Arctic plant communities east of the Mackenzie Delta

1974 ◽  
Vol 52 (7) ◽  
pp. 1731-1745 ◽  
Author(s):  
Ian G. W. Corns
Keyword(s):  
Plant Communities ◽  
Aerial Photography ◽  
Community Type ◽  
Two Dimensional ◽  
Areal Extent ◽  
Mackenzie Delta ◽  
Floristic Similarity ◽  
Tundra Vegetation ◽  
Community Types ◽  
Tall Shrub

Tundra vegetation was analyzed on the basis of 64 sampled and 12 described stands representing a wide variety of plant community types immediately east of the Mackenzie Delta, Northwest Territories. Five main types (Tall Shrub – Herb, Medium Shrub (alder), Low Shrub – Heath, Herb – Low Shrub – Heath, and Herb) and 11 subgroups were distinguished and classified on the basis of floristic similarity using a two-dimensional ordination and by physiognomy. A total of 70 species were sampled or observed in the stands. Floristically, the Sedge–Cottongrass–Heath type was the most diverse and the Wet-Sedge Polygon – Herb type, the least diverse. The areal extent of each major community type was determined using aerial photography for Richards Island, Caribou Hills, Eskimo Lakes, Tuktoyaktuk, and Atkinson Point study areas.

scholarly journals Plant Community Distribution, Dynamics, Fuel Loads, and Fire Behavior in Bryce Canyon National Park

1989 ◽  
Vol 13 ◽  
pp. 21-24
Author(s):  
David Roberts ◽  
Gregory Hallsten ◽  
Doug Wight
Keyword(s):  
Plant Communities ◽  
National Park ◽  
Fire Behavior ◽  
Community Type ◽  
Distribution Dynamics ◽  
Fuel Loads ◽  
Disturbance Response ◽  
Community Types ◽  
Successional Development ◽  
Succession Model

This research program incorporates four primary objectives: (1) develop a comprehensive vegetation classification for Bryce Canyon National Park and to map the current and potential vegetation for the park; (2) develop a vital attributes succession model which depicts the successional development and disturbance response of plant communities in Bryce Canyon; (3) determine and characterize the fuel loads typical of each successional community type; (4) predict the behavior of fires occurring in each of the successional community types.

Exploring the Relationship Between Social Interaction, Cognitive Processing and Learning Achievements in a MOOC Discussion Forum

2021 ◽  
pp. 073563312110273
Author(s):  
Zhi Liu ◽  
Ning Zhang ◽  
Xian Peng ◽  
Sannyuya Liu ◽  
Zongkai Yang ◽  
...  
Keyword(s):  
Social Network ◽  
Social Interaction ◽  
Network Analysis ◽  
Cognitive Processing ◽  
Learning Analytics ◽  
Discussion Forum ◽  
Community Type ◽  
Eigenvector Centrality ◽  
Community Types ◽  
The Relationship

In the field of learning analytics, mining the regularities of social interaction and cognitive processing have drawn increasing attention. Nevertheless, in MOOCs, there is a lack of investigations on the combination of social and cognitive behavioral patterns. To fill in this gap, this study aimed to uncover the relationship between social interaction, cognitive processing, and learning achievements in a MOOC discussion forum. Specifically, we collected the 3925 participants’ forum data throughout 16 weeks. Social network analysis and epistemic network analysis were jointly adopted to investigate differences in social interaction, cognitive processing between two achievement groups, and the differences in cognitive processing networks between two types of communities. Finally, moderation analysis was employed to examine the moderating effect of community types between cognitive processing and learning achievements. Results indicated that: (1) the high- and low-achieving groups presented significant differences in terms of degree, betweenness, and eigenvector centrality; (2) the stronger cognitive connections were found within the high-achieving group and the instructor-led community; (3) the cognitive processing indicators including insight, discrepancy, and tentative were significantly negative predictors of learning achievements, whereas inhibition and exclusive were significantly positive predictors; (4) the community type moderated the relationship between cognitive processing and learning achievements.

