Changes In Soil Respiration Rates Research Articles

Responses of moss biocrusts respiration to simulated grazing and trampling disturbance with different intensities on the fenced forestland of Loess Plateau, China

The changes in soil properties caused by grazing and trampling are important reasons for the changes in soil respiration rates, carbon fixation, and emission. However, the effects of different intensities of grazing and trampling on biocrusts respiration rate are unclear. In this study, we simulated grazing and trampling disturbances of 10%, 30%, 50%, and 70% intensity on moss biocrusts developed in aeolian sandy soil on Loess Plateau, with undisturbed moss biocrusts serving as a control. The changes in respiration rate of moss biocrusts were monitored continuously, and its responses to different disturbance intensities were analyzed. The results showed that: 1) moderate disturbance stimulated moss biocrusts respiration, while heavy disturbance inhibited that. The respiration rate of moss biocrusts was increased by 41.1% and 22.2% at disturbance intensities of 10% and 30%, but was decreased by 8.9% and 15.3% at disturbance intensities of 50% and 70%, respectively. 2) The trampling disturbance significantly changed soil temperature but did not affect soil water content. In comparison to the control, soil temperature of biocrusts was decreased by 0.4 and 1.2 ℃ at disturbance intensities of 10% and 30%, but it was increased by 1.1 and 1.0 ℃ at disturbance intensities of 50% and 70%, respectively. 3) The respiration rate of moss biocrusts showed a significant exponential relationship with soil temperature and a linear positive relationship with soil water content under different disturbance intensities. However, the correlation between respiration rate of moss biocrust and the characteristics of moss biocrust was not significant. Soil temperature and water content could explain 70.6%-96.3% and 49.1%-70.0% of the total variation of respiration rate of moss biocrusts, respectively. In conclusion, grazing and trampling affected the respiration rate of moss biocrusts, with short-term moderate grazing and trampling would have positive effects. On the other hand, excessive grazing and trampling would reduce the rate of moss biocrust respiration. As a result, future studies on soil carbon balance of the Loess Plateau should consider the effects of grazing and trampling on biocrust respiration.

The Effects of Aerated Irrigation on Soil Respiration and the Yield of the Maize Root Zone

To investigate the effect of aerated irrigation on the soil environment and yield in the root zone of maize, and to provide a basis for the extension of aerated irrigation, a 2-year experiment (2020–2021) was conducted at the Zhanjiang National Soil Quality Observation Experiment Station, with two experimental observations per year (spring-summer and fall-winter) to investigate the effects of aerated irrigation (AI) and non-aerated irrigation (CK) on soil respiration rate, soil temperature, water content, oxygen content, soil bacterial biomass and root biomass. We used partial least square regression analysis (PLSR) to establish the regression equations of soil respiration rate, soil temperature, water content, oxygen content, soil bacterial biomass and root biomass under the two treatments, and the screening of the main soil environmental factors affecting changes in soil respiration rate under aerated irrigation technology. The results showed that, compared with CK, the AI treatment significantly increased the soil respiration rate and soil oxygen content (15.38~17.87% and 18.94~25.17%, respectively), as well as the root biomass and soil bacterial biomass (14.99~19.09% and 35.10~45.59%, respectively), and reduced the soil water content by 5.33~12.71% (p < 0.05). The effects of different treatments on soil temperature were not significant. The mean fruit yield with AI treatment was also 7.16~20.51% higher (p < 0.05) than that with CK, and the stem thickness and leaf area of maize plants were significantly increased (9.31~17.06% and 8.68~15.20%, respectively (p < 0.05)). The regression fitting results showed that the soil respiration rate is quadratic polynomial negatively correlated with soil temperature, water content and soil oxygen, and the power function is positively correlated with root biomass and bacterial biomass under the two treatments. The variable importance for projection (VIP) values of the PLSR model showed a soil temperature VIP = 1.51, soil oxygen content VIP = 1.42 and root biomass VIP = 1.40, demonstrating that aerated irrigation technology can drive soil respiration rate by changing soil oxygen content and root biomass. Furthermore, the improvements in soil aeration conditions and respiration with AI appeared to facilitate the improvement in fruit yields, which also suggests the economic benefits of AI.

Bacteria are more sensitive than fungi to moisture in eroded soil by natural grass vegetation restoration on the Loess Plateau

Community composition and respiration rates of bacterial and fungal communities from grass-covered eroded soils of the Loess Plateau responded differently to constant and increasing soil moisture (SM) regimes. The soils were incubated with SM contents of 5%, 30%, and 45% and with wetting processes in the SM ranges from 5% to 30% (5–30%), from 5% to 30% to 45% (5–30–45%) and from 30% to 45% (30–45%); high-throughput sequencing and co-occurrence network analyses were applied to investigate the different responses of the bacterial and fungal communities to changed SM. Our results showed that bacteria were more sensitive than fungi to changes in SM. The dominant bacterial communities converted from Actinobacterial to Proteobacteria and Acidobacteria in 5–30–45% wetting procedure. Firmicutes preferred wet condition and exhibited slow resilience. However, no difference was observed for the Chloroflexi communities across any sample. The obvious difference in fungal composition was found between the wetting process of 5–30–45% and constant 45% SM. During the 5–30–45% procedure, the respiration rate was higher than that at 30–45% procedure after incubation for 24 days. The respiration rate in 5–30% procedure was lower than that of 5–30–45% process after incubation for 16–27 days. The larger effects on bacterial response than on fungi were verified in network analysis. Multiple stepwise regression analysis showed that 84.40% of the variation in bacterial richness and diversity as well as fungal diversity can be explained by changes in soil respiration rate in response to wetting procedure. Understanding the response of difference between bacterial and fungal community composition, phylum-levels networks and respiration rate to changes in SM is essential for the management of plant-soil-water relationship in the ecosystem after natural vegetation restoration on the Loess Plateau.

