Total Soil Respiration Research Articles

Significance of soil respiration from biological activity in the degradation processes of different types of organic matter

Soil respiration is a major component of global carbon cycle. Therefore, it is crucial to understand the environmental controls on soil respiration for evaluating potential response of ecosystems to climate change. In a temperate deciduous forest (located in Northern-Hungary) we added or removed aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture, and soil temperature. Soil CO2 efflux was measured at each plot using soda-lime method. Temperature sensitivity of soil respiration (Q10) was monitored via measuring soil temperature on an hourly basis, while soil moisture was determined monthly. Soil respiration increased in control plots from the second year after implementing the treatment, but results showed fluctuations from one year to another. The effect of doubled litter was less significant than the effect of removal. Removed litter and root inputs caused substantial decrease in soil respiration. We found that temperature was more influential in the control of soil respiration than soil moisture. In plots with no litter Q10 varied in the largest interval. For treatment with doubled litter layer, temperature sensitivity of CO2 efflux did not change considerably. The effect of increasing soil temperature is more conspicuous to soil respiration in litter removal treatments since lack of litter causes greater irradiation. When exclusively leaf litter was considered, the effect of temperature on soil respiration was lower in treatments with added litter than with removed litter. Our results reveal that soil life is impacted by the absence of organic matter, rather than by an excess of organic matter. Results of CO2 emission from soils with different organic matter content can contribute to sustainable land use, considering the changed climatic factors caused by global climate change.

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.

Soil Microbial Respiration in Subtaiga and Forest-Steppe Ecosystems of European Russia: Field and Laboratory Approaches

Our study focuses on testing laboratory measurements of soil microbial respiration as a proxy that in the field conditions. The soil microbial respiration was measured in field (MRfield) and laboratory (MRlab) conditions monthly (from May to October) in subtaiga (mixed forest, meadow) and forest-steppe (broad-leaved forest, virgin steppe) ecosystems of the European Russia. The MRfield was determined through soil respiration partitioning by the conventional substrate-induced respiration method. The MRlab was measured as basal respiration of 10 cm topsoil at 22°C and 60% water holding capacity. The contribution of MRfield to total soil respiration varied during the growing season from 25 to 82% for subtaiga and from 41 to 88% for forest-steppe. The MRfield for studied ecosystems varied from 2.2 to 21.7 g СО2/(m2 d), while MRlab was from 3.5 to 18.6 g СО2/(m2 d). Similar results obtained by field and laboratory approaches were in 50% of measurements in the subtaiga ecosystems and in almost 20% of cases on the forest-steppe. The average MRfield and MRlab for growing season did not significantly differ for all studied ecosystems. These findings demonstrate possible prospects of using laboratory measurement of soil microbial respiration during the growing season to approximate and predict average MRfield for various ecosystems.

Effects of Experimental Throughfall Exclusion on Soil Respiration in a Continental Coniferous Stand, South Korea

Severe droughts and changing precipitation patterns could alter the biogeochemical properties of the soil, affecting soil carbon cycles in forest ecosystems. A throughfall exclusion (TFE) experiment was conducted in a continental climate coniferous stand in Gangwon Province, Korea, to examine the effects of excluding rainfall on total soil respiration (SR), heterotrophic soil respiration (HR), autotrophic soil respiration (AR), sapling diameter growth, and soil bacterial communities from July 2016 to October 2017. The soil water content (SWC) was significantly decreased by the exclusion of the throughfall, resulting in changes in the bacterial communities, and subsequently a decrease in HR. Although AR did not present significant differences between the control and TFE plots, the rate of sapling growth was significantly lower in the TFE plots compared with that in the control plots. An exponential function relating SR to soil temperature accounted for 0.61% and 0.82% of the variance in SR in the control and TFE plots, respectively (Q10 = 2.48 and 2.86, respectively). Furthermore, a multivariate nonlinear model based on soil temperature and SWC explained 0.89% and 0.88% of the variance in SR in the control and TFE plots, respectively. When soil temperature was high, SR showed high fluctuations due to SWC variation. However, when SWC was low, we detected relatively small fluctuations in SR due to soil temperature. The results of this study show that the activity of soil microbial and root respiration during the growing season may be lower under future drought conditions.

