Forest Soil Respiration Research Articles

Increased Litter Greatly Enhancing Soil Respiration in Betula platyphylla Forests of Permafrost Region, Northeast China

The change of litter input can affect soil respiration (Rs) by influencing the availability of soil organic carbon and nutrients, regulating soil microenvironments, thus resulting in a profound influence on soil carbon cycle of the forest ecosystem. We conducted an aboveground litterfall manipulation experiment in different-aged Betula platyphylla forests (25-, 40- and 61-year-old) of the permafrost region, located in the northeast of China, during May to October in 2018, with each stand treated with doubling litter (litter addition, DL), litter exclusion (no-litter, NL) and control litter (CK). Our results indicated that Rs decreased under NL treatment compared with CK treatment. The effect size lessened with the increase in the stand age; the greatest reduction was found for young Betula platyphylla forest (24.46% for 25-year-old stand) and tended to stabilize with the growth of forest with the reduction of 15.65% and 15.23% for 40-and 61- year-old stands, respectively. Meanwhile, under DL treatment, Rs increased by 27.38%, 23.83% and 23.58% on 25-, 40- and 61-year-old stands, respectively. Our results also showed that the increase caused by DL treatment was larger than the reduction caused by NL treatment, leading to a priming effect, especially on 40- and 61-year-old stands. The change in litter input was the principal factor affecting the change of Rs under litter manipulation. The soil temperature was also a main factor affecting the contribution rate of litter to Rs of different-aged stands, which had a significant positive exponential correlation with Rs. This suggests that there is a significant relationship between litter and Rs, which consequently influences the soil carbon cycle in Betula platyphylla forests of the permafrost region, Northeast China. Our finding indicated the increased litter enhanced the Rs in Betula platyphylla forest, which may consequently increase the carbon emission in a warming climate in the future. It is of great importance for future forest management in the permafrost region, Northeast China.

High leaf area index inhibits net primary production in global temperate forest ecosystems.

Within limited growth age in some regions, forest production, including gross primary production (GPP) and net primary production (NPP), was linearly correlated with leaf area index (LAI). However, over wide range of growth age in the global scale, LAI patterns of forest production are unclear. Here, we compiled a subset from the Global Soil Respiration Database (SRDB) for global temperate forest ecosystems. The subset database mainly included forest production, soil respiration, and LAI data in 493 study sites over wide range of forest growth age (0-500years). The results showed that LAI initially increased rapidly, reached a peak at juvenility, decreased slowly until maturity, and again increased possibly with further forest aging (R2 = 0.21, P < 0.001). We found that the dynamics of both GPP and NPP across global temperate forest ecosystems were driven by LAI. GPP initially increased and subsequently stabilized with increasing LAI. NPP peaked at LAI of about 5.6m2m-2, and subsequently decreased. The decrease in NPP resulted from the asymptotic increase in GPP and the continuing decrease in the NPP/GPP ratio with increasing LAI. The decline in the NPP/GPP ratio resulted from the significant increase in autotrophic respiration (Ra), and especially after canopy closure, Ra increased more quickly with increasing LAI than GPP. These results will improve our understanding of the control of LAI on ecosystem production.