The Obscuring Effects of Calcite Dissolution and Formation on Quantifying Soil Respiration

AbstractDrylands occupy nearly 40% of the land surface and comprise a globally significant carbon reservoir. Dryland‐atmosphere carbon exchange may regulate interannual variability in atmospheric CO2. Quantifying soil respiration rates in these environments is often complicated by the presence of calcium carbonates, which are a common feature of dryland soils. We show with high‐precision O2 measurements in a laboratory potted soil experiment that respiration rates after watering were similar in control and carbonate treatment soils. However, CO2 concentrations were up to 72% lower in the carbonate treatment soil because CO2 was initially consumed during calcite dissolution. Subsequently, CO2 concentrations were over 166% greater in the carbonate treatment soil as respiration slowed and calcite precipitated, releasing CO2. Elevated δ13C values of soil CO2 (>6‰ higher in the treatment than control) confirm that observed differences were due to calcite dissolution. These findings demonstrate that calcite dissolution and precipitation can occur rapidly enough to affect soil gas compositions and that changes in soil CO2 are not always directly related to changes in soil respiration rates. Studies of local soil respiration rates and carbon exchange are likely to be influenced by dissolution and precipitation of calcium carbonates in soils. We estimate that one fifth of global soil respiration occurs in soils that contain some amount of soil carbonate, underscoring the need to account for its obscuring effects when trying to quantify soil respiration and net ecosystem exchange on a regional or global scale.

Effects of nitrogen deposition and biochar amendment on soil respiration in a Torreya grandis orchard

Torreya grandis is an important economic nut tree species in southeastern China, but there is little information about its CO2 efflux under increasing atmospheric nitrogen (N) deposition. There are few studies that assess the response of soil respiration to biochar applications in orchard soils under N deposition conditions. We investigated changes in soil respiration rate and other environmental factors under a factorial combination of biochar amendment (BC0: 0 t ha−1, BC1: 20 t ha−1, BC2: 40 t ha−1) and simulated additional N deposition (N0: 0 kg N ha−1 yr−1, NL: 30 kg N ha−1 yr−1 and NH: 60 kg N ha−1 yr−1) treatments over three years (2016–2018). Soil respiration rate showed significant seasonal changes, with the highest rates occurring in summer and the lowest occurring in winter. The annual CO2 emission amount of the control was 3.1 ± 0.03 kg CO2 m−2. Nitrogen deposition significantly increased soil respiration, but the positive effects of high-N treatment decreased over time. Meanwhile, N deposition significantly decreased both the soil temperature sensitivity (Q10-soil) and air temperature sensitivity (Q10-air) of soil respiration. Biochar amendment significantly increased soil respiration in the first and third years. However, only BC2 reduced Q10-soil and Q10-air. The effects of biochar amendment on soil respiration varied with the level of N deposition. Three-factor analysis of variance showed that N deposition, biochar amendment, and time all had significant effects on soil respiration. Our results indicate that biochar could not effectively inhibit the promotion effect of N deposition on soil respiration in T. grandis orchard but may reduce soil carbon emission caused by future climate warming.

Temperature sensitivity of soil respiration to nitrogen and phosphorous fertilization: Does soil initial fertility matter?

Temperature sensitivity of soil respiration (Q10) is an important parameter when modeling the effects of global warming on terrestrial ecosystem carbon release. Widely applied chemical fertilizers can significantly affect soil productivity and carbon cycling in agroecosystems. However, little is known about how Q10 responds to chemical fertilization under different levels of initial soil fertility. On the Chinese Loess Plateau, changes in soil respiration rates and Q10 were investigated in soils of two fertility levels: low fertility (L) and high fertility (H). For each soil fertility level, there was one control plot and one chemical fertilized plot (+NP), which in total formed four treatments: L, L + NP, H and H + NP. All the treatments were replicated for three times on a continuous winter wheat cropping system. Respiration rates of surface soil in each treatment were in situ monitored from October 2010 through September 2015. Our results showed that after NP fertilization, soil respiration rates were increased by 46% in low fertility soil, yet only by 14% in high fertility soil (P < 0.05). The Q10 after NP fertilization was significantly decreased by 6.9% in low fertility soil, but was unchanged in the high fertility soil. The Q10 variation might be attributed to the different response of microbial respiration Q10 in the two soils. The decreased Q10 with NP fertilization in the low fertility soil was possibly due to N-induced increase of substrate quality for soil microbes and increased activities of both cellobiohydrolase and polyphenol oxidase. In the high fertility soil, the unchanged Q10 with NP fertilization may be the integrated result of less affected substrate quality and neutral response of polyphenol oxidase activity. Overall, our results suggested that the effects of NP fertilization on soil respiration and its temperature sensitivity varied with soil initial fertility levels, and therefore must be properly accounted for when estimating potential effects of local agricultural management to regional agroecosystems under future climate conditions.

