N fractions. This study highlights tree seasonal growth driven by nutrient alteration might be characterized by leaf N fractions rather than C fractions in subtropical forests. [Display omitted] •P addition decreased and increased tree growth in growing and dormant seasons.•P addition increased needle total N and protein N in both seasons.•Needle C fractions showed minor respond to nutrient addition.•Young needle N fractions are higher than old needle, opposite in C fractions.•Seasonal growth was regulated by N fractions rather than C fractions.