Труды сотрудников ИЛ им. В.Н. Сукачева СО РАН

/ J. Lloyd, O. Shibistova et al // Tellus. Series B: Chemical and physical meteorology. - 2002. - Vol. 54B, № 5. - С. 590-610
Аннотация: We present a first analysis of data (June 1998 to December 2000) from the long-term eddy covariance site established in a Pinus sylvestris stand near Zotino in central Siberia as part of the EUROSIBERIAN CARBONFLUX project. As well as examining seasonal patterns in netecosystem exchange (N-E), daily, seasonal and annual estimates of the canopy photosynthesis (or gross primary productivity, G(P)) were obtained using N-E and ecosystem respiration measurements. Although the forest was a small (but significant) source of CO2 throughout the snow season (typically mid-October to early May) there was a rapid commencement of photosynthetic capacity shortly following the commencement of above-zero air temperatures in spring: in 1999 the forest went from a quiescent state to significant photosynthetic activity in only a few days. Nevertheless, canopy photosynthetic capacity was observed to continue to increase slowly throughout the summer months for both 1999 and 2000, reaching a maximum capacity in early August. During September there was a marked decline in canopy photosynthesis which was only partially attributable to less favourable environmental conditions. This suggests a reduction in canopy photosynthetic capacity in autumn, perhaps associated with the cold hardening process. For individual time periods the canopy. photosynthetic rate was mostly dependent upon incoming photon irradiance. However, reductions in both canopy conductance and overall photosynthetic rate in response to high canopy-to-air vapour differences were clearly evident on hot dry days. The relationship between canopy conductance and photosynthesis was examined using Cowan's notion of optimality in which stomata serve to maximise the marginal evaporative cost of plant carbon gain. The associated Lagrangian multiplier (lambda) was surprisingly constant throughout the growing season. Somewhat remarkably, however, its value was markedly different between years, being 416 mol mol(-1) in 1999 but 815 mol mol(-1) in 2000. Overall the forest was a substantial sink for CO2 in both 1999 and 2000: around 13 Mol C m(-2) a(-1). Data from this experiment, when combined with estimates of net primary productivity from biomass sampling suggest that about 20% of this sink was associated with increasing plant biomass and about 80% with an increase in the litter and soil organic carbon pools. This high implied rate of carbon accumulation in the litter soil organic matter pool seems unsustainable in the long term and is hard to explain on the basis of current knowledge.

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Держатели документа:
Russian Acad Sci, VN Sukachev Forest Inst, Siberian Branch, Krasnoyarsk 66003, Russia

Доп.точки доступа:
Lloyd, J.; Лойд Дж.; Shibistova, Olga Borisovna; Шибистова, Ольга Борисовна

[Text] / A. . Arneth [et al.] // Glob. Biogeochem. Cycle. - 2002. - Vol. 16, Is. 1. - Ст. 1005, DOI 10.1029/2000GB001374. - Cited References: 70 . - 13. - ISSN 0886-6236РУБ Environmental Sciences + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: [1] Twenty tree ring C-13/C-12 ratio chronologies from Pinus sylvestris (Scots pine) trees were determined from five locations sampled along the Yenisei River, spaced over a total distance of similar to1000 km between the cities of Turuhansk (66degreesN) and Krasnoyarsk (56degreesN). The transect covered the major part of the natural distribution of Scots pine in the region with median growing season temperatures and precipitation varying from 12.2degreesC and 218 mm to 14.0degreesC and 278 mm for Turuhansk and Krasnoyarsk, respectively. A key focus of the study was to investigate the effects of variations in temperature, precipitation, and atmospheric CO2 concentration on long-and short-term variation in photosynthetic C-13 discrimination during photosynthesis and the marginal cost of tree water use, as reflected in the differences in the historical records of the C-13/C-12 ratio in wood cellulose compared to that of the atmosphere (Delta(13)C(c)). In 17 of the 20 samples, trees Delta(13)C(c) has declined during the last 150 years, particularly so during the second half of the twentieth century. Using a model of stomatal behaviour combined with a process-based photosynthesis model, we deduce that this trend indicates a long-term decrease in canopy stomatal conductance, probably in response to increasing atmospheric CO2 concentrations. This response being observed for most trees along the transect is suggestive of widespread decreases in Delta(13)C(c) and increased water use efficiency for Scots pine in central Siberia over the last century. Overlying short-term variations in Delta(13)C(c) were also accounted for by the model and were related to variations in growing season soil water deficit and atmospheric humidity.

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Scopus

Держатели документа:
Manaaki Whenua, Landcare Res, Lincoln, New Zealand
Max Planck Inst Biogeochem, D-07701 Jena, Germany
Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200, Australia
Inst Evolut & Ecol Problems, Svertsov Lab, Moscow 117071, Russia
VN Sukachev Inst Forest, Krasnoyarsk 660036, Russia
Univ S Bohemia, Fac Biol Sci, Ceske Budejovice, Czech Republic
Inst Soil Biol AS CR, Ceske Budejovice, Czech Republic

Доп.точки доступа:
Arneth, A...; Lloyd, J...; Santruckova, H...; Bird, M...; Grigoryev, S...; Kalaschnikov, Y.N.; Gleixner, G...; Schulze, E.D.