Natural plant recolonization of surficial disturbances, Tuktoyaktuk Peninsula Region, Northwest Territories

1973 ◽  
Vol 51 (11) ◽  
pp. 2177-2196 ◽  
Author(s):  
Helios Hernandez
Keyword(s):  
Plant Cover ◽  
Mineral Soil ◽  
Energy Budgets ◽  
Mackenzie Delta ◽  
Calamagrostis Canadensis ◽  
Disturbed Areas ◽  
Sedge Meadows ◽  
Tall Shrub ◽  
Seismic Lines ◽  
Plant Recolonization

Seismic lines or winter roads were sampled where they passed through three different plant communities in the Mackenzie Delta and through four of the major tundra communities in the Tuktoyaktuk Peninsula. Winter seismic lines have been less detrimental than summer lines for all communities examined. Although winter roads through upland areas remove most of the vegetation cover, the peat layer usually remains intact and soil energy budgets are relatively little affected. Wetland sedge meadows are highly susceptible to summer disturbance but least affected by winter operations. Winter-disturbed forested and tall shrub communities recover faster initially than similarly disturbed upland tundra communities.Eriophorum vaginatum and Carex bigelowii appeared to be stimulated by disturbances which did not eliminate them, with Eriophorum often flowering more abundantly in disturbed areas. This probably results from warmer soils and greater nutrient uptake.Summer seismic lines (1965), originally bladed to permafrost, resulted in exposure of mineral soil and thus led to secondary succession in tundra communities. Arctagrostis latifolia, Calamagrostis canadensis, Poa arctica, and Luzula confusa are the most typical and abundant pioneers of upland mesic sites. Wet sites are colonized predominantly by Arctophila fulva and Carex aquatilis. Once established, these species expanded rhizomatously. Six years after exposure of mineral soil, plant cover was usually 30 to 50%.Thaw was generally increased 80 to 100% where mineral soil was exposed, 30 to 50% if the peat remained intact, and 10% if plant cover was little altered. Subsurface ice has occasionally been exposed, resulting in thermokarst subsidence. Water erosion has not been a factor, probably because of the low precipitation in the region.

Growth of Uneven-Aged Stands in New York's Adirondack Mountains

1987 ◽  
Vol 4 (3) ◽  
pp. 136-139
Author(s):  
Thomas J. Temple ◽  
Ralph D. Nyland ◽  
Philip J. Craul
Keyword(s):  
Basal Area ◽  
Community Type ◽  
Individual Species ◽  
Forest Site ◽  
Adirondack Mountains ◽  
Soil Series ◽  
Annual Increment ◽  
Periodic Treatment ◽  
Community Types ◽  
Species Groups

Abstract Prediction equations are presented for total standing volume and periodic annual increment among unevenaged stands in New York's Adirondacks. These use stand basal area, plus selected physical site and vegetal characteristics of the stand. Few plots located across a range of community types or soil series differed significantly in volume increment, suggesting that neither the community type nor soil series provides a reliable basis for forest site productivity classification. Hardwoods grow better than conifers on the deeper less podzolized soils, and individual species or species groups grow differently from one community type to another. Yet, the superior growth of one tends to compensate for the mediocre performance of others within some community types, resulting in similar levels of total stand growth between communities. Findings indicate which species to favor in marking different stands for periodic treatment. North. J. Appl. For. 4:136-139, Sept. 1987.

Vegetation of eastern Unalaska Island, Aleutian Islands, AlaskaThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.

Botany ◽  
2010 ◽  
Vol 88 (4) ◽  
pp. 366-388 ◽  
Author(s):  
Stephen S. Talbot ◽  
Wilfred B. Schofield ◽  
Sandra L. Talbot ◽  
Fred J.A. Daniëls
Keyword(s):  
Plant Communities ◽  
Aleutian Islands ◽  
Compositional Variation ◽  
Ecological Groups ◽  
Widespread Species ◽  
Vaccinium Uliginosum ◽  
The Matrix ◽  
Community Types ◽  
Coastal Meadows ◽  
Selection Of

Plant communities of Unalaska Island in the eastern Aleutian Islands of western Alaska, and their relationship to environmental variables, were studied using a combined Braun-Blanquet and multivariate approach. Seventy relevés represented the range of structural and compositional variation in the matrix of vegetation and landform zonation. Eleven major community types were distinguished within six physiognomic–ecological groups: I. Dry coastal meadows: Honckenya peploides beach meadow, Leymus mollis dune meadow. II. Mesic meadows: Athyrium filix-femina – Aconitum maximum meadow, Athyrium filix-femina – Calamagrostis nutkaensis meadow, Erigeron peregrinus – Thelypteris quelpaertensis meadow. III. Wet snowbed meadow: Carex nigricans snowbed meadow. IV. Heath: Linnaea borealis – Empetrum nigrum heath, Phyllodoce aleutica heath, Vaccinium uliginosum – Thamnolia vermicularis fellfield. V. Mire: Carex pluriflora – Plantago macrocarpa mire. VI. Deciduous shrub thicket: Salix barclayi – Athyrium filix-femina thicket. These were interpreted as a complex gradient primarily influenced by soil moisture, elevation, and pH. Phytogeographical and syntaxonomical analysis of the plant communities indicated that the dry coastal meadows, most of the heaths, and the mire vegetation belonged, respectively, to the widespread classes Honckenyo–Elymetea, Loiseleurio–Vaccinietea, and Scheuchzerio–Caricetea, characterized by their circumpolar and widespread species. Amphi-Beringian species were likely diagnostic of amphi-Beringian syntaxa, many of these yet to be described.