秦岭太白山不同林带土壤微生物呼吸速率及其影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 秦岭太白山不同林带土壤微生物呼吸速率及其影响因素 DOI: 10.5846/stxb201905171016 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金青年基金（41601578）；中国博士后特别资助（2018T111089）；森林生态系统可持续经营教育部重点实验室（东北林业大学）开发基金（KFJJ2019ZD01） The soil microbial respiration rate and its influencing factors in different forest belts of Taibai Mountain, Qinling Mountains Author: Affiliation: 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:为探究森林土壤微生物呼吸对温度的敏感性及其影响因素，在太白山选取典型的4个不同海拔的林带（锐齿栎林、辽东栎林、红桦林、牛皮桦林）的0-10 cm表层土壤为对象，分别在15、25、35℃下进行控温培养实验并测量其土壤呼吸速率、微生物量和胞外酶活性等指标。结果表明：1）在1-20 d与20-72 d时的微生物呼吸速率分别呈现波动下降趋势与缓慢下降趋势，相比于其初始速率平均下降了68%与90%；表明高温在短期内促进土壤呼吸；2）太白山地区土壤温度敏感系数（Q10）随温度的升高而降低；3）在培养过程中，出现15℃和25℃下微生物量先增多后减少，35℃下微生物量一直减少的现象，并且胞外酶是影响土壤微生物呼吸的重要因素，其中BG（β-葡萄糖苷酶）是胞外酶中最重要的影响因子；4）培养72 d以后，BG已无法为微生物生长繁殖提供充足的碳，在25℃和35℃下，由BX（β-木糖苷酶）提供的碳已成为微生物生长繁殖的重要碳源之一。在15℃和25℃下，N是培养前期限制土壤呼吸的因素，C是后期限制因素；在35℃下，N一直是限制土壤呼吸的因素。在15℃和35℃下，土壤呼吸不存在P限制；在25℃的培养前期，P是限制土壤呼吸的因子，而在培养后期不存在P限制。本研究结果阐明抑制土壤碳排放的关键在于抑制土壤微生物呼吸，揭示了在胞外酶驱动下的土壤碳循环特征，为准确预测全球未来气候变化的趋势提供理论基础。 Abstract:Soil microbial respiration is a major source of CO2 efflux to the atmosphere from forest ecosystems and plays a decisive role in predicting future global climate change. A typical temperate forest ecosystem, the Taibai Mountain contains a mosaic of stands with various attitudes. The objective of the present study was to investigate the trends and influencing factors of microbial respiration in temperate forest soils without external carbon input. In the Taibai Mountain, 0-10 cm topsoil of typical forest belts of different altitudes (Quercus aliena var. acuteserrata, Q. liaotungensis, Betula albosinensis, and B. albosinensis var. septentrionalis) were sampled and incubated at 15 ℃, 25 ℃, and 35 ℃. The microbial respiration rate showed a fluctuating downward trend and a slowly decreasing trend at Days 1-20 and Days 20-72, with a 68% and 90% decrease compared to the initial rate, respectively. Thus, high temperature promoted soil respiration in the short term whereas it retarded soil respiration in the long term. The temperature sensitivity index (Q10) of the soil in the Taibai Mountain decreased with warming. Microbial biomass increased initially and then decreased during the incubation at 15 ℃ and 25 ℃, whereas it decreased throughout the incubation at 35 ℃. Furthermore, BG (β-1,4-glucosidase) was the most important extracellular enzyme affecting microbial respiration. After 72 days of incubation, BG failed to provide adequate carbon for microbial growth and reproduction. At 25 ℃ and 35 ℃, the carbon provided by BX (β-1,4-xylosidase) became one of the most important carbon sources for microbial growth and reproduction. At 15 ℃ and 25 ℃, N was the limiting factor for soil respiration during the early incubation stage and C was the limiting factor for the later stage; at 35 ℃, N was the limiting factor of soil respiration throughout the incubation. At 15 ℃ and 35 ℃, there was no P limitation for soil respiration; however, P was a limiting factor for soil respiration during the early incubation stage at 25 ℃. The results of this study demonstrated that the key to limiting soil carbon emissions is to retard soil microbial respiration, with extracellular enzymes significantly influencing soil microbial respiration. 参考文献 相似文献 引证文献

