Slope, aspect, and slope position as factors controlling grassland communities in the coulees of the Oldman River, Alberta

1987 ◽  
Vol 65 (7) ◽  
pp. 1371-1378 ◽  
Author(s):  
V. J. Lieffers ◽  
P. A. Larkin-Lieffers
Keyword(s):  
Environmental Variables ◽  
Bouteloua Gracilis ◽  
Slope Position ◽  
Slope Aspect ◽  
Artemisia Frigida ◽  
Energy Aspect ◽  
Koeleria Macrantha ◽  
Stipa Comata ◽  
Direct Ordination ◽  
Oldman River

Vegetation and environmental variables were examined in some coulees of the Oldman River near Lethbridge, Alta. Principal components analysis of environmental variables indicated that solar energy, aspect, soil Mg2+, [Formula: see text], and moisture were related to the first axis of variation. Slope position, soil [Formula: see text], moisture, K+, [Formula: see text], and amount of bare ground were related to a second axis of variation. There was a large range in species diversity among plots; most diverse plots were on north-facing slopes. Direct ordination of vegetation data indicated that slope position and aspect were most important in describing distribution of species. Koeleria macrantha, Bouteloua gracilis, Stipa comata, and Artemisia frigida were found on most coulee positions. Hymenoxys richardsonii, Machaeranthera grindeloides, Astragalus spatulatus, and Eriogonum flavum were mostly restricted to summit and upper slope positions. Anemone patens, Geum triflorum, Thermopsis rhombifolia, and others were most abundant on north- and east-facing slopes. Fewer species (e.g., the C4 Aristida longiseta and the cactus Coryphantha vivipara) were mostly confined to south-facing positions.

Models of the distribution and abundance of ground-dwelling mammals in the eucalypt forests of north-eastern New South Wales in relation to environmental variables

2002 ◽  
Vol 29 (3) ◽  
pp. 313 ◽  
Author(s):  
P. C. Catling ◽  
R. J. Burt ◽  
R. I. Forrester
Keyword(s):  
Environmental Variables ◽  
New South ◽  
New South Wales ◽  
Slope Position ◽  
Slope Aspect ◽  
Significant Variable ◽  
South Wales ◽  
North Eastern ◽  
Eucalypt Forests ◽  
A Site

Statistical models are presented of the distribution and abundance of ground-dwelling mammals in eucalypt forests in relation to environmental variables within an area of approximately 24 000 km2 in north-eastern New South Wales. Environmental variables are defined as climatic or topographic variables that may be useful to map the distribution of fauna. The environmental variables examined were season, temperature, rainfall, elevation, lithology, steepness of slope, position on slope, aspect and landform profile. The probability of recording some species was higher in spring than autumn and many species were in highest abundance in areas of low temperature (high elevation). Although aspect was a significant variable in a number of models, no species was absent from any aspect category. Mid-slopes down to and including creeks and drainage lines were particularly important for many species, as were areas with flatter terrain. Although we have modelled environmental variables only there will no doubt be longer-term interactions between habitat and environmental variables. Fundamentally, environmental variables will determine the type of habitat present at a site, and the distribution of canopy communities, at least, can be predicted from environmental variables. However, other studies have shown for ground-dwelling mammals that environmental variables contribute little and it is the state of the habitat locally, and particularly the understorey, that determines their presence and abundance at a site. The results are discussed in relation to similar models using habitat variables and in relation to the use of such models in the management of ground-dwelling fauna in forests.

Spatial distribution of soil phosphorus and herbage mass in beef cattle pastures: effects of slope aspect and slope position

2010 ◽  
Vol 89 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Gilbert C. Sigua ◽  
Samuel W. Coleman ◽  
Joseph Albano ◽  
Mimi Williams
Keyword(s):  
Spatial Distribution ◽  
Beef Cattle ◽  
Soil Phosphorus ◽  
Slope Position ◽  
Slope Aspect

Wheat Crops and Native Prairie in Relation to the Nutritional Ecology of Camnula pellucida (Scudder) (Orthoptera: Acrididae) in Saskatchewan

