Application and comparison of spatial models in analyzing tree-genetics field trials

1990 ◽  
Vol 20 (5) ◽  
pp. 536-546 ◽  
Author(s):  
Steen Magnussen
Keyword(s):  
Classical Model ◽  
Substantial Reduction ◽  
Spatial Models ◽  
Tree Height ◽  
Process Models ◽  
Spatial Process ◽  
Spatial Analyses ◽  
Spatial Covariance ◽  
Significant Difference ◽  
Tree Genetics

Tree height of jack pine full-sib families, originating from all possible combinations of three parental provenances and growing on three sites, was analyzed with 1 classical model and 11 nearest-neighbour spatial process models. Extension of the classical linear model with spatial interaction terms was deemed necessary in light of significant neighbourhood correlations among effect-free observations (residuals) on two of the three sites. The strength and extent of spatial and temporal correlations are demonstrated in both visual and tabular form. Only 4 of the 11 spatial models provided a substantial reduction (5–20%) in the significant difference between two estimates of full-sib family tree height. Spatial adjustments averaged 1–3% at the family level, with few families adjusted by more than 10%. The cumulative (temporal) effect of spatial covariance was demonstrated in rank correlations between adjusted and observed family means. No simple trends were obtained when adjusted variance components and heritabilities were compared with their unadjusted counter-parts, but most models tended to deflate genetic effects and reduce heritabilities. It is concluded that although spatial analyses provide an attractive tool for the experimenter, the lack of a cause and effect hypothesis in forest genetic trials necessitates model searching without the guarantee of true treatment effects. Spatial analysis provides good indicators of the need to collect additional site information for more powerful analyses. Careful planning and intensive site preparation may greatly reduce spatial covariances and the need for spatial analyses.

scholarly journals Effects of habitat edges on vegetation structure and the vulnerable golden-brown mouse lemur (Microcebus ravelobensis) in northwestern Madagascar

BMC Ecology ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Bertrand Andriatsitohaina ◽  
Daniel Romero-Mujalli ◽  
Malcolm S. Ramsay ◽  
Frederik Kiene ◽  
Solofonirina Rasoloharijaona ◽  
...  
Keyword(s):  
Body Mass ◽  
Edge Effects ◽  
Vegetation Structure ◽  
Species Abundance ◽  
Tree Height ◽  
Logistic Function ◽  
Study Region ◽  
Large Trees ◽  
Significant Difference ◽  
Vegetation Parameters

Abstract Background Edge effects can influence species composition and community structure as a result of changes in microenvironment and edaphic variables. We investigated effects of habitat edges on vegetation structure, abundance and body mass of one vulnerable Microcebus species in northwestern Madagascar. We trapped mouse lemurs along four 1000-m transects (total of 2424 trap nights) that ran perpendicular to the forest edge. We installed 16 pairs of 20 m2 vegetation plots along each transect and measured nine vegetation parameters. To determine the responses of the vegetation and animals to an increasing distance to the edge, we tested the fit of four alternative mathematical functions (linear, power, logistic and unimodal) to the data and derived the depth of edge influence (DEI) for all parameters. Results Logistic and unimodal functions best explained edge responses of vegetation parameters, and the logistic function performed best for abundance and body mass of M. ravelobensis. The DEI varied between 50 m (no. of seedlings, no. of liana, dbh of large trees [dbh ≥ 10 cm]) and 460 m (tree height of large trees) for the vegetation parameters, whereas it was 340 m for M. ravelobensis abundance and 390 m for body mass, corresponding best to the DEI of small tree [dbh < 10 cm] density (360 m). Small trees were significantly taller and the density of seedlings was higher in the interior than in the edge habitat. However, there was no significant difference in M. ravelobensis abundance and body mass between interior and edge habitats, suggesting that M. ravelobensis did not show a strong edge response in the study region. Finally, regression analyses revealed three negative (species abundance and three vegetation parameters) and two positive relationships (body mass and two vegetation parameters), suggesting an impact of vegetation structure on M. ravelobensis which may be partly independent of edge effects. Conclusions A comparison of our results with previous findings reveals that edge effects are variable in space in a small nocturnal primate from Madagascar. Such an ecological plasticity could be extremely relevant for mitigating species responses to habitat loss and anthropogenic disturbances.

scholarly journals SPATIAL CONVERGENCE OF THE GROSS VALUE OF PRODUCTION OF FIREWOOD IN THE MESOREGIONS OF THE BRAZILIAN NORTHEAST