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.

How Simulations of the Land Carbon Sink Are Biased by Ignoring Fluvial Carbon Transfers: A Case Study for the Amazon Basin

Summary Land-surface models are important tools for simulation of the past, present, and future capacity of terrestrial ecosystems to absorb anthropogenic CO2 emissions. However, fluvial carbon (C) transfers are presently neglected in these models. Using the Amazon basin as a case study, we show that this negligence leads to significant underestimation of the net uptake of atmospheric C while terrestrial C storage changes are overestimated. These biases arise from the fact that C—in reality, leached from soils and exported through the river network—is instead represented as partly being respired and partly being stored in soils. Moreover, these biases scale mainly to the fluvial C export to the coast, despite aquatic CO2 emission to the atmosphere being the major pathway of riverine C exports. We further show that fluvial C transfers may change significantly in response to changes in either hydrology or in atmospheric C uptake by vegetation.

Drainage increases CO2 and N2 O emissions from tropical peat soils.

Tropical peatlands are vital ecosystems that play an important role in global carbon storage and cycles. Current estimates of greenhouse gases from these peatlands are uncertain as emissions vary with environmental conditions. This study provides the first comprehensive analysis of managed and natural tropical peatland GHG fluxes: heterotrophic (i.e. soil respiration without roots), total CO2 respiration rates, CH4 and N2 O fluxes. The study documents studies that measure GHG fluxes from the soil (n=372) from various land uses, groundwater levels and environmental conditions. We found that total soil respiration was larger in managed peat ecosystems (median=52.3MgCO2 ha-1 year-1 ) than in natural forest (median=35.9MgCO2 ha-1 year-1 ). Groundwater level had a stronger effect on soil CO2 emission than land use. Every 100mm drop of groundwater level caused an increase of 5.1 and 3.7MgCO2 ha-1 year-1 for plantation and cropping land use, respectively. Where groundwater is deep (≥0.5m), heterotrophic respiration constituted 84% of the total emissions. N2 O emissions were significantly larger at deeper groundwater levels, where every drop in 100mm of groundwater level resulted in an exponential emission increase (exp(0.7)kgNha-1 year-1 ). Deeper groundwater levels induced high N2 O emissions, which constitute about 15% of total GHG emissions. CH4 emissions were large where groundwater is shallow; however, they were substantially smaller than other GHG emissions. When compared to temperate and boreal peatland soils, tropical peatlands had, on average, double the CO2 emissions. Surprisingly, the CO2 emission rates in tropical peatlands were in the same magnitude as tropical mineral soils. This comprehensive analysis provides a great understanding of the GHG dynamics within tropical peat soils that can be used as a guide for policymakers to create suitable programmes to manage the sustainability of peatlands effectively.

Effects of grazing exclusion on soil respiration components in an alpine meadow on the north-eastern Qinghai-Tibet Plateau

Grazing exclusion has been widely used to restore degraded grasslands worldwide. Total soil respiration (Rs) (consisting of heterotrophic respiration (Rh, microbes and soil fauna respiration) and autotrophic respiration (Ra, plant root and their symbionts respiration)) play a critical role in the global carbon (C) balance. Quantifying Rs, Rh and Ra in relation to different grazing exclusion durations is vital to better understanding the impact of grassland management on global C cycling. However, how Rs and its components respond to different grazing exclusion durations remain unclear. Therefore, in this study, a trenching method was used to separate the Ra and Rh in an alpine meadow with different grazing exclusion durations (0, 4, 7, 10 and 12 years) on the north-eastern Qinghai-Tibet Plateau. Our results demonstrated that the growing season Rs, Rh and Ra showed nonlinear (hump-shaped) response patterns with the length of grazing exclusion, with a peak point at the 7-year grazing exclusion. Meanwhile, grazing exclusion treatments significantly increased the Rs, Rh and Ra compared to the grazed site. Grazing exclusion substantially increased the soil respiration temperature sensitivity (Q10) values of Rs, Rh and Ra. Moreover, the Q10 values of Ra and Rh showed hump-shaped response patterns with the length of grazing exclusion, with a threshold of 7 years grazing exclusion. The annual Ra/Rs ratio ranged from 53% to 69% during the growing season, indicating that changes in soil respiration were mainly determined by changes in autotrophic respiration. In addition, soil temperature could better explain Rh (R2 = 0.89–0.94) than Ra (R2 = 0.84–0.9). Our research highlights the nonlinear response of Rs, Rh and Ra to the length of grazing exclusion, and suggests that different grazing exclusion durations should be considered for better evaluating the impact of grassland management on global C cycling on the north-eastern Qinghai-Tibet Plateau.

