Ecosystem, tundra

On the wide shore terraces of fjords and on the slopes of hills and low mountains, the Arctic Tundra ecosystems occur. The mosses and lichens are predominant with... 

Figure 1. Polar and Tundra ecosystem area in the Northern Hemisphere.

We can compare these values with those characterizing the fluxes of trace metals in biogeochemical cycles. The biological productivity of the Polar Tundra ecosystem grown on the low terrace in the region of Barentsberg, Spitzbergen Island, is shown in Table 5. 

The tundra zone and corresponding tundra ecosystems occupy the northernmost strip of the continental area of Eurasia and North America bathed by the seas of the Arctic basin. The climate conditions of the tundra zone provide for a higher productivity of ecosystems and higher activity of biogeochemical cycles of various elements as compared with the Arctic ecosystems. The mosses, lichens, and herbaceous plant species are predominant in the northern part of the Tundra ecosystems and shrubs are prevalent in the southern part. 

The ash contents of the total trace elements and nitrogen are similar in Tundra ecosystem biomass. The highest concentrations, >0.1% by dry ash weight, are typical for Ca, K, Mg, P, and Si. We can note the increase of iron, aluminum and silicon contents in the underground parts of any plants. 

The biomass of Tundra ecosystems gradually increases from 4-7 ton/ha for moss-lichen tundra to 28-29 ton/ha by dry weight for low-bush tundra. In the northern tundra, the plant biomass and dead organic matter are eventually shared. Southwards this percentage tends to diminish, and low-bush living biomass is smaller than dead plant remains mass. A typical feature of the Tundra ecosystems plant species is the prevalence of underground matter (roots) up to 70-80% of the total biomass. 

Table 7. The partition of Tundra ecosystem biomass, ton/ha (after Rodin and Bazilevich, 1976).

The average mass distribution of Tundra ecosystems is as shown in Table 7. 

Table 8. Annual fluxes of chemical species in the Low-Bush Moss Tundra ecosystem (after Dobrovolsky, 1994).

The flux of chemical elements per unit area in tundra ecosystems is not proportional to the plant uptake. Presumably, some elements, like Zn and Cu, are taken up selectively, whereas other trace elements, like Ti, Zr, V, or Y, are absorbed passively, depending on their content in the environmental media. 

The microbial activity in forest soils is much more intense in comparison with Tundra ecosystems. Fungi, bacteria and actinomycetes play a significant role in degradation of carbohydrates of forest litterfall (Box 1). 

Kling, G. W. 1995. Land-water linkages The influence of terrestrial diversity on aquatic systems. In Role of Biodiversity in Arctic and Alpine Tundra Ecosystems (F. S. Chapin and C, Korner, Eds.), pp. 297—310. Springer-Verlag, New York. 

Bonan G. B., Chapin F. S., Ill, and Thompson S. L. (1995) Boreal forest and tundra ecosystems as components of the climate system. Climat. Change 29, 145-167. 

Oechel W. C., Hastings S. J., Vourlitis G., Jenkins M., Riechers G., and Grulke N. (1993) Recent change of arctic tundra ecosystems from a net carbon dioxide sink to a source. Nature 361, 520—523. 

Hanson, W.C., Transuranic elements in arctic tundra ecosystems. In W.C. Hanson (Ed.), Transuranic Elements in the Environment pp. 441-458. U.S. Dept, of Energy, DOE/TIC-22800, Technical Information Centre, Springfield, VA, USA, 1980. 

Diaz, A., Pefaur, J. E., Durant, P. 1997. Ecology of the South American paramos with emphasis on the fauna of the Venezuelan Ptomos. F. E. Wielgolaski (ed.). Polar and alpine Tundra. Ecosystems of the World. . Elsevier, Amsterdam, pp. 263-310. 

Compare the biological and biogeochemical characteristics of Tundra and Polar ecosystems. Explain the role of climate and soil chemical composition in the formation of biogeochemical turnover in Tundra ecosystems. 

The Tundra ecosystems are represented by the Eurasian geographical region with primitive humid Podzols, Cryic Gleysols, Histosols, Litosols and Regosols. 

This part of Tundra ecosystems covers the northern coasts of the continent and the southern part of the North American archipelago. In the north it is bounded by the Arctic desert and in the south by the Boreal Taiga Forest ecosystems. 

As in Eurasia, the southern boundary of the Tundra ecosystems in North America deviates considerably from strictly latitudinal direction. In Labrador, cooled by the cold current, and on the shores of cold Hudson Bay, the Tundra ecosystems penetrate south to 54° N. To the west of Hudson Bay, with the increasing continentality of the climate, the boundary between Tundra and Boreal Taiga Forest ecosystems is... 

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