2018 ◽  
Vol 42 (2) ◽  
Author(s):  
Luiz Moreira Coelho Junior ◽  
Kalyne de Lourdes da Costa Martins ◽  
Magno Vamberto Batista da Silva
Keyword(s):  
Spatial Dependence ◽  
Classical Model ◽  
Spatial Models ◽  
Information Criterion ◽  
Spatial Error ◽  
Spatial Convergence ◽  
Spatial Autoregressive ◽  
Classical Linear Regression ◽  
Object Of Study ◽  
Brazilian Northeast

ABSTRACT This paper analyzed the process of convergence in the gross value of wood production in mesoregions of Northeast Brazil, in the period of 1994 and 2013. The object of study was the Gross Value of Production (GVP) of firewood per km2 of the mesoregions of the Northeast of Brazil. In the methodology the Absolute Convergence Model was applied and estimated through the classical model and spatial models. In the spatial approach we used the Spatial Autoregressive Model (SAR) and the Spatial Error Model (SEM). From the results obtained, the following conclusions were reached: The mesoregions of the Northeast of Brazil had an average fall of 3.94% a.a. of the GVP/km2 of native wood for the period 1994 to 2013. Considering the classical linear regression model, convergence was verified and also the presence of spatial dependence for GVP/km2 of firewood. In order to correct the spatial dependence, the SAR and SEM Models were adequate and according to Akaike's Information Criterion and used the rook matrix the SEM was configured the best model. This study showed the importance of the involvement of the spatial question in the models, either by the overlap of information of the GVP and in the development of public policies that positively affect the neighborhood.

scholarly journals Cholecalciferol v. ergocalciferol for 25-hydroxyvitamin D (25(OH)D) repletion in chronic kidney disease: a randomised clinical trial

2016 ◽  
Vol 116 (12) ◽  
pp. 2074-2081 ◽  
Author(s):  
James B. Wetmore ◽  
Cassandra Kimber ◽  
Jonathan D. Mahnken ◽  
Jason R. Stubbs
Keyword(s):  
Clinical Trial ◽  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Mineral Metabolism ◽  
Substantial Reduction ◽  
Randomised Clinical Trial ◽  
Optimal Method ◽  
Hydroxyvitamin D ◽  
Significant Difference ◽  
25 Hydroxyvitamin D

AbstractPatients with chronic kidney disease (CKD) demonstrate complex mineral metabolism derangements and a high prevalence of vitamin D deficiency. However, the optimal method of 25-hydroxyvitamin D (25(OH)D) repletion is unknown, and trials analysing the comparative efficacy of cholecalciferol and ergocalciferol in this population are lacking. We conducted a randomised clinical trial of cholecalciferol 1250μg (50 000 IU) weekly v. ergocalciferol 1250μg (50 000 IU) weekly for 12 weeks in forty-four non-dialysis-dependent patients with stage 3–5 CKD. The primary outcome was change in total 25(OH)D from baseline to week 12 (immediately after therapy). Secondary analyses included the change in 1,25-dihydroxyvitamin D (1,25(OH)2D), parathyroid hormone (PTH), D2 and D3 sub-fractions of 25(OH)D and 1,25(OH)2D and total 25(OH)D from baseline to week 18 (6 weeks after therapy). Cholecalciferol therapy yielded a greater change in total 25(OH)D (45·0 (sd 16·5) ng/ml) v. ergocalciferol (30·7 (sd 15·3) ng/ml) from baseline to week 12 (P<0·01); this observation partially resulted from a substantial reduction in the 25(OH)D3 sub-fraction with ergocalciferol. However, following cessation of therapy, no statistical difference was observed for total 25(OH)D change from baseline to week 18 between cholecalciferol and ergocalciferol groups (22·4 (sd 12·7) v. 17·6 (sd 8·9) ng/ml, respectively; P=0·17). We observed no significant difference between these therapies with regard to changes in serum PTH or 1,25(OH)2D. Therapy with cholecalciferol, compared with ergocalciferol, is more effective at raising serum 25(OH)D in non-dialysis-dependent CKD patients while active therapy is ongoing. However, levels of 25(OH)D declined substantially in both arms following cessation of therapy, suggesting the need for maintenance therapy to sustain levels.

