•On windthrown trees, more fruit bodies develop on stems compared to roots.•Uplifted roots favor the formation of fruit bodies on spruce stumps.•H. annosum produces fruit bodies on decayed spruce as ...frequently as H. parviporum.•Abundant fruit body formation occurs on drained peat soil.
Because intensive forestry favors the spread of Heterobasidion spp., increasing amounts of decayed Norway spruce (Picea abies) wood in forest stands should be taken into account in the management of commercial forests. Spruce wood colonized by Heterobasidion spp. ensures fruit body formation, which increases the risk of new infections by basidiospores and, subsequently, the spread of Heterobasidion root rot. To date, very little is known about the prevalence of Heterobasidion fruit bodies on decayed spruce wood in different environments. To assess Heterobasidion fruit body production on various soil types and on different parts of trees, more than 36,000 fruit bodies on 425 decayed logs, 321 decayed trees, and 262 stumps of Norway spruce located on mineral and peat soils were surveyed. The most abundant fruit body formation occurred on infected spruce logs left on peat soil. Significantly more fruit bodies (average total fruit body area cm2 m−3) were found on logs on drained peat soil compared to drained mineral soil (4960 and 2674 cm2, respectively). On stems of windthrown, uprooted trees, approximately three times more actively sporulating fruit bodies were formed compared to roots. Further, approximately two times more Heterobasidion fruit bodies occurred on the roots of partly uplifted stumps than on stumps with roots remaining in the soil. H. parviporum was identified in 88% and H. annosum in 12% of analyzed spruce individuals. In cases where the tree was infected by H. annosum s.s., fruit bodies of this fungus were also commonly produced on spruce wood. Abundant development of fruit bodies was also observed in abandoned agricultural and pasture lands. Moreover, rich vegetation in fertile forest types favored fruit body development on both mineral and peat soils. On such sites, infected logs and windthrown trees, as well as partly uplifted spruce stumps, should be removed to limit the spread of Heterobasidion spp. by basidiospores.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•We investigated stand and tree features on spruce response to climate.•Age, competition, disturbance, elevation interact to modify growth–climate response.•Tree growth was mainly temperature-driven ...but water availability was also important.•Old trees and low-elevation dense stands are vulnerable to drought.
Stands and trees may exhibit different climate–growth responses compared to neighbouring forests and individuals. The study of these differences is crucial to understanding the effects of climate change on the growth and vulnerability of forests and trees. In this research we analyse the growth responsiveness of primary Norway spruce forests to climate as a function of different stand (elevation, aspect, slope, crowding, historic disturbance regime) and tree (age, tree-to-tree competition) features in the Romanian Carpathians. Climate–growth relationships were analysed using Pearson correlation coefficients between ring-width indices (RWIs) and climate variables. The influence of stand and tree characteristics on the RWI responses to climate were investigated using linear mixed-effects models. Elevation greatly modulated the climate–growth associations and it frequently interacted with competition intensity or tree age to differentially influence growth responsiveness to climate. Old trees were more sensitive to climate than young trees, but while old tree’s response to climate highly depended on elevation (e.g. positive influence of summer temperature on old trees’ RWIs at high elevations, but negative effect at low elevations), differences of the young trees’ response across the elevation gradient were less evident. The severity of the past disturbance also modified the climate–growth associations because of contrasting canopy structures. Our results suggest that although an increase in temperature might enhance growth at high elevations, it may also induce growth declines due to drought stress at lower elevations, particularly for old trees or trees growing under high levels of competition, which may increase their vulnerability to disturbances.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Over time, stand density reduction in Norway spruce (Picea abies (L.) Karst.) (a) reduces total yield degressively and increases dominat diameter propressively, (b) reduces total yield less through ...thinning from above than through thinning from below, (c) reduces total yield more severely on rich compared to poor sites (SI 45 vs. SI 25), (d) accelerates dominant diameter more on rich compared to poor sites (stand age always 100 y, SI 40 in (a) and (b)).