Carbon Organic Content under Organic and Conventional Paddy Field and its Effect on Biological Activities (A Case Study in Pati Regency, Indonesia)

The low organic matter content of paddy soils impacts the declining quality of land. Without the efforts to enrich the soil organic matter (SOM) content, the productivity of paddy fields will decrease or the need for inorganic fertilizers will increase to reach the level of yield. The present research aims to determine the effect of differences in organic and conventional paddy fields management practices on soil organic carbon (SOC) content and biological activities. The research was conducted from July to September 2018 on organic and conventional paddy fields in Dukuhseti Sub-district, Pati Regency, Central Java, Indonesia. Sampling points were taken from six organic samples in the organic paddy fields while the other six samples were taken from conventional paddy fields. The variables observed in this research were organic C, pH, total N soil, total bacterial colonies, soil respiration and microbial biomass C. The results show that the organic C content in the organic paddy field (2.4%) was higher than that of the conventional paddy field (1.8%). The C content of organic paddy fields increased by 0.6%. The differences of the total bacterial colonies, soil respiration and microbial biomass C between organic paddy fields and conventional paddy fields were 11.5 CFU g<sup>-1</sup>, 7.42 mg CO<sub>2</sub> week<sup>-1</sup> and 0.51 µg g<sup>-1</sup>, respectively, because the use of organic farming systems could improve the biological nature of soils and caused biological activity in organic paddy fields to have the highest value compared to conventional paddy fields.

Sifat Biologi Tanah Pada Lahan Aplikasi dan Tanpa Aplikasi Tandan Kosong Kelapa Sawit di Adolina PT. Perkebunan Nusantara IV

Oil palm empty fruit bunches (OPEFB) is one of the solid wastes from the processing of palm oil into crude palm oil. Generally, OPEFB is used as mulch on oil palm plantations. This study aims to compare the soil biological properties on land with the application of OPEFB and land without the application of OPEFB in a depth of 0-20 cm and 20-40 cm. Soil sampling was carried out at Adolina, PT Perkebunan Nusantara IV, in block 06 A (land with the application of OPEFB) and block 06 B (land without the application of OPEFB). The observation parameters are organic matter content, total microbes, and soil respiration. Then, the data analysis results are processed with SPSS version 20. The test was using a t-test. The research results of oil palm empty fruit bunches application with a dose of 35 tons ha-1 which were applied evenly without layering on the oil palm plantations aged 13 years can increased soil organic matter content at a depth of 0-20 cm but does not increase total microbes and soil respiration both at a depth of 0-20 cm and at a depth of 20-40 cm compared with total microbes and soil respiration on land without the application of OPEFB.