scholarly journals FUZZY C-MEANS ALGORITHM FOR SEGMENTATION OF AERIAL PHOTOGRAPHY DATA OBTAINED USING UNMANNED AERIAL VEHICLE

2015 ◽  
Vol XL-5/W6 ◽  
pp. 113-115 ◽  
Author(s):  
M. V. Akinin ◽  
N. V. Akinina ◽  
A. Y. Klochkov ◽  
M. B. Nikiforov ◽  
A. V. Sokolova
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Aerial Photography ◽  
Experimental Studies ◽  
Two Dimensional ◽  
Fuzzy C Means ◽  
Aerial Vehicles ◽  
Short Period ◽  
Aerial Vehicle ◽  
Fuzzy C Means Algorithm

The report reviewed the algorithm fuzzy c-means, performs image segmentation, give an estimate of the quality of his work on the criterion of Xie-Beni, contain the results of experimental studies of the algorithm in the context of solving the problem of drawing up detailed two-dimensional maps with the use of unmanned aerial vehicles. According to the results of the experiment concluded that the possibility of applying the algorithm in problems of decoding images obtained as a result of aerial photography. The considered algorithm can significantly break the original image into a plurality of segments (clusters) in a relatively short period of time, which is achieved by modification of the original k-means algorithm to work in a fuzzy task.

scholarly journals Plant Community Analysis along Environmental Gradients in Moist Afromontane Forest of Gerba Dima, South-western Ethiopia

2020 ◽  
Author(s):  
Abyot Dibaba Hundie ◽  
Teshome Soromessa Urgessa ◽  
Bikila Warkineh Dullo
Keyword(s):  
Cluster Analysis ◽  
Species Diversity ◽  
Plant Species ◽  
Plant Community ◽  
Plant Communities ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Regional Government ◽  
Community Types ◽  
Western Ethiopia

Abstract Background This study was carried out in Gerba Dima Forest, South-Western Ethiopia, to determine the floristic composition, species diversity and community types along environmental gradients. Ninety sample plots having a size of 25 × 25 m (625 m2) were laid by employing stratified random sampling. Nested plots were used to sample plants of different sizes and different environmental variables. All woody plant species with Diameter at breast height (DBH) ≥ 2.5 cm and height ≥ 1.5 m were recorded in 25 m X 25 m plots. Within the major plots, five 3 m x 3 m subplots (9 m2) was used to collect shrubs with dbh < 2.5 cm and > 1.5 m height. Within each 9 m2subplots, two 1 m2 subplots were used to collect data on the species and abundance of herbaceous plants. Hierarchical (agglomerative) cluster analysis was performed using the free statistical software R version 3.6.1 using package cluster to classify the vegetation into plant community types. Redundancy Analysis (RDA) ordination was used in describing the pattern of plant communities along an environmental gradient. Result One hundred and eighty plant species belonging to 145 genera, 69 families and comprising of 15 endemic species were recorded. Cluster analysis resulted in five different plant communities and this result was supported by the ordination result. RDA result showed altitude was the main environmental variable in determining the plant communities. The ANOVA test indicated that the five community types differ significantly from each other with regard to EC and K. Conclusions The studied forest can play a significant role in biodiversity conservation since it harbours high species diversity and richness. Thus, all Stakeholders including Oromia Forest and wildlife enterprise (OFWE) and the regional government should work to designate the forest as a biosphere reserve and being registered under UNESCO.

scholarly journals Macrofungi of raised and transitional bogs of Pomerania

2013 ◽  
Vol 101 ◽  
pp. 1-142 ◽  
Author(s):  
Małgorzata Stasińska
Keyword(s):  
Plant Communities ◽  
Environmental Variables ◽  
Chemical Properties ◽  
Permanent Plots ◽  
Community Type ◽  
Rare Plant ◽  
Ecological Groups ◽  
Eriophorum Vaginatum ◽  
Ecological Features ◽  
Ecological Scale

