scholarly journals Shrub and dwarf shrub communities of Sangilen Plateau

2021 ◽  
Vol 38 ◽  
pp. 00143
Author(s):  
Evgeny Zibzeev ◽  
Natalia Igay ◽  
Evgeny Sinkovskiy ◽  
Sergey Savchuk ◽  
Vladimir Lebed’ko
Keyword(s):  
Dwarf Shrub ◽  
Dwarf Shrubs ◽  
High Incidence ◽  
Dwarf Birch

The paper presents a detailed ecological and caenotic characteristic of dwarf shrub and shrub communities growing in the highmountain belt of the Sangilen Plateau. The communities investigated were referred to the class of Loiseleurio-Vaccinietea Eggler 1952. The dwarf birch thickets with prevalence of Betula rotundifolia and the high incidence of Caragana jubata, Juniperus pseudosabina, J. sibirica, Pentaphylloides fruticosa, Salix glauca, Spiraea alpina were referred to the union of Carici tristis–Betulion rotundifoliae Zibzeev et al. 2018 of the order of Betuletalia rotundifoliae Mirkin at al. ex Chytrý Pešout et Anenkhonov 1993. Communities with dominant calciphilous shrubs and dwarf shrubs, such as Rhododendron adamsii, Caragana jubata, Salix berberifolia, S. reticulata, were referred to the union of Saxifrago oppositifoliae–Rhododendrion adamsii Zibzeev et al. 2018 of the order of Rhododendro-Vaccinietalia Br.-Bl. ex Daniels 1994.

scholarly journals Architecture of dwarf shrubs and dwarf subshrubs of the genus of Thymus L. and Scutellaria L. (Lamiaceae)

2021 ◽  
Vol 38 ◽  
pp. 00021
Author(s):  
Vera Cheryomushkina ◽  
Evgeniya Talovskaya ◽  
Alexandra Guseva
Keyword(s):  
Central Asia ◽  
Life Form ◽  
Wide Distribution ◽  
Spatial Position ◽  
Dwarf Shrub ◽  
Habitat Conditions ◽  
Dwarf Shrubs ◽  
First Time ◽  
Architectural Unit

The structure of 24 species of Thymus and 12 species of Scutellaria was studied using the architectural approach. For the first time, an architectural unit was described, it is a branched sympodial axis. The architectural unit consists of sympodial axes n+1 order, formation shoots, branching shoots, ephemerous shoots. The wide distribution of species and development of species in contrasting habitat conditions is due to the diversity of sympodial axes and shoots that are part of the architectural unit. Depending on the type of branching and the spatial position of sympodial axes, six modifications of architectural unit were identified. It is established that the structure of mature individuals are formed due to the repetition one of the same modification of architectural unit or a combination different modifications of architectural unit. Each of the variants of the combination determines the type of life form (dwarf shrub or dwarf subshrub) and biomorph (monocentric, dense polycentric, sparse polycentric) and depends on the conditions of the ecotope. The identified modifications of the architectural unit and the variants of their combination determine the strategy for the development of dwarf shrubs and dwarf subshrubs in the development of Northern and Central Asia.

Responses of carbon and nitrogen concentrations in high arctic plants to experimental warming

2001 ◽  
Vol 79 (6) ◽  
pp. 711-718 ◽  
Author(s):  
Anne Tolvanen ◽  
Gregory HR Henry
Keyword(s):  
Nutrient Uptake ◽  
Plant Species ◽  
Ellesmere Island ◽  
Total Carbon ◽  
Dwarf Shrub ◽  
Dwarf Shrubs ◽  
N Concentration ◽  
Cassiope Tetragona ◽  
Increased Risk ◽  
Nitrogen Concentrations

