Abstract
Data on the distribution of the plant communities, their productivity and major carbon stores held in the mountain tundra vegetation and soils are presented. It was revealed, that extreme snow-bed communities had the lowest total biomass (662 g/m2), with the main root portion in the mineral soil horizons. Dwarf shrubs-dominated heath on gentle mountain slope had the highest total biomass (2406 g/m2), with woody perennial stems prevailing in the aboveground portion, and the main root portion concentrated in the organic horizon. The grass and sedge meadows situated in the hollow had the greatest total net primary production (215 g/m2), and roots evenly distributed in the whole soil profile.
Total amount of carbon reserved in the ecosystem (that includes carbon stored in the aboveground and belowground biomass, in the organic horizon, and in the mineral soil horizons to 30 cm depth) was lowest in snow-bed and lichen-dominated tundra (6183 g/m2 and 6337 g/m2), and highest in the dwarf shrubs and grasses-dominated tundra (25261 g/m2 and 20407 g/m2), that was comparable with total carbon stored in the boreal forest ecosystems. The major part of carbon (95-97%) in tundra ecosystems was stored in soils (organic and mineral soil horizons).
Keywords
Mountain tundra, topography/snow gradient, biomass, carbon stock.
1. Introduction
Tundra plant communities are known to have low productivity and limited distribution in the world, but the total amount of carbon held in tundra biome is rather high. The carbon pool in tundra soil is referred as 13.7% of world amount of carbon stored in the soil (Ajtay et al., 1979). This estimate usually is derived using a various extrapolation techniques, but this method is not feasible without full study of spatial uneven structure of tundra landscape.
The objective of this investigation is to determine variation of such ecosystem characteristics as composition and biomass of plant cover, and soils along the topography/snow gradient, and evaluate the carbon accumulation in context of ecosystem position as to this gradient.
2. Site description and methods
2.1. Site description
Field studies were conducted in the Khibiny Mountains situated in central part of Murmansk Province, NW Russia. These low mountains (800-1000 m) represent the alkaline intrusion and richest type of bedrocks in Murmansk Province. Owing to recent glaciation, the mountains have flat surfaces and steep slopes with well-developed moraine deposits at the bottoms.
In general, the Murmansk Province has a maritime climate, with moderately cold, snowy winters, and short, cool summers, but the climate of the central part of Murmansk Province is more continental, than the climate of the eastern and coastal parts. Meteorological data are available from the Handbook of Climate of USSR (Anon. 1965, 1968) for the station Kirovsk (67o34’N, 33o36’E; 349 masl.). The mean annual average air temperature is -1.2°C, for July +12°C, and for January-February -13°C. Maximum annual temperatures in mountains are less than in lowlands. The averaged growing season is 95 days. Snow cover lasts about 200 days, and its distribution is strongly affected by wind and topography. The annual average precipitation is 712 mm, with highest in August (60 mm), and lowest in February (20 mm). Most part of the Murmansk Province is covered by complex of northern taiga and wetlands, only coastal lowlands are considered as the southern zone of the sub-arctic tundra (Alexandrova, 1977). Birch forests form a well-defined band between taiga forests and sub-arctic tundra.
There exist three vegetation belts or zones in Khibiny Mountains – counterparts of analogous zones in lowlands – coniferous forests, mountain birch forest and mountain tundra. Four field sites were selected in tundra belt, at about 570 m above sea level and represented a catena that comprises wind-exposed ridgetop, gentle south-exposed slope, snow- and water-accumulated depression and snow-bed.
2.2. Methods
Air temperature and humidity was recorded daily by the hygrothermographs, which have been sheltered at a height of 30 cm. Soil temperature was recorded by the soil thermometers at the depth 10 and 5 cm.
Plant communities along the topography/snow gradient were described following Braun-Blanquet and mapped. Nomenclature for vascular plants follows Cherepanov (1995), for mosses Ignatov & Afonina (1992), for liverworts Konstantinova et al (1992) and for lichens Santesson (1993).