武夷山不同林龄甜槠林土壤呼吸特征及影响因素

为揭示中亚热带常绿阔叶林群落优势种一甜槠天然林不同林龄林下土壤呼吸（Soil respiration，R_S）差异及影响因素，采用LI-8100开路式土壤碳通量系统对武夷山自然保护区不同林龄（18、36、54、72 a）天然甜槠林进行了1年的野外原位测定。结果表明：（1）不同林龄甜槠林R_S季节动态呈现明显的单峰趋势，林龄对冬季R_S影响并不显著（P>0.05），秋季18 a甜槠林R_S与其他3种林龄差异显著（P<0.05），林龄对土壤含水率的季节变化没有显著影响（P>0.05）；（2）不同林龄甜槠林5 cm深土壤温度与R_S拟合R²明显高于土壤含水率与R_S拟合R²，随着林龄增大，R_S温度敏感性指数Q₁₀值呈上升趋势，依次为1.551、1.589、1.640、1.664，且54、72 a甜槠林R_S温度敏感性指数Q₁₀值显著高于18、36 a（P<0.05）；（3）土壤含水率与5 cm深土壤温度共同解释了R_S变异的86%-90.3%；0-60 cm土层根系生物量与5 cm深土壤温度共同解释了R_S变异的88.3%-91.8%，由此可见，生物因子与非生物因子双因素拟合可以更好地解释不同林龄R_S差异。在对未来森林植被土壤呼吸及碳汇功能进行研究时，应在考虑林龄及季节差异的基础上，加强对生物因子的测定。;Soil respiration, as an important ecological process of material cycle and energy flow in forest ecosystem, is one of the main fluxes in the global carbon cycle, and plays an important role in the global carbon cycle and carbon balance. There are many factors that affect forest soil respiration, mainly non-biological factors such as soil temperature, water content and air temperature, etc. However, with different climatic zones and forest types, forest age has an important impact on carbon storage and carbon distribution in forest ecosystems, and there is also great uncertainty of the impact on soil respiration. In this paper, soil carbon flux system LI-8100 was used to measure soil respiration and its components in Castanopsis eyrei forests (18 a, 36 a, 54 a, and 72 a) of different forest ages in Wuyishan Nature Reserve. Meanwhile, soil temperature of 5 cm depth and soil water content were simultaneously measured. The results showed that: (1) the seasonal dynamics of soil respiration in Castanopsis eyrei forests with different forest ages presented a single peak trend, and the effect of forest age on soil respiration in winter was not significant (P>0.05). The soil respiration in 18 a Castanopsis eyrei forests in autumn was significantly different from that of the other three forest ages (P<0.05), and the forest age had no significant effect on the seasonal changes of soil water content (P>0.05). (2) Fitting R² of soil temperature of 5 cm depth and soil respiration in different forest age Castanopsis eyrei forest was significantly higher than fitting R² of soil water content with soil respiration. With the increase of forest age, the Q₁₀ value of soil respiration temperature sensitivity index showed an upward trend, which was 1.551, 1.589, 1.640 and 1.664 in turn, while the Q₁₀ value of soil respiration temperature sensitivity index of 54 a and 72 a Castanopsis eyrei forest was significantly higher than that of 18 a and 36 a Castanopsis eyrei forest (P<0.05). (3) Soil water content and soil temperature of 5 cm depth together explain 86%-90.3% of soil respiration variation. The root biomass of 0-60 cm soil layer and soil temperature of 5 cm depth jointly explain 88.3%-91.8% of soil respiration variation. Thus it can be seen that the two-factor fitting of biological factor and abiotic factor can better explain the soil respiration variation of different forest ages. When studying the soil respiration and carbon sink function of forest vegetation in the future, the determination of biological factors should be strengthened on the basis of considering the difference of forest age and season.

Seasonality, drivers, and isotopic composition of soil CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; fluxes from tropical forests of the Congo Basin

Abstract. Soil respiration is an important carbon flux and key process determining the net ecosystem production of terrestrial ecosystems. To address the lack of quantification and understanding of seasonality in soil respiration of tropical forests in the Congo Basin, soil CO2 fluxes and potential controlling factors were measured annually in two dominant forest types (lowland and montane) of the Congo Basin over 2 years at varying temporal resolution. Soil CO2 fluxes from the Congo Basin resulted in 3.45 ± 1.14 and 3.13 ± 1.22 µmol CO2 m−2 s−1 for lowland and montane forests, respectively. Soil CO2 fluxes in montane forest soils showed a clear seasonality with decreasing flux rates during the dry season. Montane forest soil CO2 fluxes were positively correlated with soil moisture, while CO2 fluxes in the lowland forest were not. Smaller differences of δ13C values of leaf litter, soil organic carbon (SOC), and soil CO2 indicated that SOC in lowland forests is more decomposed than in montane forests, suggesting that respiration is controlled by C availability rather than environmental factors. In general, C in montane forests was more enriched in 13C throughout the whole cascade of carbon intake via photosynthesis, litterfall, SOC, and soil CO2 compared to lowland forests, pointing to a more open system. Even though soil CO2 fluxes are similarly high in lowland and montane forests of the Congo Basin, the drivers of them seem to be different, i.e., soil moisture for montane forest and C availability for lowland forest.

A simple model for partitioning forest soil respiration based on root allometry

Partitioning soil respiration (Rs) into heterotrophic (Rh) and autotrophic (Ra) compartments is an important first step in understanding the response of soil carbon flux to changes in climate. This is because Rh and Ra respond differently to changing environmental conditions. However, the methods currently used to partition Rs have high costs and large uncertainties. In this study, we developed a simple model to partition forest Rs based on root biomass, Rs=Rh+∑i=1n[ci×DBHidi×f(Di)], which the latter is modelled as the sum of root biomass density (MT) derived from an existing root allometric equation (MT=c×DBHd, where DBH is tree diameter at breast height) multiplied by a horizonal distance function (f(D)) based on the relationship between in situ Rs and distance (D) from the tree base. We applied this model to a complex tropical natural forest in Southeast Asia by inputting a site-specific root allometric equation and in situ Rs–D function to obtain: Rs=Rh+c′∑i=1n(DBHi2.59×Di−0.452). Compared to studies that used the classical root biomass regression, our results show a stronger linear correlation between Rs and simulated root biomass density (r2 = 0.797). By using the y-intercept (i.e. no root biomass at all), Rh was estimated to contribute 66.9 ± 5.7% to total Rs. We validated the root-allometry-based model by using the trenching method. In our study area, it took about 1 week (6.5 days) for tree roots to die after trenching, and Rh/Rs ratios estimated from our model were about 2.7% higher than those estimated with the trenching method. With the increasing number of allometry equations for global woody plants, the model has the potential of being used to partition Rs in various forests at regional or global scales.