scholarly journals Predicting Growing Stock Volume of Eucalyptus Plantations Using 3-D Point Clouds Derived from UAV Imagery and ALS Data

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 905 ◽  
Author(s):  
Guerra-Hernández ◽  
Cosenza ◽  
Cardil ◽  
Silva ◽  
Botequim ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Basal Area ◽  
Remote Sensing Data ◽  
Tree Height ◽  
Point Clouds ◽  
Volume Estimation ◽  
P Value ◽  
Test Statistic ◽  
Individual Tree ◽  
Significant Difference

Estimating forest inventory variables is important in monitoring forest resources and mitigating climate change. In this respect, forest managers require flexible, non-destructive methods for estimating volume and biomass. High-resolution and low-cost remote sensing data are increasingly available to measure three-dimensional (3D) canopy structure and to model forest structural attributes. The main objective of this study was to evaluate and compare the individual tree volume estimates derived from high-density point clouds obtained from airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) in Eucalyptus spp. plantations. Object-based image analysis (OBIA) techniques were applied for individual tree crown (ITC) delineation. The ITC algorithm applied correctly detected and delineated 199 trees from ALS-derived data, while 192 trees were correctly identified using DAP-based point clouds acquired from Unmanned Aerial Vehicles (UAV), representing accuracy levels of respectively 62% and 60%. Addressing volume modelling, non-linear regression fit based on individual tree height and individual crown area derived from the ITC provided the following results: Model Efficiency (Mef) = 0.43 and 0.46, Root Mean Square Error (RMSE) = 0.030 m3 and 0.026 m3, rRMSE = 20.31% and 19.97%, and an approximately unbiased results (0.025 m3 and 0.0004 m3) using DAP and ALS-based estimations, respectively. No significant difference was found between the observed value (field data) and volume estimation from ALS and DAP (p-value from t-test statistic = 0.99 and 0.98, respectively). The proposed approaches could also be used to estimate basal area or biomass stocks in Eucalyptus spp. plantations.

scholarly journals The effect of a stress and anxiety coping program on objective structured clinical examination performance among nursing students in shiraz, Iran

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Sadaf Mojarrab ◽  
Leila Bazrafkan ◽  
Azita Jaberi
Keyword(s):  
Nursing Students ◽  
Clinical Examination ◽  
Relaxation Training ◽  
Substantial Reduction ◽  
Intervention Group ◽  
Demographic Characteristics ◽  
Objective Structured Clinical Examination ◽  
Control Group ◽  
Significant Difference ◽  
Exam Anxiety

Abstract Background Evaluation of the competence and practical skills of nursing students, using the objective structured clinical examination (OSCE), is an integral part of the nursing education program. However, their performance could be negatively influenced by a significant level of stress and anxiety prior to the test. The present study aimed to evaluate the effect of an anxiety coping program on the OSCE performance level of first-year nursing students in Shiraz, Iran. Methods The present quasi-experimental study was conducted among 76 nursing students; control group (n = 35) and intervention group (n = 41). To attain the study purpose, the intervention group received a pre-exam anxiety coping program that included relaxation and soothing techniques, diaphragmatic breathing training, and progressive muscle relaxation training accompanied by light instrumental music, while the control group received no intervention before the exam. Data collection instruments included a demographic characteristics form and State-Trait Anxiety Inventory (STAI) questionnaire. Demographic characteristics of the participants indicated an overall homogeneity within the study population. The STAI questionnaire was filled in before and after the OSCE and the results were compared with those of the control group. The data were analysed using SPSS software (version 22.0). P < 0.05 was considered statistically significant. Results As a result of the anxiety coping program, a substantial reduction in the anxiety score (by 11.61 units) in the intervention group was observed. There was a significant difference in the pre- and post-exam anxiety scores between the control and intervention groups (P < 0.001). The anxiety coping program improved the examination results of nursing students in the final exam compared to the midterm results (an increase of 0.9487 units, P < 0.001). Conclusion The anxiety coping program reduced the anxiety level among nursing students and improved their OSCE results. Our findings can be utilized to better evaluate clinical activities in different medical and paramedical groups. Moreover, educators can implement such coping programs prior to evaluations in order to effectively assess the knowledge, attitude, and performance of the students.

scholarly journals Translating environmental xenobiotic fate models across scales

