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1.
Estimation of soil organic carbon (SOC) pools and fluxes bears large uncertainties because SOC stocks vary greatly over geographical space and through time.Although development of the U.S.Soil Survey Geographic Database (SSURGO),currently the most detailed level with a map scale ranging from 1:12 000 to 1:63 360,has involved substantial government funds and coordinated network efforts,very few studies have utilized it for soil carbon assessment at the large landscape scale.The objectives of this study were to 1) compare estimates in soil organic matter among SSURGO,the State Soil Geographic Database (STATSGO),and referenced field measurements at the soil map unit;2) examine the influence of missing data on SOC estimation by SSURGO and STATSGO;3) quantify spatial differences in SOC estimation between SSURGO and STATSGO,specifically for the state of Louisiana;and 4) assess scale effects on soil organic carbon density (SOCD) estimates from a soil map unit to a watershed and a river basin scale.SOC was estimated using soil attributes of SSURGO and STATSGO including soil organic matter (SOM) content,soil layer depth,and bulk density.Paired t-test,correlation,and regression analyses were performed to investigate various relations of SOC and SOM among the datasets.There were positive relations of SOC estimates between SSURGO and STATSGO at the soil map unit (R2=0.56,n=86,t=1.65,P=0.102;depth:30 cm).However,the SOC estimated by STATSGO were 9%,33% and 36% lower for the upper 30-cm,the upper 1-m,and the maximal depth (up to 2.75 m) soils,respectively,than those from SSURGO.The difference tended to increase as the spatial scale changes from the soil map unit to the watershed and river basin scales.Compared with the referenced field measurements,the estimates in SOM by SSURGO showed a closer match than those of STATSGO,indicating that the former was more accurate than the latter in SOC estimation,both in spatial and temporal resolutions.Further applications of SSURGO in SOC estimation for the entire United States could improve the accuracy of soil carbon accounting in regional and national carbon balances. 相似文献
2.
HU Peng-Jie GAN Yuan-Yuan TANG Ye-Tao ZHANG Quan-Fang JIANG Dan YAO Nan QIU Rong-Liang 《土壤圈》2012,22(4):497-507
Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon (SOC). SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998-2100 were simulated using stochastic modelling. Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration. Therefore, there was a counteract effect on SOC dynamics between climate warming and elevated CO2 . For different soil erosion extents, warming 1 C and elevated atmospheric CO2 resulted in SOC increase at least 15%, while warming 5 C and elevated CO2 resulted in SOC decrease more than 29%. SOC predictions with uncertainty assessment were conducted for different scenarios of soil erosion, climate change, and elevated CO2 . Statistically, SOC decreased linearly with the probability. SOC also decreased with time and the degree of soil erosion. For example, in 2100 with a probability of 50%, SOC was 1 617, 1 167, and 892 g m 2 , respectively, for no, minimum, and maximum soil erosion. Under climate warming 5 C and elevated CO2 , the soil carbon pools became a carbon source to the atmosphere (P > 95%). The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2 . 相似文献
3.
The priming effect (PE) plays a critical role in the control of soil carbon (C) cycling and influences the alteration of soil organic C (SOC) decomposition by fresh C input.However,drivers of PE for the fast and slow SOC pools remain unclear because of the varying results from individual studies.Using meta-analysis in combination with boosted regression tree (BRT) analysis,we evaluated the relative contribution of multiple drivers of PE with substrate and their patterns across each driver gradient.The results showed that the variability of PE was larger for the fast SOC pool than for the slow SOC pool.Based on the BRT analysis,67%and 34%of the variation in PE were explained for the fast and slow SOC pools,respectively.There were seven determinants of PE for the fast SOC pool,with soil total nitrogen (N) content being the most important,followed by,in a descending order,substrate C:N ratio,soil moisture,soil clay content,soil pH,substrate addition rate,and SOC content.The directions of PE were negative when soil total N content and substrate C:N ratio were below 2 g kg~(-1)and 20,respectively,but the directions changed from negative to positive with increasing levels of this two factors.Soils with optimal water content (50%–70%of the water-holding capacity) or moderately low pH (5–6) were prone to producing a greater PE.For the slow SOC pool,soil p H and soil total N content substantially explained the variation in PE.The magnitude of PE was likely to decrease with increasing soil pH for the slow SOC pool.In addition,the magnitude of PE slightly fluctuated with soil N content for the slow SOC pool.Overall,this meta-analysis provided new insights into the distinctive PEs for different SOC pools and indicated knowledge gaps between PE and its regulating factors for the slow SOC pool. 相似文献
4.
