An incubation study of temperature sensitivity of greenhouse gas fluxes in three land-cover types near Sydney, Australia

Antecedent soil moisture before freezing can affect greenhouse gases (GHG) fluxes from soils during thaw, but their critical threshold values for GHG fluxes and the underlying mechanisms are still not clear. By using packed soil-core incubation experiments, we have studied nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes from a mature broadleaf and Korean pine-mixed forest soil and an adjacent white birch forest soil with nine levels of soil moisture ranging from 10 to 90% water-filled pore space (WFPS) during a 2-month freezing at −8°C and the following 10-day thaw at 10°C. The threshold values of soil moisture ranged from 50 to 70% WFPS for CH4 uptake and from 70 to 90% WFPS for N2O and CO2 emissions from the two soils during the freeze-thaw period. Under the optimum soil moisture condition, fulvic-like compounds with high bioavailability contributed more than 60% of dissolved organic matter (DOM) in the soil. Cumulative N2O emissions from forest soils during the freeze-thaw period were greatest when the concentration ratio of nitrate-N to dissolved organic carbon (DOC) was 0.04 g N g−1 C. Cumulative soil CO2 emissions and CH4 uptake during the freeze-thaw period were both regulated by the interaction between soil DOC and net N mineralization. The activities of β-1,4-glucosidase and β-1,4-N-acetyl-glucosaminidase, microbial biomass C and N, and the microbial biomass C-to-N ratios, were all significantly correlated to the soil N2O, CO2, and CH4 fluxes. Overall, upon a freeze-thaw period with different soil moistures, GHG fluxes from forest soils were jointly regulated by inorganic N and DOC concentrations, and related to the labile components of DOM released into the soil, which could be strictly controlled by the related microbial properties.

Terrestrial ecosystems play a critical role in regulating the emission and uptake of the most important greenhouse gases (GHGs) such as CO2, CH4, and N2O. However, the effects of grazing on these GHG fluxes in different steppe types remain unclear. Here, we compared the effects of grazing on seasonal CO2, CH4, and N2O fluxes in the meadow (MS), typical (TS), and desert (DS) temperate steppe ecosystems in northern China. CO2 emission rates increased from 311.4 ± 73.2 to 349.6 ± 55.4 mg·m−2·h−1 in MS, but decreased in TS (from 341.3 ± 93.0 to 239.5 ± 81.9 mg·m−2·h−1) and DS (from 212.1 ± 53.7 to 163.0 ± 83.4 mg·m−2·h−1) in response to summer grazing (SG). N2O emission rates increased in MS from 4.7 ± 2.2 to 8.1 ± 3.4 μg·m−2·h−1, but not significantly changed in TS (9.2 ± 4.2 vs. 8.4 ± 2.4 μg·m−2·h−1) and DS (6.3 ± 1.5 vs. 5.7 ± 1.6 μg·m−2·h−1) by SG. CH4 uptake rates increased in MS from 33.0 ± 11.7 to 47.1 ± 10.4 μg·m−2·h−1 and decreased from 64.4 ± 7.6 to 56.2 ± 5.9 μg·m−2·h−1 in TS in response to SG. In MS and DS, N2O emissions were positively related to seasonal CO2 emissions and negatively related to CH4 uptakes. No significant relationships were found between GHG fluxes in TS. Summer grazing did not affect the relationship between CO2 and N2O emissions in MS, but reduced the relationship by enhancing the effect of aboveground biomass (AGB) on N2O emission in DS. The significant negative relationship between CH4 uptake and N2O emission in MS and DS could be attributed to the significant relationship between soil temperature (ST) and AGB in MS and to the significant effects of soil moisture on both CH4 uptake and N2O emission in DS. The decrease in the magnitude of the correlation coefficients between CH4 uptake and N2O emission by SG was due to the negative relationship between ST and AGB simultaneously in MS and DS. Our results suggest that effects of SG on GHG fluxes varied in different steppes and the relationship among GHGs was steppe‐dependent and SG also changed the relationship by affecting GHG fluxes induced by varied soil and environmental factors.

Grazing reduced greenhouse gas fluxes in Inner Mongolia grasslands: A meta-analysis

Response of soil greenhouse gas fluxes to warming: A global meta‐analysis of field studies

Responses of soil greenhouse gas fluxes to land management in forests and grasslands: A global meta-analysis.

