Effects of seasonal precipitation regimes on microbial biomass and extracellular enzyme activity during shrub foliar litter decomposition in a subtropical forest.

Elucidating the mechanisms underlying microbial biomass and extracellular enzyme activity responses to the seasonal precipitation regime during foliar litter decomposition is highly important for understanding the material cycle of forest ecosystems in the context of global climate change; however, the specific underlying mechanisms remain unclear. Hence, a precipitation manipulation experiment involving a control (CK) and treatments with decreased precipitation in the dry season and extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season and proportionally increased precipitation in the wet season (IP) was conducted in a subtropical evergreen broad-leaved forest in China from October 2020 to October 2021. The moisture, microbial biomass, and extracellular enzyme activities of foliar litter from two dominant shrub species, Phyllostachys violascens and Alangium chinense, were measured at six stages during the dry and wet seasons. The results showed that (1) both IE and IP significantly decreased the microbial biomass carbon and microbial biomass nitrogen content and the activities of ß-1,4-glucosidase, ß-1,4-N-acetylglucosaminidase, acid phosphatase and cellulase in the dry season, while the opposite effects were observed in the wet season. (2) Compared with those of IE, the effects of IP on foliar litter microbial biomass and extracellular enzyme activity were more significant. (3) The results from the partial least squares model indicated that extracellular enzyme activity during foliar litter decomposition was strongly controlled by the foliar litter water content, microbial biomass nitrogen, the ratio of total carbon to total phosphorus, foliar litter total carbon, and foliar litter total nitrogen. These results provide an important theoretical basis for elucidating the microbial mechanisms driving litter decomposition in a subtropical forest under global climate change scenarios.

[Effect of seasonal distribution in precipitation on soil nitrogen mineralization in a subtropical forest]. / é™æ°´å­£èŠ‚æ€§åˆ†é å¯¹äºšçƒ­å¸¦æ£®æž—åœŸå£¤æ°®çŸ¿åŒ–çš„å½±å“.

Soil N mineralization is a key process of nutrient cycling in ecosystems. The mechanism of the seasonal distribution of precipitation on soil N mineralization remains unclear. We conducted a precipitation manipulation experiment in a subtropical forest in the middle and lower reaches of the Yangtze River in China from 2020 to 2022, with three treatments, including control (CK), decreased precipitation in the dry season with extremely increased precipitation in the wet season (T1), and decreased precipitation in the dry season with proportionally increased precipitation in the wet season (T2). With in situ resin core method, we explored the effect of seasonal distribution of precipitation on soil N mineralization. The results showed that T1 and T2 significantly decreased dry season net nitrification rate by 57.9% and 72.5% and the net N mineralization rate by 82.5% and 89.6%, respectively, and significantly increased wet season net nitrification rate by 64.3% and 79.5% and net N mineralization rate by 64.2% and 81.1%, respectively. Proportionally increased precipitation in the wet season was more conducive to soil N mine-ralization process than extremely increased precipitation in the wet season. Results of the structural equation model showed that change in seasonal distribution of precipitation could significantly affect soil N mineralization processes in the subtropical forest by changing soil water content, ammonium nitrogen, microbial biomass nitrogen, and soil C:N. Our results had important reference for understanding soil nitrogen cycling and other ecological processes, and were conducive to more accurate assessment on the impacts of future changes in seasonal precipitation pattern on subtropical forest ecosystems.

Synergistic effects of arbuscular mycorrhizal fungi and biochar are highly beneficial to Ligustrum lucidum seedlings in Cd-contaminated soil.