Litter was defined as the surface organic soil horizons. 25x25 cm soil and organic horizon sods (to the parent rocks depth) were collected at each harvesting for root biomass. Roots were extracted from organic and mineral soil horizons. Organic horizon was separated from mineral soil horizon, and sorted in accordance to decomposition degree. Samples of organic horizon were taken every ten days to determine the moisture content that was calculated from weight loss after oven-drying at 105o to a constant weight. Soil samples were collected from all soil horizons and roots were removed by hands. Soil horizons nomenclature was according to the Russian soil classification (1997). Soil texture was recorded by field observation and the rock fragment was estimated in the field. Color of each horizon was described in accordance with scale of Munsel.
Standing crop and net production were sampled by harvesting 25x25 cm plots in August, when it was assumed to peak, four replicate samples for each element of the catena (16 samples). In addition 25x25 cm sod blocks were collected for stem base and roots biomass information to the parent material. Aboveground standing crop was sorted to species, and then divided into standing ‘live’ (annual increment and ‘old’ shoots, taking separately leaves and branches) and standing dead. Green portion of mosses as well as ‘live’ parts of lichen thallomes were counted as standing crop, with dead portion estimated as an organic horizon. Aboveground production was estimated as the annual shoot-leaves increment, and increment of mosses and lichens was counted as, respectively, 20% and 5% of their standing crop. All plant material was ovendried at 105oC prior to weighting. The standing crop and production values per m2 were calculated using biomass information per species for each field site.
Total carbon stored in ecosystem at each landscape unit was estimated to 30 cm deep - to that area a major portion of roots is confined. The total organic carbon (TOC) stored in ecosystem was calculated as a sum of soil organic carbon (SOC) (which includes organic carbon of mineral soil horizons and carbon of the organic horizon) and carbon in the plants of the phytocoenosis (aboveground and belowground portions). Carbon content in plant was calculated using carbon concentration in oven-dry leaves and stems of vascular plants, or green portion of plants for mosses, or lichen thallomes (%) by Tjurin procedure (Ponomareva & Plotnikova, 1975) and biomass of this tissue or organ, or portion of plant (g). Carbon content in the organic soil horizon was calculated using its concentration in its sub-layers (%) and biomass of given sub-layers (g). Organic carbon held in each mineral soil horizon was calculated using its concentration in root-free soil of this horizon (%), by Tjurin procedure, soil bulk density (g/cm3) and thickness of layer (cm); then summed to know total organic carbon content in mineral soil horizons.
3. Results and Discussion
3.1. Plant communities and soils
Four tundra sites of the catena occupied contrasting landscape positions and have different soil morphology (see description of profiles below) and plant cover (Table 1). The mountain ridgetop has thin snow cover in the winter, that thaws in April – early May, and experiences drought in summer. Yellow lichens (Flavocetraria nivalis, F. cucullata, Alectoria ochroleuca) take dominance here, with minor portion of dwarf shrubs and mosses. These plant communities belong to Association Cetrarietum nivalis Dahl 1956.
Gentle slopes below the ridgetop is protected with snow, that thaws early enough in spring at the end of May-first decade of June, to make a growing season ideal for mountain tundra plants. Here, the dwarf shrubs (Vaccinium myrtillus, Empetrum hermaphroditum) form a dense field layer, with mesophilous pleurocarpic mosses (Pleurozium schreberi, Dicranum spp.) making a ground cover. Plant communities are ascribed to Association Phyllodoco-Vaccinietum myrtilli Nordh. 1943.
Alluvial depression, where melting water stays till the end of June, is characterized by luxuriant cover of grasses Avenella flexuosa, Anthoxanthum alpinum, Nardus stricta. These plant communities belong to Association Anthoxantho (alpini)-Deschampsietum flexuosi Nordh. 1943.
In snow-bed site, snow melts as late as the middle of July, giving a much shorter growing season. Only a limited number of vascular plants can grow here, such as Harrimanella hypnoides and Salix polaris, such mosses as Kiaeria starkei, liverworts as Gymnomitrion spp., lichens as Stereocaulon alpinum, Solorina crocea being the most characteristic species. Plant communities belong to Association Cassiopo-Salicetum herbaceae Nordh. 1936. Here, in mountains of Murmansk Province, the snow-bed communities represent a retreat since the Glacial Period.
