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Mixed forests are suggested as a strategic adaptation of forest management to climate change. Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) are tree species of high economic and ecological value for European forestry. Both species coexist naturally in a large part of their distributions but there is a lack of knowledge on the ecological functioning of mixtures of these species and how to manage such stands. This paper analyses these species' intra- and inter-specific competition, including size-symmetric vs. size-asymmetric competition, and explore the effect of weather conditions on tree growth and competition. We studied basal area growth at tree level for Scots pine and Norway spruce in mixed versus pure stands in 22 triplets of fully-stocked plots along a broad range of ecological conditions across Europe. Stand inventory and increment cores provided insights into how species mixing modifies tree growth compared with neighbouring pure stands. Five different competition indices, weather variables and their interactions were included and checked in basal area growth models using a linear mixed model approach. Interspecific size-asymmetric competition strongly influenced growth for both tree species, and was modulated by weather conditions. However, species height stratification in mixed stands resulted in a greater tree basal area growth of Scots pine (10.5 em(2) year(-1)) than in pure stands (9.3 em(2) year(-1)), as this species occupies the upper canopy layer. Scots pine growth depended on temperature and drought, whereas Norway spruce growth was influenced only by drought. Interspecific site-asymmetric competition increased in cold winters for Scots pine, and decreased after a drought year for Norway spruce. Although mixtures of these species may reduce tree size for Norway spruce, our results suggest that this could be offset by faster growth in Scots pine. How inter-specific competition and weather conditions alter tree growth may have strong implications for the management of Scots pine-Norway spruce mixtures along the rotation period into the ongoing climate change scenario.

Studies on the effects of stump harvesting on forest biodiversity are scarce and studies on long-term effects are until now non-existent. We evaluated such long-term effects by sampling beetles at 14 clear-cuts with and 14 clear-cuts without stump harvesting; harvesting had been done 21–28 years before this study. By using window traps, we collected 6429 individuals belonging to 432 species in 55 taxonomic families. To control for potentially confounding effects of among-site variations in landscape setting we also assessed forest age and volume of deciduous trees within the forest surrounding each site. The long-term effects from harvesting on beetle abundance, species richness and species composition was generally small in comparison to the influence of the characteristics of the surrounding forests. The species richness of the beetle family Latridiidae and the functional group fungivores appeared, however, to be negatively affected by the previous stump harvesting, while several other groups showed strong associations to the characteristics of the surrounding forest. We found little support for considerable long-term effects of stump harvesting on beetles flying in the stands. Long-term effects of stump harvesting at the landscape scale accumulated from harvest of many localities may still be severe, and should be the subject of future studies.

Boreal forests receive nitrogen-(N)-enrichment via atmospheric deposition and industrial fertilization. While it is known that N-enrichment can intensify interactions with natural antagonists, it remains poorly understood how genetic variability in plant defense chemistry can affect biotic interactions and height growth in N-enriched environments. We grew replicates of five low- and high-tannin Populus tremula genotypes, respectively, under three N-treatments (ambient, 15, and 150 kg N ha−1 yr−1). We assessed shoot blight occurrence (i.e. symptoms caused by Venturia fungi) during four growing seasons, and tree height growth during the same period. Damage by Venturia spp. increased with N-addition during all years, likely due to enhanced foliar quality. Low–tannin plants showed higher incidences of Venturia infection than high-tannin plants, regardless of the N-input-level. Height responded to an N-by-tannin-group interaction, which occurred because high-tannin plants grew taller than low-tannin plants at the high N-treatment, but not under the other N-levels. This pattern indicates that innate resource investment into tannin production yields a positive effect on growth under N-enriched conditions. Given that N-deposition is increasing globally, our research suggests that further studies are needed to investigate how N-enrichment interacts with plant defense traits globally. Moreover, our research suggests that N-deposition may provide an advantage for well-defended, high-tannin plants; and further, that genetic diversity in plant defense may be a key mechanism by which plant populations respond to this change.

Boreal forest ecosystems are generally highly sensitive to logging and other forestry activities. Thus, commercial forestry has had major effects on the forests and landscape structure in northern Sweden since the middle of the 19th Century, when it rapidly extended across the region. Lichens (which constitute up to 80% of reindeer forage in winter and early spring) have often been amongst the most severely affected ecosystem components. The overall aim of the present study was to analyze how forestry has influenced the potential supply of ground-growing lichens as winter forage for the reindeer in this region over the past ca. 100 years. For this purpose, we analysed changes in forest and stand structure in Scots pine-dominated (Pinus sylvestris L.) reindeer wintering areas in the southern part of the county Norrbotten (covering ca. 58,000 ha) using detailed historical forest inventories and management plans. We found that the amount of the forest types considered potentially good pasture (mainly middleaged and old pine forests) decreased during the first part of the 20th Century. However, the quality of grazing grounds was improved by forestry during this time mainly because selective logging made the forests more open which benefits lichen growth. During the last part of the 20th century forestry impaired the quality of grazing grounds in several ways, e.g. by clear-cutting and intensified use of various silviculturalmeasures. We conclude that ca. 30–50% of the winter grazing grounds have been lost in the study area because of intensive forest management during the last century. The spatially precise historical information about the affects of forestry on lichen pasture provided in this study can be used to direct forest management which will facilitate and promote reindeer herding in the future.

The aim of this paper is to evaluate relationships between decomposition rates of Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta var. contorta) needle litter in the late stage of decomposition (>30% accumulated mass loss), and the progressively changing concentrations of manganese (Mn), nitrogen (N), and acid unhydrolyzable residue (AUR), as well as mean annual temperature (MAT) and mean annual precipitation (MAP). Using available long-term decomposition studies on pine needle litter in a climate gradient in Sweden, we calculated annual mass loss and related to concentrations of Mn, N, and AUR at the start of each one-year period as well as to MAT and MAP. We investigated these relationships for (i) all data on annual mass loss combined and (ii) annual mass loss for five different decomposition categories as defined by accumulated mass loss. We found highly significant, negative, and dominant relationships between annual mass loss and N (R-2 = 0.39) and AUR (R-2 = 0.39), a slight but significant positive relationship to Mn (R-2 = 0.08) and a significant negative relationship to MAT (R-2 = 0.06). The relationships were dynamic, and changed with accumulated mass loss. The rate-dampening effect of N decreased to be a rate-enhancing effect at c. 60-80% accumulated mass loss. A similar trend was found for AUR, becoming rate-enhancing at 70-80% accumulated mass loss. For Scots pine needle litter the effect of MAT on mass loss decreased with increasing accumulated mass loss and changed to a rate-dampening effect at c. 50-70% accumulated mass loss. Mn showed a stimulating effect on mass loss rate in all categories whereas MAP showed no effect in this mainly boreal climatic gradient. The current approach indicates a method for detailed studies of rate-regulating factors for litter decomposition.