Carbon fractions in soils apparently vary not only in space, but also over time. A lack of knowledge on the seasonal variability of labile carbon fractions under arable land hampers the reliability and comparability of soil organic carbon(SOC) surveys from different studies. Therefore, we studied the seasonal variability of two SOC fractions, particulate organic matter(POM) and dissolved organic carbon(DOC), under maize cropping: POM was determined as the SOC content in particle-size fractions, and DOC was measured as the water-extractable SOC(WESOC) of air-dried soil. Ammonium, nitrate, and water-extractable nitrogen were measured as potential regulating factors of WESOC formation because carbon and nitrogen cycles in soils are strongly connected. There was a significant annual variation of WESOC(coefficient of variation(CV) = 30%). Temporal variations of SOC in particle-size fractions were smaller than those of WESOC. The stocks of SOC in particle-size fractions decreased with decreasing particle sizes, exhibiting a CV of 20%for the coarse sand-size fraction(250–2 000 μm), of 9% for the fine sand-size fraction(50–250 μm), and of 5% for the silt-size fraction(20–50 μm). The WESOC and SOC in particle-size fractions both peaked in March and reached the minimum in May/June and August, respectively. These results indicate the importance of the time of soil sampling during the course of a year, especially when investigating WESOC. 相似文献
5.
中国农田土壤有机碳贮存的空间特征 总被引：2，自引：0，他引：2
The soil organic carbon (SOC) pool is the largest component of terrestrial carbon pools. With the construction of a geographically referenced database taken from the second national general soil survey materials and based on 1546 typical cropland soil profiles, the paddy field and dryland SOC storage among quantified to characterize the spatial pattern of cropland SOC storage in China regions of China were systematically to examine the relationship between mean annual temperature, precipitation, soil texture features arid SOC content. In all regions, paddy soils had higher SOC storage than dryland soils, and cropland SOC content was the highest in Southwest China. Climate controlled the spatial distribution of SOC in both paddy and dryland soils, with SOC storage increasing with increasing precipitation and decreasing with increasing temperature. 相似文献
6.
Desert ecosystems are characterized by sparse vegetation that affects both abiotic parameters and soil biota along the soil profile.This study was conducted in 2010–2011 in a loess plain in the northern Negev Desert highlands, Israel, to test two main hypotheses:1) the abundance and diversity of microarthropods would vary seasonally in the top 30-cm soil layer, but would be relatively stable at soil depths between 30 and 50 cm and 2) soil microarthropods would be more abundant in soils under shrubs with large litter accumulations than under shrubs with less litter or bare soil. Soil samples were collected each season from the 0–50 cm profile at10-cm intervals under the canopies of Hammada scoparia and Zygophyllum dumosum and from the bare interspaces between them.Soil moisture and soil organic carbon in the top 30-cm layers varied seasonally, but there was little variation in the soil layers deeper than 30 cm. Soil mites were most abundant in the top 30-cm soil layer in autumn and winter, with the highest number of families found in winter. There were no differences in soil microarthropod abundance attributable to the presence or absence of shrubs of either species. The microarthropod communities of the microhabitats studied consisted of Acari, Psocoptera, and Collembola. The Acari were mostly identified to the family level and were dominated by Oribatida(55%) and Prostigmata(41%) in all seasons and microhabitats, while the psocopterans were most abundant in summer. These results are opposite to those obtained in other studies in similar xeric environments. Moreover, our findings were not in line with our hypothesis that a better microhabitat played a major role in microarthropod community composition, diversity, and density. 相似文献
7.