Urbanization and fragmentation mediate temperate forest carbon cycle response to climate

Forest fragmentation is ubiquitous across urban and rural areas. While there is mounting evidence that forest fragmentation alters the terrestrial carbon cycle, the extent to which differences in ambient growing conditions between urban and rural landscapes mediate forest response to fragmentation and climate remains unexamined. This study integrates field measurements of forest structure, growth, and soil respiration with climate data and high-resolution land-cover maps to quantify forest carbon storage and sequestration patterns along edge-to-interior gradients. These data were used to contrast the response of temperate broadleaf forests to non-forest edges within rural and urban landscapes. We find that forest growth rates in both rural and urban landscapes nearly double from the forest interior to edge. Additionally, these edge-induced enhancements in forest growth are not offset by concurrent increases in total soil respiration observed across our sites. Forest productivity generally increases near edges because of increases in leaf area, but elevated air temperature at the edge tempers this response and imparts greater sensitivity of forest growth to heat. In particular, the adverse impacts of heat on forest growth are two to three times larger in urban than rural landscapes. We demonstrate that the highly fragmented nature of urban forests compared to rural forests makes them a stronger carbon sink per unit area, but also much more vulnerable to a warming climate. Collectively, our results highlight the need to include the effects of both urbanization and fragmentation when quantifying regional carbon balance and its response to a changing climate.

Biotic and abiotic properties most closely associated with subtropical forest soil respiration differ in wet and dry seasons: A 10-year in situ study

Forest ecosystems greatly affect the global carbon (C) budget. Because subtropical regions typically have wet and dry seasons that are likely to differ in their effects on soil respiration, our estimates of carbon dioxide (CO2) emissions from subtropical soil would be improved by consideration of both wet and dry seasons rather than wet seasons alone. In this 10-year study, we determined soil respiration rates (SRRs) and soil properties in a typical subtropical forest in southern China, and we quantified the relationships between SRRs and soil abiotic and biotic properties during the dry and wet seasons. During the 10 years, soil organic carbon contents, microbial biomass, and fine root biomass were generally higher in the wet season than in the dry season. Microbial biomass C and fine root biomass were positively associated with precipitation in dry seasons but negatively associated with precipitation in wet seasons. The SRRs of wet season were consistently and significantly higher than the counterparts of dry season, with the average SRR being 5.94 ± 0.32 μmol CO2 m−2 s−1 in the wet season and 1.56 ± 0.41 μmol CO2 m−2 s−1 in the dry season. In the wet and dry seasons, cumulative CO2 emissions were positively correlated with microbial biomass C and fine root biomass, but the abiotic and biotic factors explaining variation in SRR differed in the wet and dry seasons. Most of the variation in SRRs was explained by fine roots in the wet season but by fine roots, microorganisms, and soil pH in the dry season. The results revealed that the precipitation generated significantly positive effects on the cumulative CO2 emissions in the dry seasons and that the fine root was the crucial factor contributing to the SRRs in wet and dry seasons.

Short Term Effects of a Changing Carbon Input on the Soil Respiration of Picea schrenkiana Forests in the Tianshan Mountains, Xinjiang

The impact of exogenous carbon input changes on forest soil respiration provides the basis for an intensive analysis of the forest carbon cycle. Based on a plant residue addition and removal control experiment, this study investigated the short-term soil respiration response to carbon input changes of Picea schrenkiana on the Tianshan Mountains during their growing season with five different carbon input treatments:control, double litter, no root, no litter, and no input. The results revealed that, during the entire observation period, the cumulative soil respiration rates were 3.38, 3.94, 2.65, 2.87, and 2.01 μmol·(m2·s)-1 in the double litter, control, no litter, no root, and no input treatments, respectively. Compared with the control treatment, the cumulative soil CO2 efflux increased by 402.65 g·m-2 in the double litter treatment, whereas it decreased by 515.00, 354.73, and 967.15 g·m-2 in the no litter, no root, and no input treatments, respectively. The mineral soil respiration, litterfall respiration, and root respiration contributed 59.46%, 21.49%, and 14.79%, respectively, to the total soil respiration rate. PCA analysis revealed that the soil respiration rate was positively correlated with the soil temperature, soil moisture, soil total phosphorus content, pH, and soil organic carbon content, and negatively correlated with the soil bulk density, while the soil total nitrogen content, carbon nitrogen ratio, and soil electrical conductivity had no effect on the soil respiration rate.