The interplay between abiotic factors and below-ground biological interactions regulates carbon exports from peatlands

Climate change projections indicate increases in CO2 emissions and DOC release from peatlands, thereby potentially transforming them from sinks to carbon sources. The individual effects of abiotic and biotic factors on peatland carbon exports and the interactions among all these factors are still poorly understood. Therefore, we conducted a field study over two years in a peatland complex by selecting four habitats differing in their dominant vegetation (shrub, grass, sedge and moss) in order to assess the links between abiotic and biotic factors and carbon release at each habitat. Accounting for the wide variability across habitats allowed us to examine the direct and indirect effects of abiotic and biotic factors on carbon cycling at the ecosystem level (i.e. the whole peatland complex). Results showed that the habitats dominated by vascular plants had the highest microbial and above-ground plant biomass, as well as the highest values of Acari and Collembola biomass, whereas Enchytraeidae biomass was dominant in the moss habitat. Furthermore, at ecosystem level, the SEM explained 75% of the total soil respiration variation and 33% of the DOC variation. Accordingly, soil respiration was directly linked to enchytraeid biomass, with these invertebrates being positively related to soil moisture. In contrast, both soil temperature and soil moisture had direct effects on microbial and Acari biomass, and the interaction between Acari biomass and below-ground plant biomass was responsible for DOC release. These findings provide new insights into the role of soil biota in carbon dynamics in peatlands, by showing that the direct effects of abiotic factors on biotic communities (both plants and soil organisms) determine how much carbon is lost from these systems (either as CO2 e or DOC).

Impact of heavy metal contamination and seasonal variations on enzyme\u2019s activity of Yamuna river soil in Delhi and NCR

Yamuna river is one of the most important rivers of India and is highly polluted. The river water and the adjacent soil are contaminated with various pollutants including heavy metals. Soil enzymes play important role in various bio-geochemical cycles and help in maintaining nutrient availability of soil. They are very sensitive toward changing environment and therefore act as a key indicator of soil health. In the present study, effects of seasonal variations and heavy metals contamination in Yamuna river water were observed on physicochemical properties and enzyme activities of soil. Soil samples were collected from ten different locations, along the course of the Yamuna river in Delhi–NCR, in three different seasons, i.e., summer, rainy and winter. These sampling sites were divided into three segments, up, middle and lower streams. The concentrations of heavy metals were found to be higher than their safe limit at all the ten sampling points. The total organic carbon content and soil respiration was significantly higher in lower stream. Dehydrogenase enzyme activity was higher in winter season, while urease and arginine deaminase enzyme activity was higher in summer season. Dehydrogenase, arginine deaminase and nitrate reductase enzyme activities were higher in lower streams, while urease enzyme shows maximum activity in the up stream. Thus, we conclude that the continuous application of Yamuna water for irrigation may degrade the soil quality.

Effect of various soil cultivation methods on some microbial soil properties

Cultivating the top 0-25 cm soil layer by ploughing cultivating method requires considerable energy, labor, and additional costs. Also, the larger soil surface caused by cultivation, the moisture content of soil can be lost easier. Therefore, in recent years soil loosening cultivation has become gained popularity, particularly to protect the moisture content of soil and reduce the risk of desertification. At the Experimental Station of Debrecen University, known as Látókép (a name, which corresponds approximately to visual image), two cultivation methods have been applied for research: (i) conventional ploughing and (ii) strip and streaked loosening cultivation methods (and variation of this method applying satellite determination of position, RTK system). In this paper, total number of bacteria, soil respiration, biomass carbon and nitrogen, net nitrification, and dehydrogenase activity were measured under irrigated and non-irrigated conditions. The aim of the research was to evaluate the effects of the various cultivation methods. Soil samples were collected in spring (May) and autumn (September). Microbiological effects on the soil resulted from various cultivation methods were compared. Results demonstrate that the loosening cultivation method (strip tillage with loosening) exerts a more favorable effect on the parameters of soil biological activity than the conventional ploughing system. The most significant effect of loosening cultivation system was experienced in the increase of microbial biomass carbon (MBC) and nitrogen (MBN) by over 80%, along with an intensified dehydrogenase activity. Loosening system yielded positive effects on the other examined biological parameters, except for the total bacteria number and soil respiration.

