共查询到20条相似文献,搜索用时 15 毫秒
1.
Vanesa Gonzalez-Quiñones Natasha C. Banning Daniel V. Murphy 《Soil biology & biochemistry》2009,41(7):1574-1576
Following collection of soil, storage prior to analyses is often required where the microbial community is unlikely to remain stable. We assessed the change in microbial community level physiological profiles (CLPP) during cold storage at 4 °C between 3 and 101 days. We hypothesized that the microbial community in soils containing less carbon would be affected more rapidly by storage. In particular we wanted to ascertain whether variability in CLPP through time masked inherent differences between soils derived from different ecosystems. Results illustrated that whilst total CO2 evolution did vary with incubation time, significant differences in microbial community structure were detected between ecosystems for all times. Thus storage time did not mask intrinsic differences in microbial community structure between ecosystems. 相似文献
2.
3.
常规岩土体变化监测方法的局限性造成采用它们来实施大型库区及周边地表形变的持续监测非常困难.为了解决大型水电站库区岩土体的高效实时变化监测这一关键问题,选取乌东德水电站库区为研究区域,根据岩土体变化类型,分别采用D-InSAR技术和假彩色合成技术对库区进行监测,提取出变动区域.最后通过2种方法的监测结果与地面验证结果的比较,验证了变化地点和岩土变动类型与分析结果相一致,达到了发现变化、监视趋势的遥感监测目的.证明了D-InSAR技术和假彩色合成技术相结合用于监测广域岩土体变化的可行性. 相似文献
4.
Detecting small temporal change of spatially varying soil properties demands precise estimation. Design– and model–based methods are compared for estimating temporal change of soil properties over finite areas. Analytical expressions for the estimators and their variances arc derived for the two approaches, and formulae for the expectations of the variances under the random–process model are developed. Among the randomized designs simple, stratified, and systematic random sampling using the arithmetic mean as estimator have been studied. Pairing the sampling positions on the different occasions increases the precision of design–based estimation if the observations are positively cross–correlated. The relative precisions of the means of stratified and systematic samples depends on the spatial correlation. Neither is more precise than the other in all circumstances. The stratified design provides an unbiased estimator for the sampling error, which is not available from systematic samples. Theoretically, the geostatistical global estimator is more precise than the estimates derived from any of the classical designs when many realizations arc repeatedly sampled at random. In practice, with only a single realization of the process, this is no longer relevant. Moreover, errors in estimating the variograms add to the total error of the method. It seems that only by sampling from large auto–correlated random fields can the precisions of the methods be compared in practice. 相似文献
5.
潮土小麦和玉米Olsen-P农学阈值及其差异分析 总被引:5,自引:2,他引:5
6.
Jianyong Wang Yingxia Liu Shaoming Wang Huiming Liu Guangqiang Fu Youcai Xiong 《Soil Use and Management》2020,36(1):93-103
Understanding the watershed-scale spatial distribution of soil salinity and its compositions is important for soil management. Here, we present the first study on the Manas River watershed in northwest China. In this study, we took soil samples in upper 20 cm of soil from 186 locations across the watershed and measured total salt concentration (TSC), salt ion composition and soil particle size distribution (PSD). We found that on average topsoil TSC tended to increase, from 3.55 g kg−1 in upstream regions to 19.40 g kg−1 in downstream regions. The stoichiometric analysis showed that the equivalence ratio of soil Cl- to SO42− increased from 0.53 in upstream regions to 2.12 in midstream regions, and further to 3.76 in downstream regions; thus, the soil types were classified into chloride–sulfate, sulfate–chloride and chloride soils types, respectively. Additionally, proportions of small (<2 μm in diameter) and large (>2,000 μm) soil particles increased, while that of medium sizes (2–50 μm) decreased from upstream to downstream, with an increasing coefficient of variance (CV) in PSD. Taken together, watershed-scale topsoil salinity may be horizontally characterized by increased TSC and Na+ & Cl− proportions, greater equivalence ratio of Cl− vs. SO42− and more balanced distribution of PSD along with surface water flow. Results demonstrated that soil salinity and its ions compositions showed a great variation across the watershed scale, suggesting that soil management may consider the spatial heterogeneity of saline–alkaline soil types, and our results provided scientific guidance for local soil management and restoration. 相似文献
7.
