Fennoscandian Boreal Forests Research Articles

Drivers of snag fall rates in Fennoscandian boreal forests

Abstract Persistence of standing dead trees (snags) is an important determinant for their role for biodiversity and dead wood associated carbon fluxes. How fast snags fall varies widely among species and regions and is further influenced by a variety of stand‐ and tree‐level factors. However, our understanding of this variation is fragmentary at best, partly due to lack of empirical data. Here, we took advantage of the accruing time series of snag observations in the Finnish, Norwegian and Swedish National Forest Inventories that have been followed in these programs since the mid‐1990s. We first harmonized observations from slightly different inventory protocols and then, using this harmonized dataset of ca. 43,000 observations that had a consistent 5‐year census interval, we modelled the probability of snags of the main boreal tree species Pinus sylvestris, Picea abies and Betula spp. falling, as a function of tree‐ and stand‐level variables, using Bayesian logistic regression modelling. The models were moderately good at predicting snags remaining standing or falling, with a correct classification rate ranging from 68% to 75% among species. In general, snag persistence increased with tree size and climatic wetness, and decreased with temperature sum, advancing stage of decay, site productivity and disturbance intensity (mainly harvesting). Synthesis and applications: The effect of harvesting demonstrates that an efficient avenue to increase the amount of snags in managed forests is protecting them during silvicultural operations. In the warmer future, negative relationship between snag persistence and temperature suggests decreasing the time snags remain standing and hence decreasing habitat availability for associated species. As decomposition rates generally increase after fall, decreasing snag persistence also implies substantially faster release of carbon from dead wood.

Tree regeneration potential in urban spruce-dominated forests is shaped by management history

With projected climate change, urban spruce-dominated forests are facing increasing risks of forest damages, encouraging management for mixed stand structures. In the major cities of southern Finland, forests are preferentially maintained continuously covered, and tree regeneration is mostly reliant on naturally emerging sapling stock. To understand the role of forest management in shaping natural tree regeneration in urban forests, we studied the occurrence and abundance of tree saplings in spruce-dominated tree stands on a management continuum ranging from partially logged to undisturbed near-natural stands. Study sites (N = 74) were located in three urban centers in southern Finland: Tampere, Lahti and Helsinki region. We analyzed the data by comparing tree regeneration potential between management classes reflecting the timing and intensity of past logging, and by relating the occurrence of saplings with current structures of the living tree stand.Compared to undisturbed stands, partially logged sites had increased regeneration of broad-leaved trees and repressed regeneration of spruce, while the most abundant sapling tree species across all management classes was rowan. We conclude that partial logging can be a successful way of directing tree regeneration towards lower dominance of spruce. However, when the canopy is only partially opened, created gaps may end up being filled primarily by rowans that are comparatively shade-tolerant. Because the ingrowth of rowan and many other broad-leaved tree species is strongly restricted by dense populations of large browsing animals in non-urban areas, urban forests may develop stand structures and tree species composition that are otherwise rare in the Fennoscandian boreal forests.

Dynamics of aerosol, humidity, and clouds in air masses travelling over Fennoscandian boreal forests

