Forests boreal

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. 

Most vegetation maps are derived from a variety of sources using different methods and made at different times. This can lead to an overlap between adjacent areas of interest, the exclusion of some areas, and the improper extrapolation of carbon densities, thus resulting in inaccurate estimates of reservoir size. We found that the biomass density of the southern North American boreal forest was over 2.5 times larger than the biomass density of the northern part of the boreal forest (55). Past estimates of boreal forest biomass density extrapolated southern biomass density values to the entire boreal forest, which in part accounts for the large overestimation (7). It is important that a consistent method be developed to map vegetation globally. 

Figure 3. Maximum and minimum extent of the boreal forest of Canada from the union and intersection respectively of Anonymous (32), Rowe (53), and Anonymous (34),...

Bonan, G. B. (1991). Atmosphere-biosphere exchange of carbon dioxide in boreal forests, /. Geophys. Res. 96, 7301-7312. 

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).

Archaea belonging to the kingdom Crenarchaeota deserve attention. Although it has been assumed that these are extreme thermophiles, members of this group have been identified by molecular techniques in other habitats, for example, soils (Buckley et al. 1998), boreal forest soil (Jurgens et al. 1997), and in plant extracts (Simon et al. 2005). 

Jurgens G, K Lindstrbm, A Saano (1997) Novel group within the kingdom Crenararchaeota from boreal forest soil. Appl Environ Microbiol 63 803-805. 

Porvari P, Verta M, Munthe J, Haapanen M. 2003. Forestry practices increase mercury and methylmercury output from boreal forest catchments. Environ Sci Technol 37 2389-2393. 

St. Louis VL, Rudd JWM, Kelly CA, Beaty KG, Flett RJ, Roulet NT. 1996. Production and loss of methylmercury and loss of total mercury from boreal forest catchments containing different types of wetlands. Environ Sci Technol 30 2719-2729. 

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. 

Garcia E, Carignan R. 1999. Impact of wildfire and clear-cutting in the boreal forest on methyhnercury in zooplankton. Can J Fish Aquat Sci 56 339-345. 

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. 

Fox GA, Yonge KS, Sealy SG. 1980. Breeding performance, pollutant burden, and eggshell thinning in Common Loons Gavia immer nesting on a boreal forest lake. Omis Scand 11 243-248. 

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. 

Malhi Y, Baldocchi DD, Jarvis PG (1999) The carbon balance of tropical, temperate and boreal forests. Plant Cell Environ 22 715-740... 

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).

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