Biodiversity and pyrogenic successions of forest ecosystems in Siberian cryolithic zone

Sukachev Institute of Forest, SB RAS, Krasnoyarsk

Head of the Institute:

Eugene A.Vaganov, Academician of the RAS
Academgorodok, Krasnoyarsk, 660036, Russia
Phone, Fax: (3912) 43-36-86;
email: ifor@krsk.infotel.ru

Principal researchers:

A.P.Abaimov, Deputy Director, Head of the Forestry Department
S.G.Prokushkin, leading researcher of the Permafrost Forest Science Laboratory
M.A.Sofronov, leading researcher of the Permafrost Forest Science Laboratory O.A.Zyryanova, senior researcher of the Permafrost Forest Science Laboratory N.D.Sorokin, Head of the Forest Microbiology Laboratory
N.N.Bugaenko, senior researcher of the Institute of Computational Modelling of SB RAS

Project objectives

Background and significance of objectives

Forest ecosystems of the Siberian cryolithic zone, which occupy more than 50% of its territory, are plant communities with unique adaptations to the harshest environmental conditions of the high latitudes. Being of great biospherical and environmental importance, these ecosystems are characterised by highly conservative biological processes, low recovery potential, higher sensitivity to natural and anthropogenic impacts as well as by the lowest plant species diversity among the northernmost forest ecosystems of Eurasia. They are the indigenous people’s habitats and their skill promotion as well. For many reasons, their genetic diversity, the diversity of plant species and plant communities have been insufficiently studied. Wildland fires are the main destabilising factors, aperiodically affecting the northern forest ecosystems. About 1.1–1.5% of the total forested cryolithic area is damaged annually by fires (Sofronov et al., 1998). The fires not only transform forest environments, but also cause prolonged or even irreversible changes to all forest components. Forest ecologists (Muntingh, 1994 and others) sound alarm about a possible environmental degradation of Siberian boreal forests, which has been increasing over recent years. The character of the fire effect is responsible for the trends in and the rate of progressive successions as well as for the change in phytodiversity. The ecologists opine that ecosystem stability depends on diversity (May, 1973; Chernov, 1991). The mechanisms of ecosystem stability and function are of great interest, especially in low-diversity boreal forests. Thus, the investigations of fire effects on forest vegetation and ambient environment postfire transformation are urgent for the northernmost forest ecosystems.

As a result of recent research, new data on the peculiarities of cryolithic forest ecosystems have been obtained. Literature data and original data obtained by the authors on sparse and closed larch forests diversity in Central Siberia have been generalised and systematised (Abaimov, Bondarev et al., 1997). A dominant role of the root competition for larch community formation and function has been established. It has been revealed that such root adaptations as the ratio between various root types, the period and the rate of root formation and development, macronutrient absorption rate and nitrogen metabolism features as well as root arrangement and adventitious roots, are responsible for larch adaptations to harsh conditions (hypothermia) at different levels (Abaimov, Prokushkin et al., 1996, 1997, 1998). Natural fire emergency features of northern forests have been established (Sofronov et al., 1998). To determine the width of Siberian near-tundra forests and their southern boundary, the ecosystem approach has been proposed (Abaimov, Sofronov, 1996). A peculiar microbe diversity of radical larch ecosystems has been determined (Sorokin, 1998). The plant species diversity (a –diversity according to R.H.Whittaker (1977)) of Siberian larch ecosystems is characterised by a considerable share (56%) of evolutionarily primitive plants and peculiar combination of subarctic and boreal species (their ratio is usually 53:47–58:42% (Abaimov, Prokushkin et al., 1997). Northern larch associations have a very complex structure. There are 4–8 species groups in them, which differ in dominance degree. As a result, the dominance–diversity curves assume a multi-step shape (Fig.) (Zyryanova, Bugaenko et al., 1998). Such a species composition has resulted from cryogenic microrelief as well as from the mix of hydrothermal and edaphic conditions.

Research plan: approaches and methods

The investigations are planned to be conducted on sample plots established for three Siberian larch formations: Larix sibirica Ledeb., L. gmelinii (Rupr.) Rupr. and L. cajanderi Mayr. Plant community diversity will be evaluated by ecological profiles method with the subsequent mapping of forest vegetation and its classification within each sample plot. To study postfire transformation of plant species and microbe diversity, the initial stages of progressive successions as well as ambient environment changes, the permanent and temporary experimental plots will be set up in forest ecosystems that are at different stages of postfire development. Forest communities undamaged by wildland fires for a long period are planned to be used as control plots (Sukachev, Zonn, 1961; The program of biogeocoenotic investigations, 1966, 1974). The quantitative species participation and their niche differentiation will be estimated by using dominance-diversity curves (Wittaker, 1980; Litvinov, 1995). Original methods developed for peculiar cryolithic conditions will be used as well.

Expected results

Expectedly, new data on modern plant species, plant communities and microbe diversity of the northernmost forest ecosystems as well as the mechanisms of their stability will be obtained. Rare and vanishing plant species will be established as well. The comparative estimation of the edaphic and thermal soil regimes in radical plant communities and the burnt areas as well as the fire influence on the nitrogen nutrition, soil and larch root respiration rate will be carried out. The peculiarities of the initial stages of postfire progressive successions and the scheme of the main succession trends in forest ecosystems of the Siberian cryolithic zone will be established.

List of publications of participants related to the project

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Fig. The dominance–diversity curves of crewberry-bearberry (A) and dwarf shrub-sphagnum with willow and dwarf birch underwood (B) larch associations.
Horizontal axis shows the rank of the species (from the highest to the smallest abundance), vertical axis shows the abundance of the species (in percent)