1963 ◽  
Vol 95 (7) ◽  
pp. 764-770 ◽  
Author(s):  
R. Pickford
Keyword(s):  
Dominant Role ◽  
Nutritional Ecology ◽  
Bouteloua Gracilis ◽  
Field Cage ◽  
Agropyron Smithii ◽  
Native Prairie ◽  
Prairie Grasses ◽  
Complete Life Cycle ◽  
Stipa Comata ◽  
Mixed Prairie

AbstractField cage experiments conducted through the complete life cycle of Camnula pellucida (Scudder) demonstrated that wheat, the major cereal crop grown in Saskatchewan, played the dominant role in the nutritional ecology of this grasshopper. A native sod mixture, comprising Stipa comata, Bouteloua gracilis, Agropyron smithii, and Carex eleocharis, four of the dominant species of the mixed prairie association, was consistently unfavourable during all stages of grasshopper growth and development. Grasshoppers reared on wheat survived better, were considerably larger and laid up to 20 times more eggs than those reared on the native prairie grasses. The presence of the native sod with wheat contributed nothing nutritionally to the food combination. The unfavourable qualities of the native grasses, although resulting in small adults, low fecundity and small pods, did not affect the hatchability of eggs laid or the development and survival of nymphs that hatched from them.

Characteristics of the Stipa Comata-Bouteloua Gracilis-Bouteloua Curtipendula Association in Northern Colorado

Ecology ◽  
1955 ◽  
Vol 36 (2) ◽  
pp. 269-280 ◽  
Author(s):  
Herbert C. Hanson
Keyword(s):  
Bouteloua Gracilis ◽  
Bouteloua Curtipendula ◽  
Northern Colorado ◽  
Stipa Comata

scholarly journals Characterizing Groundwater Potential Using GIS-Based Machine Learning Model in Chihe River Basin, China

2021 ◽  
Author(s):  
Dejian Wang ◽  
Jiazhong Qian ◽  
Lei Ma ◽  
Weidong Zhao ◽  
Di Gao ◽  
...  
Keyword(s):  
Machine Learning ◽  
Water Resources ◽  
River Basin ◽  
Environmental Variables ◽  
Groundwater Potential ◽  
High Potential ◽  
Slope Aspect ◽  
Learning Models ◽  
Topographic Wetness Index ◽  
Machine Learning Models

Abstract Mapping of groundwater potential over space, built by synergizing environmental variables and machine learning models, was of great significance for regional water resources management. Taking the Chihe River basin in Anhui province as an example, thirteen influence factors were used to predict the spatial distribution of groundwater, including elevation, slope, aspect, plan curvature, profile curvature, topographic wetness index (TWI), drainage density, distance to rivers, distance to faults, lithology, soil type, land use, and normalized difference vegetation index (NDVI). The potential of groundwater resource in this region was predicted using GIS-based machine learning models, including logistic regression (LR), deep neural networks (DNN), and random forest (RF) model. Then, the accuracy of prediction results was evaluated by calculating the RMSE, MAE and R evaluation index. The results show that there is no collinearity among the 13 environmental impact factors, which can provide corresponding environmental variables for the evaluation of regional groundwater potential. Machine learning models show that groundwater potential is concentrated in moderate to high potential areas. Among them, the moderate to the high potential of this area accounted for 81.14% in the LR model, 90.36% and 87.55% in the DNN model and the RF model, respectively. According to the result of these evaluation indexes, the three models all have high prediction accuracy, among which the LR model performs more prominently. The good prediction capabilities of these machine learning technologies can provide a reliable scientific basis for spatial prediction of groundwater potential and management of water resources.

scholarly journals Determining the use of Sentinel-2A MSI for wildfire burning and severity detection

2019 ◽  
Author(s):  
Sawyer Reid stippa ◽  
George Petropoulos ◽  
Konstantinos P. Ferentinos
Keyword(s):  
Land Cover ◽  
Environmental Variables ◽  
Slope Aspect ◽  
Electromagnetic Spectrum ◽  
Variable Degree ◽  
Management Service ◽  
Spectral Indices ◽  
Spectral Angle Mapper ◽  
Sentinel 2A ◽  
Burnt Areas

