红松阔叶混交林林隙0cm地温的地统计学分析

[目的]揭示小兴安岭红松阔叶混交林林隙0 cm地面温度的时空变化规律。[方法]以小兴安岭原始红松阔叶混交林林隙为研究对象,采用网格法布点,通过对生长季内林隙各样点0 cm地面温度的连续观测,利用基本统计学和地统计学的方法研究林隙0 cm地面温度的时空分布格局。[结果]林隙地面温度不同,空间样点之间存在异质性,且异质性的强度、尺度和空间结构组成随时间的延长而改变,各月0 cm平均地面温度斑块形状复杂,林隙0 cm地面温度从大到小依次为6、7、8、9月,月平均0 cm地温的最大值和最小值分布位置不固定,同一月份地面温度从大到小为空旷地、林隙、郁闭林分。[结论]该研究可为红松阔叶混交林的可持续经营提供基础数据和理论参考。     

Site-Specific Nitrogen Management in Rice Using Remote Sensing and Geostatistics

Proper doses of nitrogenous fertilizer are most important for rice production system because a large part of the nitrogen may be lost if it is not applied judiciously. A study was conducted covering five blocks of Balasore and two blocks of Bhadrak districts. Soil samples were collected randomly, and field visit was conducted during peak vegetative stage of rice. Two approaches have been used in this study for estimating the site-specific nitrogen (N) requirement in the study area. In one approach, geostatisical analysis and kriging was used to develop the soil test–based N recommendation map by which a minimum of 72 kg N ha^?1 and maximum of 94 kg N ha^?1 were recommended. In a second approach, remote sensing was used and N recommendation map was developed using the moderate-resolution imaging spectroradiometer (MODIS) leaf area index (LAI) and normalized difference vegetation index (NDVI) satellite data, and a minimum requirement of 60 kg N ha^?1 and maximum of 120 kg N ha^?1 was estimated through this approach.     

Spatial variability of water retention parameters and saturated hydraulic conductivity in a calcareous Inceptisols (Khuzestan province of Iran) under sugarcane cropping

The objective of this study was to quantify inherent spatial variability and spatial cross-correlation of the van Genuchten retention parameters and saturated hydraulic conductivity (K_s) of surface and subsurface layers in a calcareous Inceptisols (Khuzestan province, Iran) under sugarcane cropping. Measurements were performed on 100-cm³ undisturbed soil cores collected at 94 locations along a 30-m-long transect with horizontal sampling distance intervals of 0.3 and 1 m at soil depths of 0–40 and 40–80 cm, respectively. Spatial variability was investigated using conventional statistics and geostatistical techniques. Coefficient of variation (CV) varied from 8.2% (for shape parameter, n at 40–80 cm depth) to 256.7% (for K_s at 0–40 cm depth). The n parameter and saturated water content, θ_s, showed a small-scale spatial heterogeneity with a maximum CV of 11.3% for the first depth and 9.2% for the second depth. Most of the hydraulic parameters at both depths showed a spatial structure and convex experimental semivariograms with dominant spherical models with the influence range of 3.2–41 m. In most cases, the extent of spatial correlation scales of cross-semivariograms for pairs of cross-correlated hydraulic variables was found to be different with reference to those relating to the direct semivariograms of correlated variables.     

基于地统计学与GIS技术的森林土壤养分空间变异性研究

以云浮市云城区和云安区森林土壤为研究对象，应用传统统计学和地统计学方法结合 GIS 技术分析其土壤养分的空间变异性，预测土壤养分空间分布。地统计学主要从空间插值模型和人工神经网络模型的角度对土壤养分的空间变异性进行诠释，并利用平均绝对误差(MAE)和均方根误差(RMSE)两个指标以及模型预测点与实测点间的相关系数作为判断模型好坏的标准。研究结果认为插值模型中泛克里格插值法在样点密度较小时显示出明显优势，而 BP-ANN 在模型的稳定性和推广性表现尤为突出，最后对泛克里格插值模型和 BP-ANN 下的有机碳、全氮、全磷、全钾4种养分空间预测分布特征进行描述。     

蔬菜地土壤重金属含量空间插值精度分析

蔬菜地土壤重金属含量影响环境安全和人类健康。采用地统计分析和GIS相结合的方法,对研究区土壤重金属镉、汞、铬、砷、铅进行空间插值和精度分析,根据交叉检验参数和相对误差指标比较普通克里格法和协同克里格法的空间预测效果。结果表明:研究区土壤重金属存在中强等变异性,在重金属间显著相关性条件下,普通克里格法对汞、镉、砷含量预测精度较高;协同克里格法对铬和铅含量预测精度较高。建议根据土壤重金属空间变异程度选择合适的空间插值方法。     

区域耕地土壤养分空间变异研究及影响因素分析——以昌宁县为例

借助GIS和地统计学方法对研究区土壤全氮、有效磷、速效钾3种土壤养分的空间变异特征进行了分析,结果表明:全氮、有效磷、速效钾符合指数模型;有效磷、速效钾的块金效应25%相似文献   

A citywide survey of the pine processionary moth Thaumetopoea pityocampa spatial distribution in Orléans (France)