Regression models for predicting soil bulk density (BD) have usually been related to organic matter content,but it remains unknown whether soil acidity modifies this relationship,particularly for afforested/reforested soils.We measured soil BD along with organic matter content and pH in an afforested/reforested area in Northwest and Northeast China.Using these measurements,we parameterized and validated three BD models:the Adams equation,and exponential and radical models.Model validation showed that the Adams equation failed to predict the BD of the afforested/reforested soils,producing a large overestimation.Incorporation of soil pH into the Adams equation significantly improved its performance.The exponential and radical models parameterized by the measured data simulated soil BD quite well,particularly when soil pH was incorporated.However,incorporation of soil texture variables into these models did not improve model performance compared with the pH-modified models.This led to the conclusion that the Adams equation,exponential,and radical models with pH modification are applicable to afforested/reforested soils with various acidities. 相似文献
8.
地中海山地土壤中团聚体的形成和有机质的储存 总被引：1，自引：0，他引：1
Soil aggregation and organic matter of soils from the pre-Pyrenean range in Catalonia (NE Spain) were studied, in order to assess their quality as carbon sinks and also to select the best soil management practices to preserve their quality. Aggregate stability, organic carbon and micromorphology were investigated. The highest amount of organic carbon was found in alluvial, deep soils (228 Mg C ha-1), and the lowest was in a shallow, stony soil with a low plant cover (78 Mg C ha-1). Subsurface horizons of degraded soils under pastures were the ones with smaller and less-stable aggregates. Fresh residues of organic matter (OM) were found mostly in interaggregate spaces. Within the aggregates there were some organic remains that were beginning to decompose, and also impregnative nodules of amorphous OM. Although OM was evenly distributed among the aggregate fractions, the larger blocky peds had more specific surface, contained less decomposed OM and had a lower organic/mineral interphase than smaller crumb aggregates, which were also more stable. Soil carbon storage was affected primarily by the OM inputs in the surface horizons. In order to store organic carbon over the mid-and long-term periods, the mechanisms favouring structuration through biological activity and creating small aggregates with intrapedal stable microporosities seemed to be the most effective. 相似文献
9.
Soil heterotrophic respiration and its temperature sensitivity are affected by various climatic and environmental factors.However,little is known about the combined effects of concurrent climatic and environmental changes,such as climatic warming,changing precipitation regimes,and increasing nitrogen(N)deposition.Therefore,in this study,we investigated the individual and combined effects of warming,wetting,and N addition on soil heterotrophic respiration and temperature sensitivity.We incubated soils collected from a temperate forest in South Korea for 60 d at two temperature levels(15 and 20℃,representing the annual mean temperature of the study site and 5℃warming,respectively),three moisture levels(10%,28%,and 50%water-filled pore space(WFPS),representing dry,moist,and wet conditions,respectively),and two N levels(without N and with N addition equivalent to 50 kg N ha-1year-1).On day 30,soils were distributed across five different temperatures(10,15,20,25,and 30℃)for 24 h to determine short-term changes in temperature sensitivity(Q10,change in respiration with 10℃increase in temperature)of soil heterotrophic respiration.After completing the incubation on day 60,we measured substrate-induced respiration(SIR)by adding six labile substrates to the three types of treatments.Wetting treatment(increase from 28%to 50%WFPS)reduced SIR by 40.8%(3.77 to 2.23μg CO2-C g-1h-1),but warming(increase from 15 to 20℃)and N addition increased SIR by 47.7%(3.77 to 5.57μg CO2-C g-1h-1)and 42.0%(3.77 to 5.35μg CO2-C g-1h-1),respectively.A combination of any two treatments did not affect SIR,but the combination of three treatments reduced SIR by 42.4%(3.70 to 2.20μg CO2-C g-1h-1).Wetting treatment increased Q10by 25.0%(2.4 to 3.0).However,warming and N addition reduced Q10by 37.5%(2.4 to 1.5)and 16.7%(2.4 to 2.0),respectively.Warming coupled with wetting did not significantly change Q10,while warming coupled with N addition reduced Q10by 33.3%(2.4 to 1.6).The combination of three treatments increased Q10by 12.5%(2.4 to 2.7).Our results demonstrated that among the three factors,soil moisture is the most important one controlling SIR and Q10.The results suggest that the effect of warming on SIR and Q10can be modified significantly by rainfall variability and elevated N availability.Therefore,this study emphasizes that concurrent climatic and environmental changes,such as increasing rainfall variability and N deposition,should be considered when predicting changes induced by warming in soil respiration and its temperature sensitivity. 相似文献
10.