Effect of land use management on greenhouse gas emissions from water stable aggregates

PDF HTML阅读 XML下载 导出引用 引用提醒 施氮对桉树人工林生长季土壤温室气体通量的影响 DOI: 10.5846/stxb201401120086 作者: 作者单位: 中国科学院生态环境研究中心城市与区域生态国家重点实验室;中国科学院大学,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室;河北师范大学生命科学学院,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(31170425);中国科学院知识创新工程重要方向项目(KZCX2-EW-QN406);中国科学院战略性先导科技专项子课题(XDA05060102) Effects of nitrogen application on soil greenhouse gas fluxes in a Eucalyptus plantation during the growing season Author: Affiliation: State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences;University of Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences;College of Life Science, Hebei Normal University, Shijiazhuang,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:施肥是维持短期轮伐人工林生产量的重要手段,为了提高肥料利用效率,缓释氮肥逐渐成为广泛采用的氮肥种类。评估缓释肥施用对人工林生长季土壤温室气体通量的影响对于全面评估人工林施肥的环境效应具有重要意义。以我国南方广泛种植的桉树林为对象,采用野外控制实验研究了4种施氮处理(对照CK:0 kg/hm2;低氮L:84.2 kg/hm2;中氮M:166.8 kg/hm2;高氮H:333.7 kg/hm2)对土壤-大气界面3种温室气体(CO2、N2O和CH4)通量的影响,结果表明:(1)4种施氮水平下CO2排放通量、N2O排放通量和CH4吸收通量分别为276.84-342.84 mg m-2 h-1、17.64-375.34 μg m-2 h-1和29.65-39.70 μg m-2 h-1;施氮显著促进了N2O的排放(P <0.01),高氮处理显著增加CO2排放和显著减少CH4吸收(P <0.05),且CO2排放通量与CH4吸收通量随着施氮量的增加分别呈现增加和减少的趋势;(2)生长季CO2和N2O排放呈现显著正相关(P <0.01),CO2排放和CH4吸收呈现显著负相关(P <0.05),N2O排放和CH4吸收呈现显著负相关(P <0.01);(3)土壤温度和土壤水分是影响CO2、N2O排放通量和CH4吸收通量的主要环境因素。结果表明:施用缓释肥显著增加了桉树林生长季土壤N2O排放量,且高氮处理还显著促进CO2排放和显著抑制CH4吸收,上述研究结果可为人工林缓释肥对土壤温室气体通量评估提供参数。 Abstract:Fertilization plays a vital role in maintaining the productivity of short-rotation plantations. Eucalyptus plantations are one of the fast-growing and high-yield plantations around the world and are numerous in south China. In order to improve nitrogen use efficiency, slow-release nitrogen fertilizers are being widely adopted. However, few studies have been done to assess the effect of slow-release fertilizer on the soil-atmosphere exchange of greenhouse gases (GHGs), such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). To clarify temporal changes of soil GHGs fluxes following slow-release N fertilizer application, field control trials with four levels of N application (Control: 0 kg/hm2; Low N: 84.2 kg/hm2; Medium N: 166.8 kg/hm2; High N: 333.7 kg/hm2) were initiated in a Eucalyptus plantation in Guangxi, southern China. At the beginning of growing season, the nitrogen fertilizer, urea formaldehyde (a kind of slow-release fertilizer), was applied according to the local fertilization practice (once a year). Static chamber and gas chromatography techniques were used to quantify soil GHGs exchange monthly during the study period from May to November 2013. Environmental factors, such as soil temperature at 5 cm depth and soil water content at 10 cm depth, were synchronously monitored while the GHGs were collected. Before N application, no significant differences were observed for soil GHGs fluxes in all N application treatments. The results showed that (1) CO2 emission fluxes, N2O emission fluxes, and CH4 absorption fluxes under four levels of nitrogen application were 276.84-342.84 mg m-2 h-1, 17.64-375.34 μg m-2 h-1 and 29.65-39.70 μg m-2 h-1, respectively. Fertilization resulted in a remarkable but short increase in soil respiration over the first 2 to 3 months during the observation period, and the differences in soil respiration between the High N treatment and the control treatment were significant. Nitrogen application significantly increased the N2O emission and persisted for 5 to 6 months after fertilization. Each N application treatment had a significant effect on N2O emission. Moreover, High N treatment had a significantly negative effect on CH4 oxidation. (2) During the growing season, CO2 emission had a significantly positive correlation with N2O emission (P < 0.01), and CH4 uptake had a significantly negative correlation with both CO2 emission and N2O emission (P < 0.05 and P < 0.01, respectively). With the increase of the amount of fertilizer, the CO2 emission fluxes increased and CH4 oxidation fluxes decreased,respectively. (3) Soil temperature and soil water content were the main factors influencing soil respiration, N2O emission, and CH4 oxidation. Soil temperature and soil water content had significantly positive effects on CO2 and N2O emission fluxes, and soil temperature had significantly negative effects on CH4 absorption fluxes. In conclusion, during the growing season in a Eucalyptus plantation, slow-release nitrogen application not only significantly in creases soil N2O emission, but also had significant effects on CO2 emission and CH4 oxidation after High N treatment. Our results can provide parameters for accurately assessing the effects of slow-release nitrogen application on GHGs fluxes in a Eucalyptus plantation. 参考文献 相似文献 引证文献

