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

Forest fire risk in Finland is estimated with the Finnish Forest Fire Index (FFI), which predicts the fuel moisture content (FMC) of the forest floor. We studied the FMC variation of four typical ground vegetation fuels, Pleurozium schreberi, Hylocomium splendens, Dicranum spp., and Cladonia spp., and raw humus in mature and recently clear-cut stands. Of these, six were sub-xeric Pinus sylvestris stands, and six mesic Picea abies stands. We analysed the ability of the FFI to predict FMC and compared it with the widely applied Canadian Fire Weather Index (FWI). We found that in addition to stand characteristics, ground layer FMC was highly dependent on the species so that Dicranum was the moistest, and Cladonia the driest. In the humus layer, the differences among species were small. Overall, the FWI was a slightly better predictor of FMC than the FFI. While the FFI generally predicted ground layer FMC well, the shape of the relationship varied among the four species. The use of auxiliary variables thus has potential in improving predictions of ignitions and forest fire risk. Knowledge of FMC variation could also benefit planning and timing of prescribed burns.Peer reviewe

Experimental evidence on biodiversity impacts of variable retention forestry, prescribed burning, and deadwood manipulation in Fennoscandia

Intensive forest management has been applied in most Fennoscandian forests for a period of almost one felling rotation. This paradigm has produced even-aged and even-structured forests of different successional stages that cover about 90% of forest land. At the same time, wildfires have been nearly eliminated in most of the Fennoscandian nature. Consequently, hundreds of species are red-listed because of forest management. To support these species, forest management requires improvements. Variable retention forestry and habitat restoration have been suggested to mitigate negative effects of forest management on biodiversity, and these have been practiced to some extent during the past few decades. Here, we review experimental results on the effects of variable retention and two restoration measures (prescribed burning and artificial addition of coarse woody debris) on different species groups in Fennoscandia. Our key findings are as follows: (i) Many species respond positively to felling within a few years, apparently due to released and often ephemeral resources, such as fresh residue and stumps. Species associated with shady conditions are negatively impacted, but any retention supports many of these, and their species composition remains almost unaffected with 50–70% retention of the initial tree volume. (ii) These effects remain detectable for at least 10–30 years or, according to some studies, nearly 100 years, e.g., in polypore fungi. (iii) Initial effects of prescribed burning on most species groups (apart from pyrophiles) are negative, but within 10–15 years post-fire sites begin to support many rare and threatened deadwood-dependent species. Epiphytic lichens, however, remain negatively affected. (iv) Artificial addition of deadwood (mostly high stumps) supports a wide spectrum of deadwood-dependent species, but the species composition differs from that of naturally died trees. (v) Moisture and micro-habitat variation are crucial for forest species at harvested sites, at least in forests dominated by Norway spruce. We conclude that felling method as such is of little importance for threatened forest species, although retention mitigates many negative effects. These species require microclimatic continuity, and maintenance and active increase of legacies, such as deadwood of different qualities (species, downed/standing, snag/log/stump, decay stage), very old trees, and tree species mixtures.202

Alhaiset säästöpuumäärät, PEFC-metsäsertifiointi ja monimuotoisuus Suomen metsissä

Non peer reviewe

Low-level retention forestry, certification, and biodiversity : case Finland

In managed forests, leaving retention trees during final harvesting has globally become a common approach to reconciling the often conflicting goals of timber production and safeguarding biodiversity and delivery of several ecosystem services. In Finland, the dominant certification scheme requires leaving low levels of retention that can benefit some specific species. However, species responses are dependent on the level of retention and the current low amounts of retention clearly do not provide the habitat quality and continuity needed for declining and red-listed forest species which are dependent on old living trees and coarse woody debris. Several factors contribute to this situation. First, the ecological benefits of the current low retention levels are further diminished by monotonous standwise use of retention, resulting in low variability of retention habitat at the landscape scale. Second, the prevailing timber-oriented management thinking may regard retention trees as an external cost to be minimized, rather than as part of an integrated approach to managing the ecosystem for specific goals. Third, the main obstacles of development may still be institutional and policy-related. The development of retention practices in Finland indicates that the aim has not been to use ecological understanding to attain specific ecological sustainability goals, but rather to define the lowest level of retention that still allows access to the market. We conclude that prevailing retention practices in Finland currently lack ecological credibility in safeguarding biodiversity and they should urgently be developed based on current scientific knowledge to meet ecological sustainability goals.peerReviewe