Abstract. Boreal forests cover vast areas of land in the high latitudes of the Northern Hemisphere, which are under amplified climate warming. The interactions between the forests and the atmosphere are known to generate a complex set of feedback processes. One feedback process, potentially producing a cooling effect, is associated with an increased reflectance of clouds due to aerosol–cloud interactions. Here, we investigate the effect that the boreal forest environment can have on cloud-related properties during the growing season. The site investigated was the SMEAR II station in Hyytiälä, Finland. Air mass back trajectories were the basis of the analysis and were used to estimate the time each air mass had spent over land prior to its arrival at the station. This enabled tracking the changes occurring in originally marine air masses as they travelled across the forested land. Only air masses arriving from the northwestern sector were investigated, as these areas have a relatively uniform forest cover and relatively little anthropogenic interference. We connected the air mass analysis with comprehensive in situ and remote-sensing data sets covering up to 11 growing seasons. We found that the properties of air masses with short land transport times, thereby less influenced by the forest, differed from those exposed to the forest environment for a longer period. The fraction of air masses with cloud condensation nuclei concentrations (at 0.2 % supersaturation) above the median value of 180 cm−3 of the analysed air masses increased from approximately 10 % to 80 % after 55 h of exposure to boreal forest, while the fraction of air masses with specific humidity above the median value of 5 g kg−1 increased from roughly 25 % to 65 %. Signs of possible resulting changes in the cloud layer were also observed from satellite measurements. Lastly, precipitation frequency increased from the average of approximately 7 % to about 12 % after a threshold of 50 h of land transport. Most of the variables showed an increase with an increasing land transport time until approximately 50–55 h, after which a balance with little further variation seemed to have been reached. This appears to be the approximate timescale in which the forest–cloud interactions take effect and the air masses adjust to the local forest environment.

Mineral Soils Are an Important Intermediate Storage Pool of Black Carbon in Fennoscandian Boreal Forests.

Approximately 40% of earth's carbon (C) stored in land vegetation and soil is within the boreal region. This large C pool is subjected to substantial removals and transformations during periodic wildfire. Fire-altered C, commonly known as pyrogenic carbon (PyC), plays a significant role in forest ecosystem functioning and composes a considerable fraction of C transport to limnic and oceanic sediments. While PyC stores are beginning to be quantified globally, knowledge is lacking regarding the drivers of their production and transport across ecosystems. This study used the chemo-thermal oxidation at 375°C (CTO-375) method to isolate a particularly refractory subset of PyC compounds, here called black carbon (BC), finding an average increase of 11.6g BC m-2 at 1year postfire in 50 separate wildfires occurring in Sweden during 2018. These increases could not be linked to proposed drivers, however BC storage in 50 additional nearby unburnt soils related strongly to soil mass while its proportion of the larger C pool related negatively to soil C:N. Fire approximately doubled BC stocks in the mineral layer but had no significant effect on BC in the organic layer where it was likely produced. Suppressed decomposition rates and low heating during fire in mineral subsoil relative to upper layers suggests potential removals of the doubled mineral layer BC are more likely transported out of the soil system than degraded in situ. Therefore, mineral soils are suggested to be an important storage pool for BC that can buffer short-term (production in fire) and long-term (cross-ecosystem transport) BC cycling.

Balancing wood production and biodiversity in intensively managed boreal forest

ABSTRACT Fennoscandian boreal forests are managed intensively for wood production, which has had a negative impact on biodiversity. The harvesting pressure on the forests is likely to increase in the future because wood is seen as an important resource in a bio-based economy. Thus, there is an urgent need to better describe the trade-offs between wood production and biodiversity, and to understand how these trade-offs can be alleviated by adapting forest management. Encompassing a broad range of biodiversity aspects, we studied how forest management can increase biodiversity indicators while maintaining or increasing current harvest levels. We found that there is considerable leeway for forestry to pursue multiple objectives simultaneously in Fennoscandian forest landscapes. We show that it is possible to both increase harvests and structural elements of importance for biodiversity compared to present levels in a forest landscape that is representative of conditions in boreal forests in northern Sweden. Achieving this requires a variation in management strategies at the landscape level, and an adaptation of management practices to explicitly consider and implement multiple objectives in the planning process.