We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same litter species and for the genus Pinus we found a range from 0.03 to 3.7 mg g(-1). Concentrations were related negatively to site mean annual temperature (MAT) and annual actual evapotranspiration (AET) for pine species litter but not for that of Norway spruce (Picea abies) as a single species. Combined data for several species showed a highly significant relationship to MAT. Manganese peroxidase is an Mn-dependent enzyme, found in white-rot fungi, essential for the degradation of lignin and ligninlike compounds. The decomposition rates of lignified litter tissue (late phase) is positively related to the litter's Mn concentration. Further, the Mn concentration is positively related to the limit value for decomposition - the higher the Mn concentration the smaller the stable litter fraction. Manganese release from decomposing litter appears at least in part to be species related. Thus was release from pine needle litter significantly faster (p < 0.001) than that from the Mn-richer litter of Norway spruce. Over Northern Europe concentrations of total Mn in mor humus as well as extractable Mn in the mineral soil increase with decreasing MAT and over a climatic gradient the Mn concentrations in Norway spruce mor increase more with decreasing MAT than in a gradient with Scots pine. Higher Mn concentrations in humus appear to decrease its stability and result in a higher release of carbon dioxide (CO2) and dissolved organic carbon (DOC). We conclude that this may explain (i) the lower amount of carbon (C) in mor layers under Norway spruce as compared to Scots pine as well as the higher amount of C in mineral soil under spruce. The increase in nitrogen (N) concentration in humus, following N fertilization resulted in a decrease in that of Mn. We have found four cases - empirical - with negative interaction between Mn and N; (i) in pine foliar litter fall concentrations of Mn decrease with site MAT whereas those of N increase, (ii) in decomposing late-stage litter with N retarding and Mn stimulating decomposition, (iii) for the stable phase, limit values are related negatively to N and positively to Mn, and (iv) Mn concentrations in humus decrease with MAT whereas those of N increase. (C) 2015 Elsevier B.V. All rights reserved.

Boreal forests account for 30% of the world's total forest cover and in many places are subject to intensive forest management, which often involves complete removal of overstory vegetation by clear-cutting. However, we still do not fully understand how forest management affects aquatic ecosystems in these landscapes. Here we asked how forest management-induced changes in environmental conditions, such as incident light and nutrient availability, affect benthic algal growth and nutrient limitation in boreal headwater streams of northern Sweden. We answered this question using a combination of correlative and experimental approaches across a range of forested streams spanning a gradient of site (e.g. canopy openness and water chemistry) and catchment-level (e.g. age of forest regrowth) parameters, with variation among the study streams influenced by different forest management histories and underlying natural variation. We found that benthic algal growth in these forested streams was largely driven by local interactions between dissolved inorganic nitrogen (N) availability and incident light reaching benthic surfaces. Greater water temperature and shallower depths were also associated with greater algal growth. Although high dissolved organic carbon (DOC) concentrations often play a role in reducing light availability to autotrophs in boreal aquatic systems, it was not an important predictor of algal growth in small forested streams despite a large DOC concentration gradient (5 – 32 mg/L). Results from experimental nutrient additions supported the role of N as a key limiting nutrient, but also revealed both spatial and seasonal factors that modulate the effects of altered nutrient availability. Overall, our results suggest that differences in how light regimes and nutrient loading respond to forest management generate small-scale variation in the controls over stream primary productivity, which likely shift in relative importance at the time scale of a forest rotation (60 to 100 years).

Little is known about how past forest management in Sweden influenced the quantity and quality of large woody debris (LWD) in streams. The present study provides information of the long-term dynamics of LWD in a reach of a boreal stream intersecting a managed forest. Dendrochronological methods were used to reconstruct mortality years of the pieces of LWD and the general history of fire and cuttings of the surrounding riparian forest. Today, spruce dominates among the living trees, whereas the LWD is dominated by birch in the forest and by pine in the stream. Fire frequency prior to active fire suppression was similar to values reported from boreal forests. Pine trees were more abundant in the riparian forest before selective logging operations and active fire suppression began in the 1800s. Many of the pieces of LWD found in the stream today died more than 200 years ago and derived from a cohort of pines that generated in the early 1600s. Pine LWD in stream channels is highly resistant to decomposition and can reside for more than 300 years. A substantial amount of the LWD found today in managed forest streams in boreal Sweden most likely derives from the time before extensive human influence and is likely to decrease further in the future. Management of riparian forests to ascertain future supply of long-lived LWD in streams should target to increase the proportion of pine trees.

Climate warming is already influencing plant migration in different parts of the world. Numerous models have been developed to forecast future plant distributions. Few studies, however, have investigated the potential effect of warming on the reproductive output of plants. Understorey forest herbs in particular, have received little attention in the debate on climate change impacts.

This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seed mass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slow colonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 km latitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006 and 2008). This study design allowed us to isolate the effects of accumulated temperature (Growing Degree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seed sowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally, we disentangled correlations between the different reproductive traits of A. nemorosa along the latitudinal gradient.

We found a clear positive relationship between accumulated temperature and seed and seedling traits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient. Seed mass and seedling mass, for instance, increased by 9.7% and 10.4%, respectively, for every 1000 °C h increase in GDH. We also derived strong correlations between several seed and seedling traits both under field conditions and in incubators. Our results indicate that seed mass, incubator-based germination percentage (Germ%_Inc) and the output of germinable seeds (product of number of seeds and Germ%_Inc divided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes) provide valuable proxies to parameterize key population processes in models.

We conclude that (1) climate warming may have a pronounced positive impact on sexual reproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit from including the temperature sensitivity of key seed traits and population processes.

Forest canopies modify microclimates and create habitats for nonvascular epiphytes, but we need to better understand the mechanisms regulating their vertical and horizontal distributions. Here we examine how canopy structure and light environment influence the 3D distribution of Usnea longissima, the world's longest lichen, and associated with old-growth forests. We quantified forest structure, vertical profile of light (PPFD transmittance fraction), and horizontal as well as vertical distribution of the lichen in a 1 ha plot dominated by Picea abies. The forest had a multi-layered canopy with mortality driven by small-scale gap dynamics. The population size of the lichen had an approximate log-normal distribution with host trees showing strong clustering. The lichen extended up to mid-canopy and had a rather sharp upper limit. Population size increased with DBH and upper limit but did not correlate with basal area. The vertical profile of light was steeper in dead than in live trees, with the lichen occurring in a zone with low-intermediate light. The horizontal distribution was linked to the vertical distribution through short-distance asexual dispersal. The lichen's 3D distribution was shaped by various interacting functional mechanisms. Its absence from the upper canopy was mainly explained by sensitivity to high light when desiccated and limited capacity for upward migration. The population dynamics was driven by source trees hosting large populations in mid-canopy. The lichen's strong association with humid, old-growth forests is explained by narrow niche preferences and dispersal limitation, and not by slow growth. Protection of multi-layered forests with long continuity of tree cover is needed to secure substrates and suitable microclimates for development of viable lichen populations. Our study highlights that the 3D distribution of lichens in forest canopies is driven by forest dynamics, canopy structure, microclimate, and lichen functional traits.