Display omitted
•Maximum yield in unthinned stands and only short-term growth acceleration by thinning.•Strongest size growth acceleration but total yield losses on rich sites.•Strongest total yield losses by thinning from below.
Many current stand management guidelines propose low initial stand densities and strong density reductions in order to lower the costs of stand establishment, to accelerate stand growth and promote the diameter growth of selected future crop trees. The long-term effects of density reductions on growth and yield, however, are often neglected; they remain open for debate due to a lack of empirical evidence.
Here we examine 22 thinning experiments in Norway spruce (Picea abies (L.) Karst.) located in Germany with 127 plots and 1209 full stand measurements to revisit the density-growth relationship. These experiments cover both short- and long-term growth reactions to thinning since their establishment in 1882.
First, we show the temporarily unimodal optimum relationship between periodical increment and stand density; and how it results in a saturation curve between stand yield and stand density in the long term. We particularly highlight how the effect of stand density reductions on growth reduces across stand development. Second, we show the dependency of total yield on the thinning (kind, severity and intensity of thinning) and site quality. Over time, unthinned stands achieve the highest total yield of stem wood. Thinning causes severe growth losses, especially on rich sites and through thinning from below; e.g. on top sites a continuous density reduction by thinning from below to 50% of the maximum density reduced the total yield by 26% or 670 m3 ha−1 till the age of 100 years.
Third, we demonstrate that the effect of thinning on the diameter of dominant trees is strongest on rich sites and similar when thinned from above or below. Over time, accelerating diameter growth incurs a high cost in terms of stand yield.
Finally, we examine the relevance of our results to population ecology and production economy. We discuss the superior yield after thinning from above, the tradeoff between tree diameter growth acceleration and yield, and the relevance of long-term experiments and their impact on silvicultural prescriptions.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Increasing soil N availability is an effective way to enhance soil organic carbon (SOC) sequestration and biomass production in N-limited ecosystems such as boreal Norway spruce forests. Alder has a ...root nodule symbiosis with Frankia, an N2-fixing bacterium, and can thus add considerable amounts of N to soil mainly through its N-rich leaf litter. The objective of this study was to determine whether the presence of grey alder at the regeneration stage had any long-term effects on soil C and N cycling and stocks and spruce growth. The study sites were two relatively fertile 40-year-old Norway spruce stands (Luhdansuo and Porkkola) in Southern Finland. At both study sites, half the spruce stand had an admixture of grey alders for approximately 10–15 years after regeneration (alder treatment), but no alder had been present in the other half (control treatment). Alders were cut from the alder treatment 25 (Luhdansuo) or 30 (Porkkola) years before the measurements. At Porkkola, alder treatment received ash fertilisation 13 years ago. We observed no significant differences in the plant-available N fluxes, measured with a microdialysis technique, or SOC stocks between treatments. The total N stock (organic horizon + 0–30 cm mineral soil) and organic horizon thickness were larger, while the microbial biomass C:N and C mineralisation rate were lower in the alder versus the control treatment at Luhdansuo. The annual ring widths of spruces were larger in the alder versus the control treatment for up to six years after alder removal at both sites, but no differences were observed in the current tree diameters or diameter increments. In conclusion, most of the current soil or tree properties did not differ significantly between treatments, possibly because the effect of alder had faded out over the 25–30 years since its removal, and because the sites were initially relatively fertile.