Micro-site conditions affect Fennoscandian forest growth

The long tradition of dendroclimatological studies in Fennoscandia is fostered by the exceptional longevity and temperature sensitivity of tree growth, as well as the existence of well-preserved subfossil wood in shallow lakes and extent peat bogs. Although some of the world’s longest ring width and density-based climate reconstructions have been developed in northern Fennoscandia, it is still unclear if differences in micro-site ecology matter, and if so, whether they have been considered sufficiently in previous studies. We developed a Fennoscandia-wide network of 44 Scots pine ring width chronologies from 22 locations between 59°–70 °N and 16°–31 °E, to assess the effects of moist lakeshores and dry inland micro-sites on tree growth. Our network reveals a strong dependency of pine growth on July temperature, which is also reflected in latitude. Differences in forest productivity between moist and dry micro-sites are likely caused by associated effects on soil temperature. While trees at moist micro-sites at western locations exhibit higher growth rates, this pattern is reversed in the continental eastern part of the network, where increased ring widths are found at drier sites. In addition to the latitudinal increase in growth sensitivity to July temperature, pines at moist sites exhibit an increased dependency of summer warmth. The highest temperature sensitivity and growth coherency, and thus greatest suitability for summer temperature reconstructions, is found in those regions where July mean temperatures range between 11.5 and 13.5 °C, and May precipitation totals do not exceed 100 mm. Our study not only provides guidance for the selection of sampling sites for tree ring-based climate reconstructions, but also reveals the effect of micro-site ecology on Fennoscandian forest growth. The manifestation of micro-site effects varies substantially over the Fennoscandian boreal forest and is predominately triggered by the geographical setting of the stand as expressed by differing abiotic site factors.

Pervasive moose browsing in boreal forests alters successional trajectories by severely suppressing keystone species

AbstractLarge herbivores can shape young forest stands and determine the successional trajectory of forested ecosystems by selectively browsing palatable species at the sapling stage. Moose (Alces alces) is the dominant vertebrate herbivore in Fennoscandian boreal forests, and high population densities have raised concerns about potential negative effects on ecosystem functioning and properties including biological diversity and timber production. We used 31 herbivore exclosures in Norway to investigate how forests developed after clear‐cutting with or without moose present. We tested how tree demography, abundances of understory plant functional groups, community composition, and plant diversity (including bryophytes) across multiple scales varied with moose exclusion. After seven years, the exclosures were dominated by deciduous trees, including many large rowan (Sorbus aucuparia) individuals, a functionally important keystone species. In contrast, the open plots subject to moose impacts (browsing, trampling, defecation) were dominated by economically important coniferous trees and there was next to no rowan recruitment to taller height classes. The biomass of large herbs and ferns was much greater inside exclosures. This study emphasizes the large immediate effect of moose on early successional boreal forest stands. Landscape‐level alterations caused by reduced deciduous dominance, and a reduction in large flowering herbs is likely to lead to cascading effects on ecosystem functioning. The management of boreal production forests needs to account for the combined effects of silvicultural practices and ungulate herbivory to ensure ecosystem functioning, but this management goal may be jeopardized in our study regions due to drastically reduced abundance of keystone species.

Soil bacteria and archaea change rapidly in the first century of Fennoscandian boreal forest development

Using a gradient of changing ground age, caused by glacial isostatic adjustment, we compared systems that spanned ages from 25 to 560-years-old. Illumina sequencing was applied to determine archaeal and bacterial composition, investigating how different phylogenetic groups change as ecosystems develop. Bacterial communities dramatically changed during early ecosystem development (p < 0.001), evidenced by significant compositional shifts between 25 and 115 year-old-soils. Although significant differences did occur in the three later aged sites, they did not change as much. This was consistent with vegetation that shifted from meadow (25 year) to alder dominated forest (115 year), to ecosystems containing spruce. Correlation networks revealed that the microbial communities became more interconnected in older age ecosystems with a two-fold increase in network density. Species richness had the opposite trend with a decreased number of species: 781 operational taxonomic units (OTUs) in the youngest ecosystem to 366 OTUs in the oldest ecosystem. The observed shifts in community composition are consistent with other reported ecosystem gradients, but here we show that not only does composition change, but as ecosystems age the network connectivity increases indicating potentially more social interactions among microbes or increasingly stringent plant-microbe-soil interactions.