Soil temperature was lower at the slope, and soil humidity was slightly higher in alluvial depression and on the slope, than on the comparable ridgetop and snow-bed sites (Tab.1). Soils of mountain tundra are derived from weathered nepheline syenits, the phosphates-rich parent material. The landform is characterized by is convex to flat-topped mountain slopes and ridges.
Sampling site 1.
Sampling date: 10.08.2000
Elevation: 570 m above sea level
Geomorphic position: Ridge crest
Stones, gravels and cobbles content: 90%.
Drainage class: somewhat excessively drained
Vegetation: lichens-dominated open plant communities of Cetrarietum nivalis.
O 0-2 cm; well-decomposed organic horizon, black (2,5Y 2/0), loose, gravely lichen crust mor, fresh, (very
high decomposed lichens remnants content), pH 4.5.
BHF 2-15 cm, very dark brown (10YR 2/2), gravely and stony sand, unclear and broken boundary, pH 5.4.
BF 15-20 cm, dark reddish brown (5YR 3/2), very gravely sand, pH 5.5.
C 31-36 cmdark yellowish brown (10YR 3/6), gravely sand, closely spaced stones, pH 5.5
Sampling site 2
Sampling date: 18.08.2000
Elevation: 568 m above sea level
Geomorphic position: gentle slope, SW aspect
Stones, gravels and cobbles content: 60-70%
Drainage class: moderately well drained
Vegetation: dwarf shrubs dominated closed plant community of Phyllodoco-Vaccinietum myrtilli
O 0-9 cm, black + dark reddish brown (5YR 2,5/1,5), well-decomposed humus (high organic matter
contents), layered, fresh, plentiful roots, pH 4.4.
H 9-15 cm, black (5YR 2,5/1), sandy humus, very high organic matter content, loose, plentiful fine roots,
gravely, gradual boundary, pH 4.8.
BH15-22 cm, black + dark reddish (5YR 2,5/1,5), stony sand, fresh, fine roots, unclear boundary, pH 4.7.
BHF 22-30 cm, dark reddish brown (5YR 2,5/2), very gravely sand, fine roots, unclear boundary, pH 5.0.
BHF30-43 cm, dark reddish brown (5YR 2,5/2), very gravely sand, fine roots, pH 5.1.
C43-48 cm grayish brown (10YR 5/2), very gravely and stony sand, pH 5.2.
Sampling site 3
Sampling date: 9.08.2000
Elevation: 560 m above sea level
Geomorphic position: alluvial depression
Stones, gravels and cobbles content: 30%
Drainage class: poorly drained
Vegetation: grasses and sedges dominated plant community of Anthoxantho (alpini)-Deschampsietum flexuosi
O10-1 cm, organic horizon of slightly decomposed grasses and sedges, fibrous humus, very dry, loose, pH 5.0.
O21-4 cm, black (5 YR 2,5/1), humus, very high fibrous organic matter contents, abundant fine and very fine
roots, fresh, pH 5.0.
H4-14 cm, black (10YR 2,5/1), sandy humus, plentiful mixed fine roots, very high half-decomposed roots
contends, fresh, pH 4.7.
BH14-21 cm, black (5YR 2,5/1), sand with illuvial humus, plentiful mixed fine roots, fresh, pH 5.0.
BHF21-28 cm, very dark grayish brown (10 YR 3/2), stony sand, fresh, pH 4.8.
BF28-45 cm, brown (10YR 4/3), plentiful fine roots, gravely and stony sand, pH 5.2.
C45-60 cm, grayish brown (2,5 Y 5/2), extremely stony sand, lithic contact composed of closely spaced
boulders, pH 5.4.
Sampling site 4
Sampling date: 6.08.2000
Elevation: 562 m above Sea level
Site position: flat snow-bed depression
Stones, gravels and cobbles content: 70-80%
Drainage class: moderately well drained
Vegetation: cushions of mosses, lichens and dwarf shrubs of Cassiopo-Salicetum herbaceae
O10-1 cm, half-decomposed organic horizon, moss mor, mainly of mosses remnants
O21-2 cm, black (5YR 2,5/1), well-decomposed, gravely and sandy mor, loose, dry, pH 5.0.