There is a need for accurate and efficient methods for quantification and characterisation of forest edges at the landscape level in order to understand and mitigate the effects of forest fragmentation on biodiversity.We present and evaluate a method for collecting detailed data on forest edges in aerial photographs by using line intersect sampling (LIS). A digital photogrammetric system was used to collect data from scanned colour infrared photographs in a managed boreal forest landscape.We focused on high-contrast edges between forest (height ≥10 m) and adjoining open habitat or young, regenerating forest (height ≤5 m). We evaluated the air photo interpretation with respect to accuracy in estimated edge length, edge detection, edge type classification and structural variables recorded in 20 m radius plots, using detailed field data as reference. The estimated length of forest edge in the air photo interpretation (52 ± 8.8 m ha^-1; mean ± standard error) was close to that in the field survey (58 ± 9.3 m ha^-1). The accuracy in edge type classification (type of open habitat) was high (88% correctly classified). Both tree height and canopy cover showed strong relationships with the field data in the forest, buttree height was underestimated by 2.3 m. Data collection was eight times faster and five times more cost-efficient in aerial photographs than in field sampling. The study shows that line intersect sampling in aerial photographs has large potential as a general tool for collecting detailed information on the quantity and characteristics of high-contrast edges in managed forest ecosystems.

Long-term data on spatial dynamics of epiphytic lichens associated with old-growth forests are fundamental for understanding how environmental factors drive their extinction and colonization in heterogeneous landscapes. This study focuses on Usnea longissima, a flagship species for biodiversity conservation. By using a long-term data set (37 yr.) of U. longissima in old Picea abies forests in Skuleskogen National Park, Sweden, we examined changes in the number of host trees, population size (sum of thallus length), extinction, colonization, dispersal, and distribution in a protected landscape. We surveyed the lichen in 1984–1985 by applying a line transect inventory and a total population inventory and tagged 355 occupied trees with an aluminium plate buried in the ground. We repeated the survey in 2021 using a metal detector and recorded GPS-position of host trees, tree and lichen population characteristics. We also measured the structure and age (tree-ring data) of the forest to understand how disturbance history influenced lichen populations. Usnea longissima occurred on 66 of the tagged trees and we recorded 141 new host trees. The number of host trees decreased with 41.7% and the population size with 41.9%. One third of the decline was caused by deterministic extinction (treefalls) and two thirds by stochastic extinction on standing trees. The probability of stochastic extinction on live trees decreased with population size in logistic regression. The decline in the sites with largest populations (35–87% loss) was more influenced by limited colonization than extinction. Colonization was highest in humid north-facing hillslopes with multi-layered forests driven by gap dynamics. The lichen was strongly dispersal-limited, with a median effective horizontal dispersal of only 3.8 m in 37 yr., explaining its strong dependence of long continuity of forest cover. The populations were clustered and had substantial local turnover, yet with stable distribution at landscape scale. The tree-ring index, growth releases and gap recruitments indicate extensive harvesting ∼ 1860–1900, but without major disturbances during the last 70–80 yr. Instead, the decline of U. longissima was probably driven by air pollution, climate change (autumn/winter mortality and heatwaves) and denser forests. Our findings highlight that the long-term survival of this lichen may be at risk even in forests having a strong level of protection.

The structure and regulation of one nuclear and one chloroplast gene was studied in Pinus sylvestris (Scots pine) and Pinus contorta (lodgepole pine). cDNA copies of the nuclear located cab genes of Pinus sylvestris, coding for the light-harvesting chlorophyll a/b-binding proteins of photosystem II (LHC-II), were cloned. cab-II genes coding for both types of LHC-II polypeptides, Types 1 and 2, were found. An analysis of the DNA sequences of several different cab-II cDNAs shows that they have a high bias for the nucleotides G and C at the third base positions of the codons, making them more similar to monocot than to dicot genes. Two of the three genes were found to be located within CpG islands. The cab-II genes were found to be expressed in dark-grown seedlings in contrast to what has been found for most angiosperms. The chloroplast genomes of conifers were shown to lack the inverted repeat organization normally found in higher plants, mosses and green algae. The psbA gene, located in the chloroplast genome and coding for the D1 polypeptide in the reaction center of photosystem II, was found to be tandemly duplicated in P. contorta. Cloning and sequence analysis of the two psbA genes and the surrounding regions showed that the duplicated segment is 1.97 kb long and that it ends 19 bp downstream from the psbA stop codon. The corresponding locus of P. sylvestris, which lacks the duplication, was cloned and characterized. A comparison with P. contorta indicates how the duplication/insertion event has occurred. A comparison of third codon position between P. contorta psbA and that of other plants indicated an almost equidistant evolutionary relationship between P. contorta, spinach (or barley) and Marchantia polymorpha.

Extensive gene flow can be detrimental to local adaptation and similarly, forestry seed sources such as seed orchards can be heavily influenced by external pollination, especially if the orchard material has been translocated a great distance. Here we conducted a coordinated genotyping-phenotyping study to examine how external pollination events and fecundity variation in a Pinus sylvestris seed orchard influence the genetic composition and the seed-lots’ autumn frost hardiness when genetic material had been translocated 630 km south. The results were then compared to those of a in situ established seed orchard. We genotyped and phenotype >1000 seedlings from these orchards, and constructed their pedigrees and scored their autumn frost tolerance in a controlled climate chamber environment. The hardiness scores were compared with a reference of nine natural stands along a latitudinal cline. We find substantial variation in fecundity and external pollination over crop years, thus unpredictable genetic composition because the contribution of some orchard clones is high in one crop but low in another. We observed that seedlings produced by mating among orchard genotypes were less hardy than expected (corresponding to an origin of −0.6°N) but the opposite in externally pollinated seedlings (+0.3 to +0.7°N). The freeze damage levels reflect the origin of parental genotypes, but to a smaller degree than expected (13% lower than expected damage levels for externally pollinate seedlings and 21% greater damage levels for internally pollinates seedlings). These results suggest that orchard parents’ origins, mating composition and orchard local environment could all affect the seed crops’ quality and their climate adaptation. Seed orchard crops are the key to realize the gain in forestry from breeding efforts. However, genetic monitoring of seed crops is necessary to improve the performance of seed orchards further and adjust deployment areas of seed crops in a timely manner for a more dynamic forestry, considering climate change and biodiversity demands.

Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream’s edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage.

Society's increased interest in renewable energy and materials put pressure on forest biomass production. Intensive fertilization of young Norway spruce (Picea abies) forest has a considerable potential to increase the production of tree biomass, but there are concerns about negative side-effects on forest ecosystem structure and function. Fertilization of young forest has a strong negative impact on light availability below the tree canopy and reduces the abundance of the forest floor vegetation. The silvicultural practice of thinning has been shown to affect composition and diversity of forest floor vegetation, and it has been proposed, but rarely tested, that the effects of fertilization are interdependent on the type of thinning performed. Here we present responses on the forest floor vegetation following 25 years of fertilization and eighth years after thinning (removing 30% or 60% of the tree basal area) in a Norway spruce forest in northern Sweden. Fertilization without thinning led to a considerable reduction in abundance of most forest floor plants. It did not affect species richness but resulted in an increased evenness. Thinning reduced the fertilization effects so that the total abundance of the vegetation was comparable to the unfertilized control plots. A considerable change in species composition had, however, taken place. Thinning favored early-successional species and pteridophytes on the account of dwarf-shrubs. Thinning also increased species richness and functional richness, while none, or negative effects were seen on evenness and functional evenness, respectively. A comparison with data from the National Forest Inventory revealed that the type of vegetation generated by fertilization, without or in combination with thinning, is a type of vegetation very uncommon in Swedish boreal forests. First, we conclude that the effects of fertilization on forest floor vegetation in young stands of Norway spruce are largely dependent on thinning regime. Secondly, fertilization will, independently of thinning, lead to considerable changes in the vegetation, including a functional shift from dwarf-shrubs with ericoid mycorrhiza to ferns and grasses with arbuscular mycorrhiza, resulting in a functional type of vegetation that is rare in this part of the boreal forest biome. Finally, in contrast to what previously has been suggested for unfertilized forests, thinning of fertilized forests may not promote late-successional species.