Spatial and seasonal variation in soil respiration along a slope in a rubber plantation and a natural forest in Xishuangbanna, Southwest China

Soil respiration is a key component of the global carbon cycle, and even small changes in soil respiration rates could result in significant changes in atmospheric CO2 levels. The conversion of tropical forests to rubber plantations in SE Asia is increasingly common, and there is a need to understand the impacts of this land-use change on soil respiration in order to revise CO2 budget calculations. This study focused on the spatial variability of soil respiration along a slope in a natural tropical rainforest and a terraced rubber plantation in Xishuangbanna, Southwest (SW) China. In each land-use type, we inserted 105 collars for soil respiration measurements. Research was conducted over one year in Xishuangbanna during May, June, July and October 2015 (wet season) and January and March 2016 (dry season). The mean annual soil respiration rate was 30% higher in natural forest than in rubber plantation and mean fluxes in the wet and dry season were 15.1 and 9.5 Mg C ha-1 yr-1 in natural forest and 11.7 and 5.7 Mg C ha-1 yr-1 in rubber plantation. Using a linear mixed effects model to assess the effect of changes in soil temperature and moisture on soil respiration, we found that soil temperature was the main driver of variation in soil respiration, explaining 48% of its seasonal variation in rubber plantation and 30% in natural forest. After including soil moisture, the model explained 70% of the variation in soil respiration in natural forest and 76% in rubber plantation. In the natural forest slope position had a significant effect on soil respiration, and soil temperature and soil moisture gradients only partly explained this correlation. In contrast, soil respiration in rubber plantation was not affected by slope position, which may be due to the terrace structure that resulted in more homogeneous environmental conditions along the slope. Further research is needed to determine whether or not these findings hold true at a landscape level.

Response of Soil Respiration and Heterotrophic Respiration to Returning of Straw and Biochar in Rape-Maize Rotation Systems

Soil respiration has become the main way of farmland ecosystem carbon emissions. Soil respiration and its responses to soil moisture and soil temperature under straw and biochar returning were investigated. Combined soil CO2 fluxes system(ACE-002/OPZ/SC) with the method of root exclusion, this study conducted a long-term field experiment in the national monitor station of soil fertility and fertilizer efficiency of purple soils. The total soil respiration and heterotrophic respiration rate and the soil hydrothermal factors were measured during the growth period of rape and maize in rape-maize rotation systems, and the difference between total soil respiration and heterotrophic respiration was calculated as the contribution of root respiration to soil respiration. There were five treatments including CK(no organic material), CS(straw), CSD(straw+microorganism), BC(biochar), CSBC(50%straw+50%biochar), which were replicated three times. The results showed that straw and biochar returning significantly affected the seasonal variations and the peak of soil respiration. In addition to BC treatment, other treatments promoted soil respiration and cumulative emissions of soil CO2. Soil respiration rate was significantly different under different treatments, the changes in soil respiration rates showed a single peak curve under all treatments, the seasonal variations in soil respiration rates under rape was 0.12-2.29 μmol·(m2·s)-1, displaying an order of CS > CSD > CSBC > CK > BC. Soil respiration was pretty complex in maize season, the seasonal variation in soil respiration rates under rape was 1.02-15.32 μmol·(m2·s)-1, displaying an order of CSD > CS > CSBC > CK > BC, the changes in soil respiration rate presented a double peak curve under CS and CSD and CSBC treatments and a single peak curve under BC and CK treatments. Heterotrophic respiration could explain 86.50%-93.94% of seasonal variations in the soil total respiration, and the contribution of root respiration(26.49%-32.86%) was significantly lower than CK treatment(53.65%).Straw and biochar returning did not change soil temperature and soil moisture. Soil temperature at 5 cm depth had significant effects on the change dynamics of soil respiration rates, but soil moisture did not. Soil temperature at 5 cm depth could explain 82%-94% of the variations in soil respiration. The values of temperature sensitivity coefficient changed from 3.28 to 4.47. Compared with CK treatment, Q10 of CS, CSD and CSBC decreased by 26.62%, 18.12%, 20.58%, respectively, while BC increased by 12.53%. There was no synergistic effect between soil temperature and soil moisture on soil respiration, the dynamic changes of soil respiration rate could be simulated by single factor index function of soil temperature. Overall, soil respiration was significantly promoted by returning of straw, straw+microorganism, straw+biochar, while it was inhibited by returning of biochar.

