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In young Norway spruce (Picea abies (L.) Karst.) stands containing an even-aged component of self-propagated birches (Betula pendula Roth and B. pubescens Ehrh.) the forest manager has the choice of removing all broad-leaved trees or of accepting a mixed stand of Norway spruce under a birch shelter. Results of stand growth simulations show that the total stand yield will be higher if the broad-leaved trees are retained. The spatial distribution pattern of trees had little influence on the outcome of the growth simulation. The simulations also showed that spruce yields will be similar, regardless of whether the spruce is grown in pure stands or is grown under a birch shelter (either 600 birches ha-', all removed at age 25, or 1 200 birches ha-', removed in two steps at age 20 and 30). The simulations showed that the highest total yield was obtained when a shelter of 2 000 birches ha-' was left after the pre-commercial thinning, then thinned at a e 20 and finally all birch was removed at age 30. The birch shelter can produce ca. 100 mf ha-' in middle Sweden if it is composed of B. pendula. The corresponding yield for a shelter of B. pubescens will be 80 m3 ha-' or less. Although height growth of the spruce will be suppressed by the birch shelter, the growth rate will increase once the shelter has been removed. Estimates of biomass production were made for both Norway spruce and birch. Mean annual dry matter production increases from 1.4 tonne ha-' yr-P with a shelter of 600 birches, to 2.4 tonne ha-' yr-' for 3 000 birches. All yield estimates refer to age 20. The harvesting cost, based on manual felling and tractor extraction, was estimated at ca. 40 SEK/MWh (200 SEK/ton dry matter). By comparison, a commercially harvested Salix plantation costs about 24 SEK/MWh. However, the cost of establishing and maintaining a Salix plantation is ca. 35 SEK/MWh, while no such costs are incurred in the production of fuelwood under the birch shelterwood system.

During 2010-2013, we investigated the effects of stump harvesting on greenhouse gas (GHG) fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) with the flux-gradient technique at four experimental plots in a hemiboreal forest in Sweden. All plots were clear-cut and soil scarified and two of the plots were additionally stump harvested. The two clear-cut plots served as control plots. Due to differences in topography, we had one wetter and one drier plot of each treatment. All plots exhibited substantial emissions of GHGs and we noted significant effects of wetness on CO2, CH4 and N2O fluxes within treatments and significant effects of stump harvesting on CO2 and N2O fluxes at the dry plots. The CO2 emissions were lower at the dry stump harvested plot than at the dry control, but when estimated emissions from the removed stumps were added, total CO2 emissions were higher at the stump harvested plot, indicating a small enhancement of soil respiration. In addition, we noted significant emissions of N2O at this plot. At the wet plots, CO2 emissions were higher at the stump harvested plot, also suggesting a treatment effect but differences in wetness and vegetation cover at these plots make this effect more uncertain. At the wet plots, we noted sustained periods (weeks to months) of net N2O uptake. During the year with simultaneous measurements of the abovementioned GHGs, GHG budgets were 1.224×103 and 1.442×103 gm-2 of CO2-equivalents at the wet and dry stump harvested plots, respectively, and 1.070×103 and 1.696×103 gm-2 of CO2-equivalents at the wet and dry control plots, respectively. CO2 fluxes dominated GHG budgets at all plots but N2O contributed with 17% at the dry stump harvested plot. For the full period 2010-2013, total carbon (CO2+CH4) budgets were 4.301×103 and 4.114×103 g m-2 of CO2-eqvivalents at the wet and dry stump harvest plots, respectively and 4.107×103 and 5.274×103 gm-2 of CO2-equivalents at the wet and dry control plots, respectively. Our results support recent studies suggesting that stump harvesting does not result in substantial increase in CO2 emissions but uncertainties regarding GHG fluxes (especially N2O) remain and more long-term measurements are needed before robust conclusions can be drawn.

The phenology of Pinus sylvestris (L.) and Picea abies (L.) Karst. seedlings. stored during winter in a cold-store (-5°C) and outdoors. respectively. was studied after planting-out on different dates from May to end of July. Seasonal changes in nitrogen and starch content were followed during the summer of planting. In pine and spruce seedlings planted from mid June to end of July. negative effects on dry weight, shoot and needle growth. bud diameter. and frost hardiness were observed. These effects were most pronounced for cold-stored seedlings and still evident after three growing seasons. Needle starch levels showed equal variations for early plantings. independently of storage treatment. but differences increased successively for later planting dates. Cold-stored seedlings showed. on all planting dates. a rapid increase in needle starch concentration. Seedlings stored outdoors had high levels of starch on early. and low levels on late planting dates. High levels of starch were found in the root system for seedlings planted in May. The results of the starch determinations were similar for both species. The nitrogen concentration in the old needles of the two species was low after planting for both storage treatments. Late planting dates resulted in low levels of nitrogen in current needles.

Landscape pattern is of primary interest to landscape ecologists and landscape metrics are used to quantify landscape pattern. Metrics are commonly defined and calculated on raster-based land cover maps. One metric is the contagion, existing in several versions, e.g., unconditional and conditional, used as a measure of fragmentation. However, mapped data is sometimes in vector-based format or there may be no mapped data but only a point sample. In this study a definition of contagion for such cases is investigated. The metric is an extension of the usual contagion, based on pairs of points at varying distances and gives a function of the distance. In this study the extended contagion is calculated for vector-based delineated real landscapes and for simulated ones. Both unconditional and conditional contagions are studied using two classification systems. The unconditional contagion function was decreasing and convex, with upper and lower limits highly correlated to the Shannon diversity index, thus carrying only area proportion information. The spatial information lies in the speed by which the function converges to the lower limit; using a proxy function this can be expressed by a single parameter b, with high values for fragmented landscapes. No proxy function was found for the conditional contagion, for which only qualitative information was found. The extended contagion is applicable both in patch mosaic models of landscapes and in gradient-based models, where landscape characteristics change continuously without distinct borders between patches. The extended contagion can be useful in sample based surveys where there no map of the entire landscape is available.

