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1.
Abiotic regulators of soil respiration in desert ecosystems 总被引：1，自引：0，他引：1
Soil temperature and soil moisture are the most important environmental factors controlling soil respiration in mesic ecosystems.
However, soil respiration and associated abiotic regulators have been poorly studied in desert ecosystems. In this study,
soil respiration was measured using an automated CO2 efflux system (LI-COR 8100), and the effects of soil temperature and moisture on the rate of soil respiration were examined
in six desert sites [three communities—Haloxylon ammodendron, Halostachys caspica and Anabasis aphylla at high (B) and low (A) vegetation coverage respectively]. It was found that soil respiration was significantly and positively
correlated with soil surface temperature. A multi-variable model of soil temperature and soil moisture could explain 61.9%
of temporal variation in soil CO2 efflux at a larger scale. There were significantly negative correlations between soil respiration and soil moisture in Haloxylon ammodendron B and Halostachys caspica B sites, which represented the driest and wettest sites, respectively. The results also showed that soil respiration displayed
obvious diurnal and seasonal patterns during the growing season. The Q10 values for Haloxylon ammodendron A and B, Halostachys caspica A and B, and Anabasis aphylla A and B sites were 1.3, 1.34, 1.58, 1.65, 1.31 and 1.17, respectively, with a cross-site average of 1.39. The results showed
that soil respiration was not positively correlated with soil moisture unlike in most mesic ecosystems. However, soil respiration
in desert ecosystems is less sensitive to temperature variation than most mesic ecosystems as indicated by the lower Q10 values possibly due to energy limitation. 相似文献
2.
Surface coal mining inevitably deforests the land, reduces carbon (C) pool and generates different land covers. To re-establish the ecosystem C pool, post-mining lands are often afforested with fast-growing trees. A field study was conducted in the 5-year-old unreclaimed dump and reclaimed coal mine dump to assess the changes in soil CO2 flux and compared with the reference forest site. Changes in soil organic carbon (SOC) and total nitrogen stocks were estimated in post-mining land. Soil CO2 flux was measured using close dynamic chamber method, and the influence of environmental variables on soil CO2 flux was determined. Woody biomass C and SOC stocks of the reference forest site were threefold higher than that of 5-year-old reclaimed site. The mean soil CO2 flux was highest in 5-year-old reclaimed dump (2.37 μmol CO2 m?2 s?1) and lowest in unreclaimed dump (0.21 μmol CO2 m?2 s?1). Soil CO2 flux was highly influenced by environmental variables, where soil temperature positively influenced the soil CO2 flux, while soil moisture, relative humidity and surface CO2 concentration negatively influenced the soil CO2 flux. Change in soil CO2 flux under different land cover depends on plant and soil characteristics and environmental variables. The study concluded that assessment of soil CO2 flux in post-mining land is important to estimate the potential of afforestation to combat increased emission of soil CO2 at regional and global scale. 相似文献
3.
在2001年秋季对贵州省荔波县茂兰国家喀斯特森林公园林地、草地植被下土壤CO2呼吸释放及岩溶表层泉水HCO3及其δ13C值的变化进行了日动态的野外监测,表明岩溶系统中土-气-水界面间存在着碳交换的日动态变化以及所伴随的同位素交换的变化,这种变化与土温的日动态有密切的关系。林地植被显示了平抑这种日动态幅度的效应,而草地植被则显示响应于温度变化的较灵敏的动态变化。这种短尺度的变化构成了表层岩溶系统对外界条件的灵敏响应,进一步揭示了在生物作用下岩溶地质作用在碳循环过程及其同位素交换上的灵敏性和动态性。其不同植被系统下的日动态差异在解释岩溶沉积记录和讨论岩溶作用与碳循环时值得充分注意 相似文献
4.
