Natural fires in the larch forest of cryolithozone: monitoring and firefighting strategy in the conditions of changing climate
V. I. KHARUK1,2,3, L. V. BURYAK1, M. L. DVINSKAYA1,3, I. A. PETROV1,2,3, E. G. SHVETSOV1, A. S. GOLYUKOV1,2,3
1Krasnoyarsk Science Centre of the Siberian Branch of Russian Academy of Science, V. N. Sukachev Institute of Forest of SB RAS, Krasnoyarsk, Russia 2Siberian Federal University, Krasnoyarsk, Russia 3Tomsk State University, Tomsk, Russia
Keywords: taiga fires, larch forests, burnt areas, fires in the permafrost zone, fighting forest fires
Abstract
Climate changes have led to an increase in fire rates throughout the entire range of larch (Larix sibirica, L. gmelinii, L. cajanderi). We tested the hypothesis that natural fires are an important factor that contributes to the functional stability and dominance of larch forests in the continuous permafrost zone. We included satellite imageries, on-ground surveys data, dendrochronological measurements and eco-climatic variables into analysis. We found that warming in the 21st century has led to an increase in the intensity and frequency of fires, moderate and extreme (>10,000 ha) burnt areas. The maximal burn areas and fire frequency observed in the northern and southern parts of the permafrost zone, respectively. The frequency of fires and burned areas are inverse exponentially dependent on precipitation, soil and ground cover moisture and atmospheric drought, and increase exponentially with air temperature increase. In the zone of continuous permafrost, larch successfully regenerates in burnt areas (up to 500+ thousand/ha of seedlings). In the zone of discontinues permafrost (southern part of the study area) the number of regeneration is 2-3 orders lower and regeneration represented mainly by hardwood species. The increasing fire frequency in the south of the larch range contributes to the partly transformation of the forested areas into grass and shrub communities. There is a high probability of larch retreat from its southern range during the process of continuous permafrost thawing. Gross primary productivity (GPP) in burned areas quickly (3-15 years) recovers to the pre-fire level. In combination with increasing GPP trends, that indicates carbon- sink role of larch forests increasing fire rate. In conditions of fire rate increase, it necessary to change firefighting strategy. It is necessary to realize (1) the impossibility of the total fires’ suppression and (2) the ecological significance of fires in the larch forests in cryolithozone, in which fires are the most important factor of supporting larch forests health and dominance. Alongside with that, periodic natural fires reduce the likelihood of catastrophic fires. It is necessary to focus the firefighting on the areas of the priority social, natural and economic importance, controlling burning outside these areas by monitoring methods.
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