(C) 2013 Elsevier B.V. All rights reserved.

The current decline of terrestrial lichens in Swedish boreal forests is a major challenge for reindeer husbandry, as lichens constitute essential grazing resources for reindeer during winter. Using a 30-year data set covering northern Sweden, we explore how the successional dynamics of lichen cover depend on several forest characteristics, as well as management strategies regarding both reindeer and forestry. We found a 36% reduction of plots with lichen cover, with a decrease in lichen cover becoming more likely in recent years. Year-round presence of reindeer in forests, compared to winter grazing only, had slightly negative impacts on lichens. We found increases in lichen cover in young forests following final harvest. However, increasing basal areas as forest grow older affected lichens negatively and supported dominance of mosses. Forest management that prioritizes less dense forests with larger trees would therefore improve the ability of lichens to persist as forage resource for reindeer.

The landscape in boreal Sweden is dominated by even-aged, single-layered forest monocultures and clearcuts. Few forest stands with a more complex, multi-layered structure remain as landscape elements. Westudied the impact that different forest management regimes have on snow conditions and the metamorphosisof snow, and discuss how these factors may affect suitability for reindeer grazing.Over two winters, we recorded the development of snow depth and hardness in clear cuts and two differentforest types, and their changes with weather events. In the forests, the dynamics of snow characteristicswere analyzed in relation to stand structure and at the level of individual trees.There were no clear differences in snow characteristics between single-layered and multi-layeredstands, although snow hardness was more variable in the latter. In single-layered stands, snow depthand hardness were spatially uniformly distributed in relation to stand characteristics. Contrastingly,the complex structure of multi-layered stands did influence snow depth significantly. However, hardnesswas highly heterogeneous in these stands. Due to the absence of tree effects, clear cuts had deeper butsofter snow than forested stands, although hardness increased towards spring.Weather affected the metamorphosis of the snow blanket. The magnitude of the effects depended onboth timing and severity of discrete weather events and forest structure, but generally weather had agreater influence on snow cover characteristics than forest structure per se. In their interaction withweather, different forest structures affect the snow and thus suitability as winter grazing area for reindeer.Reindeer herders, therefore, require diversity in the landscape in order to respond to such weathervariations and their impact on grazing conditions.

The introduction of exotic tree species can have profound effects on the native environment, including habitat use and movement patterns of animals, as well as becoming a management challenge for other land users. Here, we used GPS data from reindeer (Rangifer tarandus) and remote sensing measurements of lichen cover and soil moisture to assess the effects of the exotic lodgepole pine (Pinus contorta) on reindeer husbandry by the Indigenous Sámi in northern Sweden. We used locational data from 67 reindeer for three winters to analyze their habitat selection at the second-order selection (placement of home range in the landscape) and third-order selection (selection of sites within the home range) in relation to land cover class, terricolous lichen cover as measure of winter forage abundance, topographic features, and distance to roads. We also analyzed remotely sensed abundance of lichens in different forest types, and the association between these forest types and soil moisture as measure of suitability as lichen habitat. Compared to native P. sylvestris, we found that reindeer avoided stands with P. contorta where trees were higher than three meters. If P. contorta was the dominant tree species, reindeer were 60 % less likely to select these stands compared to stands with P. sylvestris, and 40 % less likely if P. contorta was less dominant at both orders of selection. We also found that reindeer selected areas with higher lichen cover. Lichen cover was lower in P. contorta stands compared to stands of the native P. sylvestris, even though P. contorta occurred mainly on dry soils usually favorable for terricolous lichens. We conclude that planting P. contorta on soils suitable for terricolous lichens is likely to reduce forage availability for reindeer and turn habitats earlier preferred by reindeer into avoided habitat, resulting in an overall reduction of winter grazing grounds. The effects of stands with P. contorta, albeit covering a comparatively small percentage of the reindeer husbandry area, need to be seen in context with generally declining terricolous lichen abundance due to land uses like forestry and other cumulative effects by external pressures on reindeer husbandry.

Forest edges have numerous implications for structure and function of forest ecosystems. Previous studies on edge quantity have used broad classifications. However, edge influence is driven by the contrast in vegetation structure between adjoining ecosystems, and thus we need detailed site-specific data to assess the role of edges in forests. We studied the variability of sharp edges in 28 boreal landscapes (4 km × 4 km) across an 830 km gradient throughout northern Sweden. Our objectives were: (1) to compare the length of natural and created edges, (2) to classify edges in detail by edge origin, maintenance and forest attributes, and (3) to examine relationships between length of edge and landscape variables. Data were collected using stereo-interpretation of high spatial resolution colour infrared aerial photographs, in combination with line intersect sampling and plots. The length of edge varied from 12 to 102 m ha⁻¹ among landscapes, with an overall mean of 54 m ha⁻¹. Created edges dominated most landscapes (mean 33 m ha⁻¹) and had greater variability than natural edges (mean 21 m ha⁻¹). Maintained edges (e.g. roads, agricultural land) were more abundant than regenerating edges caused by logging. Thirty percent of total edges adjoined narrow linear features. Seventy percent adjoined wider patches and showed high variability (35 classes). Overall, high-contrast edges towards mature forest dominated, i.e. ones that may experience strong edge influence. The amount of edge increased with percent of landscape affected by disturbance, and decreased with latitude and elevation. This study shows that edges are both abundant and highly variable in boreal forests and that forestry is the main driver behind edge creation. Detailed classification of edges based on site-specific forest and patch attributes may help to estimate edge influence at landscape level, and can guide experimental design for examining the impact of edges on structure and function of forest ecosystems.

Management of boreal forests for timber production has caused changes in forest structures and disturbance regimes, which have influenced a wide range of organisms. The aim of this study was to evaluate how composition of epigaeic (ground-living) beetle assemblages is influenced by stand age and management history in a heavily managed boreal forest landscape. We compared the epigaeic assemblages among stands of three ages: (1) young (8-25 years) and (2) middle-aged (40-58 years) stands regrown after clear-cutting, and mature stands (80-130 years) that had been selectively cut historically but never clear felled. We sampled epigaeic beetles in each of 42 stands, using 10 pitfall traps during seven summer weeks. More than 9000 specimens were collected and identified. The assemblages in young stands differed from those in middle-aged and mature stands, both for the Staphylinidae (rove beetles) and all beetle families combined. Carabidae (ground beetles) composition differed between young and middle aged stands only, and assemblages of Curculionidae (weevils, bark beetles and allies) differed between young and mature stands only. Assemblages of Leiodidae (round fungus beetles) had similar composition in all three stand types. Considering all families, young stands generally harbored fewer species and lower abundances compared with middle aged and mature stands. However, the Leiodidae had similar species richness in all three stand types. The lack of differences in assemblage composition, species richness and abundance between middle aged and mature stands suggests that epigaeic beetle assemblages recolonize following clear-felling. However, our collections included large numbers of unique and usually rare species in mature stands, indicating that old forest is important for the conservation of epigaeic beetles. Furthermore, the lower abundance of these beetles in young stands indicates that an increasing proportion of young stands on managed landscapes will reduce the overall abundances of epigaeic beetle species, with potentially negative impacts on recolonization.