Design-based and model-based methods of estimating temporal change of soil properties over a finite area have been compared. Two large fields of auto- and cross-correlated data were simulated, each representing the spatial distribution of a variable at one time. The fields were then sampled repeatedly. The means of stratified and systematic random samples and geostatistical global estimates were used to infer the mean difference between the fields. All estimators were unbiased, but their variances differed. Pairing the positions on the two occasions increased the precision of the design–based estimates. Systematic sampling was slightly more precise than stratified sampling. Kriging was less precise than both because some of the sample information must be used to estimate the variograms at short lags. Neither balanced differences nor the normal formula for simple random sampling predicted the estimation variances of small (n< 50) systematic samples accurately. For larger samples the method of balanced differences performed well. If the spatial variation is unknown in advance and only small samples can be taken then stratified random sampling with two observations per stratum is the preferred design. It resulted in the best combination of precision and accuracy in predicting the sampling error. 相似文献
8.
Soil biology,soil ecology,and global change 总被引:2,自引:0,他引:2
Summary This overview paper addresses aspects of scaling in space and time, and scaling in relation to micro-and macrohabitats. Ecological processes in soils are examined for possible generalizations about processes and organisms, across a wide range of different habitats. Problems of scaling in space and time that have an important impact on processes associated with global change are outlined. 相似文献
9.
I. Aalders R. L. Hough W. Towers H. I. J. Black B. C. Ball B. S. Griffiths D. W. Hopkins A. Lilly B. M. McKenzie R. M. Rees A. Sinclair C. Watson & C. D. Campbell 《European Journal of Soil Science》2009,60(5):833-843
Two contrasting phases of work are described that help inform the development and requirements of a soil monitoring system: firstly, the development and application of a multi-criterion analysis of soil quality indicators grounded in the basic natural sciences; and secondly, scrutiny of the outcome of that process by a wide range of non-specialist but key stakeholders at a workshop. This process ensures that the final monitoring design meets both the scientific rigour expected from a monitoring system and as far as possible meets the aspirations of policy and regulatory stakeholders. Individual indicators of soil quality were evaluated in terms of their applicability against a number of important environmental and logistical parameters and therefore their overall fitness for purpose. These included relevance to different soil types, functions, habitats and threats to soil, the inherent variability of soil, and a range of technical aspects such as analytical complexity, precision and reproducibility of analytical results and whether a standard operating procedure (SOP) existed for the technique. A tiered approach to soil monitoring was supported by workshop delegates. This will require indicators that are suitable and effective at national, site-specific and process-level scales. In addition, the opportunities for synchronizing soil monitoring with air and water quality monitoring should be considered and the potential for integrating on-site measurements with remote methods should be researched further. It was considered by workshop attendees that soil monitoring should be rooted in pedological principles (i.e. recognizing defined soil horizons) to ensure that results can be extrapolated from individual sites and to retain flexibility. 相似文献
10.
Eric Paterson 《Soil biology & biochemistry》2009,41(6):1352-1354
The paper by Kemmitt et al. [2008. Mineralization of native soil organic matter is not regulated by the size, activity or composition of the soil microbial biomass - a new perspective. Soil Biology and Biochemistry 40, 61-73] proposing the existence of an abiotic regulatory gate that controls the rate-limiting step of stabilised soil organic matter (SOM) mineralization, has initiated a fundamental and far-reaching debate. In this contribution the implications of a functioning abiotic regulatory gate are considered in the context of microbial community diversity and soil carbon cycling. I argue that although the evidence presented in support of the regulatory gate is strong, abiotic routes for SOM-mineralization function in parallel with biologically mediated mechanisms. Evidence is now accumulating that, in the presence of plant-inputs to soil, enhanced microbial mobilisation of SOM into biomass is a quantitatively important and ubiquitous process. I argue that this mineralization of SOM is fuelled by energy-rich substrates and is driven by microbial nutrient-demand. This implies that the mineralization of stabilised SOM and the turnover of C-inputs from current vegetation are intimately linked through the functioning of microbial communities associated with plants. This suggests that the microbial ‘eye of the needle’ is a crucial control-point in determining the carbon balance of soils. Fortunately, there are now excellent methods that allow quantification of SOM- and plant-derived C-fluxes through the members of soil microbial communities, and will also allow quantification of the relative importance of the abiotic and biotic routes of SOM-mineralization. 相似文献
11.