Most studies on dissimilatory nitrate reduction to ammonium (DNRA) in paddy soils were conducted in the laboratory and in situ studies are in need for better understanding of the DNRA process.In this study,in situ incubations of soil DNRA using 15 N tracer were carried out in paddy fields under conventional water (CW) and low water (LW) managements to explore the potential of soil DNRA after liquid cattle waste (LCW) application and to investigate the impacts of soil redox potential (Eh) and labile carbon on DNRA.DNRA rates ranged from 3.06 to 10.40 mg N kg 1 dry soil d 1,which accounted for 8.55%-12.36% and 3.88%-25.44% of consumption of added NO 3-15 N when Eh at 5 cm soil depth ranged from 230 to 414 mV and 225 to 65 mV,respectively.DNRA rates showed no significant difference in paddy soils under two water managements although soil Eh and/or dissolved organic carbon (DOC) were more favorable for DNRA in the paddy soil under CW management 1 d before,or 5 and 7 d after LCW application.Soil DNRA rates were negatively correlated with soil Eh (P < 0.05,n=5) but positively correlated with soil DOC (P < 0.05,n=5) in the paddy soil under LW management,while no significant correlations were shown in the paddy soil under CW management.The potential of DNRA measured in situ was consistent with previous laboratory studies;and the controlling factors of DNRA in paddy soils might be different under different water managements,probably due to the presence of different microfloras of DNRA. 相似文献
11.
Microbial activity in soil is known to be controlled by various factors. However, the operating mechanisms have not yet been clearly identified, particularly under climate change conditions, although they are crucial for understanding carbon dynamics in terrestrial ecosystems. In this study, a natural incubation experiment was carried out using intact soil cores transferred from high altitude(1 500 m) to low(900 m) altitude to mimic climate change scenarios in a typical cold-temperate mountainous area in Japan. Soil microbial activities, indicated by substrate-induced respiration(SIR) and metabolic quotient(q CO2), together with soil physicalchemical properties(abiotic factors) and soil functional enzyme and microbial properties(biotic factors), were investigated throughout the growing season in 2013. Results of principal component analysis(PCA) indicated that soil microbial biomass carbon(MBC) andβ-glucosidase activity were the most important factors characterizing the responses of soil microbes to global warming. Although there was a statistical difference of 2.82 ℃ between the two altitudes, such variations in soil physical-chemical properties did not show any remarkable effect on soil microbial activities, suggesting that they might indirectly impact carbon dynamics through biotic factors such as soil functional enzymes. It was also found that the biotic factors mainly controlled soil microbial activities at elevated temperature,which might trigger the inner soil dynamics to respond to the changing environment. Future studies should hence take more biotic variables into account for accurately projecting the responses of soil metabolic activities to climate change. 相似文献
12.
Grassland ecosystems contain ∼12% of global soil organic carbon (C) stocks and are located in regions where global climate change will likely alter the timing and size of precipitation events, increasing soil moisture variability. In response to increased soil moisture variability and other forms of stress, microorganisms can induce ecosystem-scale alterations in C and N cycling processes through alterations in their function. We explored the influence of physiological stress on microbial communities by manipulating moisture variability in soils from four grassland sites in the Great Plains, representing a precipitation gradient of 485-1003 mm y−1. Keeping water totals constant, we manipulated the frequency and size of water additions and dry down periods in these soils by applying water in two different, two-week long wetting-drying cycles in a 72-day laboratory incubation. To assess the effects of the treatments on microbial community function, we measured C mineralization, N dynamics, extracellular enzyme activities (EEA) and a proxy for substrate use efficiency. In soils from all four sites undergoing a long interval (LI) treatment for which added water was applied once at the beginning of each two-week cycle, 1.4-2.0 times more C was mineralized compared to soils undergoing a short interval (SI) treatment, for which four wetting events were evenly distributed over each two-week cycle. A proxy for carbon use efficiency (CUE) suggests declines in this parameter with the greater soil moisture stress imposed in LI soils from all four different native soil moisture regimes. A decline in CUE in LI soils may have been related to an increased effort by microbes to obtain N-rich organic substrates for use as protection against osmotic shock, consistent with EEA data. These results contrast with similar in situ studies of response to increased soil moisture variability and may indicate divergent autotrophic vs. heterotrophic responses to increased moisture variability. Increases in microbial N demand and decreases in microbial CUE with increased moisture variability observed in this study, regardless of the soils’ site of origin, imply that these systems may experience enhanced heterotrophic CO2 release and declines in plant-available N with climate change. This has particularly important implications for C budgets in these grasslands when coupled with the declines in net primary productivity reported in other studies as a result of increases in precipitation variability across the region. 相似文献
13.