Fire history in a western Fennoscandian boreal forest as influenced by human land use and climate

AbstractKnowing the historical variation in fire regimes is instrumental in managing forests today and in predicting what may happen in the future. By cross‐dating 745 fire scars in 378 samples of remnant Scots pines, we delineated 254 individual forest fires during the past 700 years in a 74‐km2 section of Trillemarka‐Rollagsfjell Nature Reserve in south‐central Norway. Fire sizes, numbers, burn rates, and frequencies were compared with historical climate proxies, vegetation maps, and written sources. The results revealed patterns consistent with a predominantly climate‐driven fire regime up to 1625, followed by periods of strong anthropogenic influence that increased fire frequency during 1600–1700s and diminished fires during 1800–1900s. This was documented by an abrupt increase in number of small fires from the early 1600s that markedly shortened fire intervals from a median of 73 to 37 yr. This shift in fire frequency coincided with a sudden appearance of early‐season fires from 1625 and onward. Whereas late‐season burn rate increased with summer temperature, no such relationship was found for early‐season fires. These results were corroborated by written sources that describe anthropogenic forest fires and slash‐and‐burn cultivation expanding with the increasing population from the late 1500s and subsequently diminishing due to increasing timber values during 1700–1800s. Whereas human activity strongly influenced the fire regime at multidecadal to centennial scales, it was the interannual variability in climate that triggered large fire events, especially during the pre‐1625 period. Prior to 1625, the percentage of years with fire tripled from 7% during cold summers (10–12°C) to 21% during warm summers (14–16°C). Burn rate increased even more, from 0.01% to 1.3% for the same temperature intervals. Ecologically, the post‐1625 period is remarkable in such a way that human activity, first by greatly increasing fire frequency and subsequently almost eradicating fires, possibly influenced the fire regime to such an extent that it may be unprecedented for millennia.

Prescribed burning is an effective and quick method to conserve rare pyrophilous forest‐dwelling flat bugs

Abstract Fire suppression and reduced volumes of dead wood have led to a major decline in pyrophilous and saproxylic insects in Fennoscandian boreal forests. As a consequence, several species are currently seriously threatened. Flat bugs (Heteroptera, Aradidae) is an important invertebrate group that includes several pyrophilous species, including many threatened ones. We explored whether specific conservation measures – prescribed burning and retention forestry – can facilitate the survival of flat bugs in managed forests. The large‐scale field experiment consisted of a burning treatment (yes/no) and four levels of logging intensity (clear‐cut, retention levels of 10 and 50 m3 ha−1, and unharvested controls). The data included 1224 individuals of 12 species, sampled over a 4‐year period. Burning increased the species richness and abundance of the pyrophilous species. Two Red‐Listed and very rare pyrophilous species, Aradus angularis J. Sahlberg (Vulnerable) and A. laeviusculus Reuter (Near Threatened), were abundant after burning. The number of non‐pyrophilous flat bugs collapsed after burning but they re‐colonised the stands quickly, becoming as abundant as at the unburned stands. Logging increased the abundance of flat bugs only when retention forestry was applied. This study shows that pyrophilous flat bugs are quickly able to locate recently burned forests and that these forests are important for their survival. The effect of fire is, however, transient at the stand level and pyrophilous species disappear almost completely quickly after fire. To maintain these species, recently burned forests with a sufficient volume of retention trees should be available continuously at the landscape level.

Impacts of natural enemies and stand characteristics on cocoon mortality of the pine sawfly &lt;i&gt;Diprion pini&lt;/i&gt; in a Fennoscandian boreal forest

We investigated the impact of natural enemies on the cocoon mortality of the common pine sawfly ( L.) during a six-year period in eastern Finland. The enemies were classified into parasitoids (insect families Chalcidoidea, Ichneumonidae, and Tachinidae), and predators (birds, small mammals, and insect families Elateridae and Carabidae). The appearance of was estimated as the intensity of annual defoliation. The impact of stand characteristics on the performance of parasitoids and predators was also investigated. Influence of the natural enemy complex on cocoon mortality of was nearly stable, butdefoliation intensity slowly declined towards the end of the study period. Annual cocoon mortality by natural enemies varied between 66% and 80%. Our results verified that the most significant mortality factors were ichneumonid parasitoids and small mammals. Random Forest classification indicated that stand characteristics, such as basal area, and coverage of lichen ( and lingonberry ( L.) affected the performance of parasites and predators. We suggest that a combination of optimal stand characteristics, abiotic environmental factors and mild to moderate control by natural enemies acted as drivers, which drove the pine sawfly population to extended gradation. For future forest health management, detailed information on abiotic and biotic regulating factors, along with long-term monitoring campaigns for conifer sawflies are needed to adapt Fennoscandian forests to altered climatic and silvicultural conditions.Diprion piniD. piniD. pini Lichenes)Vaccinium vitis-idaea