There is a growing recognition that urban trees provide various valuable benefits and services such as enhanced human wellbeing. However, they also have a cost in terms of public health either directly (allergies) or by harboring species representing health risk for humans. This paper focuses on such a forest insect species, the pine processionary moth Thaumetopoea pityocampa. Its caterpillars develop gregariously during winter in a conspicuous silk nest in coniferous hosts. When disturbed, the larvae release urticating hairs that cause human or animal serious health problems. The purpose of our survey was to (1) inventory all individual trees belonging to potential host species and estimate the density of T. pityocampa (2) assess the spatial pattern of the insect population at the city scale. We conducted an exhaustive inventory of potential coniferous host trees in five municipalities (ca. 5000 ha) in the north of Orléans, France. Each tree was identified, geo-referenced and the number of moth nests it hosted was counted. A total of 9321 urban trees representing 11 coniferous taxonomic units were investigated. The distribution of T. pityocampa exhibited a marked spatial structure citywide. Geostatistics allowed to draw risk maps revealing strong patchiness. We provide the first estimate of T. pityocampa host tree preference in an urban context and found that Pinus nigra, P. pinaster and P. sylvestris were the most attacked trees. We also report numerous cases of T. pityocampa occurrence on the exotic ornamental Himalayan cedar Cedrus deodara. The management implications of our findings are two-fold: (1) risk maps constitute a useful framework for communication and public information, and can help developing control strategies; (2) some species frequently used for ornamental purposes are poor quality hosts regarding T. pityocampa and should therefore be preferred in public place usually frequented by vulnerable people (schools, nurseries, hospitals).     

Geostatistical interpolation and aggregation of crop growth model outputs

Many crop growth models require daily meteorological data. Consequently, model simulations can be obtained only at a limited number of locations, i.e. at weather stations with long-term records of daily data. To estimate the potential crop production at country level, we present in this study a geostatistical approach for spatial interpolation and aggregation of crop growth model outputs. As case study, we interpolated, simulated and aggregated crop growth model outputs of sorghum and millet in West-Africa. We used crop growth model outputs to calibrate a linear regression model using environmental covariates as predictors. The spatial regression residuals were investigated for spatial correlation. The linear regression model and the spatial correlation of residuals together were used to predict theoretical crop yield at all locations using kriging with external drift. A spatial standard deviation comes along with this prediction, indicating the uncertainty of the prediction. In combination with land use data and country borders, we summed the crop yield predictions to determine an area total. With spatial stochastic simulation, we estimated the uncertainty of that total production potential as well as the spatial cumulative distribution function. We compared our results with the prevailing agro-ecological Climate Zones approach used for spatial aggregation. Linear regression could explain up to 70% of the spatial variation of the yield. In three out of four cases the regression residuals showed spatial correlation. The potential crop production per country according to the Climate Zones approach was in all countries and cases except one within the 95% prediction interval as obtained after yield aggregation. We concluded that the geostatistical approach can estimate a country’s crop production, including a quantification of uncertainty. In addition, we stress the importance of the use of geostatistics to create tools for crop modelling scientists to explore relationships between yields and spatial environmental variables and to assist policy makers with tangible results on yield gaps at multiple levels of spatial aggregation.     

邛海盆地土壤氮素空间变异特征与影响因素研究

以西昌市邛海盆地为研究区域,随机均匀布点采集386个耕作层土壤样点,分析化验土壤理化性质,运用地统计学方法和GIS技术研究邛海盆地表层土壤氮素含量的空间变异特征,利用方差分析、缓冲区分析和回归分析定量分析区域内土壤氮素空间变异的影响因素。研究结果表明,研究区表层土壤全氮和速效氮含量分别为(1.85±0.51)g/kg和(138.5±47.7)mg/kg,属较丰富水平,变异系数分别为27.52%和32.24%,属中等差异强度;土壤全氮和速效氮具有中等程度的空间相关性,空间变异均以随机变异为主,具有各向异性特征,在西北-东南方向上空间变异相对剧烈;研究区土壤全氮和速效氮含量总体上呈条带状或斑块状分布特征,高值区主要位于西昌市的东南郊区,并以此高值中心向南、向东和向北3个方向逐步递减,低值区主要出现在邛海北面近湖岸地带。影响因素分析结果表明,土地利用方式、土壤母质、土壤质地、土壤p H值、城镇、河流、邛海湖对土壤全氮和速效氮空间变异具有显著影响,而道路对土壤氮素空间变异影响不显著。     

基于GIS的精确农业合理采样与施肥间距研究

在GIS软件平台下对采样点进行行列删减,人为减小采样密度,运用地统计学方法制作养分分布图,并与原始采样方案进行形状和面积对比,选取合理的删减方案作为土壤养分的合理采样方案.碱解氮、速效磷和速效钾的合理采样间距分别为64 m×51 m、32 m×76 m和32 m×25 m.为综合考虑多种养分,提出3条综合采样测土原则.提出了调整施肥间距的实现方法,自动变量施肥宜采用"大网格采样、小网格施肥",手动变量施肥则宜采用"小网格采样、大网格施肥".试验表明提出的方法实现了定性与定量相结合来研究土壤采样间距.