Föreliggande arbete behandlar köldskador och plantdöd resp. överlevnadsförmåga hos tallplantor i en proveniensförsöksserie utlagd 1952-1955. Denna serie omfattar 30 planteringsytor fördelade större delen av Sverige med en sammanlagd areal av 36 ha. Här har endast material från 20 försöksytor kommit till användning, nämligen från de ytor, som är belägna norr om 60' N. I denna del av Sverige har under perioden 1953-1964 inträffat betydande köldskador, vilka observerats icke blott på försöksytorna utan även i andra planteringar och på träd intill en ålder av 20 år. Inom vissa områden var planteringarna mycket skadade och i några fall har de t. o. m. helt gått ut. Orsaken till köldskadorna och till den stora avgången har tillskrivits olika faktorer. Detta arbete har i främsta rummet avsett undersökning av den typ av köldskador, som har betecknats såsom "basal stem girdle" eller "strangulering" ("strangulation sicknes", "Trocken Gürtel", "Einschnürung") och dess samband med extrema klimatforhållanden under vissa år. Även förekomsten av andra slag av köldskador och skador förorsakade av andra klimatfaktorer har emellertid beaktats.

• Beståndets stamtäthet/ljusmiljö var avgörande för plantornas etablering och tillväxt • Plantans avstånd till närmaste skärmträd påverkade inte dess tillväxt i lika stor utsträckning som beståndets stamtäthet • Plantornas tillväxt kunde inte förbättras med näringsbevattning i de beståndstyper där ljusnivåerna var låga

Why do citizens’ decisions made because they favour the mitigation of climate change outnumber those made because they favour adaptation to its impacts? Using data collected in a survey of 338 citizens of Malmö, Sweden, we tested two hypotheses. H1: the motivation for personal decisions because they favour adaptation to the impacts of climate change correlates with the decision-making agent´s knowledge of specific local impacts of climate change, and H2: the motivation for personal decisions because they favour mitigation of climate change correlates with the risk perception of the decision-making agent. While decisions made because they favour mitigation correlated with negative net values of expected impacts of climate change (risk perception), decisions made because they favour adaptation correlated with its absolute value unless tipping point behaviour occurred. Tipping point behaviour occurs here when the decision-making agent abstains from decisions in response to climate change in spite of a strongly negative or positive net value of expected impacts. Hence, the decision-making agents´ lack of knowledge of specific climate change impacts inhibited decisions promoting adaptation. Moreover, positive experiences of climate change inhibited mitigation decisions. Discussing the results, we emphasised the importance of understanding the drivers of adaptation and mitigation decisions. In particular, we stress that attention needs to be paid to the balance between decisions solving problems ‘here and now’ and those focusing on the ‘there and then’.

Wetland CH4 emissions are among the most uncertain components of the global CH4 budget. The complex nature of wetland CH4 processes makes it challenging to identify causal relationships for improving our understanding and predictability of CH4 emissions. In this study, we used the flux measurements of CH4 from eddy covariance towers (30 sites from 4 wetlands types: bog, fen, marsh, and wet tundra) to construct a causality-constrained machine learning (ML) framework to explain the regulative factors and to capture CH4 emissions at sub -seasonal scale. We found that soil temperature is the dominant factor for CH4 emissions in all studied wetland types. Ecosystem respiration (CO2) and gross primary productivity exert controls at bog, fen, and marsh sites with lagged responses of days to weeks. Integrating these asynchronous environmental and biological causal relationships in predictive models significantly improved model performance. More importantly, modeled CH4 emissions differed by up to a factor of 4 under a +1C warming scenario when causality constraints were considered. These results highlight the significant role of causality in modeling wetland CH(4 )emissions especially under future warming conditions, while traditional data-driven ML models may reproduce observations for the wrong reasons. Our proposed causality-guided model could benefit predictive modeling, large-scale upscaling, data gap-filling, and surrogate modeling of wetland CH4 emissions within earth system land models. Peer reviewed

In Sweden, the majority of forest area has been altered by industrial forestry over the decades. Almost 30 years ago, a shift towards biodiversity-oriented forest management practices occurred. Here we took advantage of long-term data collected by the Swedish National Forest Inventory to track developmental changes in forest structural components over this time. We assessed changes in structural components that play an important role in biodiversity (dead wood, large living trees, tree species composition, and understory vegetation) in four forest types with descending tiers of biodiversity protection: protected areas, woodland key habitats, low-productivity forests and production forests. Overall, we found a positive trend in the volumes of dead wood and large living trees, as well as in tree species diversity, while there was a general decline in understory vegetation coverage. Most observed changes were consistent with the intended outcomes of the current forest policy, adapted in the early 1990s. The implementation of retention forestry is likely driving some of the observed changes in forest structural components in the south. In contrast, we observed no changes in any of the focal structural components in the north, which could be attributed to the ongoing clear-cutting of forests previously managed less intensively. Dead wood and large living trees increased not only in managed, but also in unmanaged forests, likely reflecting historical management. The increased tree species diversity can be explained through current forest management practices that encourages maintenance of additional tree species. Decreasing understory vegetation coverage in both dense managed and unmanaged forests suggests that factors other than forestry contribute to the ongoing changes in understory vegetation in Swedish forests. Overall, the observed increase in structural components has not yet been reflected in documented improvements for red-listed forest species, which may be due to delays in species responses to small improvements, as well as a lack of detailed monitoring. Similarly, the increased availability of forest structural components might still be insufficient to meet the specific habitat requirements of red-listed species.