黄土和风沙土藓结皮土壤呼吸对模拟降雨的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土和风沙土藓结皮土壤呼吸对模拟降雨的响应 DOI: 10.5846/stxb201604050611 作者: 作者单位: 中国农业大学,沈阳农业大学水利学院;沈阳农业大学水利学院,沈阳农业大学水利学院;沈阳农业大学水利学院,中国农业大学资源与环境学院,沈阳农业大学水利学院;沈阳农业大学水利学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41671221）；中央高校基本科研业务费专项资金（2016QC007，2016QC063） Responses of soil respiration of moss-dominated biological soil crusts to simulated rainfall on loess and aeolian soils in the Loess Plateau of China Author: Affiliation: China Agricultural University,,,, 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:生物结皮土壤呼吸是干旱和半干旱生态系统碳循环的重要组成部分，但目前其对降雨的响应规律尚不明确。针对黄土高原黄土和风沙土上发育的藓结皮，分别进行2、4、6、10、20、30、40 mm的模拟降雨，并使用便携式土壤碳通量分析仪测定雨前和雨后藓结皮的呼吸速率，对比分析降雨量对藓结皮呼吸速率的影响；同时，在40 mm降雨后的0-24 h连续测定藓结皮的呼吸速率变化，分析藓结皮呼吸速率随雨后历时的变化规律。结果显示，7种降雨量后两种土壤上藓结皮的呼吸速率均显著升高，黄土上藓结皮呼吸速度的增幅为2.89-6.38倍，风沙土上藓结皮呼吸速率的增幅为0.73-4.38倍。0-6 mm降雨中，两种土壤上藓结皮的呼吸速率均随降雨量增加而迅速升高，二者成显著线性正相关关系；6-40 mm降雨中，黄土上藓结皮的呼吸速率随降雨量增加而缓慢升高，但风沙土上藓结皮的呼吸速率随降雨量增加而快速降低。两种土壤上藓结皮的呼吸速率随雨后历时表现出相似的变化规律，即雨后迅速升高、之后逐渐降低，并在24 h左右回归到雨前水平；但黄土上藓结皮的呼吸速率在雨后即刻达到峰值，而风沙土上藓结皮的呼吸速率在雨后30 min左右方达到峰值。黄土上藓结皮的呼吸速率一致高于风沙土上的藓结皮，前者在不同降雨量和雨后历时中平均比后者高150.0%和59.6%。此外，藓结皮呼吸速率与表层土壤含水量存有显著相关关系，在含水量较低（小于约4%）时二者显著正相关，在含水量较高（大于约4%）时二者对于黄土上藓结皮为正相关、对于风沙土上藓结皮为负相关。研究表明，黄土高原藓结皮土壤呼吸对降雨响应快速而直接，但其响应规律对于黄土和风沙土上的藓结皮是不同的，总体而言黄土上藓结皮对降雨的响应更为持久有效。 Abstract:The respiration of biological soil crusts is an important contribution to carbon cycling in arid and semiarid ecosystems, but soil crust responses to rainfall have not yet been fully investigated. In this study, we conducted a series of simulated rainfall experiments with different rainfall intensities (2, 4, 6, 10, 20, 30, 40 mm) for moss-dominated biological soil crusts (hereafter moss crusts) on loess and aeolian soils in the Loess Plateau of China. The soil respiration rates of the moss crusts were measured before and after the simulated rainfall with a portable CO2/H2O Analyzer (LI-COR LI-840). Afterwards, the soil respiration rates of the moss crusts with 40 mm rainfall were continually measured at 0-24 h (0, 0.25, 0.5, 1, 2, 12, 24 h) after the rainfall. Finally, the soil respiration responses of the moss crusts to rainfall were determined from rainfall intensity and time after rainfall. The following results were obtained in this study. (1) The soil respiration rates of the moss crusts were consistently and significantly increased after the simulated rainfall. Compared with the soil respiration rates before the rainfall, the soil respiration rates of the moss crusts on loess soil were increased by 2.89-6.38 times, whereas the soil respiration rates of the moss crusts on aeolian soil were increased by 0.73-4.38 times. (2) In the 0-6 mm rainfall experiments, the soil respiration rates of the moss crusts, both on loess and aeolian soils, linearly increased with increasing rainfall. Correspondingly, in the 6-40 mm rainfall experiments, the soil respiration rates of the moss crusts on loess soil slightly increased with increasing rainfall, whereas the soil respiration rates of the moss crusts on aeolian soil sharply decreased with increasing rainfall. (3) Changes in soil respiration rates during 0-24 h after the rainfall event were similar for the moss crusts on loess and aeolian soils; they both rapidly increased immediately after the rainfall and then gradually decreased to their original levels before the rainfall during 0-24 h. The soil respiration rates of the moss crusts on loess soil reached their maximum values almost immediately after the rainfall event; however, the soil respiration rates of the moss crusts on aeolian soil reached their maximum values approximately 30 min after the rainfall event. (4) The soil respiration rates of the moss crusts on loess soil were 150.0% and 59.6% higher than that on aeolian soil under different rainfall intensities and at different times after the rainfall, respectively. (5) The soil respiration rates of the moss crusts were significantly positively correlated with surface soil water content (0-5 cm) when soil was dry ( < 4%). However, when soil was wet ( > 4%), the soil respiration rates of the moss crusts on loess soil were positively correlated with surface soil water content, but that on aeolian soil were negatively correlated with surface soil water content. From this study, we concluded that the soil respiration of the moss crusts on the Loess Plateau of China responded directly and sensitively to rainfall events, but the responses were different for the moss crusts on loess and aeolian soils. It appeared that the moss crusts on loess soil responded more efficiently to rainfall compared with that on aeolian soil. 参考文献 相似文献 引证文献

Medium-term dynamics of soil respiration in a Mediterranean mountain ecosystem: The effects of burn severity, post-fire burnt-wood management, and slope-aspect

The interaction between burn severity and subsequent post-fire logging practices may exert a direct effect on soil respiration (SR) in recently burnt stands. This effect is associated with the modification of microclimatic conditions, soil carbon inputs, and the decay rates of woody detritus. In addition, slope aspect may determine SR rates by modifying the microclimatic conditions in post-fire environments. In this study, we assessed the changes in SR rates during the early (1.5–4 years) post-fire stages in a burnt and logged Spanish Black pine forest along a burn-severity gradient: (1) an unburnt site (UB), (2) a low burn-severity site (LS), (3) a south-facing high burn-severity site (HSS), and (4) a north-facing high burn-severity site (HSN). Monthly or fortnightly manual SR measurements (SRM) were taken at midday between 2011 and 2013. In addition, we also quantified the litter layer and fine-root biomass at each site. Multiple regression models combining abiotic (both soil temperature and water content, Ts and SWC, respectively) and biotic (tree diameter at breast height, 1.30m) were used for midday SRM modelling. For temporal and spatial scaling of SR at the stand-level, we performed 8 seasonal campaigns of automated SR measurements (SRA) along 4 linear gradients from trees or stumps to inter-tree/stump gaps with the aim of: (1) determining the main soil-surface areas (soil close to trees or stumps and/or soil away from them; SC and SA soil, respectively) and (2) correcting the modelled daily daytime and night-time SRM rates.Our results showed a significant reduction in fine-root biomass at the burnt sites, although over the 3-year study period this figure did tend to increase. The amount of litter was similar between sites suggesting that logging practices may influence the amount of post-fire detritus. We also found that the spatial variability in soil microclimate was high and was primarily influenced by post-fire canopy cover as well as the slope aspect. SR rates significantly varied between years and were higher in SA soil compared to SC soil at all the sites we studied. Higher SR rates were observed close to stumps compared to those close to trees, highlighting the large relative contribution of this decaying debris to post-fire SR rates. In the medium-term, the combined effect of fire and logging practices may lead to an increase in the annual stand-level SR at high burn-severity sites after fire. In contrast, the interaction between fire and logging practices did not alter the post-fire SR rates at the LS site during the same time period. Our results also underscored the dependence of post-fire SR rates on the slope aspects within the high-severity fire area. Finally, this study showed that our integrated spatio-temporal approach could be a useful tool for obtaining more accurate SR estimates for short-, medium- and long-term stand-scale carbon cycling studies in burnt areas.