Deer browsing effects on temperate forest soil nitrogen cycling shift from positive to negative across fertility gradients

Herbivores impact soil biogeochemical processes, often increasing nutrient cycling rates under high nutrient availability and decreasing nutrient cycling rates under low nutrient availability. These patterns are far from universal, and interactions between habitat fertility and herbivore effects are under continuing investigation. By sampling inside and outside a network of deer exclosures, we determined deer browsing effects on temperate forest soil nitrogen (N) and carbon (C) cycling along a gradient of soil and litter C–N ratios across our network of sites. Deer browsing increased net N mineralization rates in high nutrient environments and decreased N mineralization rates in low nutrient environments, whereas browsing decreased CO2 respiration rates in high nutrient environments and increased CO2 respiration rates in low nutrient environments. Differences in deer browsing effects on soil processes could be explained by plant responses to herbivory across gradients of resource availability. To our knowledge, our study is one of the first to show that deer browsing can have significant effects on net N mineralization and C respiration in temperate forest soils and that the direction and magnitude of deer browsing effects on soil N and C cycling vary across fertility gradients.

Soil respiration and its responses to biotic and abiotic factors in patchy remnant forests and urban green landscapes of Tianjin, China

Soil respiration (Rs) of forests plays an important role in the global carbon cycle. However, patchy remnant forests and their Rs characteristics are rarely studied. In this study, the diurnal and seasonal dynamics of the Rs of three patchy remnant forests and two urban green landscapes were determined using a portable soil carbon flux automatic analyzer in the urban fringe of Tianjin, China. Then, the effects of abiotic and biotic factors on the Rs of the patchy remnant forests and urban green landscapes were evaluated. Results showed that the patchy remnant forests had higher Rs than the urban green landscapes throughout the year. However, the Rs responses of the patchy remnant forests to soil temperature (ST) were more modest than those of the urban green landscapes, which indicated the higher resistant capacity to global warming of the former than the latter. In contrast to the pair traits of Rs-ST, fit lines of Rs and soil water content (SWC) showed an opposite trend in the growing and dormant periods. In the growing season, the slopes of Rs-SWC were similar between the patchy remnant forests and the urban green landscapes. The higher y-intercept of the patchy remnant forests indicated their larger water use efficiency than the urban green landscapes. In the dormant period, the higher slope of Rs-SWC for the patchy remnant forests suggested they were more sensitive to changes in SWC than the urban green landscapes. Meanwhile, the linear slopes of Rs and fine root biomass (FRB) were lower in the patchy remnant forests than in the urban green landscapes, which demonstrated that the Rs of the patchy remnant forests increased gently with increasing FRB. In addition, Rs was positively correlated with the amounts of bacteria and actinomycetes but negatively correlated with fungi. Results of canonical correlation analysis showed that the first two driving factors on the Rs of the patchy remnant forests were ST and FRB.

Soil respiration in temperate forests is increased by a shift from coniferous to deciduous trees but not by an increase in temperature

The rate of litter and soil organic matter decomposition depends on temperature and on leaf carbon content and its availability to decomposers. The effects of these variables on decomposition in temperate forest soils are incompletely understood although future increases are predicted for temperature, the ratio of litter fractions, and the ratio of deciduous to coniferous forests. In this study, a 14-month laboratory incubation experiment of adding deciduous (beech) and coniferous (spruce) litter to soil (Cambisol) was carried out to test the effects of litter fraction, tree species, and temperature on soil respiration (as indicated by CO2 release).The addition of the soluble and insoluble litter fractions as well as the whole tissue caused an increase in soil respiration (relative to the no-addition treatment). The effect of the soluble fraction, however, was less persistent than the effects of whole tissue or insoluble fractions, which suggests generally greater long-term effects of the latter fractions on soil respiration. Fractions derived from the beech litter increased soil respiration more than those derived from the spruce litter. This trend was especially apparent with the soluble litter fraction. A temperature increase of 3 °C caused no difference in soil respiration after the addition of beech litter fractions and even reduced soil respiration after the addition of spruce litter fractions. These results suggest that a future increase in the soluble fraction coupled with a shift in tree species composition from coniferous to deciduous might lead to an increase in soil respiration and thus to an increase in CO2 release from the forest floor. The results, however, also suggest that a 3 °C increase in temperature will not lead to increases in CO2 release from the forest floor, even if deciduous trees become more abundant.