Impact of warming and nitrogen addition on soil greenhouse gas fluxes: A global perspective

The compaction of forest soils can deteriorate soil aeration, leading to decreased CH4 uptake and increased N2O efflux. Black alder (Alnus glutinosa) may accelerate soil structure regeneration as it can grow roots under anaerobic soil conditions. However, symbiotic nitrogen fixation by alder can have undesirable side-effects on greenhouse gas (GHG) fluxes. In this study, we evaluated the possible trade-off between alder-mediated structure recovery and GHG emissions. We compared two directly adjacent 15-year old beech (Fagus sylvatica) and alder stands (loamy texture, pH 5–6), including old planted skid trails. The last soil trafficking on the skid trails took place in 1999. GHG fluxes were measured over one year. Undisturbed plots with beech had a moderately higher total porosity and were lower in soil moisture and soil organic carbon than undisturbed alder plots. No differences in mineral nitrogen were found. N2O emissions in the undisturbed beech stand were 0.4 kg ha−1 y−1 and 3.1 kg ha−1 y−1 in the undisturbed alder stand. CH4 uptake was 4.0 kg ha−1 y−1 and 1.5 kg ha−1 y−1 under beech and alder, respectively. On the beech planted skid trail, topsoil compaction was still evident by reduced macro porosity and soil aeration; on the alder planted skid trail, soil structure of the uppermost soil layer was completely recovered. Skid trail N2O fluxes under beech were five times higher and CH4 oxidation was 0.6 times lower compared to the adjacent undisturbed beech stand. Under alder, no skid-trail-effects on GHG fluxes were evident. Multiple regression modelling revealed that N2O and CH4 emissions were mainly governed by soil aeration and soil temperature. Compared to beech, alder considerably increased net fluxes of GHG on undisturbed plots. However, for skid trails we suggest that black alder improves soil structure without deterioration of the stand’s greenhouse gas balance, when planted only on the compacted areas.

Topography-related controls on N2O emission and CH4 uptake in a tropical rainforest catchment

BackgroundChanges in soil greenhouse gas (GHG) fluxes caused by nitrogen (N) addition are considered as the key factors contributing to global climate change (global warming and altered precipitation regimes), which in turn alters the feedback between N addition and soil GHG fluxes. However, the effects of N addition on soil GHG emissions under climate change are highly variable and context-dependent, so that further syntheses are required. Here, a meta-analysis of the interactive effects of N addition and climate change (warming and altered precipitation) on the fluxes of three main soil GHGs [carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)] was conducted by synthesizing 2103 observations retrieved from 57 peer-reviewed articles on multiple terrestrial ecosystems globally.ResultsThe interactive effects of N addition and climate change on GHG fluxes were generally additive. The combination of N addition and warming or altered precipitation increased N2O emissions significantly while it had minimal effects on CO2 emissions and CH4 uptake, and the effects on CH4 emissions could not be evaluated. Moreover, the magnitude of the combined effects did not differ significantly from the effects of N addition alone. Apparently, the combined effects on CO2 and CH4 varied among ecosystem types due to differences in soil moisture, which was in contrast to the soil N2O emission responses. The soil GHG flux responses to combined N addition and climate change also varied among different climatic conditions and experimental methods.ConclusionOverall, our findings indicate that the effects of N addition and climate change on soil GHG fluxes were relatively independent, i.e. combined effects of N addition and climate change were equal to or not significantly different from the sum of their respective individual effects. The effects of N addition on soil GHG fluxes influence the feedbacks between climate change and soil GHG fluxes.

Previous research has investigated the effects of different grazing intensities on soil surface greenhouse gas (GHG) emissions, whereas the dynamics of GHG production and consumption within the soil profile and their responses to different grazing intensities remain unclear. In this study, a field experiment was conducted in 2017 and 2018 to evaluate the influences of three grazing intensities (none, light, heavy) on both soil surface and subsurface (0–60 cm) GHG fluxes estimated using chamber-based and concentration gradient-based methods, respectively. Results showed that soil at lower depths (30–60 cm) had higher carbon dioxide (CO2) concentrations but lower methane (CH4) concentrations. In contrast, soil profile nitrous oxide (N2O) concentration did not vary with depth, possibly resulting from the relatively low soil moisture in the semiarid grassland, which increased air diffusivity across the soil profile. Grassland soil acted as a source of N2O and CO2 production but as a sink for CH4 uptake, which mainly attributed to the topsoil (0–5 cm for N2O, and 0–15 cm for CO2 and CH4). The estimated soil surface GHG flux rates based on the concentration gradient method did not align well with those directly measured using the chamber method. Furthermore, the cumulative N2O flux over the study period was significantly higher for the concentration gradient method than the chamber method, whereas a contrary result was observed for CO2 emission and CH4 uptake. This study confirms that the grassland soil serves as an important source of CO2 and N2O emissions and a weak sink for CH4 consumption, playing a crucial role in the annual carbon budget of livestock-grazed grassland ecosystems.

