Ecosystem, boreal forest

The response of tundra, bogs, and moist or wet boreal forest to new climate regimes is expected to be large. Sufficient research to characterize the response of these ecosystems over the next 50 to 100 years is a high priority. 

Fig. 8. Frost resistance in populations of Abies sachalinensis within the boreal forest ecosystem, (a) Frost resistance and variance in resistance with altitude (b) seed characteristics of populations all grown in the lowlands (after Eiga Sakai, 1984).

Hintelmann H, Harris, R, Heyes A, Hurley J, Kelly C, Krabbenhoft D, Lindberg S, Rudd J, Scott K, St. Louis V. 2002. Reactivity and mobility of new and old mercury deposition in a boreal forest ecosystem during the first year of the METAALICUS study. Environ Sci Technol 36 5034-5040. 

St. Louis VL, Rudd JWM, Kelly CA, Beaty KG, Bloom NS, and Flett RJ. 1994. Importance of wetlands as sources of methyl mercury to boreal forest ecosystems. Can J Fish Aquat Sci 51 1065-1076. 

Meili M. 1991. Mercury in boreal forest lake ecosystems. Comprehensive summaries of Uppsala Dissertations from the Faculty of Science, Report No. 336, Uppsala University, Sweden. 

Huchinson T.C., Whilby L.M. The effects of acid rainfall and heavy metals particulates on a boreal forest ecosystem near the Sudbury smelting region of Canada. Water Air Soil Pollut 1977 7 421 438. 

The Boreal and Sub-Boreal Forest ecosystems represent the forests of cold and temperate climate. These ecosystems occupy an extended zone in the northern part of the Northern Hemisphere. The total area is 16.8 x 106 km2, or 11.2% from the whole World s territory. 

The plant species biomass of Boreal and Sub-Boreal Forest ecosystems accumulates a significant part of living matter of the whole planet. This value is about 700 x 106 tons of dry weight. The biomass per unit area of different Forest ecosystems varies from 100 to 300 ton/ha and even 400 ton/ha in the Eastern European Oak Forest ecosystems. The annual net primary productivity, NPP, varies from 4.5 to 9.0 ton/ha (Table 1). 

Ecosystems taiga forest south taiga forest sub-boreal forest... 

Since nitrogen is a nutrient, which limits the productivity of almost all Boreal and Sub-Boreal Forest ecosystems, its biogeochemical cycling is relatively well understood at present. The major N transformations and fluxes are shown in Figure 3. 

Denitrification, a dissimilatory pathway of nitrate reduction (see Section 3.3 also) into nitrogen oxides, N2O, and dinitrogen, N2, is performed by a wide variety of microorganisms in the forest ecosystems. Measurable rates of N20 production have been observed in many forest soils. The values from 2.1 to 4.0 kg/ha/yr are typical for forest soils in various places of Boreal and Sub-Boreal Forest ecosystems. All in situ studies (field monitoring) of denitrification in forest soils have shown large spatial and temporal variability in response to varying soils characteristics such as acidity, temperature, moisture, oxygen, ambient nitrate and available carbon. 

However, the microbial activity is depressed during long and severe wintertime, and this leads to an accumulation of semi-mineralizable plant residues on the soil surface. With the increasing duration of cold season from south to north, the mass of these half-destroyed remains enlarges from 15 ton/ha of dry organic matter in Broad-Leaved Sub-Boreal Forest ecosystems to 80-85 ton/ha in Northern Taiga Forest ecosystems. 

The data of Table 3 provide a general characteristic of trace element fluxes in Boreal and Sub-Boreal Forest ecosystems. 

Figure 8. Relative distribution ofN, P and K in the Boreal Forest ecosystem. Total amounts for the different fractions are given, expect for in the mineral soils down to 30 cm depth, where exchangeable amounts are given for P and K (Nihlgard et al., 1994).

The Broad-Leaved Forest ecosystems are widespread in regions of Sub-Boreal climate zone with a well balanced precipitationrevapotranspiration ratio. The southern periphery of the vast belt of Eurasian boreal and Sub-Boreal Forest ecosystems is represented by Oak Forest ecosystems. These ecosystems exhibit both the largest biomass and annual NPP rates in comparison with other forest ecosystems of this zone. However, the dead mass surface organic matter is 2-3 time less than that of coniferous forests. 

Figure 12. The profile distribution of vanadium (1) and copper (2) in typical Podzol of Boreal Forest ecosystems (ppm, 1 N HCl extraction) (Dobrovolsky, 1994).

Box 3. Distribution of various forms of trace metals in podzols of boreal forest ecosystems (after Dobrovolsky, 1994)... 

Table 10. Distribution of copper and cobalt in Podzols of East European Boreal Forest ecosystems.

Melin J. and Wallberg L. Distribution and retention of cesium in Swedish boreal forest ecosystems, in The Chernobyl fallout in Sweden, results from a research program on environmental radiology, ed. J. Moberg, Stockholm, Swedish Radiat. Protect. Inst., 1991, pp. 467-475. 

Figure 6.1. Ecosystem area and soil carbon content to 3-m depth. Lower Panel Global areal extent of major ecosystems, transformed by land use in yellow, untransformed in purple. Data from Hassan et al. (2005) except for Mediterranean-climate ecosystems transformation impact is from Myers et al. (2000) and ocean surface area is from Hassan et al. (2005). Upper Panel Total C stores in plant biomass, soil, yedoma/permafrost. D, deserts G S(tr), tropical grasslands and savannas G(te), temperate grasslands ME, Mediterranean ecosystems F(tr), tropical forests F(te), temperate forests F(b), boreal forests T, tundra FW, freshwater lakes and wetlands C, croplands O, oceans. Data are from Sabine et al. (2004), except C content of yedoma permafrost and permafrost (hght blue columns, left and right, respectively Zimov et al., 2006), and ocean organic C content (dissolved plus particulate organic Denman et al., 2007). This figure considers soil C to 3-m depth (Jobbagy and Jackson, 2000). Approximate carbon content of the atmosphere is indicated by the dotted lines for last glacial maximum (LGM), pre-industrial (P-IND) and current (about 2000). Reprinted from Fischlin et al. (2007) in IPCC (2007). See color insert.

Unfortunately, due to the global and poorly studied character of correlation between climate change and vegetation cover behavior (forest ecosystems, in particular), at present there are no reliable estimates of the climate change consequences for their productivity. The problems arising here are just beginning to be studied. This especially refers to the boreal forests that cover 15% of the land area (75% of them are in Eurasia, mainly in Russia). It is in these forests that the intensive gas and heat exchange with the atmosphere takes place. 

Integrated nutrient cycles in boreal forest ecosystems - the role of mycorrhizal fungi... 

Integrated nutrient cycles in boreal forest ecosystems... 

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