BHF2-8 cm, very dark gray (10YR 3/1), gravely sand, loose, fresh, plentiful roots, unclear boundary, pH 5.0.
BHF8-12 cm, very dark grayish brown (10YR 3/2), humic, gravely sand, loose, fresh, plentiful roots, pH 5.2.
BF12-30 cm, grayish brown (10YR 4/2), gravely sand, a lot of cobbles and large gravel, pH 5.4.
BF30-40 cm, grayish brown (2,5 Y 5/2), very gravely sand, lithic contact composed of closely spaced cobbles
and large gravel, pH 5.6.
Soils of all landscape units can be referred as tundra Podbures, sandy, with very high coarse gravel and stone content. The common feature of mountain tundra soil in Khibiny Mountains is the absence of podzolic horizon E and development of illuvial-Al- Fe-humus horizon (Pereverzev et al., 2001).
The fraction of organic horizon as well as the thickness of soil profile was minimal on the ridgetop and snow-bed site, and maximal on the slope (Fig.2). Organic matter stored was similar in all elements of catena, with exception of dwarf shrub community, where the largest organic matter stock (13443 g/m2) was found. Organic horizon is well-layered here and comprises thick decomposed sub-layer (12733 g/m2).
3.2. Total standing crop, aboveground biomass and net annual production.
The standing crop differs essentially in different landscape units of catena (Fig.1, Tab. 2). The highest total and aboveground biomass were determined in dwarf shrubs dominated plant communities on the slope (2406 g/m2 and 756 g/m2, respectively), and lowest - in snow-bed plant community (662 g/m2 and 286 g/m2). Total biomass of meadows (2360 g/m2) was comparable with dwarf shrubs dominated community, but aboveground portion was much lower. Dwarf-shrubs and lichen communities have almost equal aboveground biomass, but well pronounced differences in its structure. In dwarf shrub community perennial shoot material of dwarf shrubs constituted prevailing portion of aboveground biomass - 55%. In lichen community lichens constituted 70% of aboveground biomass.
In all of the plant communities investigated only 2-4 prevailing species contributed the major part of aboveground standing crops. In meadow community two species - Avenella flexuosa, Nardus stricta – made up of 76% of the aboveground biomass. In dwarf-shrub community two dwarf shrubs Empetrum hermaphroditum, Vaccinium myrtillus and one lichen species Cetraria islandica contributed 90% of the total aboveground biomass. In lichen community two dominant lichen species Flavocetraria nivalis and Alectoria ochroleuca made up to 50% of aboveground biomass. In snow-bed community four species (Harrimanella hypnoides, Kiaeria starkei, Cetraria islandica, Stereocaulon alpinum) contribute more than 70% of aboveground biomass.
Annual net production of the aboveground biomass averaged at 45 g/m2 in snow-bed, 67 g/m2 in lichen, 131 g/m2 in dwarf shrub and 214 g/m2 in meadow that was the highest (Tab.2). Primary production constituted 9-17% of aboveground biomass, with exception of meadow community, where annual green shoot increment constituted major part (65%) of aboveground biomass.
In meadow and dwarf shrub communities the major part of aboveground production was contributed by vascular plants (by graminoids in meadow), 90 and 71%, respectively. In lichen community lichens contributed almost 70% of the total aboveground production, and production of evergreen dwarf shrubs and of deciduous dwarf shrubs was equal (15%). In snow-bed community annual production of vascular plants, mosses and lichens constituted 52%, 18% and 30%, respectively, of total production.
Data for reasonably comparable tundra plant communities were achieved for Taimyr Peninsula (northern Siberia) and north-eastern Siberia (Bazilevich, 1993). Data of aboveground biomass (3500 g/m2), and primary production (500 g/m2) in dwarf shrubs-dominated tundra of Taimyr were higher than data received in Khibiny mountains And results received in north-western Siberia (aboveground biomass 1310 g/m2 and primary production 220 g/m2) were similar to our data. Aboveground vascular biomass data estimated for major North American arctic plant communities were between 50 g/m2 and 500 g/m2(Chapin and Shaver, 1985) that correspond to our data on aboveground biomass of snow-bed and meadow communities. Several types of meadows were reported to have the highest total biomass (2305 g/m2) and net primary production (165 g/m2) in arctic tundra of Devon Isl. (Muc, 1977), that was very similar with mountain tundra meadows of Khibiny mountains.
