Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1–3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.
Relationships involving the transfer of nitrogen (N) among Salix reinii (willow), Larix kaempferi (larch), and mycorrhizal fungi were investigated in a ridge and hillslope on the volcano Mount Koma in northern Japan using a two‐pool fungal model. This model estimated N transfer among the examined taxa by measuring changes in the stable isotope ratio of N (δ15N). Although N content in tephra was low at both sites, it was higher on the ridge than on the hillslope, and higher in the willow patch than on bare ground or in the larch understory. The non‐mycorrhizal sedge (Carex oxyandra) exhibited non‐significant differences between the two sites regarding δ15N for N obtained from tephra. Larches developed a relationship with larch‐specific Suillus mycorrhizal fungal species in the roots, and had a lower foliar δ15N on the hillslope than on the ridge. The larch δ15N increased during the growing season, while the willow δ15N remained stable. The dependence of larch on mycorrhizal fungi for N uptake was 3–5 % on the ridge and 56–76 % on the hillslope in autumn. Therefore, larches exhibited a flexible symbiotic relationship with mycorrhizal fungi for obtaining N. Over 45 % of the N taken up by willow plants was obtained from mycorrhizal fungi at both sites. In conclusion, willow plants promoted N deposition in tephra through the litter supply, and formed a stable relationship with mycorrhizal fungi. This enabled successful revegetation with larch plants, which exhibited flexibility in terms of N uptake (i.e., dependent on mycorrhizae or from tephra).
Anuran larvae can form the largest animal biomass seasonally in freshwater environments, yet, they are still one of the least-studied taxa in terms of nutrient regeneration. The present study tested whether sympatric tadpoles regenerate nutrients at similar rates and ratios, and whether increased intraspecific competition (hereafter ‘competition’) alters patterns of excretion. We quantified rates and ratios of excretion (dissolved nitrogen (N) from ammonia, phosphorus (P) from total dissolved P, and N:P ratio) in three pond-dwelling Japanese tadpoles (Pelophylax nigromaculatus, Rhacophorus schlegelii, Hyla japonica), and tested the effect of competition on excretion in Pelophylax nigromaculatus and Rhacophorus arboreus. The three co-occurring species regenerated nutrients at different rates and ratios; H. japonica excreted nutrients and produced faecal pellets at the lowest rates. Inside field enclosures, increasing tadpole density reduced the quantity but not the quality of excretion by the tadpoles, suggesting higher nutrient sequestration, likely to maintain a stoichiometrically balanced growth under limited resources. Differences in rates and ratios of excretion have previously been shown to have various effects on community structure by affecting primary productivity, highlighting the importance of species identity and interactions on ecosystem function.
We measured differences in %C, %N, 13C and 15N of plant functional types 17 (PFTs) between burned and unburned ground surfaces soon after a wildfire on a north-18 facing slope in interior Alaska. The C and N were measured for 16 species and 19 Sphagnum litter. 13C differed among the PFTs and was low for trees and shrubs, 20 suggesting that woody stems slowed C dynamics or showed low water use efficiency. 21 15N concentrations suggested that the herbaceous plants depended less on the 22 mycorrhizal associations that became weak on the burned surfaces. The shrub leaves 23 showed the lowest 15N of PFTs and showed higher 15N on the burned surface, showing 24 that N transfer from the soils to the leaves in the shrubs was slowed by the wildfire. 25 Mosses showed the highest C/N ratio. Sphagnum litter decomposed faster on the burned 26 surface, and %N and 15N in the litter increased from the second to third year on both 27 burned and unburned surfaces, while %C changed little. In conclusion, the responses to 28 the wildfire differed among the PFTs as characterized by their C and N dynamics. 29 30 Key words: Burned and unburned ground surface, carbon (C) and nitrogen (N), Alaskan 31 taiga, plant functional type, stable isotope
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.