Forest soil respiration and exoenzyme activity in western North America following thinning, residue removal for biofuel production, and compensatory soil amendments

AbstractCellulosic biofuel from forest thinning operations is a potential renewable energy source in regions with overstocked forests such as those in western United States. However, it is possible that biomass removal can deplete nutrients from soil, which can alter soil respiration (Rs) and exoenzyme properties, and potentially impact tree growth. This study evaluates the impact of biomass removal on Rs and exoenzyme properties and the capacity of soil amendments to counteract any potential effects. At two study locations, we created four post‐thinning biomass retention levels: full biomass removal (0×), full biomass retention (1×), double biomass retention (2×), and a no‐thin treatment. Four soil amendment treatments were applied to each biomass retention level: N fertilizer (F), biochar (B), fertilizer plus biochar (FB), and an untreated control (C). We evaluated treatment effects on Rs and activity of four exoenzymes to represent C‐cycling, N‐release, and P‐release processes. Biomass retention levels had no effect on Rs (p = .42) or exoenzyme activities (p &gt; .29). Variation in exoenzyme activity was explained by location, season, soil organic matter, soil moisture content, and temperature. Variation in Rs was explained by the same variables, in addition to C‐cycling exoenzyme activity and soil pH. Soil amendments had no effect on exoenzyme activities (p &gt; .49), and no main effect on Rs (p = .48), though amendments influenced Rs differently at each location (p = .02). Short‐term findings suggest small‐diameter biomass removal for cellulosic biofuel production will not impact Rs and exoenzyme properties, and paired with our tree growth study, provide evidence that biofuel systems are a feasible renewable energy source in the western North America.

模拟酸雨对我国亚热带毛竹林土壤呼吸及微生物多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟酸雨对我国亚热带毛竹林土壤呼吸及微生物多样性的影响 DOI: 10.5846/stxb201905241073 作者: 作者单位: 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（31770680）；浙江省自然科学基金项目（LY15C160005，LQ19C160013） Effects of simulated acid rain on soil respiration and microbial diversity in Moso bamboo forest in subtropical China Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)，Zhejiang Provincial Natural Science Foundation 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:酸沉降造成的土壤持续酸化对毛竹林生态系统碳循环具有重要的影响，为量化酸沉降我国亚热带毛竹林土壤的影响，于2016年在浙江省杭州临安天目山国家级自然保护区毛竹林持续开展了2年野外模拟酸雨淋溶土壤实验，设置pH 4.0（T1）和pH 2.0（T2）两个模拟酸雨处理，以pH 5.8天然湖水为对照（CK），分析酸雨作用下土壤CO2排放及土壤微生物多样性的变化趋势，并明确毛竹林土壤呼吸、土壤微生物及土壤理化性质三者之间的关系。结果表明：土壤呼吸速率在酸雨作用下经过缓冲期后呈现先促进后抑制的变化，作用强度表现为：T2>T1。不同处理的土壤呼吸对温度的敏感性由高到低依次是：T2、CK、T1。PCR-DGGE分析表明，模拟酸雨改变了土壤微生物菌群结构，T2处理抑制了土壤细菌的多样性和丰富度，而T1处理对土壤真菌多样性和丰富度具有促进作用。土壤pH值、有效钾、可溶有机碳、微生物量碳、碱解氮和有效磷对土壤微生物群落结构及土壤呼吸具有显著的影响（P<0.05）。综上所述，模拟酸雨能够显著抑制毛竹林的土壤呼吸，并改变土壤微生物群落结构及多样性，这些结果为进一步研究毛竹林土壤生态系统对环境问题响应机制提供理论基础。 Abstract:Acid rain is an important phenomena in global climate change and it can strongly influence forest ecology. Many studies have shown the impacts of acid rain on soil respiration, but the results are very different due to the different species and environmental conditions. The persistent acidification of soil caused by acid rain has an important impact on the carbon cycle of the Moso bamboo forest ecosystem. To quantify the effect of acid rain on the soil ecosystem of Moso bamboo forest in subtropical China, the experiment of soil by simulated acid rain in the field was carried out for two years of 2016-2018. Two treatments of the simulated acid rain with pH value of 4.0 (T1) and 2.0 (T2) were set, at the same time taking pH value of 5.8 (CK) as control. The relationship between soil CO2 emission and soil microbial diversity in the Moso bamboo forest of Tianmu Mountain National Nature Reserve under the simulated acid rain was analyzed, and the relationship between soil respiration, soil microbial and soil physical and chemical properties in subtropical Moso bamboo forest was determined. The results showed that soil respiration rate increased firstly and then decreased after the buffer period under the action of acid rain, and the intensity of the action was T2>T1. The sensitivity of soil respiration to temperature in different treatments from high to low was T2, CK, T1, and increased seasonally with increasing temperature. PCR-DGGE analysis showed that strong acid rain treatment inhibited the growth of soil bacterial community and the order of soil bacteria diversity and richness from high to low was CK, T1, and T2. The weak acid rain had a positive effect on the diversity and abundance of soil fungi, and the opposite was strong acid rain. The effects of acid rain resulted in the decrease or disappearance of Bacillus, Caulobacter, Cystobacteraceae, Bradyrhizobium and Candida, as well as inhibiting soil respiration, while Carnobacterium, Propionibacterium, and Clostridium played greater roles in soil respiration under the simulated acid rain. Soil pH, available potassium, soluble organic carbon and microbial biomass carbon were closely and positively correlated with the soil microbial community structure under simulated acid rain treatment, while alkali nitrogen and available phosphorus were negatively correlated with the soil microbial community structure. In general, simulated acid rain can significantly inhibit soil respiration in Moso bamboo forests, and change soil microbial community structure and diversity. These results provide theoretical basis for further study on the response mechanism of soil ecosystem of Moso bamboo forest to environmental problems. 参考文献 相似文献 引证文献

