Effects of Excess Nitrogen (N) on Fine Root Growth in Tropical Forests of Contrasting N Status

编号 010036001

推送时间 20220912

研究领域 森林生态 

年份 2022 

类型 期刊 

语种 英语

标题 Effects of Excess Nitrogen (N) on Fine Root Growth in Tropical Forests of Contrasting N Status

来源期刊 forest

期 第360期

发表时间 20220819

关键词 nitrogen deposition;  fine root vitality;  fine root chemistry;  soil acidification;  tropical forest; 

摘要 Elevated nitrogen (N) deposition may further acidify soils in tropical forests. Yet, we have limited evidence on this prediction and it remained unclear how this would affect fine root growth therein. Here, we report responses of fine root biomass, vitality, and chemistry, as well as related soil parameters to eight years of N additions in three tropical forests different in initial soil N status, with one primary forest being N-saturated, and another two younger forests (one secondary forest and one planted forest) less N-rich. Results showed that in the primary forest, fine root biomass decreased and fine root necromass increased following N addition, resulting in lower live fine root proportion (fine root vitality). Declining fine root vitality was associated with fine root Fe accumulation and soil acidification indicated by regression analysis. These alterations of fine root growth and chemistry co-occurred with soil pH decline, soil exchangeable Fe3+ mobilization, exchangeable Ca2+, and Mg2+ depletion after N treatments in the primary forest. In contrast, N addition only elevated fine root K, Al, and Fe content in the secondary forest. In the planted forest, moderate but significant decreases in soil pH, soil exchangeable K+, and Mg2+ were found after N treatment, with fine root biomass negatively correlated with soil exchangeable Al3+ and Al3+/(Ca2+ + Mg2+) ratio. Our results suggested that long-term N fertilization may negatively affect fine root growth, via severed soil acidification, Fe mobilization, and base cation depletion in highly acidified, N-saturated primary tropical forests. Initial forest N status, influenced by different land-use history, mediates N deposition effects on fine root growth. View Full-Text

服务人员 王璐

服务院士 蒋有绪

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