Weak response of bryophyte assemblages to second commercial thinning in boreal spruce forest of south-central Sweden

Forest management regimes dictate the composition and structure of large parts of the Fennoscandian boreal forest region. The understanding of thinning impacts on understorey plant communities is considerably lower compared to the effects of final felling. We studied the response of bryophyte assemblages to second commercial thinning in spruce-dominated stands sampled to be representative of the dominant forest type of south-central Sweden. Eighteen stands were analysed 6–12 years after second commercial thinning, and were compared with six stands commercially thinned only once, at two spatial scales (0.1 and 0.01 ha), with stand ages varying between 52 and 66 years. We found few strong differences in bryophyte species richness and no differences in bryophyte species composition between stands thinned once or twice. More pioneer species were found in stands thinned only once, a result that needs further study. Species richness declined significantly with time since thinning on both investigated spatial scales. Canopy cover significantly affected the composition of forest floor species. Thinning effects over longer time periods need further study, and also effects in different forest types along productivity gradients. For nature conservation, studies targeted towards thinning response of uncommon species connected to specific habitats and substrates will be essential.

Stand management optimization – the role of simplifications

BackgroundStudies on optimal stand management often make simplifications or restrict the choice of treatments. Examples of simplifications are neglecting natural regeneration that appears on a plantation site, omitting advance regeneration in simulations, or restricting thinning treatments to low thinning (thinning from below).MethodsThis study analyzed the impacts of simplifications on the optimization results for Fennoscandian boreal forests. Management of pine and spruce plantations was optimized by gradually reducing the number of simplifying assumptions.ResultsForced low thinning, cleaning the plantation from the natural regeneration of mixed species and ignoring advance regeneration all had a major impact on optimization results. High thinning (thinning from above) resulted in higher NPV and longer rotation length than thinning from below. It was profitable to leave a mixed stand in the tending treatment of young plantation. When advance regeneration was taken into account, it was profitable to increase the number of thinnings and postpone final felling. In the optimal management, both pine and spruce plantation was gradually converted into uneven-aged mixture of spruce and birch.ConclusionsThe results suggest that, with the current management costs and timber price level, it may be profitable to switch to continuous cover management on medium growing sites of Fennoscandian boreal forests.

Strong anthropogenic signals in historic forest fire regime: a detailed spatiotemporal case study from south-central Norway

To better understand the historic range of variability in the fire regime of Fennoscandian boreal forests we cross-dated 736 fire scars of remnant Scots pine (Pinus sylvestris L.) wood samples in a 3.6 km2 section of the Trillemarka-Rollagsfjell Reserve of south-central Norway. Using a kernel range application in GIS we spatially delineated 57 individual forest fires between 1350 and the present. We found a strong anthropogenic signal in the fire regime from 1600 and onwards: (i) infrequent variably sized fires prior to 1600 shifted to frequent fires gradually decreasing in size during the 1600s and 1700s, with only a few small fires after 1800; (ii) time intervals between fires and the hazard of burning showed substantial differences pre- and post-1600; (iii) fire seasonality changed from late- to early-season fires from the 1626 fire and onwards; and (iv) fire severity decreased gradually over time. Written sources corroborated our results, narrating a history where anthropogenic forest fires and slash-and-burn cultivation expanded with the increasing population from the late 1500s. Concurrently, timber resources increased in value, gradually forcing slash-and-burn cultivators to abandon fires on forest land. Our results strengthen and expand previous Fennoscandian findings on the anthropogenic influence of historic fire regimes.