The study presents the effect of soil erosion on vegetation, soil accumulation (SA), SA rate (SAR), soil quality, soil mass, and the soil organic carbon (SOC) pool in Brown Andosols and Histosols in a 24-km2 area in southwest Iceland. Undisturbed prehistoric soils were distinguished from disturbed historic soils using tephrochronology. Soil erosion has been severe during historic time (last 1135 yr), resulting in the increase of the soil mass deposited in soils covered by vegetation by a factor of 7.3-9.2 and net loss of soil in unvegetated areas. The SAR correlated positively with SOC sequestration. SOC is easily transported and, given the extensive accumulation of soil, the net effect of burial and subsequent reduction in decomposition is to increase SOC storage. Nevertheless, the increased accumulation and soil depletion has decreased soil quality, including the SOC, and reduced soil resistance to erosion with the depleted SOC contributing to enrichment of atmospheric CO2. The initial terrestrial disturbance was triggered by anthropogenic land use during the Medieval Warm Period, followed by volcanic activity approximately three centuries later. The combination of harsh climate during the Little Ice Age and drastic anthropogenic perturbations has led to land degradation at a catastrophic scale. 相似文献
5.
Release of CO2 from surface ocean water owing to precipitation of CaCO3 and the imbalance between biological production of organic matter and its respiration, and their net removal from surface
water to sedimentary storage was studied by means of a quotient θ = (CO2 flux to the atmosphere)/(CaCO3 precipitated). θ depends not only on water temperature and atmospheric CO2 concentration but also on the CaCO3 and organic carbon masses formed. In CO2 generation by CaCO3 precipitation, θ varies from a fraction of 0.44 to 0.79, increasing with decreasing temperature (25 to 5°C), increasing atmospheric
CO2 concentration (195–375 ppmv), and increasing CaCO3 precipitated mass (up to 45% of the initial DIC concentration in surface water). Primary production and net storage of organic
carbon counteracts the CO2 production by carbonate precipitation and it results in lower CO2 emissions from the surface layer. When atmospheric CO2 increases due to the ocean-to-atmosphere flux rather than remaining constant, the amount of CO2 transferred is a non-linear function of the surface layer thickness because of the back-pressure of the rising atmospheric
CO2. For a surface ocean layer approximated by a 50-m-thick euphotic zone that receives input of inorganic and organic carbon
from land, the calculated CO2 flux to the atmosphere is a function of the CaCO3 and Corg net storage rates. In general, the carbonate storage rate has been greater than that of organic carbon. The CO2 flux near the Last Glacial Maximum is 17 to 7×1012 mol/yr (0.2–0.08 Gt C/yr), reflecting the range of organic carbon storage rates in sediments, and for pre-industrial time
it is 38–42×1012 mol/yr (0.46–0.50 Gt C/yr). Within the imbalanced global carbon cycle, our estimates indicate that prior to anthropogenic
emissions of CO2 to the atmosphere the land organic reservoir was gaining carbon and the surface ocean was losing carbon, calcium, and total
alkalinity owing to the CaCO3 storage and consequent emission of CO2. These results are in agreement with the conclusions of a number of other investigators. As the CO2 uptake in mineral weathering is a major flux in the global carbon cycle, the CO2 weathering pathway that originates in the CO2 produced by remineralization of soil humus rather than by direct uptake from the atmosphere may reduce the relatively large
imbalances of the atmosphere and land organic reservoir at 102–104-year time scales. 相似文献
6.
The effect of precipitation events on inorganic carbon in soil and shallow groundwater,Konza Prairie LTER Site,NE Kansas,USA 总被引：1，自引：0，他引：1
Monthly sampling for 1 year at the Konza Prairie LTER (Long-Term Ecological Research) Site in northeastern Kansas shows a connection between the annual cycles of CO2 in soil air and shallow groundwater DIC (dissolved inorganic C). Soil air CO2 reached 6–7% in July to mid-August, when moisture was not limiting to soil respiration. Following the annual maximum there was a sequential decrease in CO2 in three soil horizons to less than 0.5% because of moisture deficiency in the late summer and temperature decline in the fall and winter. Groundwater pCO2 reached its maximum of 5% in October; the lag-time of 2–3 months may correspond to the travel time of soil-generated CO2 to the water table. The time-variable CO2 caused an annual carbonate-mineral saturation cycle, intensifying limestone dissolution and DIC production when CO2 was high. 相似文献
7.
