Nutrient limitation of woody debris decomposition in a tropical forest: contrasting effects of N and P addition. (24th June 2015)

• Record Type: Journal Article
• Authors: Chen, Yao; Sayer, Emma J.; Li, Zhian; Mo, Qifeng; Li, Yingwen; Ding, Yongzhen; Wang, Jun; Lu, Xiankai; Tang, Jianwu; Wang, Faming
• Editors: Larjavaara, Markku
• Is Part Of: Functional ecology. Volume 30:Number 2(2016)
• Page Start: 295
• Page End: 304
• Publication Date: 2015-06-24
• Subjects: coarse woody debris -- CWD -- decay -- deposition -- fertilization -- fine woody debris -- nutrient addition -- tropical soil; Ecology -- Periodicals; 574.505
• DOI: 10.1111/1365-2435.12471
• Languages: English
• ISSNs: 0269-8463

Abstract

Summary: Tropical forests represent a major terrestrial store of carbon (C), a large proportion of which is contained in the soil and decaying organic matter. Woody debris plays a key role in forest C dynamics because it contains a sizeable proportion of total forest C. Understanding the factors controlling the decomposition of organic matter in general, and woody debris in particular, is hence critical to assessing changes in tropical C storage. We conducted a factorial fertilization experiment in a tropical forest in South China to investigate the influence of nitrogen (N) and phosphorus (P) availability on woody debris decomposition using branch segments (5 cm diameter) of four species ( Acacia auriculaeformis, Aphanamixis polystachya, Schefflera octophylla, and Carallia brachiata ) in plots fertilized with +N, +P, or +NP, and controls. Fertilization with +P and +NP increased decomposition rates by 5–53%, and the magnitude was species specific. Contrary to expectations, we observed no negative effect of +N addition on decay rates or mass loss of woody debris in any of the four study species. Decomposition rates of woody debris were higher in species with lower C : P ratios regardless of treatment. We observed significant accumulation of P in the woody debris of all species in plots fertilized with +P and +NP during the early stages of decomposition. N release from woody debris of Acacia (N‐fixing) was greater in the +P plots towards the end of the study, whereas fertilization with +N had no impact on the patterns of nutrient release during decomposition. Synthesis : Our results indicate that decomposition of woody debris is primarily constrained by P availability in this tropical forest. However, contrary to expectations, +N addition did not exacerbate P limitation. It is conceivable that decay rates of woody debris in tropical forests can be predicted by C : P or lignin : P ratios, but additional work with more tree species is needed to determine whether the patterns we observed are more generally applicable. Abstract : Lay Summary