Age and growth patterns of old Norway spruce trees in Trillemarka forest, Norway

Old trees represent key features of old-growth forests and are important elements for maintaining biodiversity. Due to extensive human exploitation of Fennoscandian boreal forests during several centuries, old Norway spruce trees have become exceedingly rare. We analysed 91 spruce trees in Trillemarka Nature Reserve, southern Norway, to investigate (1) the maximum age of living trees, (2) growth rates of different-age trees and (3) growth trends in very old trees. Increment cores were taken from trees in selected old-growth stands located at 700–850 m a.s.l. Twelve spruce trees had an estimated total age of >400 years, the oldest one being 529 years and presumably the oldest known still living Norway spruce in northern Europe. A negative relationship between growth rate (basal area increment) and total age was observed, being most distinct for growth rates at 126–275 years and less marked for early stage growth (26–75 years). Thus, high age apparently was related more to low growth rates at adult and old stages of life rather than at the earlier stage. Among the trees >400 years, many of them did not show growth decrease with advancing age, indicating that ageing did not reduce growth. We conclude that the maximum age of stand-forming Fennoscandian Norway spruce trees would be in the range of 500–600 years.

Guild composition and habitat use of voles in 2 forest landscapes in south‐eastern Norway

It is widely believed that intensive forestry has influenced small mammal population dynamics, and thereby the entire mammalian community in Fennoscandian boreal forests. The nature of these impacts on the different species is subject to debate. We live-trapped voles between 2006 and 2009 in 2 commercially harvested forests in south-eastern Norway. We investigated the variation in vole abundance among habitat types (e.g. mature forest and clear-cut) and the hypothesis that graminivorous species such as field voles (Microtus agrestis L.) benefit from clear-cuts at the expense of forest dwellers (i.e. the bank vole, Myodes glareolus Schreb.), using fine-scale descriptors of the ground vegetation. We could not find support for the hypothesis that field voles show a preference for clear-cuts, and their overall abundance was low, while bank voles were the dominant species in all habitat types, including clear-cuts in the peak and pre-peak years. We found a positive association between bank vole abundance and bilberry (Vaccinium myrtillus L.) availability rather than a specific habitat type. Low field vole density in clear-cuts might be due to variation in local productivity and ground vegetation as well as to large variation in the species temporal dynamics. The latter is particularly associated with the widespread decline of field voles in Scandinavia. Logging has the potential to negatively affect bank vole population dynamics because of the negative effect on bilberry development.

Estimation of nutrient removals in stem-only and whole-tree harvesting of Scots pine, Norway spruce, and birch stands with generalized nutrient equations

Whole-tree harvesting (WTH), where logging residues are removed in addition to stems, is widely practised in Fennoscandian boreal forests. WTH increases the export of nutrients from forest ecosystems. The extent of nutrient removals may depend on tree species, harvesting method, and the intensity of harvesting. We developed generalized nutrient equations for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies Karsten), and birch (Betula pendula Roth and Betula pubescens Ehrh.) stands to be able to calculate the amounts of nitrogen, phosphorus, potassium, and calcium in stems and above-ground biomass (stem and crown) as a function of stand volume. The equations were based on Fennoscandian literature data from 34 pine, 26 spruce, and 5 birch stands, and they explained, depending on the tree species and nutrient, 61–99% and 56–87% of the variation in the nutrient amounts of stems and above-ground biomass, respectively. The calculations based on the equations showed that nutrient removals caused by stem-only harvesting (SOH) and WTH per harvested stem m3 were smaller in pine than in spruce and birch stands. If the same volume of stem is harvested, nutrient removals are, in general, nearly equal at thinnings and final cuttings in SOH, but larger in thinnings than final cuttings in WTH. If the principal aim is to minimize the nutrient removals per harvested stem m3, the harvesting should be done at mature pine stands. The effect of biomass removal on overall site nutrient status depends on site-specific factors such as atmospheric deposition, weathering of minerals, and the size of the nutrient pools in the soil.