Accurate, reliable, and timely burn severity maps are necessary for planning, managing and rehabilitation after wildfires. This study aimed at assessing the ability of the Sentinel-2A satellite to detect burnt areas and separate burning severity levels. It also attempted to measure the spectral separability of the different bands and derived indices commonly used to detect burnt areas. A short investigation into the associated environmental variables present in the burnt landscape was also performed to explore the presence of any correlation. As a case study a wildfire occurred in the Sierra de Gata region of the province of Caceres in North-Eastern Spain was used. A range of spectral indices were computed, including the Normalized Difference Vegetation Index (NDVI) and the Normalized Burn Ratio (NBR). The potential added value of the three new Red Edge bands that come with the Sentinel-2A MSI sensor were also used. The slope, aspect, fractional vegetation cover and terrain roughness were all derived to produce environmental variables. The burning severity was tested using Spectral Angle Mapper (SAM) classifier. European Environment Agency’s CORINE land cover map was also used to produce the land cover types found in the burned area. The Copernicus Emergency Management Service have produced a grading map for the fire using 0.5m resolution Pleiades imagery, that was used as reference. Results showed a variable degree of correlation between the burning severity and the tested herein spectral indices. The visible part of the electromagnetic spectrum was not well suited to discern burned from unburned land cover. The NBRb12 (short-wave infrared 2 – SWIR2) produced the best results for detecting burnt areas. SAM resulted in a 73% overall accuracy in thematic mapping. None of the environmental variables appeared to have a significant impact on the burning severity. All in all, our study result showed that Sentinel-2 MSI sensor can be used to discern burnt areas and burning severity. However, further studies in different regions using the same dataset types and methods should be implemented before generalizing the results of the current study.

scholarly journals Determining the Use of Sentinel-2A MSI for Wildfire Burning and 1 Severity Detection

2020 ◽  
Author(s):  
Alexander R. Brown ◽  
George Petropoulos ◽  
Konstantinos P. Ferentinos
Keyword(s):  
Land Cover ◽  
Environmental Variables ◽  
Slope Aspect ◽  
Electromagnetic Spectrum ◽  
Variable Degree ◽  
Management Service ◽  
Spectral Indices ◽  
Spectral Angle Mapper ◽  
Sentinel 2A ◽  
Burnt Areas

Accurate, reliable, and timely burn severity maps are necessary for planning, managing and rehabilitation after wildfires. This study aimed at assessing the ability of the Sentinel-2A satellite to detect burnt areas and separate burning severity levels. It also attempted to measure the spectral separability of the different bands and derived indices commonly used to detect burnt areas. A short investigation into the associated environmental variables present in the burnt landscape was also performed to explore the presence of any correlation. As a case study, a wildfire occurred in the Sierra de Gata region of the province of Caceres in North-Eastern Spain was used. A range of spectral indices was computed, including the Normalized Difference Vegetation Index (NDVI) and theNormalized Burn Ratio (NBR). The potential added value of the three new Red Edge bands that come with the Sentinel-2A MSI sensor was also used. The slope, aspect, fractional vegetation cover and terrain roughness were all derived to produce environmental variables. The burning severity was tested using the Spectral Angle Mapper (SAM) classifier. European Environment Agency’s CORINE land cover map was also used to produce the land cover types found in the burned area. The Copernicus Emergency Management Service have produced a grading mapfor the fire using 0.5 m resolution Pleiades imagery, that was used as reference. Results showed a variable degree of correlation between the burning severity and the tested herein spectral indices. The visible part of the electromagnetic spectrum was not well suited to discern burned from unburned land cover. The NBRb12 (short-wave infrared 2 – SWIR2) produced the best results for detecting burnt areas. SAM resulted in a 73% overall accuracy in thematic mapping. None of the environmental variables appeared to have a significant impact on the burning severity. All in all, our study result showed that Sentinel-2 MSI sensor can be used to discern burnt areas and burning severity. However, further studies in different regions using the same dataset types and methods should be implemented before generalizing the results of the current study.

scholarly journals Diversity of Woodland Communities and Plant Species along an Altitudinal Gradient in the Guancen Mountains, China

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Dongping Meng ◽  
Jin-Tun Zhang ◽  
Min Li
Keyword(s):  
Species Diversity ◽  
Environmental Variables ◽  
Altitudinal Gradient ◽  
Diversity Indices ◽  
Slope Aspect ◽  
Mountain Range ◽  
Species Analysis ◽  
Species Diversity Indices ◽  
Composition Structure ◽  
Woodland Communities