Interdependencies between temperature and moisture sensitivities of CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emissions in European land ecosystems

Abstract. Soil respiration is one of the largest terrestrial fluxes of carbon dioxide (CO2) to the atmosphere. Hence, small changes in soil respiration rates could have large effects on atmospheric CO2. In order to assess CO2 emissions from diverse European soils with different land-use types and climate (soil moisture and temperature), we conducted a laboratory incubation experiment. Emission measurements of CO2 under controlled conditions were conducted using soil monoliths of nine sites from a European flux network (ÉCLAIRE). The sites are located all over Europe – from the United Kingdom in the west to Ukraine in the east, and from Italy in the south to Finland in the north – and can be separated according to four land-use types (forests, grasslands, arable lands and one peatland). Intact soil cores were incubated in the laboratory in a two-way factorial design, with temperature (5, 10, 15, 20 and 25 °C) and water-filled pore space (WFPS; 5, 20, 40, 60 and 80 %) as the independent variables, while CO2 flux was the response variable. The latter was measured with an automated laboratory incubation measurement system. Land use generally had a substantial influence on carbon dioxide fluxes, with the order of CO2 emission rates of the different land-use types being grassland &gt; peatland &gt; forest/arable land (P &lt; 0.001). CO2 efflux responded strongly to varying temperature and moisture content with optimum moisture contents for CO2 emissions between 40 and 70 % WFPS and a positive relationship between CO2 emissions and temperature. The relationship between temperature and CO2 emissions could be well described by a Gaussian model. Q10 values ranged between 0.86 and 10.85 and were negatively related to temperature for most of the moisture contents and sites investigated. At higher temperatures the effect of water and temperature on Q10 was very low. In addition, under cold temperatures Q10 varied with moisture contents, indicating a stronger prospective effect of rain events in cold areas on temperature sensitivity. At both coniferous forest sites we found a strong increase in the temperature sensitivity at a moisture range between 20 and 40 % WFPS. We developed a new approach to calculate moisture sensitivity (MS) of CO2 efflux. MS was calculated as the slope of a polynomial function of second degree. Moisture sensitivities were highest under dry and wet conditions. In addition we found a positive relationship between MS of CO2 efflux and temperature for both arable lands.

鼎湖山季风常绿阔叶林土壤微生物量碳和有机碳对模拟酸雨的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 鼎湖山季风常绿阔叶林土壤微生物量碳和有机碳对模拟酸雨的响应 DOI: 10.5846/stxb201404010615 作者: 作者单位: 中国科学院华南植物园,中国科学院华南植物园，华南农业大学,中国科学院华南植物园 广州,中国科学院华南植物园 广州,中国科学院华南植物园 广州,中国科学院华南植物园 广州 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院战略性先导科技专项(XDA05050205) Effects of simulated acid rain on soil microbial biomass carbon and total organic carbon in a monsoon evergreen broadleaved forest at the Dinghushan Nature Reserve Author: Affiliation: South China Botanical Garden,Chinese Academy of Sciences,Guangzhou,,South China Botanical Garden,Chinese Academy of Sciences,Guangzhou,South China Botanical Garden,Chinese Academy of Sciences,Guangzhou,South China Botanical Garden,Chinese Academy of Sciences,Guangzhou,South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 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:在鼎湖山季风常绿阔叶林设置人工模拟酸雨实验,研究土壤总有机碳含量、微生物量碳含量、土壤pH值和土壤呼吸速率几个指标对不同酸处理梯度(CK:pH值4.5的天然湖水;T1:pH值4.0;T2:pH值3.5;T3:pH值3.0)的响应。结果表明,在模拟酸雨的持续作用下,样地土壤酸化有加剧趋势。2011年的6月(CK:(603.76±46.18) mg/kg, T1:(565.41±44.48) mg/kg, T2:(521.58±30.92) mg/kg, T3:(509.49±19.40) mg/kg)、12月(CK:(488.92±22.71) mg/kg, T1:(379.65±49.46) mg/kg, T2:(346.08±33.81) mg/kg, T3:(318.00±52.35) mg/kg)和2012年6月(CK:(540.48±39.11) mg/kg, T1:(492.30±43.15) mg/kg, T2:(489.65±51.39) mg/kg, T3:(428.53±49.66) mg/kg) 3次测定的土壤微生物量碳含量有随模拟酸雨强度增加而显著降低的趋势,高强度的酸处理T3显著低于CK值(P <0.05);土壤呼吸速率在各处理中的响应与土壤微生物量碳含量变化一致。由于旱季和湿季的土壤温湿度相差较大,以上各指标在旱湿两季的差异明显,表现为湿季大于旱季。由于土壤总有机碳含量变化缓慢,其在各酸梯度处理下无显著差异(P >0.05)。以上结果显示,长期酸雨作用使土壤酸化不断加剧,并降低了土壤微生物量碳的含量,抑制了土壤的呼吸速率,有利于土壤碳的累积,但对土壤总有机碳的影响仍需长期实验研究。 Abstract:Soil is not only a pivotal link connecting the atmosphere, hydrosphere, biosphere, and lithosphere, but also an important component of carbon cycling. Meanwhile, soil is the largest carbon pool in terrestrial ecosystems, with approximately 1500 Pg of C stored in the upper meter of soil. Even small changes in forest soil composition can result in significant consequences for carbon cycling. Soil organic carbon is easily affected by environmental conditions and its stability plays an important role in forest soil. Although soil microbial biomass carbon (SMBC), one of the soil organic carbon fractions, accounts for only a small fraction of soil total organic carbon (TOC), it is more sensitive to environmental change and its turnover rate is faster than that of TOC. Consequently, SMBC is considered an early indicator of changes to TOC. Many studies of SMBC and TOC responses to acid rain have been carried out in temperate forests in developed countries such as Europe and the United States. However, very few such studies have been carried out in the subtropical forests of southern China, despite the fact that acid rain is a serious environmental threat in this region. We conducted a field experiment to simulate acid rain (SAR) in a monsoon evergreen broadleaved forest (BF) in the Dinghushan Nature Reserve of southern China. We investigated the responses of SMBC, TOC, soil pH, and soil respiration rate to SAR. The SAR treatments included control (CK, pH ≈ 4.5; natural lake water), T1 (pH=4.0), T2 (pH=3.5), and T3 (pH=3.0). The acidic solutions consisted of H2SO4 and HNO3 (1 : 1 mole ratio) in natural lake water. Results showed that pH values of forest topsoil decreased gradually with the increase of acidity, indicating increased soil acidification due to SAR. This phenomenon was consistent with results from other studies conducted at the Dinghushan Nature Reserve. Concentrations of SMBC in June 2011 ((603.76±46.18) mg/kg for CK, (565.41±44.48) mg/kg for T1, (521.58±30.92) mg/kg for T2, (509.49±19.40) mg/kg for T3), December 2011 ((488.92±22.71) mg/kg for CK, (379.65±49.46) mg/kg for T1, (346.08±33.81) mg/kg for T2, (318.00±52.35) mg/kg for T3), and June 2012 ((540.48±39.11) mg/kg for CK, (492.30±43.15) mg/kg for T1, (489.65±51.39) mg/kg for T2, (428.53±49.66) mg/kg for T3) were depressed by SAR, and SMBC contents in T3 treatments were significantly lower than in CK treatments (P < 0.05) at all three sampling times. Meanwhile, changes in soil respiration rates induced by SAR were similar to those in SMBC. Because soil moisture and temperature differed between seasons, all measured variables (soil pH, SMBC, TOC, and soil respiration rates) were higher in the warm-wet season than in the dry season. Due to its relative stability, concentrations of TOC did not significantly differ among the four treatments (P > 0.05). Our results indicate that long-term acid rain is likely to reduce the SMBC content and respiration rate of forest soil; these changes are expected to have positive effects on the accumulation of soil organic carbon. However, the effects of acid rain on TOC storage need to be further investigated. 参考文献 相似文献 引证文献