3.3. Belowground biomass.
Belowground data are based on root material collected from soil sods (25x25 cm). Sampling extended for the full depth to parent rocks in all communities. Average belowground biomass was highest in meadow communities, 2034 g/m2 and roots contributed 86 % of total biomass (Tab.3, Fig. 1). Belowground data showed that in meadow community roots were evenly distributed in the soil profile, meanwhile in dwarf shrub community major portion of root biomass occurred in the organic horizon, and in snow-bed and lichen communities in the mineral soil horizons.
Belowground/aboveground biomass ratio varies from 0.56 to 6.2, and is minimal in plant communities of extreme snow free habitat, where lichens prevail, and a number of species of vascular plants and its phytomass are small. In meadow community belowground biomass (that included roots, rhizomes, clumps base and tillering zone of graminoids) was almost six times higher, than aboveground biomass. The large belowground biomass and belowground/aboveground biomass ratio in dwarf shrubs dominated and meadow communities was consistent with that reported for relatively mesic low arctic habitats (Andreev, 1966; Muc, 1977).
Structure of biomass of communities on the snow/topography gradient is closely associated with soil conditions (Fig.2). Roots distribution characterizes the soil conditions on the soil profile. In dwarf shrubs communities on the slope the major portion of roots was in the wet and aerated thick organic horizon. Meadow communities in alluvial depression demonstrated uniform distribution of roots in the soil profile. The profile is enriched by decomposed humus resulting from root decay. Both soil profiles in meadow and dwarf shrubs dominated communities have thick humic (‘peregnoy’) horizon.
In lichen-dominated and snow-bed communities, where the organic horizon was thin, the main portion of roots was concentrated in mineral horizons. These communities are situated in contrasting habitats and differ essentially in species composition and proportions of groups of plants, but formed similar root biomass. Vascular plants of lichen-dominated community on ridge crest (which proportion in aboveground biomass was only 30%) form almost the same root biomass as vascular plants of snow-bed habitat that contributed 52% of aboveground biomass of the whole community. It is most likely the shortened growing period in snow-bed habitat limited number of vascular plants, which form small aboveground and belowground biomass. Both habitats have relatively low soil moisture that limits the root growth, nevertheless, on the ridge crest, where the growth season is much longer, belowground biomass is higher, than in snow-bed habitat. Soil profile of snow-bed habitat showed a general resemblance with that in the lichen community. Soil profile is short, the organo-mineral (BH, BHF) horizon, where humus is bound with Al and Fe weathered from bedrocks, is expressed.
3.4. Carbon contents
Carbon contents in tundra plant species and plants tissues vary from 35% to 53% (Tab.3). Annual and perennial tissues of dwarf shrubs contain more carbon (45-52%), than leaves and shoots of grasses (41-44%) and mosses (41-43%). Carbon contents in the lichen thallomes is lowest (34-39%).
The distribution of carbon in ecosystems of snow/topography gradient does not follow the snow/topography gradient (Tab. 4). As to total biomass of community, carbon stored was maximal in dwarf shrub (1010 g/m2) and meadow (1005 g/m2) communities, which is three times as higher as in snow-bed community (272 g/m2). Belowground biomass holds more carbon, than the aboveground portion (with exception of lichens-dominated community).
Our results are higher than average values of carbon reserved in phytomass of mountain tundra of Kola Peninsula used for calculating of carbon storage in the tundra ecosystems of Russia (Karelin et al., 1995).
The commonly accepted assumption for carbon storage calculation is that 1 kg of dry phytomass contains 0.45 kg of carbon (Ajtay et al.,1979). But concentration of carbon calculated for plant communities on the base of carbon concentration in tundra plants of Khibiny mountains (Tab. 4) proved to be lower (from 40.1g to 42.6 g of carbon on 100 g of dry phytomass).