Study on plant diversity is the base of woodland conservation. The Guancen Mountains are the northern end of Luliang mountain range in North China. Fifty-three quadrats of10 m×20 mof woodland communities were randomly established along an altitudinal gradient. Data for species composition and environmental variables were measured and recorded in each quadrat. To investigate the variation of woodland communities, a Two-Way Indicator Species Analysis (TWINSPAN) and a Canonical Correspondence Analysis (CCA) were conducted, while species diversity indices were used to analyse the relationships between species diversity and environmental variables in this study. The results showed that there were eight communities of woodland vegetation; each of them had their own characteristics in composition, structure, and environment. The variation of woodland communities was significantly related to elevation and also related to slope, slope aspect, and litter thickness. The cumulative percentage variance of species-environment relation for the first three CCA axes was 93.5%. Elevation was revealed as the factor which most influenced community distribution and species diversity. Species diversity was negatively correlated with elevation, slope aspect, and litter thickness, but positively with slope. Species richness and heterogeneity increased first and then decreased but evenness decreased significantly with increasing elevation. Species diversity was correlated with slope, slope aspect, and litter thickness.

scholarly journals Distribution of Charophyte Oospores in the Curonian Lagoon and their Relationship to Environmental Forcing

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 117
Author(s):  
Vaiva Stragauskaitė ◽  
Martynas Bučas ◽  
Georg Martin
Keyword(s):  
Environmental Factors ◽  
Coastal Waters ◽  
Environmental Variables ◽  
Boosted Regression Trees ◽  
Slope Aspect ◽  
Curonian Lagoon ◽  
Eastern Shore ◽  
The Baltic Sea ◽  
Environmental Forcing ◽  
The Baltic

Lack of knowledge about distribution of charophyte fructifications and importance of environmental conditions in the Baltic Sea coastal waters fostered us to assess the spatial-temporal patterns of oospore bank in relationship with environmental factors in the Curonian Lagoon (Lithuanian part). We mapped the distribution of oospores in 2017–2019. The importance of environmental factors was determined by the cluster analysis and boosted regression trees. Four oospores species were recorded up to 4 m depth. The highest mean densities (58,000 ind·m−2) of viable fructifications were found along the eastern shore, where the densest charophyte stands were recorded. Viable fructifications showed a clear pattern of filling the oospore bank after the vegetation season and a depletion during the summer as they germinated. The distance from charophyte stands, salinity, bottom slope aspect, and wave exposure were the most important environmental variables. Full fructifications mostly occurred within <0.5 km distance from the charophyte stands restricted to flat and sheltered areas exposed to the northern and eastern slopes. Empty fructifications were mostly found within <2 km distance from the charophyte stands but their high density was limited to <1 km distance from the charophyte stands and on the northeastern bottom slopes and >1.5 salinity.

GERMINATION AND EARLY GROWTH OF GRASSES AT FOUR ROOT-ZONE TEMPERATURES

1968 ◽  
Vol 48 (2) ◽  
pp. 119-127 ◽  
Author(s):  
S. Smoliak ◽  
A. Johnston
Keyword(s):  
Introduced Species ◽  
Native Species ◽  
Root Zone ◽  
Bouteloua Gracilis ◽  
Early Growth ◽  
Grass Species ◽  
Growth Stages ◽  
Native Grass ◽  
Andropogon Scoparius ◽  
Stipa Comata

Six native grass species, Bouteloua gracilis, Stipa comata, Koeleria cristata, Festuca scabrella, Andropogon scoparius, and Danthonia parryi, and six introduced grass species, Elymus junceus, Bromus inermis, Agropyron cristatum, Agropyron tricophorum, Festuca rubra, and Dactylis glomerata, were germinated and grown for 90 days at root-zone temperatures of 7, 13, 18, and 27 °C. In general, the introduced species were superior to the native species in percentage germination and speed of germination and germinated, emerged and grew more readily at lower root-zone temperatures. Introduced species produced about 10 times as much weight of leaf and about eight times as much weight of root as did the native species at comparable growth stages. The chances of establishment and successful early growth of seeded stands appeared to be better with introduced grass species than with native grass species.

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