Regional Environmental Changes in Siberia and Their Global Consequences by Pavel Ya. Groisman & Garik Gutman

Author:Pavel Ya. Groisman & Garik Gutman
Language: eng
Format: epub
Publisher: Springer Netherlands, Dordrecht

6.2.2.2 Net Primary Production of Ecosystems

Historically, numerous empirical data on NPP of Russian forests were biased due to two reasons: (1) they are based on destructive in situ measurements with intervals of weeks and months that do not account for a substantial part of NPP (e.g., root exudates or volatile organic compounds, VOC) which could reach 15–20 % and more in boreal forests (Vogt et al. 1986) and (2) the typical incompleteness of NPP measurements of some components of ecosystems, like fine roots and below-ground parts of shrubs and the green forest floor (Schulze et al. 1999; Vasiliev et al. 2001). In order to eliminate bias, a new “semi-empirical” method for evaluation of NPP of Northern Eurasian forest ecosystems was developed (Shvidenko et al. 2007a, 2008). The method is based on simulation of biological production of forest ecosystems using aggregation of regional empirical regularities of growth of forest stands and dynamic models of live biomass of forest ecosystems. The method does not have any recognized biases in contrast to existing empirical methods of assessment of forest NPP on large areas. This method has been used for assessing forest NPP.

NPP for other classes of natural vegetation has been assessed based on empirical in situ measurements. In general, such measurements also have shortcomings similar to the above mentioned for forests (e.g., Vasiliev et al. 2001); however, we were not able to avoid these. NPP of agricultural land was defined similarly to live biomass of this land class.

The total annual NPP of Siberian ecosystems is estimated at 2.76 Pg C  year−1, or 257 g  C m−2 year−1. By land classes, agricultural lands have the highest NPP (402 g  C m−2 year−1) and open woodlands – the smallest (84 g  C m−2 year−1); 97.5 % of open woodlands are situated in northern zones of Siberia, mostly in the forest-tundra ecotone – this is the reason for such low productivity. NPP of forests is estimated at 283 g  C m−2 year−1. NPP of all land classes has clear zonal gradients (Table 6.9).

To our knowledge, there were no previous estimates of NPP for the entire region. The estimates for forests of individual regions reported by Usoltsev et al. (2011) are consistent with our results. Only one recent estimate of forest NPP for the Asian part of Russia has been reported – at 277 g  C year−1 for 2003 (Shvidenko et al. 2008). Note that previous estimates of NPP for all terrestrial ecosystems over the entire country are very diverse – from 2.75 Pg C  year−1 (Filipchuk and Moiseev 2003) for the ∼2000s to annual averages of 4.35 Pg C  year−1 for 1988–1992 (Nilsson et al. 2003) and 4.73 Pg C  year−1 for 1996–2002 (Zavarzin 2007) and up to 5.1  ±  0.36 Pg C  year−1 for 2003–2008 (Shvidenko et al. 2010b). The latter paper reports NPP for Asian Russian forests that is very close to the above estimate of forest NPP (Table 6.8) – at 1.68 Pg C  year−1 against 1.70 Pg C  year−1.Table 6.8Net primary production

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