Partitioning of total soil respiration into root, rhizosphere and basal-soil CO2 fluxes in contrasting rice production systems

Soil respiration contributes significantly to ecosystem respiration and is vital in the context of climate change research. In a season-long experiment we studied total soil respiration (TSR) and its partitioning into root respiration, rhizospheric respiration (RhR) and basal-soil respiration in four contrasting rice production systems: irrigated lowland (IL) (cv. Gayatri); organic nutrient managed irrigated lowland (OIL) (cv. Geetanjali); system of rice intensification (SRI) (cv. Swarna); and aerobic rice system (Aerobic) (cv. APO). We considered TSR to be the sum of root respiration, RhR and basal-soil respiration. Irrespective of the rice production system, TSR was higher at panicle initiation stage. Considering all four systems, the RhR contributed the most (59–83%) and basal-soil respiration the least (10–19%) to the TSR. Mean RhR showed the trend of Aerobic > SRI > IL > OIL across the growing seasons and indicated higher rhizosphere activities in the aerobic system. Mean root respiration showed a trend of IL > OIL > SRI > Aerobic and mean basal-soil respiration had SRI > IL > OIL > Aerobic. Soil labile carbon pools and heterotrophic populations were higher in OIL and dehydrogenase activity was higher in SRI. Microbial biomass carbon, readily mineralisable carbon, dehydrogenase activity and the heterotroph population showed positive correlations with RhR. Hence, regulation of RhR is crucial and can be achieved through rhizosphere modifications linked with labile carbon pools and soil enzymatic activities by plant physiological modification or through soil carbon stabilisation.

Soil respiration dynamics in forage-based and cereal-based cropping systems in central Italy

ABSTRACT: Studies that have investigated soil carbon dynamics under Mediterranean conditions are scarce and fragmented and contrasting results have often been reported. This study aimed to fill some gaps in our knowledge by: (i) determining annual dynamics of total (RS) and heterotrophic (RH) soil respiration; (ii) estimating annual cumulative RS and RH; and (iii) investigating the relationships between RS and RH and soil temperature and water content. The study was carried out in central Italy, for a plain and a hilly site, with the focus on two main cropping systems: an alfalfa-based forage system and a wheat-based rotation system. RS and RH showed different dynamics, with spatial and temporal variability across these sites. Estimated annual cumulative RS fluxes were 8.97 and 7.43 t C ha–1 yr–1 for the plain and hilly alfalfa-based sites, respectively, and 4.67 and 5.22 t C ha–1 yr–1 for the plain and hilly wheat-based sites, respectively. The RH components of RS were 4.26 and 3.52 t C ha–1 yr–1 for the plain and hilly alfalfa-based sites, respectively, and 3.89 and 2.45 t C ha–1 yr–1 for the plain and hilly wheat-based sites, respectively. A model with a combination of soil temperature and soil water content explained 43 % to 49 % and 33 % to 67 % of the annual variation of RS and RH, respectively. These findings help to extend our knowledge of Mediterranean cropping systems, although further studies are needed to clarify the effects of management practices on the modelling of soil respiration efflux.

Assessing soil resilience across an agricultural land retirement chronosequence

Reestablishment of perennial vegetation can improve soil conditions on intensively cultivated lands, but the timeframe required to recover uncultivated soil quality is not well understood. This study aimed to measure the recovery of soil physical (bulk density, aggregate stability, and water infiltration rate), biological (total microbial biomass and soil respiration), and chemical (surface soil organic carbon [SOC]) parameters across a 30-year land retirement chronosequence. Soil parameters on lands retired under long- and short-term Conservation Reserve Program (CRP) enrollment periods were compared to undisturbed and actively cropped lands, and chronofunctions were utilized to estimate the time required to achieve uncultivated soil quality. Results showed that short-term enrollment was not sufficient to restore any parameters to uncultivated quality, although bulk density, water infiltration, soil respiration, and total organic carbon (C) levels generally trended toward the undisturbed condition. No significant differences between the uncultivated and 30-year CRP enrollment for aggregate stability and total microbial biomass suggests uncultivated soil quality was restored within 30 years of land retirement. Based on chronofunction analysis, an estimated period of 53 years would be necessary to return bulk density and soil respiration to undisturbed quality on retired land. Water infiltration and SOC had the longest predicted recovery time of 75 and 128 years, respectively. These results suggest soil properties recover at varying rates once retired into perennial grassland systems, and long-term land retirement is necessary to restore soil properties to precultivation condition and maintain high quality soils capable of providing key ecosystem services.