Effects of warming and nitrogen fertilization on GHG flux in the permafrost region of an alpine meadow

Agroforestry systems are widely applied in China and have both economic and ecological benefits. However, relatively few prior studies have investigated the relative ecological benefits of various agroforestry systems. In the present study, the static chamber method, quantitative polymerase chain reaction, high throughput sequencing were used to establish the differences in greenhouse gases (GHGs) fluxes and explore the bacterial and fungal populations affecting GHGs fluxes under different agroforestry systems, including pure Moso bamboo forest (CK), bamboo + Bletilla striata (BB), bamboo + Dictyophora indusiata (BD), and bamboo + chickens (BC). The highest cumulative CH4 uptake and N2O emission in spring occurred in BB while the highest cumulative CO2 emission and global warming potential (GWP) in spring occurred in BC. The Methylomirabilaceae were the key methanotrophs influencing the comparative differences in NO3 −associated CH4 uptake among the various agroforestry systems. N2O emission was associated with pH, and nitrifiers such as the ammonia-oxidizing archaea and bacteria (Nitrospiraceae and Nitrosomonadaceae) rather than denitrifiers may be the key microbes affecting N2O emission in different agroforestry systems. The bacteria Actinobacteriota and Fibrobacteres and the fungi Ascomycetes and Basidiomycota were the primary microbial taxa influencing CO2 emission. The lignin-decomposing Basidiomycota played more important roles in CO2 emission than the cellulose-decomposing fungi and bacteria under the various agroforestry systems. CO2 emission was positively correlated with NO3 − in the bacterial community and was negatively correlated with NO3 − in the fungal community, implying two C decomposition mechanisms caused by denitrification dominated in bacteria and those caused by microbial nitrogen mining dominated in fungi. The foregoing results suggested that bamboo + B. striata had comparatively higher ecological benefits as it is associated with low GWP and external C fixation. The present study provided valuable information for screening bamboo-based agroforestry systems with high ecological benefits. It also elucidated the microbial mechanism explaining the observed differences in GHGs fluxes between the various agroforestry systems.

Impacts of forest management on greenhouse gas (GHG) fluxes have not been well documented. Therefore, we examined GHG fluxes from Pacific Northwest Douglas‐fir [ Pseudotsuga menziesii (Mirb.) Franco] forest soils as affected by fertilizer type (no fertilizer or 224 kg N ha −1 as either urea or coated urea fertilizer [CUF]), stand age (younger vs. older), and parent material (sedimentary vs. volcanic). Following spring fertilization, soil GHG fluxes were measured for four seasons. Daily N 2 O (0.17 mg N 2 O‐N m −2 d −1 ) and CO 2 (2.32 g CO 2 –C m −2 d −1 ) emissions increased with urea application compared with the control (N 2 O: 0.09 mg N 2 O‐N m −2 d −1 ; CO 2 : 1.87 g CO 2 –C m −2 d −1 ); however, CUF did not. Daily CH 4 uptake was inhibited with both urea (0.95 mg CH 4 –C m −2 d −1 ) and CUF (0.91 mg CH 4 –C m −2 d −1 ) compared with the control (1.12 mg CH 4 –C m −2 d −1 ). Nitrous oxide fluxes and CH 4 uptake were greater in older stands. Sedimentary parent material emitted more N 2 O and inhibited CH 4 uptake relative to volcanic parent material. Urea increased annual N 2 O flux by 0.48 kg N 2 O‐N ha −1 yr −1 and CO 2 flux by 1.6 Mg CO 2 –C ha −1 yr −1 and decreased CH 4 uptake by 0.7 kg CH 4 –C ha −1 yr −1 . The global‐warming potential (GWP) after urea and CUF application was 1.7 and 1.1 Mg CO 2 equivalent ha −1 yr −1 , respectively, greater than the unfertilized control for the first year after fertilization. Nitrogen fertilization had little or no effect on GWP when considered the added growth benefit from fertilization.