Many saproxylic beetles do not feed on wood directly but on fungi colonizing the wood. The volume of decaying wood has decreased drastically in Scandinavian managed forest landscapes in recent years, so improved knowledge on the interactions between beetles and wood-decaying fungi is important for the long-term persistence of these trophic partners. Sporocarps of polypores are known to emit volatiles attracting both fungivorous and predatory beetles, but it is unknown whether some beetles are also attracted to odours from the mycelia. The aim of this experiment was to test the attraction of beetles to volatiles from the sporocarps and mycelia of wood-decaying fungi. In a randomized block design, six substrate types: Fomitopsis pinicola sporocarp, F. pinicola mycelium-infected wood, Fomitopsis rosea sporocarp, F. rosea mycelium-infected wood, Phellinus chrysoloma sporocarp and Phlebia centrifuga mycelium-infected wood were attached separately to specially designed window traps in four old-growth spruce forests in northern Sweden. Empty traps and traps with sterilised wood were used as controls. We found no significant differences in the species richness or abundance of saproxylic beetles between the control and sterilised wood and the fungal substrates. However, two abundant species showed significant preferences for one substrate type. The bark beetle Dryocoetes autographus preferred F. rosea mycelium-infected wood and the rove beetle Lordithon lunulatus preferred fruiting bodies of F. pinicola. The results indicate that some species do discriminate between volatiles emitted by different polypore species and also between volatiles emitted by the sporocarps and mycelia from the same species. Our data indicate a hitherto unknown interdependence between D. autographus and F. rosea. We conclude that present knowledge on interactions between beetles and wood-decaying fungi is limited and further studies are needed to enhance our ability to design appropriate conservation strategies in the forest landscape.

Dead wood is a critical resource for forest biodiversity and widely used as an indicator for sustainable forest management. Based on data from the Swedish National Forest Inventory we provide baseline information and analyze trends in volume and distribution of dead wood in Swedish managed forests during 15 years. The data are based on ≈30,000 sample plots inventoried during three periods (1994–1998; 2003–2007 and 2008–2012). The forest policy has since 1994 emphasized the need to increase the amount of dead wood in Swedish forests. The average volume of dead wood in Sweden has increased by 25% (from 6.1 to 7.6 m³ ha⁻¹) since the mid-1990s, but patterns differed among regions and tree species. The volume of conifer dead wood (mainly from Picea abies) has increased in the southern part of the country, but remained stable or decreased in the northern part. Heterogeneity of dead wood types was low in terms of species, diameter and decay classes, potentially negatively impacting on biodiversity. Overall, we found only minor effects of the current forest policy since most of the increase can be attributed to storm events creating a pulse of hard dead wood. Therefore, the implementation of established policy instruments (e.g. legislation and voluntary certification schemes) need to be revisited. In addition to the retention of dead trees during forestry operations, policy makers should consider calling for more large-scale targeted creation of dead trees and management methods with longer rotation cycles.

Traditional clear-fell forestry greatly alters community structure and ecosystem function within boreal forests and alternative management practices may reduce these impacts. Continuous-cover forestry can maintain similar invertebrate and plant communities to unmanaged forest, but whether this extends to soil fungal communities remains unclear. Within four sites across the mid-boreal zone of Sweden, we conducted a comprehensive study to assess the impact of continuous-cover and clear-felling on soil fungi and chemical properties within Norway spruce dominated forests, using unmanaged forest as a control. We sampled soils for chemical properties (pH, carbon, nitrogen, C/N and Organic matter) and used both surveys of fungal fruiting bodies and state of the DNA metabarcoding techniques to assess treatment effects on soil fungal communities. We found that forest management practices had significant effects soil pH, C and C/N ratio and that continuous-cover forestry had more similar soil properties to unmanaged forest. Furthermore, the biodiversity of fruiting bodies, as expressed by species richness and Shannon’s diversity index, was higher in continuous-cover forestry and unmanaged forest compared to clear-felled areas. However, the opposite was true for the diversity of soil fungal communities, which was probably due to the high level of disturbance in clear-felled areas, and thus, ample habitat for early successional colonisers and some remnants of mature forest communities. However, in agreement with predictions we found that the composition of both fruiting body and soil fungal communities broadly similar in continuous-cover and unmanaged forest, but fundamentally different to clear-felled areas. Consequently, our findings highlight that continuous-cover forestry is an alternative to conventional practise, maintaining communities associated with unmanaged forest and mimicking natural disturbance regimes.

Are current estimates of silicate minerals weathering rates precise enough to predict whether nutrient pools will recover after forest harvesting? Answering this question seems crucial for sustainable forestry practices on silicate dominated soils. In this paper, we synthesize estimated Ca and K weathering rates (derived using seven different approaches) from a forested area in northern Sweden (the Svartberget-Krycklan catchment) to evaluate the precision of weathering rate estimates. The methods were: mass-balance budgets (catchment and pedon-scale); long-term weathering losses inferred from weathered soil profiles (using zirconium as a conservative tracer); strontium isotopes (Sr-86/Sr-85) as proxy for catchment export of geogenic Ca; climate based regressions; a steady-state, process-based weathering model (PROFILE) and a dynamic, conceptual catchment geochemistry model (MAGIC). The different methods predict average weathering rates of 0.67 +/- 0.71 g Ca m(-2) year(-1) (mean +/- stdev) and 0.39 +/- 0.38 g K m(-2) year(-1), suggesting a cumulative weathering release during a forest rotation period of 100 years that is the same magnitude as losses induced by forest harvesting at the end of the period. Clearly, forestry practices have the capacity to significantly alter the long-term nutrient status of the soil and cation concentrations in soil-water runoff. However, the precision in weathering estimates are lower than that needed to distinguish between effects on nutrient pools by different forest practices (complete-tree harvesting versus conventional stem only harvest). Therefore, we argue that nutrient budgets, where weathering rates play a crucial role, cannot be used as basis for resolving whether different harvesting techniques will allow nutrient pools to recover within one rotation period. Clearly, this hampers the prerequisite for sound decision making regarding forestry practices on silicate mineral dominated soils. (C) 2010 Elsevier B.V. All rights reserved.