•We studied the effects of alder on soil properties 25-30 years after its removal.•The past presence of grey alder increased soil N stock of a Norway spruce stand.•Alder had increased the organic horizon thickness in one of our study sites.•Soil organic C stock was not significantly affected by the past presence of alder.•Alder caused an increase in spruce ring widths, lasting for six years.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Interactions between Norway spruce trees and bacteria and fungi in nutrient limited boreal forests can be beneficial for tree growth and fitness. Tree-level effects of anthropogenic nutrient addition ...have been well studied, however understanding of the long-term effects on the associated microbiota is limited. Here, we report on the sensitivity of microbial community composition to the growing season and nutrient additions. High-throughput sequencing of the bacterial 16S rRNA gene and fungal ITS1 region was used to characterise changes in the microbial community after application of a complete mineral nutrient mixture for five and 25 years. The experiment was conducted using the Flakaliden forest research site in northern boreal Sweden and included naturally low nutrient control plots. Needle and fine root samples of Norway spruce were sampled in addition to bulk soil during one growing season to provide comprehensive insight into phyllosphere and belowground microbiota community changes. The phyllosphere microbiota was compositionally distinct from the belowground communities and phyllosphere diversity increased significantly over the growing season but was not influenced by the improved nutrient status of the trees. In both root and soil samples, alpha diversity of fungal, in particular ectomycorrhizal fungi (EMF), and bacterial communities increased after long-term nutrient optimisation, and with increasing years of treatment the composition of the fungal and bacterial communities changed toward a community with a higher relative abundance of nitrophilic EMF and bacterial species but did not cause complete loss of nitrophobic species from the ecosystem. From this, we conclude that 25 years of continuous nutrient addition to a boreal spruce stand increased phylotype richness and diversity of the microbiota in the soil, and at the root-soil interface, suggesting that long-term anthropogenic nutrient inputs can have positive effects on belowground biodiversity that may enhance ecosystem robustness. Future studies are needed to assess the impact of these changes to the microbiota on ecosystem carbon storage and nitrogen cycling in boreal forests.
•Long-term nutrient addition increases belowground biodiversity in boreal forest soils.•Increasing soil nutrition leads to higher diversity in ectomycorrhizal communities.•Copiotrophic taxa are favoured by long-term nutrient addition.•Phyllosphere microbiota are responsive to season and not to soil nutrient status.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Display omitted
•Patterns of tree mortality differed among individual phases of beetle outbreak.•Dispersal distances decreased with increasing outbreak intensity.•Beetle infestations reached upper ...tree line in the Tatra Mts.•Distance to infestation source well predicts following year’s infestations.•Type of infestation source affects spatial distribution of new infestations.
The European spruce bark beetle (Ips typographus) causes widespread Norway spruce (Picea abies) mortality in European forests. The pattern of landscape-level tree mortality varies over the course of beetle outbreak and by the presence and location of active breeding sites. Increased understanding of rules governing the unmanaged spread of beetle-induced tree mortality over the landscape would help to optimise management control strategies on the borderline between highly valuable protected areas and surrounding managed forests.
Our study aimed to quantify the dynamics of standing tree infestation patterns from two infestation sources: windthrow and previous-year beetle infestations. Specifically, we (i) evaluated dispersal distances between the nearest infestation source and new infestations, (ii) quantified size and shape of infestation spots, (iii) modelled an infestation gradient and (iv) probability of new infestation during the incipient, peak and decline phases of beetle outbreak. Based on one- and two-year records of colour-infrared aerial photography, taken between 2005 and 2015, we identified windthrown and beetle-killed trees in the non-intervention zone of Tatra National Park, Slovakia (Central Europe).
The size and compactness of infestation spots evolved from small and simple to more extended and complex shapes during beetle epidemics. In total, 40% of infestations were smaller than 100 m2 and 79% smaller than 500 m2. Spot growth dominated over spot initiation, with the mean spot growth extent during peak epidemic (54.8 m). Beetle infestations reached the upper tree line (1605 m a.s.l.). In total, 71% of new infestations emerged within 100 m and 97% within 500 m from an infestations source. Emergence of new infestations varied between infestation sources and phases of beetle outbreak. New beetle infestations emerged near windthrown locations during incipient and peak phases and near source beetle infestations during peak and decline phases following inverse power-law function. We found that the forest within 100 m from the active infestation compared to more distant buffers had the highest risk of infestations. The distance to previous-year infestations should be considered as one of the main factors in determining the risk of subsequent tree mortality, especially if other predictors are absent. If the active wind disturbances or beetle infestations neighbour the border of the unmanaged protected area, the search and sanitation felling of active breeding trees should be concentrated within 500 m from the border of unmanaged protected areas in order to restrain the spread of beetle infestations from nature reserve to surrounding managed forests.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
•Although tree stem growth is ubiquitous with huge ecological implications, it is poorly understood.•Quantification of diel patterns in both water and carbon relations is critical for a complete ...understanding.•Anatomy and ecophysiology should be combined in new experiments and models to build an integrated theory.•An integrated theory is much needed to understand and predict trends in stem growth as impacted by climate.
