Autotrophic and heterotrophic soil respiration in cryolithozone: quantifying the contributions and methodological approaches (the case of soils of the north Western Siberia)
O. Yu. Goncharova, G. V. Matyshak, M. V. Timofeeva, A. R. Sefilian, A. A. Bobrik, M. O. Tarkhov
Lomonosov Moscow State University, Moscow, Russia
Keywords: корневое дыхание, микробное дыхание, торфяники, сосняки, метод интеграции компонентов, метод регрессии, метод затенения, root respiration, microbial respiration, palsa, pine forests, component integration method, regression method, shading method
Abstract
In the course of research conducted in the continuous and discontinuous permafrost zone of the north of Western Siberia, the values of autotrophic (root) and heterotrophic (microbial) soil respiration and their ratio for typical ecosystems of the area were estimated. The data were obtained on the basis of a complex of field, laboratory and calculation methods: shading; root exclusion method (comparing emissions at similar sites with and without vegetation); method of components integration or separate incubation; regression method. For soils of plateau palsa, the root contribution to total soil respiration was 16-30 % by shading method and 14 ± 6 % by the components integration method. For soils of shrub-green moss pine forests, the contribution of root respiration was 60 %, for lichen pine forests - 30 %. It can be assumed that in forest ecosystems of the studied area the contribution of root-derived respiration is even higher, which is due to undercount in some methods tree roots respiration and / or rhizomicrobial microorganisms respiration and priming effect. The contribution of root respiration in soils of mound palsa averaged 40 %. For tundra with frost boil ecosystems, the variation of the contribution of root respiration was 15-70 %, depending on the location on the cryogenic micro-relief (boils, inter-boils). All used methods have disadvantages, some assumptions. These require additional studies to clarify or correct the results. The interpretation of the results are not always obvious. When using different techniques, similar results were obtained with a large number of replications of experiments over several seasons. The paper also presents data on the absolute values of the specific roots respiration for different species and size fractions, the value of the root biomass and the microbial respiration of the soils of different permafrost landscapes.
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