Research on retention forestry in Northern Europe

Retention approaches in forest management are today common in several North European countries, integrated into the clearcutting practice as a way to promote biodiversity and maintain ecosystem functions. Individual green trees and retention patches (tree groups) are retained at final harvest, and deadwood is left at site or created. Here, we review research on retention in Sweden, Finland, Norway, the Baltic States, and NW Russia, with special focus on biodiversity. Following the first publication in 1994, about 180 peer-reviewed articles have been published. We present results from a systematic search of the retention literature, separated into the following topics: buffer zones, retention patches, high stumps, other types of deadwood, European aspen Populus tremula, and cost-efficiency. Russian literature is synthesized separately since studies from this region have so far almost exclusively been published in the Russian language. Furthermore, we describe six ongoing large-scale, replicated experiments with varying retention levels, five in Finland and one in Sweden, and summarize their main results. Among main conclusions for practice from the literature and experiments are that retention patches as large as 0.5 ha and 10-m-wide buffers to watercourses are not enough to maintain pre-harvest species composition but survival of forest species is still larger than on conventional clearcuts. Deadwood on clearcuts may present important habitats to saproxylic species, including rare and red-listed ones and a prioritization of tree species per stand is recommended. We identify several important future research directions including switch of focus towards the landscape as well as the species population level. Surveys in parts of European Russia where retention has been unintentionally implemented already for a century would indicate possible future trajectories of biodiversity and their drivers in other regions of Northern Europe. A stronger link to ecological theory would help in study designs and in the formulation of predicted outcomes.202

Säästöpuumetsätaloudella monimuotoisuutta talousmetsiin

Non peer reviewe

Stakeholders' Perceptions about Fire Impacts on Lithuanian Protected Areas

The aim of this work is to study Lithuanian stakeholders' perceptions of fire impacts in protected areas. For this study, the stakeholders consisted of foresters, ecologists and farmers. A clear understanding of the opinions of stakeholders about fire effects on environmental, social and economic aspects of Lithuanian protected areas will allow an assessment of the stakeholders' reaction to fire policy, including government measures towards fire prevention, suppression and application of prescribed fire to landscape management. The results showed that stakeholders in general think that fire is not a threat to Lithuania and to the ecological processes in the protected areas. However, they agree that fires have negative impacts on soil properties and fertility but are not to an irremediable or irrecoverable extent. Stakeholders disagree that fire has positive consequences for agricultural and cattle activities but agreed that vegetation recovers quickly. They do not see fire as a social and economic problem, do not agree that prescribed fire could be used to landscape management, and believe that mechanical thinning is a better management tool than prescribed fire. Stakeholders agree that fire does not have negative impacts on the biodiversity. These opinions depended on the age group of the respondent but especially on the respondent's professional occupation

Short-term low-severity spring grassland fire impacts on soil extractable elements and soil ratios in Lithuania.

Spring grassland fires are common in boreal areas as a consequence of slash and burn agriculture used to remove dry grass to increase soil nutrient properties and crop production. However, fewworks have investigated fire impacts on these grassland ecosystems, especially in the immediate period after the fire. The objective of this work was to study the short-termimpacts of a spring grassland fire in Lithuania. Four days after the firewe established a 400 m2 sampling grid within the burned area and in an adjacent unburned area with the same topographical, hydrological and pedological characteristics. Wecollected topsoil samples immediately after the fire (0 months), 2, 5, 7 and 9 months after the fire. We analysed soil pH, electrical conductivity (EC), major nutrients including calcium(Ca), magnesium(Mg), sodium(Na), and potassium(K), and theminor elements aluminium(Al), manganese (Mn), iron (Fe) and zinc (Zn). We also calculated the soil Na and K adsorption ratio (SPAR), Ca:Mg and Ca:Al. The results showed that this low-severity grassland fire significantly decreased soil pH, Al, and Mn but increased EC, Ca,Mg, and K,. There was no effect on Na, Fe, and Zn. Therewas a decrease of EC, Ca,Mg, and Na from 0months after the fire until 7 months after the fire,with an increase during the last sampling period. Fire did not significantly affect SPAR. Ca:Mg decreased significantly immediately after the fire, but not to critical levels. Ca:Al increased after the fire, reducing the potential effects of Al on plants. Overall, fire impactsweremainly limited to the immediate period after the fire

Habitat quality is more important than matrix quality for bird communities in protected areas

Protected areas are meant to preserve native local communities within their boundaries, but they are not independent from their surroundings. Impoverished habitat quality in the matrix might influence the species composition within the protected areas through biotic homogenization. The aim of this study was to determine the impacts of matrix quality on species richness and trait composition of bird communities from the Finnish reserve area network and whether the communities are being subject of biotic homogenization due to the lowered quality of the landscape matrix. We used joint species distribution modeling to study how characteristics of the Finnish forest reserves and the quality of their surrounding matrix alter species and trait compositions of forest birds. The proportion of old forest within the reserves was the main factor in explaining the bird community composition, and the bird communities within the reserves did not strongly depend on the quality of the matrix. Yet, in line with the homogenization theory, the beta-diversity within reserves embedded in low-quality matrix was lower than that in high-quality matrix, and the average abundance of regionally abundant species was higher. Influence of habitat quality on bird community composition was largely explained by the species' functional traits. Most importantly, the community specialization index was low, and average body size was high in areas with low proportion of old forest. We conclude that for conserving local bird communities in northern Finnish protected forests, it is currently more important to improve or maintain habitat quality within the reserves than in the surrounding matrix. Nevertheless, we found signals of bird community homogenization, and thus, activities that decrease the quality of the matrix are a threat for bird communities.Peer reviewe