Ecosystem boreal

Rinne, I, Ruuskanen, T.M., Reissell, A., Taipale, R., Hakola, H., Kulmala, M. (2005) On-line PTR-MS measurements of atmospheric concentrations of volatile organic compounds in a European boreal forest ecosystem. Boreal Environment Research, 10, 425-436. 

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. 

Larsen, J. A. The Boreal Ecosystem Academic Press New York, NY, 1980. 

Longer ice-core records show that methane concentrations have varied on a variety of time scales over the past 220 000 years (Fig. 18-15) Qouzel et al, 1993 Brook et al, 1996). Wetlands in tropical (30° S to 30° N) and boreal (50° N to 70° N) regions are the dominant natural methane source. As a result, ice-core records for preanthropogenic times have been interpreted as records of changes in methane emissions from wetlands. Studies of modem wetlands indicate that methane emissions are positively correlated with temperature, precipitation, and net ecosystem productivity (Schlesinger, 1996). 

Wind-throw and wind-snap of forest trees is a normal process in natural forests (Spurr Barnes, 1980). Runkle (1982) has estimated that, annually, as much as 1% of the area of a forested ecosystem may be blown (or fall) over and create canopy gaps. Such a figure appears to be appropriate for a range of forested ecosystems from equatorial to boreal. The canopy gaps are critical for the establishment of new species and maintaining species diversity in the forest (Woodward, 1987). 

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).

St. Louis VL, Rudd JW, Kelly CA, Hall BD, Rolfhus KR, Scott KJ, Lindberg SE, Dong W. 2001. The importance of the forest canopy to fluxes of methyl mercury and total mercury to boreal ecosystems. Environ Sci Technol 35 3089-3098. 

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. 

The low temperatures and low soil pH that usually prevail at higher altitudes and latitudes (e.g., heathlands) restrain nitrification and (to a lesser extent) ammonification (92). Studies of N relations in temperate and boreal ecosystems have dem-... 

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. 

Table 3 presents the averaged data for the whole forest area of Boreal and Sub-Boreal zone. However, there are definite peculiarities of biological and biogeochemical cycles in the individual ecosystems. We will consider the Spruce Forest ecosystem of the Karelia region, Russia. These ecosystems occur in the wide area of the Karelia, south from 63° N. 

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 statistical estimation of heavy metal concentrations in the Spruce Forest ecosystems of the Boreal climatic zone is the subject of wide variation, with coefficient of variation from 36 to 330%. However, we can note the clear trend in biogeochemical peculiarities and relevant exposure to heavy metal uptakes by dominant plant species. 

Table 7. The statistics of heavy metal contents in the major plant species of Spruce Forest ecosystems of Boreal zone, Karelia, Russia (after Dobrovolsky, 1994).

There are significant differences between biogeochemical cycling in forest and swampy ecosystems of the Boreal climate zone. The annual growth (NPP) of moor vegetation is about 3.5 ton/ha, which is twice as small as that in a forest ecosystem. In the bog, the degradation of dead organic matter proceeds at a much smaller rate than in the forest. The mass of peat accumulated within a period of 100 years accounts for... 

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.

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