浙江古田山亚热带常绿阔叶林不同干扰强度下土壤呼吸的日动态与季节变化

The aims of this study were to investigate the diurnal and seasonal variations in soil respiration in different broad-leaved forest types with different degrees of human disturbance, to identify the major abiotic and biotic factors affecting the daily and seasonal patterns of soil respiration, and to evaluate the effects of different forest management types and human disturbance on soil respiration in subtropical forests. We selected four different 1 hm2 forests with different degrees of human disturbance in Gutianshan, Zhejiang Province: An old-growth forest (OF, almost no human disturbance); two secondary forests (SF1, a secondary forest regrown after clear cutting about 50 years ago, and SF2, a secondary forest regrown after clear cutting about 50 years ago and selective cutting about 20 years ago); and a plantation forest (AF, planted about 20 years ago). We measured the diurnal and seasonal changes in soil respiration rates in each plot every month from May 2011 to July 2012. We also measured soil temperature and water content of the surface soil layer during sampling. The annual means of daily accumulated soil carbon release were 1.48, 1.48, 1.51, and 0.87 g C m-2 d-1 in OF, SF1, SF2, and AF plots, respectively. The soil respiration rate in AF was significantly lower than those in the other three forest types. On the diurnal scale, there were no significant variations in soil respiration rates among the four forest types. Our results indicated that the rate of soil respiration measured any time during the day can be used to predict daily accumulated soil carbon release. Significant positive relationships were found between soil respiration and surface soil temperature ( R 2=0.88-0.94) for all four forest types. There were no significant relationships between soil respiration and soil water content. The Q10 value of OF was significantly higher than those of the other three forest types. The results showed that the soil respiration rate and its sensitivity to temperature were significantly decreased in the plantation with the most intense human disturbance (AF). The soil respiration rates and Q10 values of both SF forests were similar to those of OF forest. Soil temperature was the most important driving factor for soil respiration. Together, our results implied that different degrees of human disturbance had different effects on soil respiration in these forests. This information is important to estimate the role of human interference in regional carbon cycles. Also, the finding that there was no significant variation in the diurnal soil respiration rates is very important for guiding further research on soil respiration in related regions.