Storms have a high potential to cause severe ecological and economic losses in forests. We performed a logistic regression analysis to create a storm damage sensitivity index for North Rhine-Westphalia, Germany, based on damage data of the storm event "Kyrill". Future storm conditions were derived from two regional climate models. We combined these measures to an impact metric, which is embedded in a broader vulnerability framework and quantifies the impacts of winter storms under climate change until 2060. Sensitivity of forest stands to windthrow was mainly driven by a high proportion of coniferous trees, a complex orography and poor quality soils. Both climate models simulated an increase in the frequency of severe storms, whereby differences between regions and models were substantial. Potential impacts will increase although they will vary among regions with the highest impacts in the mountainous regions. Our results emphasise the need for combining storm damage sensitivity with climate change signals in order to develop forest protection measures.

Riparian forests (RFs) along streams and rivers in forested landscapes provide many ecosystem functions that are important for the biodiversity and biogeochemistry of both terrestrial and aquatic ecosystems. In riverine landscapes, many of these ecological and biogeochemical functions have been found to be maximized in riparian areas with discharge of upland-originating groundwater (GW). This ecological significance, and the fact that riparian areas with GW discharge are important sources of many chemical elements in streams and rivers, makes these places important hotspots in the landscape. The natural functioning of RFs is however threatened by poorly designed management practices, with forestry being one of the most important examples in timber producing regions. Logging operations in riparian, but also in adjoining upland forests, threaten to alter many riparian functions. This effect is accelerated in GW discharge hotspots because of their sensitive soils and the high connectivity with uphill areas. We thus argue that forestry practices should give higher consideration to riparian GW discharge areas, and we demonstrate how improved riparian buffer zone management can be incorporated into every-day forestry planning. We offer a practical tool for more optimized site-specific riparian buffer design by using model-derived high resolution maps with detailed information about wetness and soil–water flow paths within RFs. We describe how such site-specific riparian buffer management differs from fixed-width buffers, which are generally applied in today’s forestry, and address some risks connected to fixed-width buffer management. We conclude that site-specific riparian management, allowing wider buffers at GW discharge areas and more narrow buffers on sites of lower ecological significance (i.e. riparian sites without GW flow paths), would benefit a variety of ecosystem services, mitigate negative effects caused by forestry and create more variable and heterogeneous riparian corridors. Finally, we show examples of how the new forestry planning can be applied.

The dominant base cations (BC: i.e., Ca(2+), Mg(2+), K(+), and Na(+)) are important in buffering soil and water acidity in both terrestrial and aquatic ecosystems. Ca(2+)., Mg(2+), and K(+) are also important in many plant physiological functions. Because BC availability is affected by changes in the nitrogen (N) cycle, we conducted a meta-analysis of previously published data to determine if N fertilization alters the availability of BC in terrestrial and stream ecosystems across biomes. We include data from 107 independent studies published in 62 different articles, taking a holistic perspective on BC by examining their responses to added N in plant foliage, bulk soil, soil solution, and stream water. Our results suggest N fertilization may accelerate BC loss from terrestrial ecosystems over time periods less than five years. We found that N additions resulted in an overall 24% decrease in the availability of exchangeable Ca(2+), Mg(2+), and K(+) in the bulk soil of boreal forest, temperate forest, and grassland biomes. Collectively, responses of BC in boreal forest, temperate forest, tropical forest, and grassland biomes increased following N fertilization by about 71% in soil solution and 48% in stream waters. Additionally, BC responses in foliage decreased in boreal forest and temperate forest biomes following N additions over time periods less than five years, but there were no significant changes over longer time periods. Despite large short-term shifts in BC responses following N additions, we did not find evidence of widespread negative impacts on ecosystems over time periods greater than five years. This analysis suggests effects of N addition on the availability of exchangeable BC may diminish over time. Although the effects on BC can be substantial over periods less than five years, there is little available evidence that N fertilization has had large-scale detrimental effects on the availability of BC needed for plant growth within terrestrial or aquatic ecosystems.

Nutrient optimization has been proposed as a way to increase boreal forest production, and involves chronic additions of liquid fertilizer with amounts of micro- and macro-nutrients adjusted annually to match tree nutritional requirements. We used a short-term (maintained since 2007) and a long-term (maintained since 1987) fertilization experiment in northern Sweden, in order to understand nutrient optimization effects on soil microbiota and mesofauna, and to explore the relationships between plant litter and microbial elemental stoichiometry. Soil microbes, soil fauna, and aboveground litter were collected from the control plots, and short- and long-term nutrient optimization plots. Correlation analyses revealed no relationships between microbial biomass and litter nutrient ratios. Litter C:N, C:P and N:P ratios declined in response to both optimization treatments; while only microbial C:P ratios declined in response to long-term nutrient optimization. Further, we found that both short- and long-term optimization treatments decreased total microbial, fungal, and bacterial PLFA biomass and shifted the microbial community structure towards a lower fungi:bacterial ratio. In contrast, abundances of most fungal- and bacterial-feeding soil biota were little affected by the nutrient optimization treatments. However, abundance of hemi-edaphic Collembola declined in response to the long-term nutrient optimization treatment. The relative abundances (%) of fungal-feeding and plant-feeding nematodes, respectively, declined and increased in response to both short-term and long-term treatments; bacterial-feeding nematodes increased relative to fungal feeders. Overall, our results demonstrate that long-term nutrient optimization aiming to increase forest production decreases litter C:N, C:P and N:P ratios, microbial C:P ratios and fungal biomass, whereas higher trophic levels are less affected.

We compared the plant understorey between stands of introduced Pinus contorta and native P. sylvestris in boreal northern Sweden using a chronosequence of 24 paired stands of P. contorta or P. sylvestris. We located one 1000 m2 sample plot in each stand in which we recorded tree variables, number of vascular plant and lichen species, and cover of the understorey of each of the groups vascular plants, bryophytes and lichens. We tested for differences between the two chronosequences and assessed relationships between the understorey and stand variables. Tree variables did not differ between stands but stands of P. contorta had more than three times greater percent ground cover of needle litter compared to stands of P. sylvestris. Naturally regenerated individuals of P. contorta occurred in five out of 12 stands of P. contorta older than 25 years. The understorey was similar between stand types in terms of species richness, cover, and species composition but the entire species pool was larger for stands of P. sylvestris than for stands of P. contorta. Thirty-eight species were only found in stands of P. sylvestris; the corresponding figure for stands of P. contorta was six species. Shade-intolerant understorey species were disfavoured in stands of P. contorta. The development at the stand level of understorey (vascular plant and lichen) species richness and cover over time was similar between stand types. In both types of stands, the number of lichen species and the percent ground cover of lichens and bryophytes increased with stand age; the corresponding values for vascular plant species did not. The results propose a more homogeneous flora in stands of P. contorta compared to stands of P. sylvestris, suggesting lower understorey species richness at the landscape scale. The larger shading effect of needles in the canopy and on the ground in stands of P. contorta, which is supposed to imply less habitat variation, might contribute to this difference.