Impacts of climate on stem growth in trees are studied in anatomical, ecophysiological, and ecological disciplines, but an integrative framework to assess those impacts remains lacking. In this opinion article, we argue that three research efforts are required to provide that integration. First, we need to identify the missing links in diel patterns in stem diameter and stem growth and relate those patterns to the underlying mechanisms that control water and carbon balance. Second, we should focus on the understudied mechanisms responsible for seasonal impacts on such diel patterns. Third, information on stem anatomy and ecophysiology should be integrated in the same experiments and mechanistic plant growth models to capture both diel and seasonal scales.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Average annual litter flux was similar for studied pine, spruce and birch stands.•Both stand age and site quality index were significant factors affecting the annual litter flux.•No significant ...relationship was established between stand basal area and litter flux.•For all tree species, the relative proportion of needles or leaves from in total annual litter flux declined with stand age.•The effect of weather conditions on the annual litter flux was revealed in continuously studied stands.
Canopy litterfall represents an essential aboveground flux in every forest ecosystem, affecting soil carbon and nutrient dynamics as well as soil fertility. However, despite the important role of the canopy litter flux in ecosysteḿs functioning and carbon sequestration, litterfall dynamics is still poorly studied in hemiboreal forests. The main aim of the current study was to estimate average annual litter fluxes in Scots pine, Norway spruce and birch (Betula pendula and Betula pubescens) stands, as well as to compile regional litter models for estimating the annual litter flux. The annual litter flux from a total of 33 pine, 15 spruce and 21 birch stands, with 85, 43 and 53 datapoints, respectively, was included in the study.
Although the annual litter flux depended on site quality index and stand age, no significant relationship was established between stand basal area and litter flux. Average annual canopy litterfall was similar for the studied tree species, being 3.24 ± 0.14 for pine, 3.62 ± 0.16 for spruce and 3.22 ± 0.07 t ha−1 yr−1 for birch across the stands of different ages. For all studied tree species, the relative proportion of needles or leaves in the total annual litter flux declined with stand age, due to the increased share of twigs and other fractions in the litter of older stands. The developed models of the litter flux allow to estimate the annual litter production of the canopy for the studied tree species on the basis of site quality index and stand age.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•We analyzed chronosequences of Picea abies and Fagus sylvatica stands.•We found small differences in biomass allocation, production and carbon content.•This increases the transferability of models ...used in carbon inventories.•We provided tree- and stand-level models for biomass and carbon mass estimates.
Despite different levels of complexity among biomass models, it is unclear how much patterns of biomass production and allocation differ between mountain and lowland forests, and how much neglecting this difference biases carbon pool estimations. To address this question, we studied chronosequences of 24 Fagus sylvatica and 24 Picea abies stands in Poland, located both in lowlands and highlands (12 stands of each species per category). We cut and weighted 192 sample trees, and we measured carbon content in wood, bark, branches and leaves. We also developed allometric tree- and stand-level models of biomass and carbon mass. Using log-transformed linear models we checked the effect sizes of elevation category (lowland and highland) on estimate output. We found small, statistically insignificant differences in biomass allocation patterns, carbon content and allometric trajectories in trees between lowland and highland stands. Tree-level allometric models without elevation category had higher accuracy than models including elevation category and explained 96.8–99.8% of biomass variability. Biomass and carbon stock of species studied was positively correlated with stand volume, age, basal area and height, and negatively with stand density. However, the differences between lowlands and highlands were low and did not exceed 38 Mg ha−1 (for P. abies foliage biomass, with model root mean squared error of 37.638 Mg ha−1). Our results revealed transferability of models developed using lowland and highland populations of the studied species. This will increase confidence in methods used to estimate carbon pools.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
PDF