全球变化条件下的土壤呼吸效应 总被引：52，自引：7，他引：52
土壤呼吸是陆地植物固定CO2尔后又释放CO2返回大气的主要途径，是与全球变化有关的一个重要过程。综述了全球变化下CO2浓度上升、全球增温、耕作方式的改变及氮沉降增加的土壤呼吸效应。大气CO2浓度的上升将增加土壤中CO2的释放通量，同时将促进土壤的碳吸存；在全球增温的情形下，土壤可能向大气中释放更多的CO2，传统的土地利用方式可能是引发温室气体CO2产生的重要原因，所有这些全球变化对土壤呼吸的作用具有不确定性。认为土壤碳库的碳储量增加并不能减缓21世纪大气CO2浓度的上升。据此讨论了该问题的对策并提出了今后土壤呼吸的一些研究方向。其中强调，尽管森林土壤碳固定能力有限，但植树造林、森林保护是一项缓解大气CO2上升的可行性对策；基于现有田间尺度CO2通量测定在不确定性方面的进展，今后应继续朝大尺度田间和模拟程序方面努力；着重回答全球变化条件下的土壤呼吸过程机理；区分土壤呼吸的不同来源以及弄清土壤呼吸黑箱系统中土壤微生物及土壤动物的功能。当然，土壤呼吸的测定方法尚有待改善。 相似文献
8.
Variation characteristics of CO2 in a newly-excavated soil profile,Chinese Loess Plateau: Excavation-induced ancient soil organic carbon decomposition 
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下载免费PDF全文 Soils of the Chinese Loess Plateau(CLP)contain substantial amounts of soil inorganic carbon(SIC),as well as recent and ancient soil organic carbon(SOC).With the advent of the Anthropocene,human perturbation,including excavation,has increased soil CO2 emission from the huge loess carbon pool.This study aims to determine the potential of loess CO2 emission induced by excavation.Soil CO2 were continuously monitored for seven years on a newly-excavated profile in the central CLP and the stable C isotope compositions of soil CO2 and SOC were used to identify their sources.The results showed that the soil CO2 concentrations ranged from 830μL·L-1 to 11190μL·L-1 with an annually reducing trend after excavation,indicating that the human excavation can induce CO2 production in loess profile.Theδ13 C of CO2 ranged from–21.27‰to–19.22‰(mean:–20.11‰),with positive deviation from top to bottom.The range of δ13CSOC was–24.0‰to–21.1‰with an average of–23.1‰.Theδ13 C-CO2 in this study has a positive relationship with the reversed CO2 concentration,and it is calculated that 80.22%of the soil CO2 in this profile is from the microbial decomposition of SOC and 19.78%from the degasification during carbonate precipitation.We conclude that the human excavation can significantly enhance the decomposition of the ancient OC in loess during the first two years after perturbation,producing and releasing soil CO2 to atmosphere. 相似文献
9.