Intensive forest management has dramatically reduced the area of old-growth forest in Fennoscandia. We examined if the proportion of old forest in a landscape affects species composition, richness and abundance of saproxylic beetles. We used tube-shaped window traps in five pairs of sites, selected so that the sites within each pair differed with respect to the proportion of old forest (>125 years) in the surrounding landscape. A landscape level inventory of the wood fungi Fomitopsis rosea, as a proxy for forest with high conservation values, was used to complement the data on old forests. In addition, to testing whether mycelia-colonised wood may attract saproxylic beetles, the tube-shaped window traps were baited with wood colonised by Fomitopsis pinicola or F. rosea. Old-forest-rich landscapes supported significantly more species and a higher abundance of saproxylic beetles than old-forest-poor landscapes. The analysis revealed a clear connection between the community composition of saproxylic beetles and the proportion of old forest and number of F. rosea fruiting bodies in the surrounding landscape (radius 3 km). The local landscape species pool thus appears to be important for the beetle species that are trapped since the composition of saproxylic beetles differed between the two landscape types. The effects of the different baits were less pronounced than the effect of landscape type, although species-specific responses to the two mycelia baits were observed. This indicates that volatiles from mycelia of wood-decaying fungi and the mycelial community may affect colonisation patterns of saproxylic beetles. Our results suggest that forest fragmentation and habitat loss have resulted in depauperate beetle faunas in old-forest-poor landscapes. Our results highlight the need to invoke a landscape scale approach for preserving biodiversity, in this case the need to maintain a sufficient proportion of forest with old growth characteristics in the managed landscape.

A growing awareness of the negative consequences of efficient fire prevention in boreal Fennoscandia has resulted in an increasing use of fire as a restoration method. The primary purpose of restoration fire is to recreate features of natural forests that have been lost during long periods of fire suppression. We used the occurrence of fruiting bodies from wood-inhabiting fungi to assess the conservation value of and gain ecological information about restoration fire in a Pinus sylvestris dominated forest. The general pattern for the majority of the species was a drastic decline the first two years after the restoration fire. However, our results clearly demonstrate that most of the species that declined the first years after the fire rebounded after four years and were frequently found on charred wood. Species that increased after the fire and often occurred on charred logs were: Antrodia sinuosa, Botryobasidium obtusisporum, Galzinia incrustans, Phlebia subserialis and Tomentella spp. In addition, three threatened, red-listed and fire-favored species were also found on heavily charred logs: Antrodia primaeva, Dichomitus squalens and Gloeophyllum carbonarium. Our results indicate that fire disturbance creates a unique type of dead wood important for fungal species richness. The results also support the use of restoration fires in maintaining forest biodiversity.

Scots pine blister rust is a rust fungal pathogen that has become more noticeable in recent years and has increased in recorded incidence in Northern Scandinavia. This has prompted an initiation of resistance breeding to the fungus in the Northern Swedish pine breeding program. To accomplish this, it is necessary to evaluate the breeding potential for increased resistance and putative impact on other breeding objective traits that may have genetic correlations to resistance. To assess the potential of the trait to be included in the breeding program we examined half sibling families in four trials of which two had high incidence of Scots pine blister rust in a range of 25.4–42.1 %. We assessed vitality and height in one year and rust lesion frequency at two later time points. We found that rust resistance had a narrow sense heritability of 0.36–0.41, while vitality reached 0.17 and height 0.25. We found a high genetic correlation between sites in rust resistance and no genetic correlation between rust resistance and either vitality or height. This means that breeding for increased resistance in Scots pine can be done effectively without risking a negative impact on established breeding objective traits and that resistance is stable across environments.

Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we revealed how the stand structure is determined by site quality and results from site-dependent partitioning of growth and mortality among the trees. We based our study on 90 mature, even-aged, fully stocked monocultures of Scots pine (Pinus sylvestris L.) sampled in 21 countries along a productivity gradient across Europe. A mini-simulation study further analyzed the site-dependency of the interplay between growth and mortality and the resulting stand structure. The overarching hypothesis was that the stand structure changes with site quality and results from the site-dependent asymmetry of competition and mortality.

First, we show that Scots pine stands structure across Europe become more homogeneous with increasing site quality. The coefficient of variation and Gini coefficient of stem diameter and tree height continuously decreased, whereas Stand Density Index and stand basal area increased with site index.

Second, we reveal a site-dependency of the growth distribution among the trees and the mortality. With increasing site index, the asymmetry of both competition and growth distribution increased and suggested, at first glance, an increase in stand heterogeneity. However, with increasing site index, mortality eliminates mainly small instead of all-sized trees, cancels the size variation and reduces the structural heterogeneity.

Third, we modelled the site-dependent interplay between growth partitioning and mortality. By scenario runs for different site conditions, we can show how the site-dependent structure at the stand level emerges from the asymmetric competition and mortality at the tree level and how the interplay changes with increasing site quality across Europe.

Our most interesting finding was that the growth partitioning became more asymmetric and structuring with increasing site quality, but that the mortality eliminated predominantly small trees, reduced their size variation and thus reversed the impact of site quality on the structure. Finally, the reverse effects of mode of growth partitioning and mortality on the stand structure resulted in the highest size variation on poor sites and decreased structural heterogeneity with increasing site quality. Since our results indicate where heterogeneous structures need silviculture interventions and where they emerge naturally, we conclude that these findings may improve system understanding and modelling and guide forest management aiming at structurally rich forests.

Changing silvicultural methods to improve habitat quality for forest organisms has become one of the main means to preserve forest biodiversity in Fennoscandia. In boreal forests, coarse woody debris (CWD) is an important substrate for red-listed species. In this study, we analyse cost-efficiency of five management measures taken in Swedish forestry, which aim at increasing CWD in managed forests: retention of living trees at harvest, artificial creation of high stumps, manual scarification at clear-cuts to avoid destruction of CWD, prolongation of the rotation period, and retention of naturally dying trees. For Norway spruce (Picea abies) stands in different parts of Sweden, we calculated the present value and predicted the amount of CWD that will be present if the same management method is used over a long time. To retain reasonable amounts of naturally dying trees was always inexpensive, and in central and northern Sweden it was more economical to retain them than to harvest them. Creation of high stumps was a cost-efficient method to increase the amount of CWD. Prolonging the rotation period was the most expensive way to increase CWD. We conclude that adopting several different measures to increase CWD in managed forests, as prescribed by certification standards today, is a good concept, but to be cost-efficient the focus should be on different measures for different parts of Sweden.

The coco de mer palm Lodoicea maldivica, endemic to the Seychelles, is a flagship species for tourism and conservation. It bears the world's largest seed for which it is currently heavily exploited across its limited range, and it is clear that harvesting at current levels cannot be maintained indefinitely. Biologically informed harvesting protocols are therefore required to move towards sustainable management that secures the long-term viability of the population and the revenue that it currently generates. Demographic modelling using population matrix models is a useful tool in these efforts as it identifies both the life stages with the strongest influence on population dynamics as well as the consequences of current use intensities. Here we provide an initial population model based on data currently available to assess the status of the largest L. maldivica population in the Vallée de Mai World Heritage Site. We estimated transition probabilities and constructed matrices to estimate the populations’ growth rate under current and alternative harvesting regimes, taking into account uncertainty regarding adult mortality and lifespan. Model projections of the population under current harvesting intensities forecast a marked decrease in the proportion of juveniles in the population and a gradually declining population over the next 200 years. Population growth rates were most sensitive to adult survival, reflecting the long generation time of this species and the remaining uncertainty in this respect. Based on this preliminary model we propose a precautionary sustainable harvesting limit for L. maldivica and discuss the challenges and opportunities of its management, including recommendations for future data collection.