Cadmium (Cd) contamination is a widespread environmental issue. There is a lack of knowledge about the impacts of applying arbuscular mycorrhizal fungi (AMF) and biochar, either alone or in their combination, on alleviating Cd phytotoxicity in Ligustrum lucidum. Therefore, a pot experiment was conducted in a greenhouse, where L. lucidum seedlings were randomly subjected to four regimes of AMF treatments (inoculation with sterilized AMF, with Rhizophagus irregularis, Diversispora versiformis, alone or a mixture of these two fungi), and two regimes of biochar treatments (with or without rice-husk biochar), as well as three regimes of Cd treatments (0, 15, and 150 mg kg-1), to examine the responses of growth, photosynthetic capabilities, soil enzymatic activities, nutritional concentrations, and Cd absorption of L. lucidum plants to the interactive effects of AMF, biochar, and Cd. The results demonstrated that under Cd contaminations, AMF alone significantly increased plant total dry weight, soil pH, and plant nitrogen (N) concentration by 84%, 3.2%, and 13.2%, respectively, and inhibited soil Cd transferring to plant shoot by 42.2%; biochar alone significantly enhanced net photosynthetic rate, soil pH, and soil catalase of non-mycorrhizal plants by 16.4%, 9%, and 11.9%, respectively, and reduced the soil Cd transferring to plant shoot by 44.7%; the additive effect between AMF and biochar greatly enhanced plant total dry weight by 101.9%, and reduced the soil Cd transferring to plant shoot by 51.6%. Furthermore, dual inoculation with D. versiformis and R. irregularis conferred more benefits on plants than the single fungal species did. Accordingly, amending Cd-contaminated soil with the combination of mixed-fungi inoculation and biochar application performed the best than either AMF or biochar alone. These responses may have been attributed to higher mycorrhizal colonization, soil pH, biomass accumulation, and biomass allocation to the roots, as well as photosynthetic capabilities. In conclusion, the combined use of mixed-fungi involving D. versiformis and R. irregularis and biochar addition had significant synergistic effects on enhancing plant performance and reducing Cd uptake of L. lucidum plants in Cd-contaminated soil.

Resistance of Mycorrhizal Cinnamomum camphora Seedlings to Salt Spray Depends on K+ and P Uptake.

Salt spray is a major environmental issue in coastal areas. Cinnamomum camphora is an economically important tree species that grows in the coastal areas of southern China. Arbuscular mycorrhizal fungi (AMF) can alleviate the detrimental effects of abiotic stress on host plants. However, the mechanism by which AMF mitigates the adverse effects of salt spray on C. camphora remains unclear. A pot experiment was conducted in a greenhouse, where C. camphora seedlings were exposed to four AMF regimes (inoculation with sterilized fungi, with Glomus tortuosum, Funneliformis mosseae, either alone or in combination) and three salt spray regimes (applied with distilled water, 7, and 14 mg NaCl cm-2) in order to investigate the influence on root functional traits and plant growth. The results showed that higher salt spray significantly decreased the K+ uptake, K+/Na+ ratio, N/P ratio, total dry weight, and salinity tolerance of non-mycorrhizal plants by 37.9%, 71%, 27.4%, 12.7%, and 221.3%, respectively, when compared with control plants grown under non-salinity conditions. Mycorrhizal inoculation, particularly with a combination of G. tortuosum and F. mosseae, greatly improved the P uptake, total dry weight, and salinity tolerance of plants grown under higher salt spray conditions by 51.0%, 36.7%, and 130.9%, respectively, when compared with their counterparts. The results show that AMF can alleviate the detrimental effects of salt spray on C. camphora seedlings. Moreover, an enhanced uptake of K+ and P accounted for the resistance of the plants to salt spray. Therefore, pre-inoculation with a combination of G. tortuosum and F. mosseae to improve nutrient acquisition is a potential method of protecting C. camphora plants against salt spray stress in coastal areas.

Global patterns and drivers of lead concentration in inland waters.

Water bodies are important carriers for lead (Pb) biogeochemical cycling, which is a key pathway of Pb transport. Although existing studies on Pb loading in inland waters have developed rapidly, a quantitative assessment of the distribution patterns and drivers of Pb concentration in inland waters at the global scale remains unclear. Here, by analyzing 1790 observations collected from 386 independent publications, we assessed the spatial distribution and drivers of Pb concentration in inland waters worldwide. We found that (1) globally, the median of Pb concentration in inland waters was 5.81 µg L-1; (2) among different inland water types, Pb concentration was higher in rivers, and the highest Pb concentration was in industrial land in terms of land use type; (3) Pb concentration in inland waters were positively driven by potential evapotranspiration, elevation and road density; and (4) Pb concentration showed a negative relationship with absolute latitude, decreasing from tropic to boreal regions. Overall, our global assessment of the patterns and drivers of Pb concentration in inland waters contributed to a better understanding of the natural and anthropogenic attributions of Pb in the inland hydrological cycling.

Effects of vegetation restoration on the concentrations of multiple metal elements in post-mining soils.