1997 ◽  
Vol 1 (4) ◽  
pp. 895-904 ◽  
Author(s):  
O. Richter ◽  
B. Diekkrüger
Keyword(s):  
Stochastic Models ◽  
Process Models ◽  
Spatial Process ◽  
Soil Parameters ◽  
Deterministic Models ◽  
Deterministic Process ◽  
Statistical Variation ◽  
Scale Models ◽  
Classical Models ◽  
Environmental Xenobiotic

Abstract. The classical models developed for degradation and transport of xenobiotics have been derived with the assumption of homogeneous environments. Unfortunately, deterministic models function well in the laboratory under homogeneous conditions but such homogeneous conditions often do not prevail in the field. A possible solution is the incorporation of the statistical variation of soil parameters into deterministic process models. This demands the development of stochastic models of spatial variability. To this end, spatial soil parameter fields are conceived as the realisation of a random spatial process. Extrapolation of local fine scale models to large heterogeneous fields is achieved by coupling deterministic process models with random spatial field models.

Relationship of sap sugar concentrations in sugar maple to ray tissue and parenchyma flecks caused by Phytobiasetosa

1980 ◽  
Vol 10 (3) ◽  
pp. 312-315 ◽  
Author(s):  
William E. Wallner ◽  
Robert A. Gregory
Keyword(s):  
Sugar Maple ◽  
Tree Height ◽  
Tree Crown ◽  
Significant Difference ◽  
Sugar Levels ◽  
Relationship Of ◽  
Root Collar

Sap sugar levels were determined for 300 sugar maple, Acersaccharum Marsh, trees. The 10 trees highest and lowest in sap sugar were sacrificed and attempts were made to calculate abundance and size of parenchyma flecks caused by Phytobiasetosa (Loew) and ray tissue per unit of xylem. Flecks occurred in up to 0.2% of the xylem, but there was no significant difference between fleck number or xylem-fleck ratio and sap sugar levels. Fleck numbers decreased with tree height; largest flecks were observed at the root collar and 8–12 m from the ground. This suggests that all P. setosa larvae do not mine from twigs in the crown to the roots, but that some mature and exit at the base of the tree crown. Trees high in sap sugar had significantly more ray tissue per unit of xylem than those low in sap sugar, a major factor in determining sap sugar concentrations.

Importance of boreal forested wetlands for epiphytic macrolichen communities

2020 ◽  
Vol 50 (12) ◽  
pp. 1333-1339
Author(s):  
Tegan Padgett ◽  
Yolanda F. Wiersma
Keyword(s):  
Community Composition ◽  
Abies Balsamea ◽  
Canopy Cover ◽  
Tree Height ◽  
Forested Wetlands ◽  
Tree Age ◽  
Forested Wetland ◽  
Forest Types ◽  
Significant Difference ◽  
Face Threats

Forested wetlands provide ecosystem services and often support elevated levels of biodiversity and rare species. However, forested wetlands are understudied and face threats such as logging and land conversion. Epiphytic lichens are abundant in forested wetlands and may be useful to help delineate microhabitats across wetland–upland gradients. We investigated epiphytic macrolichen richness, diversity, and community composition in 15 sites in the Avalon Forest Ecoregion, Newfoundland, Canada. Within each site, we set up three parallel 40 m transects in (i) the forested wetland, (ii) the ecotone, and (iii) the upland forest. Along each transect, we selected five balsam fir (Abies balsamea (L.) Mill.) trees 10 m apart and surveyed for macrolichens on the lower bole. We collected data on tree height and tree diameter at breast height, which differed significantly among forest types. We also collected data on tree age and canopy cover, which did not differ significantly among forest types. Contrary to hypotheses suggesting that biodiversity is highest in ecotones, we found that mean macrolichen richness was significantly higher in wetlands, lower in the ecotones, and lowest in upland forests, and macrolichen diversity followed a similar pattern but with no significant difference among groups. Macrolichen community composition significantly differed among wetlands, ecotones, and upland forests. A lichen of conservation concern, Erioderma pedicellatum (Hue) P.M. Jørg., was detected primarily in forested wetlands, highlighting wetlands as key habitats for rare epiphytic macrolichens.

Directional Rates of Change Under Spatial Process Models

2003 ◽  
Vol 98 (464) ◽  
pp. 946-954 ◽  
Author(s):  
Sudipto Banerjee ◽  
Alan E Gelfand ◽  
C. F Sirmans
Keyword(s):  
Process Models ◽  
Spatial Process ◽  
Rates Of Change
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