Human activities have had pronounced impacts on soil properties. Conifer afforestation in the uplands has caused significant decreases in soil pH and in the quality and turnover of organic matter. Acid deposition has increased soil acidity by a similar amount to conifer afforestation but has been shown to affect soils at greater depths. Acid deposition has also increased the mobility of trace metals in the soil and therefore increased metal concentrations in drainage waters. Applications of sewage sludge to the soil have been shown to increase metal concentrations, although most of the Scottish soils affected have high trace metal binding capacities. Intensification of arable cultivation in the lowlands has reduced organic matter concentrations, structural stability and soil workability, and has had effects on soil erodibility. Human trampling, while highly localised, affects sensitive mountain soils in popular areas, leading to loss of surface organic horizons, and therefore, carbon storage. The future impacts of human activities on the soil may be exacerbated by changing climate, and the need to monitor and predict these will not diminish. 相似文献
12.
Soil carbon stocks are commonly quantified at fixed depths as the product of soil bulk density, depth and organic carbon (OC) concentration. However, this method systematically overestimates OC stocks in treatments with greater bulk densities such as minimum tillage, exaggerating their benefits. Its use has compromised estimates of OC change where bulk densities differed between treatments or over time periods. We argue that its use should be discontinued and a considerable body of past research re‐evaluated. Accurate OC estimations must be based on quantification in equivalent soil masses (ESMs). The objective of this publication is to encourage accurate quantification of changes in OC stocks and other soil properties using ESM procedures by developing a simple procedure to quantify OC in multiple soil layers. We explain errors inherent in fixed depth procedures and show how these errors are eliminated using ESM methods. We describe a new ESM procedure for calculating OC stocks in multiple soil layers and show that it can be implemented without bulk density sampling, which reduces sampling time and facilitates evaluations at greater depths, where bulk density sampling is difficult. A spreadsheet has been developed to facilitate calculations. A sample adjustment procedure is described to facilitate OC quantification in a single equivalent soil mass layer from the surface, when multiple‐layer quantification is not necessary. 相似文献
13.
14.
Ken Cullings 《Soil biology & biochemistry》2010,42(11):1976-1981
We used a combination of molecular, culture and biochemical methods to test the hypothesis that severe infection of pine by dwarf mistletoe (genus Arceuthobium) has significant effects on structure and function of soil fungal communities, and on carbon cycling in soils. PCR and DNA sequencing of the basidiomycete communities in paired blocks of uninfected and infected trees revealed: (1) that the top, organic soil layer in this system is inhabited almost exclusively by ectomycorrhizal fungi; (2) no difference in species richness (6 species core−1 in both) or Shannon-Wiener evenness (0.740 and 0.747 in uninfected and infected blocks respectively), however Shannon-Wiener diversity was significantly greater in infected blocks (1.19 vs 1.94 in uninfected and infected blocks respectively, P < 0.05); (3) significant differences in basidiomycete species composition, with nearly complete absence of two system co-dominant Russula species in infected blocks, and replacement of one co-dominant Piloderma species with another in infected plots, indicating physiological variability within the genus. Soil fungal physiological diversity measured using the Fungilog system was significantly greater in terms of both number of carbon substrates used by culturable soil fungi (both ascomycetes and basidiomycetes) in infected blocks, and the rate at which these substrates were used. Soil enzyme assays revealed greater laccase, peroxidase, and cellulase activities in soils associated with infected trees. Thus, event cascades associated with severe dwarf mistletoe infection not only significantly affected soil fungal species composition and increased species diversity, but also impacted on carbon-related function and functional diversity. Given the geographic range of this pathogen, and forecasts that epidemics of this disease will increase in range in severity with global climate change, these effects have the potential to significantly impact local and global carbon budgets. 相似文献
15.