稻田土壤碳循环是我国陆地生态系统碳循环的重要组成部分。促进稻田生态系统碳的固定及稳定对减缓全球气候变化起着不容忽视的作用。微生物主导的有机碳转化过程是土壤碳循环研究的核心,微生物同化代谢介导的细胞残体迭代积累在土壤有机碳长期截获和稳定过程中发挥重要作用。与旱地土壤相比,关于稻田土壤中微生物残体积累动态对外源有机物质如作物秸秆输入的响应及主要影响因子的认识还相对有限,对微生物通过同化作用参与土壤固碳的过程和机制尚缺乏系统认识。基于此,本文介绍了微生物残体对土壤有机碳库形成和积累的重要性及评价指标,重点探讨了秸秆还田对稻田土壤微生物残体积累动态以及外源秸秆碳形成细胞残体转化过程的影响,分析了影响微生物残体积累转化的主要气候因素和土壤因素,最后提出了未来应借助先进的光谱和高分辨率成像技术并结合同位素示踪对微生物残体的稳定性与机理开展更为深入的研究。 相似文献
14.
植被恢复是影响土壤有机碳库动态变化的关键过程之一,阐明植被恢复过程中土壤有机碳的固持动态及其驱动机制,是全球变化下碳循环研究的热点和前沿问题。本文综述了近年来国内外关于植被恢复过程中土壤有机碳固定动态及其驱动机制方面的研究,剖析植被恢复中土壤有机碳固持动态及其影响因素,探讨植物碳输入对土壤有机碳动态变化的影响机制,揭示植被恢复中土壤有机碳固定的物理、化学和微生物驱动机制,并对目前研究中存在的问题进行总结,进而提出关于植被恢复的土壤固碳效应研究,亟需在土壤有机碳组分的动态、微生物结构和功能,以及植物—土壤—微生物对土壤有机碳固持的协同作用机制等方面进一步加强。本综述可为植被恢复与土壤固碳稳定机制研究指明未来的方向,进而为促进我国植被恢复的土壤碳循环研究,科学评价生态系统土壤固碳潜力和有效实施生态系统碳汇管理提供科学参考。 相似文献
15.
宁夏环香山地区压砂地土壤微生物结构及功能多样性研究 总被引：2，自引：1，他引：2
对压砂地不同利用年限下的土壤微生物群落结构及功能多样性进行了分析。研究结果表明,压砂地不同利用年限的土壤微生物群落总菌数整体上明显低于农田对照,且随着压砂利用年限的增加土壤微生物总菌数呈逐年下降的趋势。压砂利用1~3a,5~10a,10~15a之间均存在显著差异<0.05)。压砂第1a对土壤微生物的功能影响很大,能明显提高微生物对C源的利用能力。压砂1a后,随着压砂利用年限的增加土壤微生物的功能明显下降,且不同压砂年限间的微生物功能差异不显著,说明农田压砂初期由于土地利用方式的改变,提高了土壤蓄水保墒及增温效果,使得土壤微生物物功能和利用强度增加,随着压砂地利用年限的增加作物对土壤养分消耗增大,而土壤中养分得不到补充,使得压砂地土壤微生物环境逐步恶化。 相似文献
16.