Ecosystem photosynthesis regulates soil respiration on a diurnal scale with a short-term time lag in a coastal wetland

Although increasing evidence has provided that soil respiration is strongly related to recent canopy photosynthesis, doubts remain as to the extent to which primary productivity controls soil respiratory and the speed of the link between soil respiration and photosynthesis. Based on the automated measurements of soil respiration and eddy covariance measurements of ecosystem photosynthesis (i.e. gross primary production, GPP) in a coastal wetland, we assessed the speed of link between ecosystem photosynthesis and soil respiration on the diurnal scale, and quantified the control of the ecosystem primary production on diurnal soil respiration. On the diurnal scale, the time of daily peak soil respiration lagged GPP but preceded soil temperature on both sunny and cloudy days. Daytime soil respiration was significantly linearly correlated with GPP with a lag of 1.5 h on sunny days and 1 h on cloudy days, respectively. By taking advantage of the natural shift of sunny and cloudy days without disturbance to the plant-soil system, our results also indicated that the changes in soil temperature and GPP together explained 53% of the changes in daytime soil respiration rates between sunny days and adjacent cloudy days. Under the same soil temperature, changes in soil respiration rates were strongly correlated with changes in GPP between sunny days and adjacent cloudy days. We therefore conclude that recent canopy photosynthesis regulates soil respiration on a diurnal scale with a short-term time lag. Thus, it is necessary to take into account the influence of photosynthesis on soil respiration in order to accurately simulate the magnitude and variation of soil respiration, especially at short and medium temporal scales.

旱作农田不同耕作土壤呼吸及其对水热因子的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 旱作农田不同耕作土壤呼吸及其对水热因子的响应 DOI: 10.5846/stxb201110071460 作者: 作者单位: 中国农业科学院农业资源与农业区划研究所;北京京诚嘉宇环境科技有限公司,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展"973"计划项目(2011CB100501);国家十二五"863"计划项目(2011AA100505);国际合作项目(2010DFA34420) Soil respiration and its responses to soil moisture and temperature under different tillage systems in dryland maize fields Author: Affiliation: Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS 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:为研究旱作农田春玉米生育期不同耕作土壤呼吸变化特征及其对水热因子的响应情况,在山西省寿阳县旱农试验基地采用红外气体分析法测定了传统耕作(CT)、少耕(RT)和免耕(NT)土壤呼吸速率,并同步测定了各土层土壤水分、温度。研究表明:在春玉米生育期内,土壤呼吸速率均呈单峰型变化趋势,峰值出现在8月;传统耕作与少耕土壤呼吸速率变化趋势基本一致,而免耕土壤与前两者相比波动幅度较大;土壤呼吸峰值与水分、温度之间无明显相关,其余时期土壤呼吸与水分、温度因子具有良好的相关性;双因子模型较单因子模型能更好的描述土壤呼吸与水分、温度之间关系,基于水热双因子(10-20 cm)的指数-幂模型能够解释土壤呼吸变化的81%-87%(P<0.01);3种耕作土壤呼吸对水热因子协同影响的敏感性表现为CT>NT>RT。 Abstract:Soil respiration and its responses to soil moisture and soil temperature under different tillage systems during the period of spring maize growth were investigated in Shouyang Dryland Farming Experimental Station, Shanxi Province, China. The soil respiration rate, soil moisture and soil temperature were determined by dynamic chamber-IRGA method, in the maize field, with three tillage practices, including conventional (CT), reduced (RT), and no-till (NT). The results showed that the changes in soil respiration rates had a single peak curve, and its peak appeared in August The seasonal variations in soil respiration rates under CT, RT and NT were 0.50-4.81, 1.11-5.44 and 0.40-5.89 μmol CO2 m-2·s-1, respectively. The trends in soil respiration between CT and RT were similar, while there was a larger fluctuation in soil respiration with NT. The regression analysis showed that soil respiration had a significant correction with soil moisture or temperature, but little at the peak values of soil respiration. Soil moisture (0-10 cm) could explain 57%-76% of seasonal variations in the soil respiration. The moisture sensitivities of soil respiration were NT>RT>CT. Soil temperature (15 cm) could explain 67%-82% of seasonal variations in the soil respiration. the Q10 was NT (2.47)>RT (2.02)>CT (1.59). The two-factor model y=aebTWc or y=a+bT+cW could better describe the relationship between soil respiration and combination of soil moisture and temperature than the one-factor model. The index-power model of combination of soil moisture and temperature (10-20 cm) y=aebTWc can explain 81%-87% of variations in soil respiration (P<0.01). The sensitivities of three tillage treatments to the combination of soil moisture and temperature were: RT>CT>NT. Soil respiration was affected differently by the hydrothermic factor or by each of the single factor. 参考文献 相似文献 引证文献

Effects of elevated O3 on soil respiration in a winter wheat - soybean rotation cropland

The increasing tropospheric ozone (O3) concentration has been reported to have negative effects on ecosystems. However, few investigations have focussed on the impacts of elevated O3 on soil respiration in cropland. This study aimed to examine the responses of soil respiration to elevated O3 with open-top chambers (OTCs) in a winter wheat (Triticum aestivum L.)–soybean (Glycine max (L.) Merr) rotation. The experiment was performed in the cropland near Nanjing city, south-east China. Seasonal changes in soil respiration rates, soil CO2 production rates, and nitrification and denitrification rates in ambient air (control) and elevated O3 (100 ppb) treatments were investigated in the 2009–10 winter wheat and 2010 soybean growing seasons. Seasonal mean soil respiration rates for the control and 100 ppb treatments were 3.16 and 2.66 μmol/m2.s, respectively, in the winter wheat growing season, and they were 3.59 and 2.51 μmol/m2.s, respectively, in the soybean growing season. Mean soil respiration rate in the control was ~29% higher than that in the 100 ppb treatment across the whole winter wheat–soybean rotation season. Elevated O3 significantly decreased soil respiration in both crops, with a larger effect observed in soybean. Mean soil CO2 production rates were reduced by ~42% in the 100 ppb O3 treatment compared with the control. No O3 effects were observed on soil nitrification and denitrification during the period monitored. A further analysis of covariance showed that soil respiration was significantly correlated with both soil temperature and moisture, and no interaction effects of O3 treatment and covariate (temperature or moisture) were observed.