Vegetation restoration is vital for soil ecological restoration in post-mining areas, but a global-scale quantitative assessment of its effects on soil metal elements is lacking. Here, we conducted a meta-analysis with 2308 paired observations collected from 137 publications to evaluate vegetation restoration effects on the concentrations of 17 metal elements, namely K, AK (available K), Ca, Na, Mg, Fe, Mn, Zn, Cu, Al, Cr, Co, Ni, Cd, Sb, Hg, and Pb in post-mining soils. We found that (1) vegetation restoration significantly increased the concentrations of K, AK, Ca, Mg and Co by 43.2, 42.5, 53.4, 53.7, and 137.2%, respectively, but did not affect the concentrations of Na, Fe, Mn, Zn, Cu, Al, Cr, Ni, Cd, Sb, Hg, and Pb; (2) the effects of vegetation restoration on soil metal concentration were seldom impacted by vegetation type, while soil depth only affected the responses of AK, Cd, and Pb concentrations to vegetation restoration, and leaf type only impacted the responses of Ca and Ni concentrations to vegetation restoration; (3) latitude, elevation, restoration year, climate, and initial soil properties were also important moderator variables of vegetation restoration effects, but their impacts varied among different metals. Overall, our results clearly showed that vegetation restoration in posting-mining areas generally have a positive effect on the concentrations of nutrient elements but did not influence that of toxic elements, which provides useful information for the restoration and reconstruction of soil ecosystem in post-mining areas.

Global characteristics and drivers of sodium and aluminum concentrations in freshly fallen plant litter.

Plant litter is not only the major component of terrestrial ecosystem net productivity, the decomposition of which is also an important process for the returns of elements, including sodium (Na) and aluminum (Al), which can be beneficial or toxic for plant growth. However, to date, the global characteristics and driving factors of Na and Al concentrations in freshly fallen litter still remain elusive. Here, we evaluated the concentrations and drivers of litter Na and Al with 491 observations extracted from 116 publications across the globe. Results showed that (1) the average concentrations of Na in leaf, branch, root, stem, bark, and reproductive tissue (flowers and fruits) litter were 0.989, 0.891, 1.820, 0.500, 1.390, and 0.500 g/kg, respectively, and the concentrations of Al in leaf, branch, and root were 0.424, 0.200 and 1.540 g/kg, respectively. (2) mycorrhizal association significantly affected litter Na and Al concentration. The highest concentration of Na was found in litter from trees associated with both arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (ECM), followed by litter from trees with AM and ECM. Lifeform, taxonomic, and leaf form had significant impacts on the concentration of Na and Al in plant litter of different tissues. (3) leaf litter Na concentration was mainly driven by mycorrhizal association, leaf form and soil phosphorus concentration, while leaf litter Al concentration was mainly controlled by mycorrhizal association, leaf form, and precipitation in the wettest month. Overall, our study clearly assessed the global patterns and influencing factors of litter Na and Al concentrations, which may help us to better understand their roles in the associated biogeochemical cycles in forest ecosystem.

Vegetation restoration effects on soil carbon and nutrient concentrations and enzymatic activities in post-mining lands are mediated by mine type, climate, and former soil properties.

Vegetation restoration is a widely used, effective, and sustainable method to improve soil quality in post-mining lands. Here we aimed to assess global patterns and driving factors of potential vegetation restoration effects on soil carbon, nutrients, and enzymatic activities. We synthesized 4838 paired observations extracted from 175 publications to evaluate the effects that vegetation restoration might have on the concentrations of soil carbon, nitrogen, and phosphorus, as well as enzymatic activities. We found that (1) vegetation restoration had consistent positive effects on the concentrations of soil organic carbon, total nitrogen, available nitrogen, ammonia, nitrate, total phosphorus, and available phosphorus on average by 85.4, 70.3, 75.7, 54.6, 58.6, 34.7, and 60.4 %, respectively. Restoration also increased the activities of catalase, alkaline phosphatase, sucrase, and urease by 63.3, 104.8, 125.5, and 124.6 %, respectively; (2) restoration effects did not vary among different vegetation types (i.e., grass, tree, shrub and their combinations) or leaf type (broadleaved, coniferous, and mixed), but were affected by mine type; and (3) latitude, climate, vegetation species richness, restoration year, and initial soil properties are important moderator variables, but their effects varied among different soil variables. Our global scale study shows how vegetation restoration can improve soil quality in post-mining lands by increasing soil carbon, nutrients, and enzymatic activities. This information is crucial to better understand the role of vegetation cover in promoting the ecological restoration of degraded mining lands.

Effects of drying-rewetting cycles on the fluxes of soil greenhouse gases.