Effects of precipitation pulses on water and carbon dioxide fluxes in two semiarid ecosystems: measurement and modeling 总被引：2，自引：2，他引：0
Jun Fan Scott B. Jones Li Bing Qi Quan Jiu Wang Ming Bin Huang 《Environmental Earth Sciences》2012,67(8):2315-2324
Modeling of soil?Cwater, ?Cheat and ?Ccarbon (C) fluxes provides an important tool for predicting mass and energy transfers based on a hydraulic-, thermal- and C-mass balance approach. Model predictions were evaluated using measured data from two water-limited study sites, one pasture and one supporting an alfalfa crop, to indentify differences between these ecosystems. Soil water content, temperature, and evapotranspiration (ET) data were used to validate soil water dynamics components of a process-based numerical model. Soil surface CO2 efflux estimates (i.e., fluxes from soil respiration) were also made to estimate soil CO2 emissions. The results show that the Hydrus-1D numerical model can be parameterized to simulate the soil hydrodynamics and CO2 fluxes measured at both locations. Rainfall and irrigation events triggering increases in plant root and microbial respiration rates were simulated to recreate observed pulsed CO2 fluxes. There were distinct differences in ET and soil CO2 effluxes between the ecosystems and watering events significantly modified the fluxes. Differences in potential evapotranspiration and soil texture could help explain these discrepancies. The results demonstrate that numerical modeling can be a useful tool for estimating soil surface fluxes in calibrated ecosystems when micrometeorological methods may not be suitable. 相似文献
10.
基于地理加权回归的青藏高原季节冻土区土壤有机碳空间分布研究 总被引：1，自引：0，他引：1
青藏高原土壤有机碳储量（soil organic carbon stocks， SOCS）对于区域生态环境演替具有重要作用， 但是其空间分布数据还比较缺乏， 特别是季节冻土区的数据较少。基于378个土壤剖面数据， 结合与土壤有机碳（soil organic carbon， SOC）相关的地形、 气候以及植被等环境因子， 使用地理加权回归（geographically weighted regression， GWR）模型模拟了青藏高原季节冻土区0 ~ 30 cm、 0 ~ 50 cm、 0 ~ 100 cm和0 ~ 200 cm深度的SOC总量和空间分布。结果表明： 青藏高原季节冻土区SOCS自东南向西北递减， 表层0 ~ 200 cm的SOC总量约15.37 Pg； 季节冻土区不同植被类型SOC从大到小依次为森林、 灌丛、 高寒草甸、 高寒草原和高寒荒漠； 各土壤类型中棕壤、 黑钙土和泥炭土的SOC最大， 而棕钙土、 棕漠土、 灰棕漠土、 风沙土、 石质土、 盐土、 冷钙土、 寒漠土以及冷漠土的SOC最小。研究结果给出了青藏高原季节冻土区SOC的总量、 空间分布及规律， 可为相关地球模式的发展提供基础数据。 相似文献
11.
Marjorie Schulz David Stonestrom Guntram Von Kiparski Corey Lawrence Carrie Masiello Art White John Fitzpatrick 《Applied Geochemistry》2011
Concentrations of CO2 in soil atmosphere and CO2 efflux were measured across a marine terrace soil chronosequence near Santa Cruz, California. Soil development, specifically the formation of an argillic horizon, has created a two-tier soil gas profile in the older terrace soils. The soil above the argillic horizon has seasonal variations in soil CO2 associated with plant respiration. The older soils with dense argillic horizons maintain a year round ～1%CO2 below the argillic horizon. The CO2efflux during the growing season is higher on the older terraces. 相似文献
12.
Biological soil crusts (BSCs) are an important cover in arid desert landscapes, and have a profound effect on the CO2 exchange in the desert system. Although a large number of studies have focused on the CO2 flux at the soil–air interface, relatively few studies have examined the soil CO2 concentration in individual layers of the soil profile. In this study, the spatiotemporal dynamics of CO2 concentration throughout the soil profile under two typical BSCs (algae crusts and moss crusts) and its driving factors were examined in a revegetated sandy area of the Tengger Desert from Mar 2010 to Oct 2012. Our results showed that the mean values of the vertical soil CO2 concentrations under algal crusts and moss crusts were 600–1,200 μmol/mol at the 0–40 cm soil profiles and increased linearly with soil depth. Daily CO2 concentrations showed a single-peak curve and often had a 1–2 h time delay after the maximum soil temperature. During the rainy season, the mean soil CO2 concentration profile was 1,200–2,000 μmol/mol, which was 2–5 times higher as compared to the dry season (400–800 μmol/mol). Annually, soil moisture content was the key limiting factor of the soil CO2 concentration, but at the daily time scale, soil temperature was the main limiting factor. Combined with infiltration depth of crusted soils, we predicted that precipitation of 10–15 mm was the most effective driving factor in arid desert regions. 相似文献
13.