Carbon concentration in the organic horizon of ecosystems on snow/topography gradient decreases from the upper to the lower sub-layer that is contiguous with mineral soil horizons (Tab.5). The largest carbon stock was in the organic horizon of the dwarf shrub community (4684 g/m2), the minimal - in the lichen and snow-bed communities (723 and 830 g/m2, respectively). Organic carbon contents held in soil mineral horizons of catena vary essentially. Carbon stock in 30-cm layer of mineral soil was largest in dwarf shrub and meadow communities (19505 g/m2 and 17380 g/m2, respectively). Such a large stock of carbon in the soil could be partly explained by the relatively large amount of phytomass and litterfall produced by these phytocoenosises, and partly by specific processes of transformation of the organic matter in tundra soil of Khibiny Mountains. There prevail processes of conservation of the organic matter in the organic horizon of tundra soils (Ushakova, 1999). Water-soluble organic matter is washing out of the organic horizon and gets fixed in illuvial soil horizon owing to rich bedrocks of Khibiny mountains (Ponomareva, 1940; Nikonov, Pereverzev, 1989).
Minimal carbon stock was in 30-cm layer of mineral soil in snow-bed and lichen communities (5081 g/m2 and 5153 g/m2, respectively). The matter is that these communities produce low phytomass and low litterfall - snow-bed community because of shortened growing season, and ridge top community because of slow rate of growth of lichens which are prevailing components of this community. Moreover, the carbon content in lichens is lowest, compared with vascular plants and mosses (Tab.3).
Similar results on average soil organic carbon stock were obtained for tundra soil of Murmansk province by Chestnykh et al. (1999), though author’s data on carbon in mountain tundra soils are lower (53.3 t/ha, or 5330 g/m2), than our results, and could be compared only with minimal carbon contents in mineral soil horizons in lichen-dominated community of Khibiny Mountains.
Total organic carbon (TOC) of tundra ecosystems along snow/topography gradient is mainly organic horizon and mineral soil horizons organic carbon, and belowground phytomass, which contributes from 95% to 99% of TOC, and aboveground phytomass of phytocoenosis make up remaining 1-5%.
4. Conclusion
Four plant community types analyzed are represented elsewhere in west-European sector of Sub-arctic and in the tundra (or ‘goltzy’) zone of mountains of central and eastern Eurasia, but only two types are referred as prevailing. Dwarf shrubs communities prevail in zonal sub-arctic tundra of Murmansk Province and on lower parts of mountains, representing here so called ‘plakor’ (or eu-climate) type of sub-arctic tundra plant cover. Lichens-dominated communities cover vast areas of bedrocks outcrops. Meadows and snow-bed plant communities are of minor occurrence and occupy small area.
Vegetation, namely, growth forms spectrum, its biomass and productivity vary along the short topographical gradient in mountain tundra, and this local gradient is closely tied to carbon stored in various landscape units. Difference between landscape units in both biomass and carbon stored may be as much as four times. In general, micro-climatic conditions of habitat (exposure, slope, snow thickness and time of thawing, soil temperature and moisture) effect the plant cover composition and structure, and these characteristics (species and growth forms, cover and abundance) determine the phytomass and litterfall produced by community. Habitat conditions and species composition (especially growth forms spectra) together with processes of transformation and migration of organic in the soil profile affect soil organic carbon stock and distribution.
The most striking characteristic concerning total organic carbon (TOC) stock and distribution within the ecosystems of mountain tundra catena is that the ecosystem of plakor (dwarf shrubs on the slope) contain largest total carbon stock and it is stored mainly in the organic and mineral soil horizons and belowground biomass (roots and rhizomes), only 1% of TOC is attributed to the aboveground biomass. In the lichen-dominated ecosystem of the ridgetop TOC is minimal and about 5% disposed at the aboveground biomass. TOC of ecosystem in snow-bed depression of the catena is almost the same as on the top of ridge despite the differences in vegetation composition.
5. Acknowledgements
We acknowledge Russian Found of Basic Research for financial support of the project (grant № 01-04-48206).