寒温带兴安落叶松林凋落物层对土壤呼吸的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 寒温带兴安落叶松林凋落物层对土壤呼吸的影响 DOI: 10.5846/stxb201811302605 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（31770488） Effect of soil litterfall on soil respiration in cold-temperate Larch forest 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:为了进一步探讨土壤凋落物层对土壤呼吸的影响，用Li-6400对大兴安岭北部3种林型（白桦-落叶松林、樟子松-落叶松林和落叶松纯林）自然状态的土壤呼吸（RS）、去凋落物后的土壤呼吸（RD）以及凋落物呼吸（RL）进行测定，结果表明：凋落物层的去除会使土壤呼吸速率降低，3种林型观测期内平均RS分别为7.32 μmol m-2 s-1、8.55 μmol m-2 s-1和6.66 μmol m-2 s-1，平均RD分别为6.46 μmol m-2 s-1、7.98 μmol m-2 s-1和5.74 μmol m-2 s-1。但去除凋落物后的土壤总呼吸速率较自然状态下分别升高了13.85%、16.21%和13.73%；凋落物的去除并不影响土壤呼吸的季节动态规律，3种林型的RS和RD均呈明显的单峰曲线变化规律，峰值均出现在8月，而RL的季节变化不明显。凋落物的去除对土壤温度和湿度的影响不显著（P>0.05），整个观测期3种林型内凋落物去除后平均土壤温度升高了0.11-0.16℃，平均含水量白桦-落叶松林和落叶松林增幅为2.92%和3.10%，而樟子松-落叶松林则下降了16.39%；RS和RD均与土壤10 cm温度（T10）呈显著正相关，凋落物层的去除使温度对呼吸的影响变大，T10可以解释3种林型RS和RD季节变化的49.7%-57.0%和56.7%-61.3%，而土壤10 cm湿度（W10）对土壤呼吸的影响均较小，且存在林型间的差异。可见，地表凋落物层是森林土壤呼吸的重要部分，凋落物层的有无对土壤呼吸和土壤温湿度都会产生较大影响，研究凋落物呼吸对于土壤呼吸具有重要意义。 Abstract:In order to understand the effect of soil litterfall on soil respiration, the Li-6400 chamber was used to measure the respiration of the soil without treatment(RS), the soil removed litterfall(RD), and the litterfall respiration(RL) in three forest types (Betula platyphylla-Larix gmelinii forest, Pinus sylvestris var. mongolica-Larix gmelinii forest, and pure Larix gmelinii forest) in northern DaXing'an Mountains. The soil respiration rate decreased when the litterfall was removed. In the observation period, the average RS were 7.32 μmol m-2 s-1, 8.55 μmol m-2 s-1, and 6.66 μmol m-2 s-1 in BL, PL, and L, respectively. The average RD were 6.46 μmol m-2 s-1, 7.98 μmol m-2 s-1 and 5.74 μmol m-2 s-1, respectively. However, the total soil respiration rate increased by 13.85%, 16.21%, and 13.73% in BL, PL, and L, respectively. The RS and RD presented a shape of single-peak curve in three forest types, which were not affected by litterfall removing. The peak values of RS and RD appeared in August, while the RL did not show an obvious seasonal dynamic. There was no significant changes (P>0.05) in soil temperature and soil humidity whenever the litterfall was removed or not. The increases in average soil temperature ranged from0.11 to 0.16℃ in three forest types. The average soil humidity increased by 2.92%, 3.10% for BL and L, respectively, while it decreased by 16.39% in PL in the observation period. There were significantly positive correlations between RS and RD and the temperature of top 10 cm(T10), which could explain 49.7%-57.0% of total changes in the seasonal dynamic of RS and 56.7%-61.3% of RD, respectively. However, the influence of the humidity of top 10 cm(W10) on soil respiration was weak and varied in three forest types. The respiration of surface litterfall is an important part of soil respiration. Also, the surface litterfall has great influence on soil respiration, soil temperature, and soil humidity. The study of litterfall respiration is of great significance for soil respiration. 参考文献 相似文献 引证文献