Micro-topographic patterns unravel controls of soil water and temperature on soil respiration in three Siberian tundra systems

Spatial and temporal patterns of soil respiration rates and controlling factors were investigated in three wet arctic tundra systems. In situ summer season carbon dioxide fluxes were measured across a range of micro-topographic positions in tussock tundra, wet sedge tundra, and low-centre polygonal tundra, at two different latitudes on the Taimyr Peninsular, central Siberia. Measurements were carried out by means of a multi-channel gas exchange system operating in continuous-flow mode. Measured soil respiration rates ranged from 0.1 g CO 2-C m −2 d −1 to 3.9 g CO 2-C m −2 d −1 and rate differences between neighbouring sites in the micro-topography (microsites) were larger than those observed between different tundra systems. Statistical analysis identified position of the water table and soil temperature at shallow depths to be common controls of soil respiration rates across all microsites, with each of these two factors explaining high proportions of the observed variations. Modelling of the response of soil respiration to soil temperature and water table for individual microsites revealed systematic differences in the response to the controlling factors between wet and drier microsites. Wet microsites – with a water table position close to the soil surface during most of the summer – showed large soil respiration rate changes with fluctuations of the water table compared to drier microsites. Wet microsites also showed consistently higher temperature sensitivity and a steeper increase of temperature sensitivity with decreasing temperatures than drier sites. Overall, Q 10 values ranged from 1.2 to 3.4. The concept of substrate availability for determining temperature sensitivity is applied to reconcile these systematic differences. The results highlight that soil respiration rates in wet tundra are foremost controlled by water table and only secondarily by soil temperature. Wet sites have a larger potential for changes in soil respiration rates under changing environmental conditions, compared to drier sites. It is concluded that understanding and forecasting gaseous carbon losses from arctic tundra soils and its implication for ecosystem-scale CO 2 fluxes and soil organic matter dynamics require good knowledge about temporal and spatial patterns of soil water conditions. The water status of tundra soils can serve as a control on the temperature sensitivity of soil respiration.

Biotic and abiotic factors controlling soil respiration rates in Picea abies stands

The response of soil respiration to varying environmental factors was studied in four Picea abies stands (47-, 87-, 111- and 146-year old) during the 1998 growing season. While within-site variations of soil CO 2 efflux (up to 1.6 μmol CO 2 m −2 s −1 ) were larger than their diurnal variability (<0.25 μmol CO 2 m −2 s −1 ), spatial variations within a site were smaller than seasonal changes in soil respiration rates (up to 4.4 μmol CO 2 m −2 s −1 ). Highest within-site variability of soil efflux was generally found during the summer months when maximum flux rates of 4–6 μmol CO 2 m −2 s −1 were reached (coefficient of variation 40%). Soil temperatures (in the O f and O h layers, and A h horizon) showed a pronounced seasonal course, in contrast to soil moisture. An exponential equation best described the relationships between soil temperature in the O f layer and soil CO 2 efflux ( r 2 between 0.75 and 0.81). However, an Arrhenius type equation always resulted in lower r 2 values (0.52–0.71). The Q 10 values ranged between 2.39 (146-year old stand) and 3.22 (87-year old stand), averaging 2.72 for the P. abies stands within the watershed. The removal of litter and organic layers generally affected soil CO 2 efflux negatively. In three of the four P. abies stands (47-, 87-, 146-year old stands), soil respiration rates were reduced by 10–20% after removal of the L and O f layer, and by 30–40% after removal of the L and most of the O f and O h layers. Thus, mineral soil respiration seemed to contribute a major fraction to the total soil CO 2 flux (>60%). Trenching shallow fine roots during collar insertion and mechanical inhibition of root in-growth during the following months allowed fine root respiration to be separated from microbial respiration only in times of highest root growth. Microbial respiration seemed to dominate the respiratory CO 2 loss from the forest floor (>70%). The comparison of the annual soil CO 2 efflux in the 47-year old P. abies stand (about 710 g C m −2 yr −1 ) with annual litterfall and root net primary productivity estimates supported this conclusion.

Processes controlling the oxygen isotope ratio of soil CO 2: analytic and numerical modeling

The 18O/ 16O ratio of soil CO 2 is important for both global and ecosystem scale budgets of the 18O/ 16O ratio of atmospheric CO 2, as well as for using this ratio as a proxy for the isotopic ratio of soil water. The 18O/ 16O ratio of soil CO 2 reflects that of soil water due to the isotope exchange which occurs during the CO 2 hydration reaction. The rate of this isotope exchange reaction strongly influences the oxygen isotope ratio of soil CO 2, and may be about two orders of magnitude slower than the isotope exchange reaction between CO 2(aq) and water (effective first order rate constant, k eff, of 10 −4 versus 10 −2 s −1 at 25°C). This difference in rate reflects transport across the soil water/soil air interface, which limits the overall rate of reaction. A diffusion-production-reaction model (Hesterberg and Siegenthaler, 1991) suggests that the 18O/ 16O ratio of soil CO 2 at depth deviates from the equilibrium value by ∼1–2‰ if k eff = 10 −4 s −1, negating the assumption that soil CO 2 is in isotopic equilibrium with soil water. A sensitivity analysis of this model indicates the following factors affect 18O/ 16O ratio of soil CO 2 (in order of decreasing importance): (1) the isotope ratio of soil water; (2) the rate constant of the isotope exchange; (3) soil air-filled pore space and tortuosity. Notably, soil respiration rate has only a minor effect. Advection of soil gas due to wind pumping has a negligible effect on the δ 18O value of soil CO 2 except in most extreme cases. Likewise, transient effects on the oxygen isotope ratio of soil CO 2 due to changes in soil respiration rate are small.

Seasonal Changes in Soil Respiration Rate in a Mulberry Field.

Seasonal Changes in Soil Respiration Rate in a Mulberry Field.