Table1. Soil temperature, soil humidity and plant communities on topography/snow landscape units in tundra zone of Khibiny Mountains
| Landscape units /their characteristics |
Ridgetop |
Slope |
Alluvial depression |
Snow-bed |
| Soil temperature, oC (deep 10 cm) |
9.8 |
8.3 |
9.2 |
9.8 |
| Soil moisture, % (deep 10 cm) |
51.14±1.85 |
58.39±0.58 |
64.13±0.99 |
47.47±2.57 |
| Plants/coverage (%) | ||||
| Total cover (%) |
75 |
100 |
100 |
95 |
| Cover of herbs and shrubs (%) |
35 |
50 |
100 |
50 |
| Cover of mosses (%) |
<1 |
15 |
5 |
75 |
| Cover of lichens (%) |
75 |
35 |
- |
50 |
| Number of species |
25 |
33 |
7 |
18 |
| Betula nana |
5 |
<1 |
- |
<1 |
| Empetrum hermaphroditum |
15 |
10 |
- |
15 |
| Vaccinium vitis-idaea |
<1 |
5 |
- |
5 |
| Phyllodoce caerulea |
<1 |
1 |
- |
<1 |
| Festuca ovina |
1 |
1 |
5 |
1 |
| Juncus trifidus |
1 |
1 |
<1 |
5 |
| Solidago lapponica |
<1 |
<1 |
<1 |
<1 |
| Polytrichum piliferum |
<1 |
<1 |
- |
<1 |
| Cetraria islandica |
15 |
35 |
- |
1 |
| Flavocetraria nivalis |
50 |
5 |
- |
- |
| Alectoria ochroleuca |
25 |
- |
- |
- |
| Vaccinium uliginosum |
15 |
5 |
- |
- |
| Thamnolia vermicularis |
1 |
1 |
- |
- |
| Cladina rangiferina |
<1 |
5 |
- |
- |
| C. mitis |
<1 |
<1 |
- |
- |
| Flavocetraria cucullata |
<1 |
<1 |
- |
- |
| Polytrichum juniperinum |
<1 |
<1 |
- |
- |
| Oxytropis sordida |
1 |
<1 |
- |
- |
| Vaccinium myrtillus |
- |
75 |
- |
5 |
| Dicranum majus |
- |
15 |
- |
- |
| Pleurozium schreberi |
- |
5 |
- |
- |
| Anthoxanthum alpinum |
- |
<1 |
5 |
- |
| Barbilophozia lycopodioides |
- |
5 |
5 |
- |
| Avenella flexuosa |
- |
5 |
75 |
<1 |
| Nardus stricta |
- |
- |
25 |
- |
| Harrimanella hypnoides |
- |
- |
- |
35 |
| Salix polaris |
- |
- |
- |
15 |
| Kiaeria starkei |
- |
- |
- |
75 |
| Stereocaulon alpinum |
- |
- |
- |
50 |
Additional taxa (occurring with coverage <1%, unless indicated otherwise):
on the top of the ridge - Dryas octopetala, Loiseleuria procumbens, Diapensia lapponica, Racomitrium lanuginosum, Tetralophozia setiformis, Alectoria nigricans, Bryocaulon divergens
on the slope - Arctostaphylos uva-ursi (5), Arctous alpina (5), Bartsia alpina, Linnaea borealis, Polygonum viviparum, Pedicularis lapponica, Huperzia selago, Hylocomium splendens, Ptilidium ciliare, Lophozia sudetica, Cladonia ecmocyna (1), C. gracilis (1)
on the snow-bed site - Gymnomitrion concinnatum (5), Gymnomitrion apiculatum (1), Solorina crocea
Table 2. Structure of biomass and productivity of the plant communities
in the topography/snow landscape units (g/m2)
| landscape units |
Snow-bed |
Alluvial depression |
Slope |
Ridgetop |
| Aboveground biomass |
286.6+15 |
327.1+33 |
756.3+67 |
730.3+46 |
|
Vascular plants
|
148.5+10 |
294.6+ |
541.0+ |
220.5+ |
|
Mosses
|
53.2+4 |
32.5+4 |
16.6+9 |
2+0.5 |
|
Lichens
|
84.9+7 |
- |
198.7+17 |
507.8+46 |
| Net primary production |
45+3 |
214+6 |
131+7 |
67+5 |
| Belowground biomass |
376+47 |
2034+173 |
1650+248 |
424+72 |
| Belowground/ aboveground ratio |
1.3 |
6.2 |
2.2 |
0.56 |
| Biomass total |
662+60 |
2360+212 |
2406+192 |
1154+138 |
Table 3. Carbon contents (%) in plants of tundra zone of Khibiny Mountains.