Yu. V. Barkhatov A. A. Tikhomirov S. A. Ushakova V. N. Shikhov S. I. Bartsev A. G. Degermendzhi 《Doklady Earth Sciences》2016,471(1):1168-1170
A sealed vegetation chamber was designed and constructed for physical simulation of climate conditions in the Subarctic zone during the spring–summer time. The small laboratory tundra-simulating ecosystem (TSE) was created for comparative evaluation of the rates of soil respiration and of the total balance of carbon fluxes in tundra ecosystems. The test experiment was performed to study the TSE response to a temperature rise in air and soil by 2°C in terms of the intensity of the СО2 flux. It was shown that this increase in temperature would cause a pronounced shift in the balance of СО2 production and utilization in the ecosystem from near-zero values to a stable generation of 24 μmol/h of CO2 per 1 kg of dry biomass. 相似文献
14.
Reshmi Sarkar 《Environmental Earth Sciences》2018,77(14):530
Increasing CO2 levels and its consequent effects have been prominent with climate change. Three out of ten transgressed planetary boundaries reflect our planet’s status at tipping point. Soil Organic Carbon (SOC) which helps soil supply water and nutrients to plants through roots is inherently related to various ecological systems and needs urgent attention. Although the total SOC globally is more than the total carbon in biosphere and atmosphere, the vulnerability of SOC due to anthropogenic activities is unavoidable. The environmental factors affecting sequestration of SOC, soil fertility, crop production, accelerated SOC removal with rising temperatures, green-house gases emissions and climate change are interrelated. Thus, it is impossible to understand and estimate the various scenarios of impacts on SOC pool with ever-changing ecosystems and related processes in soil environment completely. Based on currently predicted climate change scenarios, if deforestation is controlled and reestablishment is achieved, tropical forests can trap atmospheric CO2 in the cheapest way and function as the largest sink on earth. The agricultural management practices (AMPs), which have been practiced in the last two decades and found helpful are suitable. However, some innovative adaptations such as crop modelling, selecting types of residue to change microbial communities, practices of grassland-grazing and low-C-emission AMPs are also necessary. To achieve the millennium development goals, we must accomplish food security, which relates all 17 sustainable development goals (SDGs) also relays agricultural systems, soil systems, ecosystem services, soil fertility and how best we nurture SOC pool with supportive AMPs. 相似文献
15.
Emma L. Yates Angela M. Detweiler Laura T. Iraci Brad M. Bebout Christopher P. McKay Kathleen Schiro Edwin J. Sheffner Cheryl A. Kelley Jovan M. Tadić Max Loewenstein 《Environmental Earth Sciences》2013,70(3):1047-1056
Alkaline soils occupy approximately 5 % of the Earth’s land surface (7 million km), and this may increase due to the global trend towards increasing desertification, yet the extent to which these soils modulate carbon dynamics on regional and global scales is inadequately studied and poorly understood. Railroad Valley (RRV) playa (Nevada, USA) is a semi-arid playa with highly alkaline soils (pH > 10) and no vegetation. The extreme, alkaline environment and absence of vascular vegetation make RRV an ideal site to investigate the role of physiochemical processes of soil-atmosphere CO2 exchange. Both field and laboratory investigations were conducted. This work shows how the atmospheric CO2 mixing ratio decreases at nighttime at RRV playa to a value well below the average global background CO2 concentration. Laboratory investigations using soil samples collected at RRV playa confirmed that CO2 uptake by RRV playa soils occurs when temperatures are decreased. Both field and laboratory studies suggest that the alkaline RRV soil acts as a CO2 reservoir during colder periods, such as at nighttime. These results highlight the importance of investigating carbon dynamics in previously understudied environments. Given how little information is available on the CO2 flux in desert and semi-arid alkaline ecosystems lacking vegetation, our findings draw attention to these environments as becoming increasingly important for carbon fluxes on regional and global scales. 相似文献
16.