Irregular precipitation caused by climate changes has resulted in frequent events of soil drying-rewetting cycles (DWC), which can strongly affect soil carbon (C) and nitrogen (N) cycling, including the fluxes of greenhouse gases (GHGs). The response of soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes to DWC events may differ among different ecosystem types and vary with experimental settings and soil properties, but these processes were not quantitatively assessed. Here, we evaluated the responses of soil GHG fluxes to DWC, compared with consistent moisture, as well as the associated driving factors with 424 paired observations collected from 47 publications of lab incubation experiments. Results showed that: (1) DWC significantly decreased soil CO2 emissions by an average of 9.7%, but did not affect the emissions and uptakes of soil CH4 and N2O; (2) DWC effects on soil GHG emissions varied significantly among different ecosystem types, with CO2 emissions significantly decreased by 6.8 and 16.3% in croplands and grasslands soils, respectively, and CH4 and N2O emissions significantly decreased and increased in wetlands and forests soils, respectively; (3) the effects of DWC on CO2 emissions were also positively regulated by organic C and N concentrations, pH, clay concentration, and soil depth, but negatively by C:N ratio and silt concentration, while DWC effects on N2O emissions were negatively controlled by C:N ratio, silt concentration, and soil depth. Overall, our results showed that CO2 emissions were significantly decreased by DWC, while the fluxes of CH4 and N2O were not affected, indicating an overall decrease of GHGs in response to DWC. Our results will be useful for a better understanding of global GHG emissions under future climate change scenario.

Global patterns and driving factors of plant litter iron, manganese, zinc, and copper concentrations.

Plant litter decomposition is not only the major source of soil carbon and macronutrients, but also an important process for the biogeochemical cycling of trace elements such as iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). The concentrations of plant litter trace elements can influence litter decomposition and element cycling across the plant and soil systems. Yet, a global perspective of the patterns and driving factors of trace elements in plant litter is missing. To bridge this knowledge gap, we quantitatively assessed the concentrations of four common trace elements, namely Fe, Mn, Zn, and Cu, of freshly fallen plant litter with 1411 observations extracted from 175 publications across the globe. Results showed that (1) the median of the average concentrations of litter Fe, Mn, Zn, and Cu were 0.200, 0.555, 0.032, and 0.006 g/kg, respectively, across litter types; (2) litter concentrations of Fe, Zn, and Cu were generally stable regardless of variations in multiple biotic and abiotic factors (e.g., plant taxonomy, climate, and soil properties); and (3) litter Mn concentration was more sensitive to environmental conditions and influenced by multiple factors, but mycorrhizal association and soil pH and nitrogen concentration were the most important ones. Overall, our study provides a clear global picture of plant litter Fe, Mn, Zn, and Cu concentrations and their driving factors, which is important for improving our understanding on their biogeochemical cycling along with litter decomposition processes.

Contrasting effects of altered precipitation regimes on soil nitrogen cycling at the global scale.

Changes in precipitation regimes can strongly affect soil nitrogen (N) cycling in terrestrial ecosystems. However, whether altered precipitation regimes may differentially affect soil N cycling between arid and humid biomes at the global scale is unclear. We conducted a meta-analysis using 1036 pairwise observations collected from 194 publications to assess the effects of increased and decreased precipitation on the input (N return from plants), storage (various forms of N in soil), and output (gaseous N emissions) of soil N in arid versus humid biomes at the global scale. We found that (1) increased precipitation significantly increased N input (+12.1%) and output (+34.9%) but decreased N storage (-13.7%), while decreased precipitation significantly decreased N input (-10.7%) and output (-34.8%) but increased N storage (+11.1%); (2) the sensitivity of soil N cycling to increased precipitation was higher in arid regions than in humid regions, while that to decreased precipitation was lower in arid regions than in humid regions; (3) the effect of altered precipitation regimes on soil N cycling was independent of precipitation type (i.e., rainfall vs. snowfall); and (4) the mean annual precipitation regulated soil N cycling in precipitation alteration experiments at the global scale. Overall, our results clearly show that the response of soil N cycling to increased versus decreased precipitation differs between arid and humid regions, indicating the uneven effect of climate change on soil N cycling between these two contrasting climate regions. This implies that ecosystem models need to consider the differential responses of N cycling to altered precipitation regimes in different climatic conditions under future global change scenarios.

Litter quality and stream physicochemical properties drive global invertebrate effects on instream litter decomposition.