The response of land snail assemblages below aspens to forest fire and clear-cutting in Fennoscandian boreal forests

Species can persist in a landscape with recurrent disturbances either through local survival or by dispersing to sites of a preferred successional stage. This study investigated in what extent forest floor dwelling land snails survived forest fires and clear-cutting. Snail fauna in LFH (litter, fermenting litter and humus) samples below retained aspen trees in disturbed areas were compared with samples under scattered aspens in adjacent forests by extracting snails from LFH samples below five aspens in several stands of each type (five forest fires, six clear-cuts, and seven undisturbed forests). LFH samples from burnt sites had a higher pH than from forests, but on average a lower abundance of individual snails (11 vs. 30 in 0.5 l LFH) and 50% lower species density (3 vs. 6 species). The abundances and species densities in the clear-cuts were less affected. There was generally a positive relationship between pH and both species density and abundance in all the stand types. Burning apparently depleted the snail fauna considerably and some species may be dependent on dispersal if they are to recover within the burnt area, while the snail assemblages at clear-cuts did not differ significantly in species composition from adjacent forests. The positive relationship between pH and snail prevalence on the burnt sites raises questions regarding the pre- and post-fire spatial variation in pH (and available minerals) within and among stands and how it relates to snail survival rates and their capacity to track suitable places after the disturbance. Retained aspens at clear-cuts seem to harbour a forest like land snail fauna.

Speciation of Organic Phosphorus in P-Immobilizing Soils: A 31P NMR Study

Phosphorus (P) is globally a crucial nutrient and in many agricultural areas the limiting factor for plant growth. Over the past 30 years several studies have been made in order to completely understand the fate and cycle of P, but knowledge is still limited, especially in the area of overall speciation and the sorption processes and mechanisms of organic P in soils Here,solution 31P NMR and solid state 31P NMR were used on humus soils to describe the P composition in soils along two productivity gradients in a Fennoscandian boreal forest who simultaneously display sorption gradients due to differences in Al and Fe levels. Phosphorus composition changed significantly along the gradients. The abundance of phosphate diesters, their degradation products and polyphosphates are more abundant in low Al and Fe sites. Phosphate mono esters, like inositole phosphate has a more pronounced presence in high Al and Fe sites. It would seem that in low Al and Fe sites the difference in speciation of organic P more closely mirrors the input of P whereas the high Al and Fe sites shows the composition of P possibly being more governed by sorption affinity.Our sampling sites include the wide range of soil properties expected to be found in boreal Fennoscandian soils and therefore provide an important view on the biogeochemistry and especially the organic P governing factors for this region.

Linking forest history and conservation efforts: Long-term impact of low-intensity timber harvest on forest structure and wood-inhabiting fungi in northern Sweden

Throughout the northern hemisphere old forests with high abundance of dead wood are rare features in most landscapes today, and the loss of dead wood constitutes a serious threat to the existence of many species. This study, using field surveys and dendrochronology, examines the relationship between wood-inhabiting fungi and past forest utilisation along a gradient of early logging activity. Data were collected in three late-successional Scots pine forests in northern Sweden. Nonmetric Multidimensional Scaling (NMS) was then used to assess differences in species composition among the forests. Our results show that minor forest logging (22–26 cut stumps ha −1) carried out a century ago may have continuing effects on forest characteristics, including dead wood dynamics and the wood-inhabiting fungal community – especially the abundance of red-listed species. The most important effects are lower numbers of logs in early and intermediate stages of decomposition. Additionally, numbers of species (including red-listed species) can be high in forests that have been subject to low levels of logging. Overall, the high species numbers recorded in this study ( n = 60–87) show that old, low-productivity pine forests harbour a considerable fraction of the total diversity of Basidiomycetes in northern Fennoscandian boreal forests. We conclude that the formation of a framework linking forest history and environmental data is vital for understanding the ecology and formulating goals for future management of these forests.