<p>The mycology of peatlands, with their specific plant communities and numerous rare plant species, has been underexplored and is poorly recognized. The main objectives of this study were to identify the species richness and diversity of macromycetes in raised and transitional bogs of Pomerania and to establish correlations between macroscopic fungi and peatland communities occurring in the area in view of environmental conditions. Investigations spanning a period of ten years were conducted at 134 sites (71 raised and 63 transitional bogs) in eight non-forest peatland communities (<em>Caricetum lasiocarpae</em>, <em>Caricetum limosae</em>, <em>Caricetum rostratae</em>, <em>Eriophoro angustifolii-Sphagnetum recurvi</em>, <em>Rhynchosporetum albae</em>, <em>Erico-Sphagnetum medii</em>, <em>Sphagnetum magellanici</em>, and the <em>Eriophorum vaginatum-Sphagnum fallax</em> community) and two forest communities (<em>Vaccinio uliginosi-Pinetum</em> and <em>Vaccinio uliginosi-Betuletum pubescentis</em>) in which 108 permanent observation plots were established for detailed examinations. A total of 191 macromycete species were recorded in the peatlands. The smallest number of species was recorded in <em>Rhynchosporetum albae</em> (12 species) and <em>Caricetum rostratae</em> (15 species). Phytocoenoses richest in fungi were <em>Vaccinio uliginosi-Pinetum</em> (102 species) and <em>Vaccinio uliginosi-Betuletum pubescentis</em> (121 species). The number of macromycete species recorded in individual peatland communities depends on the community type and is not conditioned by the number of observations and the number and the total area of permanent plots. Five mycosociologico-ecological groups of macroscopic fungi were distinguished based on numerical analyses. Four groups comprise species of fungi associated with a specific phytocoenosis or a group of phytocoenoses. One group consists of fungi with a broader ecological scale. The majority of environmental variables representing the substrate’s chemical properties, humidity and pH show a statistically significant influence on the diversity of macroscopic fungi species in the peatland communities. Cartogram maps of the distribution of 21 species of peatland fungi are included and geographico-ecological features of the species are briefly described.</p>

scholarly journals CO2 Flux Characteristics of Different Plant Communities in a Subtropical Urban Ecosystem

2019 ◽  
Vol 11 (18) ◽  
pp. 4879
Author(s):  
Kaidi Zhang ◽  
Yuan Gong ◽  
Hao Fa ◽  
Min Zhao
Keyword(s):  
Plant Community ◽  
Plant Communities ◽  
Carbon Sink ◽  
Co2 Flux ◽  
Observation System ◽  
Cinnamomum Camphora ◽  
Urban Greening ◽  
Contribution Rate ◽  
Metasequoia Glyptostroboides ◽  
Community Types

Shanghai, China, is a city that is relatively representative of various cities in China due to its geographical location and socio-economic dynamics. The role of urban vegetation in the carbon cycle of urban developments in these types of cities is now being studied. We focus on identifying which urban plant community types have a greater influence on CO2 flux in cities, thus providing a scientific basis for low-carbon urban greening. Based on the eddy covariance (EC) observation system, ART Footprint Tool, plant inventory, and ecological community classification, we show that the CO2 flux characteristics of different plant communities vary temporally. The carbon sink duration during summer was the longest (up to 10 h) and the carbon sink duration was the shortest during winter (7.5 h). In addition, we discovered that the CO2 flux contribution rates of different plant community types are distinct. The annual average CO2 contribution rates of the Cinnamomum camphora-Trachycarpus fortunei community and the Metasequoia glyptostroboides+Sabina chinensis community are 11.88% and 0.93%, respectively. The CO2 flux contribution rate of the same plant community differs according to season. The CO2 contribution rate of the Cinnamomum camphora-Trachycarpus fortunei community exhibits local maxima during winter and summer, with a maximum difference of 11.16%. In contrast, the Metasequoia glyptostroboides+Sabina chinensis community has a CO2 contribution rate of 0.35% during the same period. In general, summer is the season with the lowest CO2 flux contribution rate of plant communities, and winter is the season with the highest CO2 flux contribution rate. However, the Cinnamomum camphora+Salix babylonica community and the Cinnamomum camphora+Sabina chinensis community present the opposite pattern. Finally, the diurnal variation characteristics of CO2 flux in different communities have the same trend, but the peak values differ significantly. Overall, daily CO2 flux peak value of the Metasequoia glyptostroboides community and the Cinnamomum camphora-Trachycarpus fortunei community indicate that these two plant communities exhibit a strong capacity for CO2 absorption in the study area. According to these research results, urban greening efforts in subtropical climates can increase the green space covered by the Cinnamomum camphora-Trachycarpus fortunei and the Metasequoia glyptostroboides community types when urban greening, so as to appropriately reduce the CO2 emitted into the atmosphere.

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