We studied total carbon (C) and nitrogen (N) concentration in five arctic plant species, Cassiope tetragona (L.) D. Don (evergreen dwarf shrub), Dryas integrifolia Vahl (semi-evergreen dwarf-shrub), Salix arctica Pall. (deciduous, dioecious dwarf shrub), Oxyria digyna (L.) Hill (forb), and Carex stans Drej. (graminoid, sedge), after five growing seasons of experimental increase in temperature. The experiments were established in different habitats along a moisture gradient in a coastal lowland at Alexandra Fiord, Ellesmere Island (79ºN). Sampling was conducted three times during the growing season. The seasonal patterns of C and N concentration were similar across all investigated species, even though the absolute concentrations differed. Nitrogen concentrations were high early in the season during the active growth period but declined later in the season. Warming decreased the N concentration and increased the C/N ratio in the three woody species, whereas N concentrations in the forb and the sedge were not affected. Although not measured directly in our study, the differences in concentrations may be due to the slower response in nutrient uptake and growth in the dwarf shrubs but increased nutrient uptake and growth in the forb and the sedge. Among-site differences were only significant in C concentrations of old tissues of Cassiope tetragona and S. arctica. Male and female S. arctica did not differ in their responses to warming. Differences among plant species in their plastic responses may relate to survival during rapid environmental change. Slow-responding dwarf shrubs may be under increased risk of competition from more responsive and faster growing species, such as forbs and graminoids.Key words: allocation, climate change, dwarf shrub, forb, graminoid, ITEX, Ellesmere Island.

Age and epiphytic lichen diversity of the dwarf shrub Helianthemumoelandicum on the island of Öland, Sweden

2009 ◽  
Vol 41 (5) ◽  
pp. 537-545 ◽  
Author(s):  
L. FRÖBERG ◽  
M. NIKLASSON ◽  
H. PALTTO ◽  
T. KNUTSSON ◽  
T. JOHANSSON
Keyword(s):  
Root Diameter ◽  
Lichen Species ◽  
Dwarf Shrub ◽  
Calcareous Grassland ◽  
Species Number ◽  
Epiphytic Lichen ◽  
Dwarf Shrubs ◽  
Lichen Diversity ◽  
Lichen Cover

AbstractLichen cover and diversity were analysed on the dwarf shrub Helianthemum oelandicum (L.) Dum.Cours. at one site in the calcareous grassland of the area known as the ‘Great Alvar’ on the Island of Öland, Sweden. The age of 22 phorophytes was determined by ring counting and varied from 8 to 41 years and was accurately predicted by the root diameter. A total of 18 lichen species was found, with a range between 0 and 13 species per phorophyte. The number of lichen species on living H. oelandicum were correlated with the phorophyte age. The number of lichen species and their coverage were greater on dead compared with living phorophytes. The species number was also higher on thin branches compared with thick branches and roots and some of the species showed preferences for dead phorophytes, and for thin branches. This study of lichen colonization and growth on dwarf shrubs in relation to phorophyte age is a new application of herbchronology.

scholarly journals Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

2016 ◽  
Vol 13 (13) ◽  
pp. 4049-4064 ◽  
Author(s):  
Inge Juszak ◽  
Werner Eugster ◽  
Monique M. P. D. Heijmans ◽  
Gabriela Schaepman-Strub
Keyword(s):  
Active Layer ◽  
Arctic Tundra ◽  
Dwarf Shrub ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Active Layer Thickness ◽  
Vegetation Types ◽  
Transmitted Radiation ◽  
Dwarf Shrubs ◽  
North East

Abstract. Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17 ± 0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and sedge vegetation with higher soil moisture.

scholarly journals Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

2016 ◽  
Author(s):  
Inge Juszak ◽  
Werner Eugster ◽  
Monique M. P. D. Heijmans ◽  
Gabriela Schaepman-Strub
Keyword(s):  
Active Layer ◽  
Arctic Tundra ◽  
Dwarf Shrub ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Active Layer Thickness ◽  
Vegetation Types ◽  
Transmitted Radiation ◽  
Dwarf Shrubs ◽  
North East

Abstract. Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17 ± 0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and sedge vegetation with higher soil moisture.

The observation of defects on (100) CdTe surfaces by chemical etching

1992 ◽  
Vol 50 (2) ◽  
pp. 1424-1425
Author(s):  
M.E. Lee
Keyword(s):  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Chemical Etching ◽  
Crystalline Perfection ◽  
Crystalline Defects ◽  
High Incidence ◽  
Crystallographic Defects ◽  
Cdznte Substrates ◽  
Device Technology

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.

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