| == Species and tissues == | == С, % == | == Species and tissues == | == С, % ==
|
| = Vascular plants = |
Non-green stems |
||
| = Leaves and live shoots = | Empetrum hermaphroditum |
40,13 |
|
| Empetrum hermaphroditum |
51,0-52,6 |
Harrimanella hypnoides |
52,64 |
| Harrimanella hypnoides |
52,5-52,8 |
Loiseleuria procumbens |
45,0-46,8 |
| Loiseleuria procumbens |
50,6-52,5 |
Vaccinium vitis-idaea |
50,24 |
| Vaccinium vitis-idaea |
49,6-51,6 |
V. uliginosum |
48,01 |
| V. uliginosum |
48,47 |
V. myrtillus |
49,22 |
| V. myrtillus |
50,31 |
Salix polaris |
48,0-48,5 |
| Salix polaris |
52,63 |
= Mosses = | |
| Festuca ovina |
42,16 |
Polytrichum juniperinum |
42,16 |
| Avenella flexuosa |
44,13 |
== Polytrichum piliferum == |
41,17 |
| Carex bigelowii |
42,16 |
Kiaeria starkei, green portion |
43,83 |
| == Juncus trifidus == |
41,45 |
«-« - brown portion |
41,39 |
| == Nardus stricta == |
42,16 |
== Lichens == | |
| == Diphasiastrum alpinum == |
40,13 |
Cetraria islandica |
36,6-37,62 |
| Avenella flexuosa |
43,8-45,9 |
Cetrariella delisei |
39,01 |
| == Juncus trifidus == |
41,45 |
Flavoetraria nivalis |
37,17 |
| == Nardus stricta == |
42,16 |
Stereocaulon alpinum |
37,75 |
Table 4. Carbon concentration / carbon stock (%/g/m2) and carbon distribution in the ecosystems of the topography/snow gradient in tundra zone of Khibiny Mountains
| Carbon content in: |
Ridgetop |
Slope |
Alluvial depression |
Snow-bed |
| Biomass total |
40.1 / 461.2 |
42.2 / 1009.7 |
42.6 / 1004.9 |
41.1 / 272.0 |
| Vascular plants |
50.7 / 111.2 |
49.8 / 263.2 |
42.9 / 126.4 |
42.9 / 72.1 |
| - annual tissues |
50.3 / 42.3 |
50.1 / 55.0 |
43.1 / 89.7 |
43.1 / 33.9 |
| - perennial tissues |
51.0 / 68.9 |
49.7 / 208.3 |
42.4 / 36.7 |
46.3 / 38.2 |
| Mosses |
41.8 / 0.8 |
42.9 / 3.1 |
41.2 / 13.4 |
41.0 / 22.1 |
| Lichens |
37.4 / 188.7 |
37.5 / 77.7 |
- |
37.8 / 32.1 |
| Aboveground biomass |
41.3 / 300.8 |
46.3 / 351.0 |
42.7 / 139.7 |
44.1 / 126.3 |
| Belowground biomass |
37.9 / 160.5 |
40.4 / 690.8 |
42.5 / 865.1 |
38.8 / 145.7 |
| Organic horizon (root-free) |
41.4 / 723 |
34.9 / 4684 |
33.8 / 2022 |
35.0 / 830 |
| - sub-layer L |
41.4 / 132 |
46.8 / 192 |
46.8 / 410 |
38.9 / 171 |
| - sub-layer F |
40.2 / 148 |
41.7 / 125 |
41.7 / 1612 |
33.2 / 659 |
| - sub-layer H |
28.2 / 443 |
34.3 / 4367 |
- |
- |
| Mineral horizons (deep to 30 cm ) |
4.0 / 5153 |
13.4 / 19505 |
9.8 / 17380 |
4.6 / 5081 |
| Ecosystem total (to 30 cm depth) |
4.8 / 6337 |
15.7 / 25261 |
11.0 / 20407 |
5.2 / 6183 |
6. References
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