由于广泛而强烈的岩浆作用,我国东部的松辽、渤海湾、莺歌海以及西部的塔里木等盆地中都有富CO2深部流体的活动。富CO2深部流体与碳酸盐岩相互作用可用Duan and Li(2008)所建立的CO2-H2O-CaCO3-NaCl体系的热力学模型来进行模拟计算。计算结果表明,富CO2深部流体在自深部向浅部运移过程中对CaCO3的溶解度会逐渐增加,到达一定深度后溶解度达到最大值,再向浅部溶解度开始逐渐降低; 也就是深部流体具有深部溶蚀碳酸盐岩-浅部沉淀碳酸盐矿物的规律。与浅部地层中的流体发生混合会使流体的CO2含量和盐度降低,会导致CaCO3的沉淀充填; 深部流体进入开启性断裂/裂缝体系中时,由于压力的降低,也会发生CaCO3的沉淀充填。深部流体的CO2含量、盐度、温度和压力的变化影响着实际的溶蚀-充填过程。塔中地区钻井也揭示了深部下奥陶统碳酸盐岩中发育有丰富的溶蚀孔隙,而在相对浅部的奥陶系灰岩和志留系砂岩中见有大量方解石的充填,这是富CO2流体深部溶蚀-浅部充填的一个较好的实例。基于理论和实际分析,本文认为在岩浆火山作用广泛发育的塔里木等盆地中下古生界深部优质碳酸盐岩储层存在的可能性。 相似文献
17.
Cristina Barrón Carlos M. Duarte Michel Frankignoulle Alberto Vieira Borges 《Estuaries and Coasts》2006,29(3):417-426
We measured monthly dissolved oxygen (DO) changes in situ benthic incubations from March 2001 to October 2002 in aPosidonia oceanica meadow and unvegetated sediments of Magalluf Bay (Mallorca Island, Spain) to determine gross primary production (GPP), community
respiration (R), and net community production (NCP). From June 2001 to October 2002, we also measured fluxes of dissolved
inorganic carbon (DIC) and total alkalinity (TAlk). The yearly integrated metabolic rates based on DO changes show that theP. oceanica communities are net autotrophic while the metabolic rates in the unvegetated benthic communities are nearly balanced. Higher
calcium carbonate (CaCO3) cycling, both in terms of production and dissolution, was observed inP. oceanica communities than in unvegetated benthic communities. In theP. oceanica meadow, the annual release of CO2 from net CaCO3 production corresponds to almost half of the CO2 uptake by NCP based on DIC incubations. In unvegetated benthic communities, the annual uptake of CO2 from net CaCO3 dissolution almost fully compensates the CO2 release by NCP based on DIC incubations. CaCO3 dynamics is potentially a major factor in CO2 benthic fluxes in seagrass and carbonate-rich temperate coastal ecosystems. 相似文献
18.
