The challenge of combining variable retention and prescribed burning in Finland

Abstract

Historically, wildfires have played an important role in forest dynamics in Fennoscandia. In Finland, the annually burned area has diminished in recent decades. This has led to a decline of fire-adapted habitat types and species, many of which have become red-listed. In Fennoscandia, there is a long tradition of silvicultural burnings to enhance tree regeneration. Recently, prescribed burnings have been modified for biodiversity goals following the recommendations that have emerged from ecological research. Prominent biodiversity gains can be obtained by combining sufficient retention levels with burnings. Consequently, burning and retention have been recommended by recent national red-list assessments, strategies, and forest-management guidelines, and they have been adopted in forest-certification standards in Finland. Contrary to these recommendations, the opposite development has taken place: (1) the ecological efficiency of the criterion concerning prescribed burning in the PEFC forestcertification standard has been impaired, (2) state funding to encourage private forest owners to apply prescribed burning was reduced significantly, and (3) prescribed burnings have been abandoned altogether in commercial state-owned forests. Traditional burnings with variable retention have also been partially replaced with burning of small retention-tree groups. This new method is less risky and cheaper, but its ecological benefits are questionable because small-sized fires produce much smaller areas of burned forest soil with less fire-affected wood than traditional silvicultural burnings. Generally, the widely accepted goal to increase burnings with retention appears difficult to achieve and would require stronger political will and economic support from the government. We identified several actions that could improve the weakened situation of fire-dependent biodiversity and recommend the following: (1) setting a clear goal and ensuring sufficient funding for the burnings-including restoration burnings in conservation areas-and targeting these to specific fire-continuum areas with sufficient retention to ensure the continuity of fire-affected habitats at landscape level; (2) renewing the current subsidizing policies to encourage private landowners to perform prescribed burnings in regeneration areas after final fellings, and to safeguard accidental forest-fire areas as set-asides; (3) renewing the current prescribed-burning criterion of the Finnish PEFC forest-certification standard with more ambitious ecological goals; and (4) reintroducing prescribed burnings in commercial state forests where management targets are under political steering.

Reviews & Syntheses: Arctic Fire Regimes and Emissions in the 21st Century

“…Intensive management via ditch network maintenance and fertilization of drained peatlands will increase timber values while also rewetting the peat (Ahtikoski and Hökkä, 2019). Prescribed burning for silvicultural retention and maintaining and regenerating pure stands can also reduce fuel loadings while increasing biodiversity (Lindberg et al, 2020).…”

Moisture content variation of ground vegetation fuels in boreal mesic and sub-xeric mineral soil forests in Finland

“…The climatological fire risk in Finland was relatively stable during the last century (Mäkelä et al 2012), so the decline in fire occurrence is explained by other factors, such as efficiency in fire detection and suppression, and changes in ignition sources, stand structure, forest fragmentation, and vegetation (Päätalo 1998;Wallenius 2011). This is also supported by the difference between the fire regimes of Finland and neighbouring Sweden, where the annual burned area has been higher and large fires frequent (Lindberg et al 2020).…”

“…Because of this, the scope of prescribed burnings in Finland has widened in recent years to a more diverse set of burnings with different ecological aims such as burnings of retention trees, restoration burnings in nature conservation areas and management burnings of sun-exposed and xeric habitats (for details see Lindberg et al 2020). The various aims also set diverse targets for fire impact and depth.…”

“…The various aims also set diverse targets for fire impact and depth. However, despite the recognized importance of fire for restoration, the overall area of prescribed burns has declined in recent decades (Lindberg et al 2020).…”

“…If the moisture of the ground layer and in some cases raw humus is too high, the burning effects are not fully achieved. In restoration burnings, more various moisture conditions are possible, since more diverse burning results are accepted (Lindberg et al 2020).…”