Soil respiration in an irrigated oasis agroecosystem: linking environmental controls with plant activities on hourly, daily and monthly timescales

To investigate the responses of different components of soil respiration to environmental factors at different timescales in a vineyard ecosystem. The trenching method was used to separate total soil respiration (TSR) into autotrophic respiration (AR) and heterotrophic respiration (HR). Soil respiration rates were measured by an LI-8100 automated flux system. On the hourly scale, there were contrasting responses in TSR, HR and AR to soil temperature at 5 cm (ST5), with clockwise hysteresis loop responses of TSR and HR to ST5 but a counterclockwise hysteresis loop between AR and ST5. The daily TSR didn’t exponentially response to ST5 during the growing season. On the monthly scale, the relationship between TSR and ST5 showed a counterclockwise hysteresis loop. Meanwhile, the diel respiration peak lagged the peak of gross primary productivity (GPP), but the monthly peak of TSR preceded the monthly peak of GPP. The daily TSR and the daily soil water content at 5 cm (SWC5) in different months showed a quadratic relationship, but there was an exponential correlation between the monthly TSR and the monthly SWC5. The relationship between soil respiration and environmental factors derived for a specific timescale cannot be directly applied to other timescales.

Total microbes and soil respiration on land without applications and with the application of oil palm empty fruit bunches in different depths

Oil palm empty fruit bunches as a by-product of palm oil fresh fruit bunches processing are generally applied in oil palm plantation areas. This research aim was to determine the effect of oil palm empty fruit bunches application on total microbes and soil respiration. This research used a factorial randomized block design. Factor I is the sampling area, consisting of areas without application and area with the application of oil palm empty fruit bunches (OPEFB). Factor II is the depth of soil sampling, consisting of a depth of 0-10 cm, depth of 10-20 cm, depth of 20-30 cm and depth of 30-40 cm. The total microbes in the area with OPEFB application were 33.373 × 106 CFU ml−1 with soil respiration of 2.257 mg CO2 day−1. On land without OPEFB application, total microbes were 16.64 × 106 CFU ml−1 with soil respiration of 12.20 mg CO2 day−1. On differences in the depth of soil sampling, the highest total microbes were found at a depth of 10-20 cm i.e. 33.998 × 106 with soil respiration of 19.14 mg CO2 day−1. The application of oil palm empty fruit bunches had a positive contribution to increase total microbes and respiration in the soil.

Precipitation variability drives the reduction of total soil respiration and heterotrophic respiration in response to nitrogen addition in a temperate forest plantation

How precipitation mediates the responses of soil respiration (Rs) and its components, i.e., heterotrophic respiration (Rh) and autotrophic respiration (Ra), to N addition remains uncertain. In an 11-year-old temperate larch plantation in northern China, we investigated the responses of Rs, Rh, and Ra to three N-addition rates (i.e., control: no N addition; low N addition: 20 kg N ha−1 year−1; and high N addition: 50 kg N ha−1 year−1) over a 6-year period that experienced high variability in precipitation. In the control plot, Rs and Rh during wet years were significantly higher than values in both normal (by 37% and 62%, respectively) and dry years (by 19% and 39%, respectively). These results indicated that increased precipitation may stimulate soil microbial biomass and activity which in turn increase Rh and thus Rs. Interestingly, Rs was not affected by N addition in normal or dry years, whereas it was negatively affected by N addition in wet years, primarily due to the decrease in Rh during the summer following N addition. Furthermore, N addition significantly increased Ra in the spring of wet years, because the N limitation was largely alleviated after N addition, and thus, roots might be more active due to higher soil water and N availability. Overall, our findings emphasize the importance of incorporating the mediating role of increased precipitation on soil C loss via respiratory processes and corresponding responses to N addition into models, with the goal of reducing uncertainty in the predictions of carbon–climate feedbacks.