The CO2 concentration of the air in Postojna Cave (400–7900 ppm) is found to be induced by CO2 sources (human respiration contributing?~?20,000–58,000 ppm per breath, outgassing of dripwater and water seeping from the vadose zone/epikarst with a pCO2 values of 5000–29,000 ppm, and underground Pivka River having pCO2 at 2344–4266 ppm) and CO2 dilution (inflow of outside air with a CO2 concentration of?~?400 ppm). Measurements show that sinking Pivka River has the lowest CO2 concentration among plausible CO2 sources but still continuously exceeds the surrounding cave air CO2 concentration. During the winter months, intensive ventilation reduces the cave air CO2 concentration to outside levels (~?400 ppm), even in the centre of the cave system. CO2 dilution is less pronounced in summer (CO2(min)?≈?800 ppm), since the ventilation rate is not as strong as in winter and the outside air that enters the cave through breathing holes and fractures is enriched with soil CO2. During spring and autumn, the daily alternation of the ventilation regime with a smaller rate of air exchange results in yearly cave air CO2 peaks of up to?~?2400 ppm. Some dead-end passages can be much less affected by ventilation, resulting in a cave air CO2 concentration of up to 7900 ppm. The strongest diurnal CO2 peaks due to human respiration were recorded during the spring holidays (increase of up to 1300 ppm day?1), compared to considerably smaller summer peaks despite peak visits (increase of?~?600 ppm day?1). 相似文献
19.
Pedro A. Hernández Germán Padilla Eleazar Padrón Nemesio M. Pérez David Calvo Dácil Nolasco Gladys Melián José Barrancos Samara Dionis Fátima Rodríguez Hirochika Sumino 《Applied Geochemistry》2012
Reported herein are the results of eight soil CO2 efflux surveys performed from 2006 to 2011 at Timanfaya Volcanic Field (TVF), Lanzarote Island with the aim of evaluating the long- and short-term temporal variations of the diffuse CO2 emission. Soil CO2 efflux values ranged from non-detectable up to 34.2 g m−2 d−1, with the highest values measured in September 2008. Conditional sequential Gaussian simulations (sGs) were applied to construct soil CO2 efflux distribution maps and to estimate the total CO2 output from the studied area at the TVF. Soil CO2 efflux maps showed a high spatial and temporal variability. Total CO2 emission rates ranged between 41 and 518 t d−1, February 2011 (winter) being the season when maximum diffuse CO2 emission rates were observed. To investigate the influence of external variables on the soil CO2 efflux, a geochemical station (LZT01) was installed at TVF to measure continuously the soil CO2 efflux between July 2010 and March 2012 Since external factors such as barometric pressure, rainfall, soil water content, soil and air temperatures, and wind speed influence strongly the observed soil CO2 effluxes, multiple regression analysis was applied to the time series recorded by the automatic geochemical station LZT01 to remove the contribution of these external factors. The influence of meteorological variables on soil CO2 efflux oscillations accounts for 13% of total variance, with barometric pressure, rainfall and/or soil water content having the most influence in the control of the soil CO2 efflux. These observations along with the results from the eight soil gas surveys performed at TVF indicate that the short and long-term trends in the diffuse CO2 degassing are mainly controlled by environmental factors. 相似文献
20.
Studying the influence of plants on soil biological variables in an arid zone is important to the understanding of soil processes and relationships between above and below ground. The objective of this study was to quantify the pattern and degree of soil heterogeneity for soil moisture and its relationship with microbial biomass carbon and soil respiration using geostatistical techniques at stand scale of an arid scrubland. The experiment was conducted in a scrubland landscape using a 2 × 2 m grid within a 16 × 14 m plot in the lower reach of Sangong River watershed in Xinjiang, northwest China. The results revealed the following: (1) Soil moisture and soil microbial biomass carbon had moderate spatial variation, but soil respiration had strong variation. Spatial variability of soil moisture in the study plot decreased when soil moisture changed from wet in April to dry in June. In addition, correlations of soil moisture with microbial biomass carbon and soil respiration were positive and significant (p < 0.005). (2) Variation of soil microbial biomass carbon and soil moisture had a strong spatial autocorrelation in the study plot, mainly induced by structural factors, and the spatial autocorrelation of microbial biomass carbon and soil respiration was mainly determined by soil moisture. (3) The location of the high-value positions of soil moisture, soil microbial biomass carbon and soil respiration were clearly around the positions of scrubs in the study plot. Such information provided some insights to explain the spatial heterogeneity of soil properties at stand scale in an arid region. 相似文献