Owais Ali WANI Shamal Shasang KUMAR Nazir HUSSAIN Anas Ibni Ali WANI Subhash BABU Parvej ALAM Megna RASHID Simona Mariana POPESCU Sheikh MANSOOR 《土壤圈》2023,33(2):250-267
Carbon(C) is a key constitutive element in living organisms(plants, microbes, animals, and humans). Carbon is also a basic component of agriculture because it plays a dynamic role in crop growth, development, nutrient cycling, soil fertility, and other agricultural features. The presence of C enhances soil physical, chemical, and biological properties. The C cycle supports all life on the Earth by transferring C between living organisms and the environment. The global climate is changing, and th... 相似文献
17.
Lei ZHOU Yonghong WU Junzhuo LIU Pengfei SUN Ying XU Jan DOLFING Robert G.M. SPENCER Erik JEPPESEN 《土壤圈》2024,34(1):36-43
Paddy fields play an important role in global carbon(C) cycling and are an important source of methane(CH4) emissions. Insights into the processes influencing the dynamics of soil organic C(SOC) in paddy fields are essential for maintaining global soil C stocks and mitigating climate change. Periphytic biofilms composed of microalgae, bacteria, and other microorganisms are ubiquitous in paddy fields, where they directly mediate the transfer of elements at the soil-water interface. How... 相似文献
18.
Wenlong Zhao Guojun Sun Fengmin Li 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(8):720-731
Abstract Estimation of the sensitivity for soil organic carbon to climate change is critical for evaluating the potential response of the terrestrial biosphere to global change. In this study, we integrated CENTURY 4.5 model with GIS to assess the soil organic carbon sensitivity to climate variable shifting and atmospheric carbon dioxide enrichment in northern Chinese grasslands. The response of top soil (0–20 cm) organic carbon to climate change depended on the relative sensitivity of net primary productivity and soil respiration. A 4°C increase in soil temperature led to a loss of 4.7% of soil organic carbon in the Alpine Meadow region, but the same temperature increase led to a maximum loss of only 2.3% of soil organic carbon in the Temperate Steppe region. The effects of precipitation changes on soil organic carbon were varied depending on the moisture level of the local grassland system. The direct effect of carbon dioxide enrichment was to reduce carbon loss throughout northern Chinese grasslands, especially in droughty regions. Alpine Meadow was the most sensitive region under climate change, and it will become the biggest potential carbon source in Chinese grasslands as climate warming continues to occur. Increased atmospheric carbon dioxide concentrations led to net carbon sequestration in all grasslands and tended to diminish the carbon loss driven by precipitation and temperature changes. 相似文献
19.
生物有机肥对土壤微生物活性的影响 总被引：39，自引：0，他引：39
通过两次连续温室玉米盆栽试验,研究了施用具有调节微生物功能的生物有机肥对土壤微生物数量与活性的影响,并利用传统平板计数法与BIOLOGECO方法相结合研究生物有机肥对土壤微生物生态的影响。结果表明,与化肥相比,施用生物有机肥可显著提高土壤微生物中3大菌群的数量;AWCD值及微生物对不同碳底物利用水平的测定结果表明,施用生物有机肥可明显提高土壤微生物对碳源的利用率,尤其土壤中的羧酸、胺类和其他类碳源等。表明生物有机肥的施用能增加土壤微生物利用碳源能力,改善微生物营养条件,使微生物保持较高活性,提高土壤微生物多样性。 相似文献
20.
土壤呼吸是陆地生态系统碳循环中的一个重要过程,也是陆地生态系统最大的二氧化碳释放源,对全球气候和环境变化产生重要影响。对国内外关于陆地生态系统土壤呼吸影响因素的研究进行综述,分析了温度、水分、土壤性质等非生物因素,植被、土壤微生物、土壤动物等生物因素以及人类活动等对土壤呼吸产生的影响。最后分析了目前有关土壤呼吸研究中存在的问题,并提出了今后努力的方向:改进和创新土壤呼吸的测量方法,拓宽土壤呼吸的研究范围,加强土壤呼吸组分的区分研究,重视人类活动对土壤呼吸影响的研究。 相似文献