Plant litter is the major source of energy and nutrients in stream ecosystems and its decomposition is vital for ecosystem nutrient cycling and functioning. Invertebrates are key contributors to instream litter decomposition, yet quantification of their effects and drivers at the global scale remains lacking. Here, we systematically synthesized data comprising 2707 observations from 141 studies of stream litter decomposition to assess the contribution and drivers of invertebrates to the decomposition process across the globe. We found that (1) the presence of invertebrates enhanced instream litter decomposition globally by an average of 74%; (2) initial litter quality and stream water physicochemical properties were equal drivers of invertebrate effects on litter decomposition, while invertebrate effects on litter decomposition were not affected by climatic region, mesh size of coarse-mesh bags or mycorrhizal association of plants providing leaf litter; and (3) the contribution of invertebrates to litter decomposition was greatest during the early stages of litter mass loss (0-20%). Our results, besides quantitatively synthesizing the global pattern of invertebrate contribution to instream litter decomposition, highlight the most significant effects of invertebrates on litter decomposition at early rather than middle or late decomposition stages, providing support for the inclusion of invertebrates in global dynamic models of litter decomposition in streams to explore mechanisms and impacts of terrestrial, aquatic, and atmospheric carbon fluxes.

Germline FOXJ2 overexpression causes male infertility via aberrant autophagy activation by LAMP2A upregulation.

Spermatogenesis is a complex biological process that produces haploid spermatozoa and requires precise regulation by many tissue-specific factors. In this study, we explored the role and mechanism of Fork head box J2 (FOXJ2, which is highly expressed in spermatocytes) in the regulation of spermatogenesis using a germline-specific conditional Foxj2 knock-in mouse model (Stra8-Cre; Foxj2 tg/tg mouse). Foxj2 overexpression in mouse testes led to spermatogenesis failure, which started at the initiation of meiosis, and resulted in male infertility. Lysosomes and autophagy-related genes were upregulated in Stra8-cre; Foxj2 tg/tg mouse testes and the number of autolysosomes in the spermatocytes in Stra8-cre; Foxj2 tg/tg mice was increased. Chromatin immunoprecipitation-PCR and Dual-luciferase reporter assays showed that Lamp2 (encoding lysosome-associated membrane protein-2) was a target of FOXJ2. Foxj2 overexpression increased the expression levels of Lamp2a and Hsc70 (70-kDa cytoplasmic heat shock protein) in the Stra8-cre; Foxj2 tg/tg mouse testes. Our results suggested that Foxj2 overexpression in the germ cells of mouse testes affects chaperone-mediated autophagy by upregulating LAMP2A, leading to spermatogenesis failure at the initiation of meiosis, thus resulting in male infertility. Our findings provide a new insight into the function of FOXJ2 in spermatogenesis and the significance of autophagy regulation in spermatogenesis.

[Impact of overexpressed FOXJ2 on mouse spermatogenesis and its action mechanism].

OBJECTIVE: To analyze the phenotype of the male reproductive system in the germline-specific conditional Foxj2 knock-in mouse model (Stra8-cre; Foxj2tg/+), identify a target gene of the transcription factor FOXJ2, and investigate the effect of the overexpression of Foxj2 on mouse spermatogenesis and its action mechanism. METHODS: Based on the Cre-loxP recombination system, we generated a germline-specific conditional Foxj2 knock-in mouse model (Stra8-cre; Foxj2tg/+). We determined male fertility by counting the number of pups per litter and the fertilization rate after intracytoplasmic sperm injection (ICSI), observed the morphology of the testes and epididymides by HE staining, examined the sperm quality by computer assisted sperm analysis (CASA), detected the expression and localization of Cx43 in the testis by RT-qPCR, Western blot and immunohistochemistry, and verified the binding site of FOXJ2 to the Cx43 promoter using ChIP-PCR and dual luciferase reporter assay. RESULTS: The number of pups per litter and fertilization rate after ICSI were lower in the Stra8-cre; Foxj2tg/+ male mice than in the controls, and so were the size and weight of the testis. HE staining exhibited obvious exfoliation of germ cells and dramatically decreased spermatocytes and spermatids in the seminiferous tubules of the Stra8-cre; Foxj2tg/+ mice. Moreover, sperm concentration in the cauda epididymides was reduced, and the transcription and expression levels of Cx43 in the testis were increased. ChIP-PCR and dual luciferase reporter assay showed direct binding of FOXJ2 to the Cx43 promoter in the testis. CONCLUSIONS: Overexpressed FOXJ2 may lead to spermatogenic failure and subfertility in Stra8-cre; Foxj2tg/+ male mice by upregulating the expression of Cx43.