Controls of Temporal Variations on Soil Respiration in a Tropical Lowland Rainforest in Hainan Island, China

Soil respiration represents the largest carbon (C) flux from terrestrial ecosystems to the atmosphere. We created a study site in tropical lowland rainforest and used static chamber method to measure the temporal variations of soil respiration and their relationship with environmental factors at monthly time scale. The temporal variations of soil respiration showed a seasonal pattern related to soil temperature (p < .01) and soil moisture (p < .05). We tested different regression models to explore the relationship between soil respiration and environmental factors. Soil respiration had a better fit with soil temperature than with soil moisture in single-factor models. At different temperatures, the Q10 values from different models changed in rather different ways. We found that the mixed quadratic model composite of soil temperature and moisture had the best-fitting effect (R2 = .74) on soil respiration and could better explain the seasonal variation. In a certain soil moisture range close to 15%, soil respiration increased with soil temperature. However, soil respiration became restricted when the moisture was greatly higher or lower than this value. Furthermore, at low soil temperatures (lower than 16°C), higher soil moisture could decrease soil respiration rapidly. Thus, soil respiration in a tropical lowland rainforest is co-controlled by soil temperature and moisture. This study expands our observations of soil respiration in tropical forests and how it responds to environmental factors, which is important for reducing errors in evaluation and scaling up of soil carbon flux in climate change studies.

Variations of belowground C and N cycling between arbuscular mycorrhizal and ectomycorrhizal forests across China

Forests associating with arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi may have distinct belowground carbon (C) and nitrogen (N) cycle processes. However, there are little available data providing evidence for the effects of trees associating with mycorrhizal type on belowground C and N cycling in forest ecosystems in China. Here, we collected a database of 26 variables related to belowground C and N cycling from 207 studies covering 209 sampling sites in China, to better understand the variations in belowground C and N cycling between the two mycorrhizal types in forest ecosystems along a climatic gradient. The AM forests had significantly lower soil total C and N contents, and soil microbial biomass C and N, than ECM forests, probably due to differences in litter quality (N and C/N) between AM and ECM forest types. In contrast, AM forests had significantly higher litter input, litter decomposition and soil respiration than ECM forests. Temperature and precipitation had significant positive effects on litter input and decomposition, soil total C and N contents, and soil respiration in AM and ECM forests. Overall, our results indicated that mycorrhizal type strongly affected belowground C and N cycle processes in forest ecosystems. Moreover, AM forests are likely more sensitive and ECM forests have a greater ability to adapt to global climate change.

Variations in Soil Respiration at Different Soil Depths and Its Influencing Factors in Forest Ecosystems in the Mountainous Area of North China

An in-depth understanding of the dominant factors controlling soil respiration is important to accurately estimate carbon cycling in forest ecosystems. However, information on variations in soil respiration at different soil depths and the influencing factors in forest is limited. This study examined the variations in soil respiration at two soil depths (0–10 and 10–20 cm) as well as the effects of soil temperature, soil water content, litter removal, and root cutting on soil respiration in three typical forest types (i.e., Pinus tabulaeformis Carrière, Platycladus orientalis (L.) Franco, and Quercus variabilis Bl.) in the mountainous area of north China from March 2013 to October 2014. The obtained results show that soil respiration exhibited strong seasonal variation and decreased with soil depth. Soil respiration was exponentially correlated to soil temperature, and soil respiration increased with soil water content until reaching threshold values (19.97% for P. tabulaeformis, 16.65% for P. orientalis, and 16.90% for Q. variabilis), followed by a decrease. Furthermore, interactions of soil temperature and water content significantly affected soil respiration at different soil depths of forest types, accounting for 68.9% to 82.6% of the seasonal variation in soil respiration. In addition to soil temperature and water content, aboveground litter and plant roots affected soil respiration differently. In the three forest types, soil respiration at two soil depths decreased by 22.97% to 29.76% after litter removal, and by 44.84% to 53.76% after root cutting. The differences in soil respiration reduction between the two soil depths are largely attributed to variations in substrate availability (e.g., soil organic content) and soil carbon input (e.g., litter and fine root biomass). The obtained findings indicate that soil respiration varies at different soil depths, and suggest that in addition to soil temperature and water content, soil carbon input and dissolved organic substances may exert a strong effect on forest soil respiration.