Forest management faces a substantial challenge with ever-more-pervasive anthropogenic impacts and growing demands on forests coupled with the increasing certainty of global change. If the capacity of forests to provide valued ecological goods and services in the future is to be maintained, new tools and approaches will be needed. Several approaches have been influential in dealing with sustainability challenges in forest management and forestry to date, two of the most notable being the ecosystem approach and adaptive management. Resilience-based approaches have now emerged as a new paradigm to deal with these challenges. This paper considers how resilience thinking might inform forest management by exploring its conceptual basis in comparison with the ecosystem approach and adaptive management as two earlier influences. We identify three novel conceptual contributions and outline some of the key challenges encountered when applying resilience thinking to the management of forests. Resilience thinking offers new conceptual contributions for dealing with large and uncertain changes, the relationships between social and ecological components of forest systems, and a new perspective on sustainability. However, there are several barriers to it informing forest management in a practical way, including means by which resilience can be measured and valued within a management context, and most importantly, how resilience can be maintained and enhanced within systems focused on resource production or service provision. Resilience thinking's contributions are largely conceptual at this stage and offer more in terms a problem-framing approach than analytical or practical tools. Decision-relevant, science-based, and solution-oriented approaches are required to tackle future forest management challenges. Resilience thinking, if developed to become more solution-orientated could offer a needed complement to current management paradigms.

(C) 2013 Elsevier B.V. All rights reserved.

The potential for combining timber and non-timber forest product extraction has been examined in the context of diversified forest management. Many tropical forests are exploited both commercially for timber and by forest-dependent communities for non-timber forest products (NTFPs). Divergences between these two uses may have significant implications for forest-dependent livelihoods. This article gathers existing examples of conflicts and complementarities between selective logging and non-timber uses of forest from the livelihood perspective. Additionally it draws on three case studies from Brazil, Cameroon and Indonesia to examine by what mechanisms, and to what extent, logging impacts forest resources of livelihood importance, as well as to consider how factors such as logging regime and forest management system may mediate such influences. By doing so we aim to shed further light on a relatively unacknowledged issue in tropical forest management and conservation.

Four specific mechanisms were identified; conflict of use and the indirect impacts of logging being those most commonly implicated in negative effects on livelihood-relevant NTFPs. Eighty two percent of reviewed articles highlighted negative impacts on NTFP availability. Examples of positive impacts were restricted to light demanding species that respond to the opening of forest structure and typically represent a small subset of those of livelihood value. Despite considerable impacts on livelihoods, in all three case studies we found evidence to support the potential for enhanced compatibility between timber extraction and the subsistence use of NTFPs. Drawing on this evidence, and findings from our review, we make specific recommendations for research, policy and management implementation. These findings have significant implications for reconciling timber and non-timber uses of tropical forests.

Mixed-species stands have been found to be more productive than would be expected from the performance of their component species in monocultures due to facilitation and complementarity between species, although these interactions depend on the combination of species present. Our study focuses on monospecific and mixed species stands of Scots pine and Norway spruce using 20 triplets established in nine countries along a climatic gradient across Europe. Differences in mean tree and stand characteristics, productivity and stand structure were assessed. Basal area increment in mixed stands was 8% higher than expected while volume increment was only 2% greater. Scots pine trees growing in mixed-species stands showed 11% larger quadratic mean diameter, 7% larger dominant diameter, 17% higher basal area and 25% higher stand volume than trees growing in mono specific stands. Norway spruce showed only a non-significant tendency to lower mean values of diameters, heights, basal area, as well standing volume in mixtures than monocultures. Stand structure indices differed between mixed stands and monocultures of Scots pine showing a greater stratification in mixed-species stands. Furthermore, the studied morphological traits showed little variability for trees growing in monospecific stands, except for diameter at breast height, crown length and crown length ratio. For trees growing in mixed stands, all the morphological traits of the trees were identified as different. Some of these morphological traits were associated with relative productivity. Nevertheless, relative productivity in mixed-species stands was not related to site conditions.

Ripley's K-function was used to investigate the changes in spatial pattern among trees in a semi-natural mixed deciduous forest in Denmark over 50 years, from 1948 to 2001. Trees larger than 10 cm diameter in breast height (dbh) were mapped at 10-year intervals in 16 blocks within two former compartments. At the start of the observation, trees were found to be regularly distributed at distances less than 10 m. This pattern changed with time in different ways, depending on tree density at the beginning of the recording. Tree density has a greater influence on the number of recruits than on the number of dead trees. New recruits were significantly aggregated and positively correlated with dead trees, which suggests that regeneration occurred in canopy gaps. Compartments with many new recruits therefore showed a change in pattern towards more random distribution or even towards aggregation. In blocks with high basal area and few recruits, the pattern changed only slightly. Past management was found to be important in generating the patterns of tree distribution.

1. Wind-damaged trees, following the severe storm of 1999, are compared with data from a 50-year monitoring of Draved Forest, Denmark, to assess differing causes of mortality through time in an unmanaged semi-natural forest. Species-specific mortality characteristics and the changing effects of tree size and growth rate (diameter increment) on mortality through time are also investigated. 2. Storm was found to be the major mortality factor affecting large trees in this forest. For smaller trees, competition was an important cause of death, as trees that were found standing dead had a slower growth rate (diameter increment) than survivors. 3. Individual species showed different mortality patterns. Betula died more often and Fagus less often than expected from their abundance. Betula, Fagus and Tilia were mainly wind-thrown, whereas for Alnus and Fraxinus, 50% of the mortality was observed as standing dead trees. 4. Both wind and competition are important mortality factors in Draved Forest. (C) 2003 Elsevier B.V. All rights reserved.

In Swedish Lappland, large national parks and nature reserves include forests with exceptional biodiversity values. While they are located in the ancient cultural landscapes of the indigenous Sami, this aspect has rarely been considered in the process of nature protection. In this study, we discuss how the preservation of Sami cultural values can be introduced and developed in forest reserves. We do this by reviewing recent research on the cultural legacy that the Sami have left in the boreal forest and discuss why so much of this legacy is found in the large areas of ecologically valuable forest that still exist in Lappland. We find that the Sami left deep imprints in the trees, in the forest structure, and in the archaeological record. We also find that the large forest reserves were created in the areas where the timber frontier arrived last, so they were less affected by both early actions of recurrent logging and by modern forestry. These forest reserves contain the ancient trees, the dead wood, and the disturbance regimes that favor biodiversity, and also a substantial Sami cultural legacy that has largely disappeared in the managed forest landscape. The preservation of this legacy is not without its challenges. We address the lack of inventory data, the poor collaboration between different authorities, and the general lack of involvement of the Sami communities; furthermore, we propose measures to overcome these shortcomings. If such measures are introduced, the value of the large and unique forest reserves of Swedish Lappland would be greatly enriched. The cultural legacies in forest dominated landscapes in northern Scandinavia is comparable to many other very northern or very southern regions in that they share a similar history of millennia of indigenous land use, with abrupt changes in modern time and also have large protected areas today.