16.
土壤侵蚀监测一直是遥感和地理信息系统应用的一个重要领域。纵观国内外土壤侵蚀遥感监测方法,概括起来有遥感影像目视解译监测法、遥感光谱分析监测法、人机交互式解译监测法、智能化土壤侵蚀监测法和模型参数化监测法5种。分析各种方法的优势及其在实际应用中所面临的困难,提出基于知识库与空间信息耦合的土壤侵蚀监测方法,以满足水土保持及其管理工作的需要。 相似文献
17.
Atmospheric general circulation models (GCMs) project that increasing atmospheric concentrations of CO2 and other greenhouse gases May, result in global changes in temperature and precipitation over the next 40-100 years. Equilibrium climate scenarios from four GCMs run under doubled CO2 conditions were examined for their effect on the climatic potential for sheet and rill erosion in the conterminous USA. Changes in the mean annual rainfall factor (R) in the Universal Soil Loss Equation (USLE) were calculated for each cropland, pastureland and rangeland sample point in the 1987 National Resources Inventory. Projected annual precipitation changes were assumed to be from differences in either storm frequency or storm intensity. With all other USLE factors held constant these changes in R translated to changes in the sheet and rill erosion national average of +2 to +16 per cent in croplands, -2 to +10 per cent in pasturelands and -5 to +22 per cent in rangelands under the eight scenarios. Land with erosion rates above the soil loss tolerance (T) level and land classified as highly erodible (eredibility index >8) also increased slightly. the results varied from model to model, region to region and depended on the assumption of frequency versus intensity changes. These results show the range of sensitivity of soil erosion potential by water under projected climate change scenarios. However, actual changes in soil erosion could be mitigated by alterations in cropping patterns and other management practices, or possibly by increased crop growth and residue production under higher atmospheric CO2 concentrations. 相似文献
18.
《Communications in Soil Science and Plant Analysis》2012,43(9-10):965-980
Abstract Vertical leaching of Na+ and Br‐ in a yellow podzolic soil has been studied in the field following an application of 370 kg ha‐1 NaBr. Soil cores to a depth of SO cm were collected on three occasions. Each core was divided into 2.5‐cm segments, and solution and exchangeable ions (Na+, Ca2+, Mg2+, K+, Br‐and Cl‐) were extracted from each segment using a centrifuge technique. The extraction technique was easy to use, and provided valuable information on the mechanisms influencing cation and anion distributions in the solution and exchange phases as a function of depth. The resulting distribution of exchangeable Na+ with depth was satisfactorily predicted using a simple mathematical model. 相似文献
19.
考虑冠层温度变化的时滞效应,可能在一定程度上能够提高土壤含水率的监测精度。该研究以灌浆期的夏玉米为研究对象,利用精密红外温度传感器(SI-411)连续监测I1(田间持水量的85%~100%)、I2(田间持水量的70%~85%)和I3(田间持水量的50%~65%)3个不同水分处理下的冠层温度,并同步获取试验地地面净辐射、大气温度、空气相对湿度等环境因子数据,以及不同水分处理小区0~10、0~20、0~30、0~40、0~60 cm不同深度处土壤含水率数据,利用高斯函数拟合冠层温度及环境因子日变化过程以此确定拟合曲线的峰值时刻,通过峰值时间差确定两者之间的时滞关系,并利用多元线性回归分析确定冠层温度的主要影响因素,最后在考虑冠层温度与主要影响因素之间时滞关系的基础上,分析冠层温度变化的时滞效应对监测土壤含水率的影响。结果表明:不同水分处理下的冠层温度峰值具有较大差异,峰值大小依次为I3、I2、I1;I1、I2、I3水分处理的冠层温度峰值时刻分别滞后净辐射约70、70、100 min,超前大气温度和相对湿度约60、60、30 min;冠层温度变化的主要影响因素为大气温度,其次为地面净辐射,最后为相对湿度;考虑时滞效应的冠气温差与土壤含水率的相关性更高,考虑时滞效应的冠气温差对土壤含水率的监测效果有一定提升。研究可为利用作物生理特性提高土壤水分监测精度提供参考。 相似文献