Typhoon enhancement of N and P release from litter and changes in the litter N:P ratio in a subtropical tidal wetland

Abstract

Litter production and decomposition are key processes controlling the capacity of wetland to store and cycle carbon (C) and nutrients. Typhoons deposit large amounts of green and semi-green (between green and withered) plant tissues and withered litter (normal litter) on wetland soils, generating a pulse of litter production. Climatic models project an increase in typhoon intensity and frequency. Elucidating the impacts of typhoons on C, N and P cycles and storage capacities in subtropical and tropical wetland areas is thus important. We analyzed the patterns and changes of litter decomposition after a typhoon in the Minjiang River estuary in southeastern China. Green litter decomposed the fastest, and the loss of mass did not differ significantly between semi-green litter, withered litter and mixed litter (all soil litter after a typhoon). During the decomposition process the remaining green litter had the highest, and withered litter the lowest N and P concentrations. The biomass loss rate of litter during the studied period was related to the initial litter N and P concentrations. Remaining litter generally increased its N:P ratio during decomposition. The ratio of the released N and P was consequently lower than the initial N:P ratio in all litter types. The typhoon enhanced the release of C, N and P from the litter (884, 12.3 and 6 kg ha −1 , respectively) by 264 days after the typhoon. The soil was accordingly enriched with organic matter and nutrients for several months, which should favor microbial growth rates (higher C, N and P availability and lower C: nutrient and N:P ratios) and increase the rates of C and nutrient cycling. If the frequency and/or intensity of typhoons increase, a constant increase in the release of N and P to the soil with lower N:P ratios could change the N and P cycles in wetlands and provide better conditions for the spread of fastgrowing species.

Litterfall production, decomposition and nutrient accumulation in Sundarbans mangrove forests, Bangladesh

“…Due to the variation of structural tissues of different components used for the present decomposition experiment, the rate of mass loss was lower than the previous study. The low decomposition rates in the present study may have been due to the progressive accumulation of more recalcitrant compounds in the litter samples, such as lignin and cellulose, as decomposition progresses (Osono and Takeda 2004;Talbot and Treseder 2012;Wang et al 2016). Our results also agree with the summarization by Gladstone-Gallagher et al (2014), who reported that decomposition rates depended on litter type, with leaves decomposing faster (63 d to decay by 50%) than pneumatophore and wood material (316 and 460 d, respectively).…”

“…Silva et al (2007) used only leaves, but the present litter used for the experiment contained dead leaves, twigs/branches, and reproductive organs. Wang et al (2016) also reported that green litter decomposed faster than mixed litter. Due to the variation of structural tissues of different components used for the present decomposition experiment, the rate of mass loss was lower than the previous study.…”

Anthropogenic global shifts in biospheric N and P concentrations and ratios and their impacts on biodiversity, ecosystem productivity, food security, and human health

“…Some studies have observed that litter decomposition is mostly related to lignin and/or secondary compounds concentrations, and only weakly dependent on litter N:P ratio both in tropical forests (Hättenschwiler & Jørgensen, ) and high latitude ecosystems (Aerts, Bodegom, & Cornelisse, ). Other studies have observed that litter decomposition rates were positively (Zhang, Gao, et al, ) or negatively (Wang, Sardans, Tong, et al, ) related to N:P ratios. These relationships between litter decomposition rates and N:P ratio strongly depend of the level of concentrations of N and P (Güsewell & Gessner, ).…”

“…Our understanding of the impacts of “extreme climatic events” on plant–soil stoichiometry is limited. For example, Wang, Sardans, Tong, et al () observed that rapid production of litter in coastal wetland during typhoons led to larger and faster releases of N and P, characterized by low N:P ratios, but the associated potential impacts on soil microbial communities and trophic chains were unclear. The projected increases in extreme climatic events indicate that quantifying the impacts on N and P cycles and their ratios is essential.…”

Storage and release of nutrients during litter decomposition for native and invasive species under different flooding intensities in a Chinese wetland

“…Three replicates of 20 g of each litter were placed in tightly sealed nylon mesh bags, 20 cm long and wide with a mesh size of 0.3 mm, and allowed to decompose (Wang et al, 2016b). The litter was a mixture of foliar and stem litter in the ratios corresponding to annual foliar:stem litter production ratios of each species.…”