Hot Spots Of Soil Respiration In A Seasonally Dry Tropical Forest In Southern Vietnam: A Brief Study Of Spatial Distribution

Many studies report asymmetrical spatial distribution of soil respiration caused by presence of areas with significantly higher emission rates (so-called hot spots). For seasonally dry tropical forest soil respiration was measured on 1 ha plot with 20m, 5m and 1 m scale in the first half of dry season. 457 measurements made in 9 series at 54 sampling points. The results suggest that lognormal spatial distribution model appears to be much more supported rather than the normal one. A statistical method proposed for estimation the mean value and its confidence interval of lognormally distributed data. The mean emission rate E(R S ) for the lognormal distribution amounted to 4.28 µmol m -2 s -1 , the 95% confidence interval is 3.93 to 4.76 µmol m -2 s -1 . However, the standard sample mean can be used as an estimator of the mean of lognormally distributed values of soil respiration if their coefficient of variance remains approximately the same as in our study (CV=0.35). Based on the data obtained and literature sources, recommendations are given on the number of sampling points for estimating the spatial average value with a given accuracy.

Soil carbon and nitrogen availability are key determinants of soil microbial biomass and respiration in forests along urbanized rivers of southern China

Although soil microbial communities have been known to play integral roles in most terrestrial biogeochemical processes, surprisingly the patterns and controls of soil microbial communities across urban forest ecosystems are poorly understood. To contribute towards addressing this critical gap, we examined the patterns of soil microbial properties and the effects of soil chemical properties on these patterns in forest ecosystems along the two rivers with different urbanization levels in the coastal city of Fuzhou in southern China. Soil microbial biomass C (MBC), microbial biomass N (MBN) and soil microbial respiration rate (SR) significantly decreased from the highly urbanized Bailongjiang River (BJR) to the less urbanized Wulongjiang River (WJR) and from the 0 − 10 cm soil depth to the 10 − 20 cm soil depth. Soil MBC/MBN and metabolic quotient (qCO2) values in BJR forest stands were not considerably different from those of WJR forest stands. Soil C and N availability determined soil MBC and MBN patterns and these four aforementioned soil variables determined SR patterns across the rivers and soil depths. Our study contributes to a better understanding of the patterns and controls of soil microbes and their activities in forest ecosystems with different urbanization levels.

Nitrogen Addition Affects Soil Respiration Primarily through Changes in Microbial Community Structure and Biomass in a Subtropical Natural Forest

Forest soil respiration plays an important role in global carbon (C) cycling. Owing to the high degree of C and nitrogen (N) cycle coupling, N deposition rates may greatly influence forest soil respiration, and possibly even global C cycling. Soil microbes play a crucial role in regulating the biosphere–atmosphere C exchange; however, how microbes respond to N addition remains uncertain. To better understand this process, the experiment was performed in the Castanopsis kawakamii Hayata Nature Reserve, in the subtropical zone of China. Treatments involved applying different levels of N (0, 40, and 80 kg ha−2 year−1) over a three-year period (January 2013–December 2015) to explore how soil physicochemical properties, respiration rate, phospholipid fatty acid (PLFA) concentration, and solid state 13C nuclear magnetic resonance responded to various N addition rate. Results showed that high levels of N addition significantly decreased soil respiration; however, low levels of N addition significantly increased soil respiration. High levels of N reduced soil pH and enhanced P and C co-limitation of microorganisms, leading to significant reductions in total PLFA and changes in the structure of microbial communities. Significant linear relationships were observed between annual cumulative respiration and the concentration of microbial biomass (total PLFA, gram-positive bacteria (G+), gram-negative bacteria (G−), total bacteria, and fungi) and the microbial community structure (G+: G− ratio). Taken together, increasing N deposition changed microbial community structure and suppressed microbial biomass, ultimately leading to recalcitrant C accumulation and soil C emissions decrease in subtropical forest.