Susan G. Conard

DETERMINING EFFECTS OF AREA BURNED AND FIRE SEVERITY ON CARBON CYCLING AND EMISSIONS IN SIBERIA

The Russian boreal forest contains about 25% of the global terrestrial biomass, and even a higher percentage of the carbon stored in litter and soils. Fire burns large areas annually, much of it in low-severity surface fires – but data on fire area and impacts or extent of varying fire severity are poor. Changes in land use, cover, and disturbance patterns such as those predicted by global climate change models, have the potential to greatly alter current fire regimes in boreal forests and to significantly impact global carbon budgets. The extent and global importance of fires in the boreal zone have often been greatly underestimated. For the 1998 fire season we estimate from remote sensing data that about 13.3 million ha burned in Siberia. This is about 5 times higher than estimates from the Russian Aerial Forest Protection Service (Avialesookhrana) for the same period. We estimate that fires in the Russian boreal forest in 1998 constituted some 14–20% of average annual global carbon emissions from forest fires. Average annual emissions from boreal zone forests may be equivalent to 23–39% of regional fossil fuel emissions in Canada and Russia, respectively. But the lack of accurate data and models introduces large potential errors into these estimates. Improved monitoring and understanding of the landscape extent and severity of fires and effects of fire on carbon storage, air chemistry, vegetation dynamics and structure, and forest health and productivity are essential to provide inputs into global and regional models of carbon cycling and atmospheric chemistry.

Changing fuel management strategies - The challenge of meeting new information and analysis needs

This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 ‘The earth, born in fire, baptized by lightning since before lifes beginning, has been and is a fire planet.’ E.V. Komarek Attitudes and policies concerning wildland fire, fire use, and fire management have changed greatly since early European settlers arrived in North America. Active suppression of wildfires accelerated early in the 20th Century, and areas burned dropped dramatically. In recent years, burned areas and cost of fires have begun to increase, in part due to fuel buildups resulting from fire suppression. The importance of fire as an ecosystem process is also being increasingly recognized. These factors are leading to changes in Federal agency fire and fuels management policies, including increased emphasis on use of prescribed fire and other treatments to reduce fuel loads and fire hazard. Changing fire management strategies have highlighted the need for better information and improved risk analysis techniques for setting regional and national priorities, and for monitoring and evaluating the ecological, economic, and social effects and tradeoffs of fuel management treatments and wildfires. The US Department of Interior and USDA Forest Service began the Joint Fire Science Program in 1998 to provide a sound scientific basis for implementing and evaluating fuel management activities. Development of remote sensing and GIS tools will play a key role in enabling land managers to evaluate hazards, monitor changes, and reduce risks to the environment and the public from wildland fires.

Land Use and Fires

Research on fire is often of an applied nature, addressing questions of how to manage landscapes for fire, how to determine fire danger, how to model fire behavior, fire impacts and post-fire succession (Martell 2001; Chuvieco 2003). This in part reflects the desire of the funding agencies to maximize the benefits from the large amounts of public money spent each year on fire management. There is an increasing body of fire research in the area of global change, for example studying the potential impacts of climate change altering fire regimes, the impact on the atmosphere in terms of emissions, radiative forcing and chemical composition and feedbacks to the surface (Scholes et al., 1996; Stocks et al., 1998; Govaerts et al., 2002).

Fire impact on carbon storage in light conifer forests of the Lower Angara region, Siberia

This study focused on structural analysis of ground carbon storage following fires in light conifer stands of the Lower Angara region (Siberia, Russia). Experimental fires of varying frontal intensity were conducted at Scots pine and mixed larch forests of southern taiga. Considerable amounts of surface and ground forest fuels (21‐38 tC ha −1 ) enhanced low- to high-intensity fires. Post-fire carbon storage decreased by 16‐49% depending on fire intensity and rate of spread, with depth of burn being 0.9‐6.6 cm. Carbon emissions varied from 4.48 to 15.89 t ha −1 depending on fire intensity and forest type. Depth of burn and carbon emissions for

Biomass dynamics of central Siberian Scots pine forests following surface fires of varying severity

In 2000–2002 nine 4-ha prescribed fires of various severities were conducted on experimental plots in mature Scots pine forest in the central Siberian taiga, Russia. Total above-ground living biomass decreased after low- and moderate-severity fires by 10 and 15%, whereas high-severity fire reduced living above-ground biomass by 83%. We monitored changes in fuel structure and biomass for 6–8 years following these fires. By 6–8 years after burning the ground fuel loading had recovered to 101, 96 and 82% of pre-fire levels after fires of low-, moderate- and high-severity. Down woody fuel loading increased by 0.18±0.04kgm–2year–1. We developed regressions relating time since fire to changes in above-ground biomass components for fires of different severity for feather moss–lichen Scots pine forest of Siberia. Our results demonstrate the importance of both burn severity and composition of pre-fire surface vegetation in determining rates and patterns of post-fire vegetation recovery on dry Scots pine sites in central Siberia.

Potential change in forest types and stand heights in central Siberia in a warming climate

Previous regional studies in Siberia have demonstrated climate warming and associated changes in distribution of vegetation and forest types, starting at the end of the 20th century. In this study we used two regional bioclimatic envelope models to simulate potential changes in forest types distribution and developed new regression models to simulate changes in stand height in tablelands and southern mountains of central Siberia under warming 21st century climate. Stand height models were based on forest inventory data (2850 plots). The forest type and stand height maps were superimposed to identify how heights would change in different forest types in future climates. Climate projections from the general circulation model Hadley HadCM3 for emission scenarios B1 and A2 for 2080s were paired with the regional bioclimatic models. Under the harsh A2 scenario, simulated changes included: a 80%–90% decrease in forest-tundra and tundra, a 30% decrease in forest area, a ~400% increase in forest-steppe, and a 2200% increase in steppe, forest-steppe and steppe would cover 55% of central Siberia. Under sufficiently moist conditions, the southern and middle taiga were simulated to benefit from 21st century climate warming. Habitats suitable for highly-productive forests (≥30–40 m stand height) were simulated to increase at the expense of less productive forests (10–20 m). In response to the more extreme A2 climate the area of these highly-productive forests would increase 10%–25%. Stand height increases of 10 m were simulated over 35%–50% of the current forest area in central Siberia. In the extremely warm A2 climate scenario, the tall trees (25–30 m) would occur over 8%–12% of area in all forest types except forest-tundra by the end of the century. In forest-steppe, trees of 30–40 m may cover some 15% of the area under sufficient moisture.