Differential effects of altered precipitation regimes on soil carbon cycles in arid versus humid terrestrial ecosystems.

Changes in precipitation regimes have significant effects on soil carbon (C) cycles; however, these effects may vary in arid versus humid areas. Additionally, the corresponding details of soil C cycles in response to altered precipitation regimes have not been well documented. Here, a meta-analysis was performed using 845 pairwise observations (control vs. increased or decreased precipitation) from 214 published articles to quantify the responses of the input process of exogenous C, the contents of various forms of C in soil, and the soil-atmosphere C fluxes relative to increased or decreased precipitation. The results showed that the effects of altered precipitation regimes did not differ between rainfall and snowfall. Increased precipitation significantly enhanced the soil C inputs, pools and outputs by 18.17%, 18.50%, and 21.04%, respectively, while decreased precipitation led to a significant decline in these soil C parameters by 10.18%, 9.96%, and 17.98%, respectively. The effects of increased precipitation on soil C cycles were more significant in arid areas (where mean annual precipitation, MAP <500 mm), but the effects of decreased precipitation were more significant in humid areas (where MAP ≥500 mm), indicating that the original MAP partially determined the responses of the soil C cycles to altered precipitation regimes. This study implies that for the same of precipitation variation, soil C cycles respond at different magnitudes: not only should the direction (decrease vs. increase) be counted but also the region (arid vs. humid) should be considered. These results deepened our understanding on regional differentiation in soil C cycles under climate change scenarios.

Effects of snow depth manipulation on the releases of carbon, nitrogen and phosphorus from the foliar litter of two temperate tree species.

The effect of snow depth on litter decomposition in cold regions has attracted substantial attention, but the importance of snow depth to the releases of carbon (C), nitrogen (N), and phosphorus (P) and the underlying mechanisms remain unclear. The releases of C, N, and P from the foliar litter of Pinus koraiensis and Quercus mongolica in response to snow depth changes were examined for 12 months in a temperate forest of Northeast China via a snow depth manipulation experiment that included snow-addition (SA), snow-removal (SR), and control (CK) treatments. We found that the SA treatment promoted the releases of C, N, and P from the foliar litter during the snow-covered season but slowed these processes during the following snow-free season; however, the SR treatment produced the opposite results. Compared with the CK treatment, the SA treatment increased the annual releases of C, N, and P by 2.52%, 0.50%, and 4.68%, respectively, whereas the SR treatment decreased the corresponding values. The elemental release during the snow-covered season was associated with the freeze-thaw cycle (FTC) and microbial biomass, whereas that during the snow-free season was mainly controlled by the temperature of the litter layer. Our findings indicated that the snow depth promoted the releases of C, N and P from the foliar litter of the two tree species, especially during the snow-covered season. These results deepen the understanding of the biogeochemical cycling in cold regions under global climate change scenarios.

Foliar litter nitrogen dynamics as affected by forest gap in the alpine forest of eastern Tibet Plateau.

There is increasing attention on the effects of seasonal snowpack on wintertime litter decomposition, as well as the processes following it, in cold biomes. However, little information is available on how litter nitrogen (N) dynamics vary with snowpack variations created by tree crown canopies in alpine forests. Therefore, to understand the effects of seasonal snowpack on litter N dynamics during different critical stages, litterbags with fir (Abies faxoniana), birch (Betula albo-sinensis), larch (Larix mastersiana) and cypress (Sabina saltuaria) foliar litter were placed on the forest floor beneath snowpack created by forest gaps in the eastern Tibet Plateau. The litterbags were sampled at the onset of freezing, deep freezing, thawing and growing stages from October 2010 to October 2012. Mass loss and N concentrations in litter were measured. Over two years of decomposition, N release occurred mainly during the first year, especially during the first winter. Litter N release rates (both in the first year and during the entire two-year decomposition study period) were higher in the center of canopy gaps than under closed canopy, regardless of species. Litter N release rates in winter were also highest in the center of canopy gaps and lowest under closed canopy, regardless of species, however the reverse was found during the growing season. Compared with broadleaf litter, needle litter N release comparisons of gap center to closed canopy showed much stronger responses to the changes in snow cover in winter and availability of sunshine during the growing season. As the decomposition proceeded, decomposing litter quality, microbial biomass and environmental temperature were important factors related to litter N release rate. This suggests that if winter warm with climate change, reduced snow cover in winter might slow down litter N release in alpine forest.