Early-stage changes in natural 13C and 15N abundance and nutrient dynamics during different litter decomposition

Abstract

Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.

Nutrient and Isotopic Dynamics of Litter Decomposition from Different Land Uses in Naturally Restoring Taihang Mountain, North China

“…The rate of litter decomposition is determined by both biotic (soil macro-fauna and microbial diversity) and abiotic (litter chemistry, soil properties, and microclimate) factors [3]. Litter decomposition is predominantly vital for forests that are extremely reliant on natural fertilization, growing on highly weathered soils/rock systems, where nutrient supply is constrained, and phosphorus and nitrogen cycling pace are slow but stable [10]. Land use conversion of forest results in the disruption of ecological processes including nutrient losses [11].…”

“…All the mechanisms that determine the availability of nutrients in aggrading forests are based on the recycling of nutrients through litter decomposition [1,4,13]. A complete understanding of litter decomposition and the extent of nutrient mobility is crucial for the development of an effective plan in order to sustain nutrient resources, especially in secondary forests that regenerate after decades [10,14]. Litter decomposition has been broadly studied in cool temperate forests [1,5], whereas information about secondary forests and other vegetation [12,15] in their recovery stage, developed on highly rugged parent material, is sparse.…”

“…Litter decomposition has been broadly studied in cool temperate forests [1,5], whereas information about secondary forests and other vegetation [12,15] in their recovery stage, developed on highly rugged parent material, is sparse. A better understanding of the temporal pattern of litter nutrients is essential for adopting the best management strategies for maintenance, conservation, and the growth of restoring (secondary) forests [10].…”

O efeito da transposição na decomposição de folhas de diferentes espécies arbóreas entre a Floresta Ombrófila Densa de Terras Baixas e Montana do litoral norte do Estado de São Paulo

“…As alterações nas concentrações de nutrientes e compostos orgânicos dos detritos foliares ao longo da decomposição provocam modificações nas razões isotópicas do C e N e evidenciam características da ação dos microrganismos ao longo do processo (GAUTAM et al, 2016). Os valores de δ 13 C dos detritos foliares podem aumentar progressivamente ao longo da decomposição em decorrência do uso seletivo de isótopos de 12 C pelos microrganismos durante sua respiração e transporte de C exógeno enriquecido em 13 C entre substratos.…”

“…Os valores de δ 13 C dos detritos foliares podem aumentar progressivamente ao longo da decomposição em decorrência do uso seletivo de isótopos de 12 C pelos microrganismos durante sua respiração e transporte de C exógeno enriquecido em 13 C entre substratos. De forma contrária, os valores de δ 13 C podem reduzir como uma consequência do acúmulo de lignina ao longo da decomposição, sendo que este composto é naturalmente empobrecido em 13 C em relação aos demais tecidos da planta (BENNER; FOGEL; SPRAGUE, 1987;WEDIN et al, 1995;CONNIN;FENG;VIRGINIA, 2001;NGAO;COTRUFO, 2011;GAUTAM et al, 2016). Embora tenha sido observado acúmulo de lignina nos detritos foliares de ambas as espécies, é evidente que este composto recalcitrante não teve influência significativa na composição isotópica do material remanescente, que permaneceu inalterada ao longo da decomposição.De forma semelhante, o acréscimo significativo de N nos detritos foliares de R. formosa e L. hoehnei ao longo da decomposição não provocou modificações nos valores de δ 15 N destes detritos, contrariando estudos anteriores que observaram mudanças significativas nos valores de δ 15 N relacionados aos processos de mineralização e imobilização de N ao longo da decomposição (CONNIN; FENG; VIRGINIA, 2001;HOBBIE;HOBBIE, 2008;GAUTAN et al, 2016).…”