Lövskog för framtiden

Denna lägesrapport från projektet ”Lövskog för framtiden” riktar sig till projektets finansiärer och dess medarbetare, men kan med fördel spridas till övriga intressenter och avnämare. Under perioden årskiftet 2011/12 till slutet av 2013 har projektet haft fyra projektmöten och varit med om att genomföra två större seminarier/exkursioner. Alla åtta delprojekt har kommit igång på ett bra sätt och enligt plan och många av delprojekten har redan producerat vetenskapliga och populärvetenskapliga artiklar eller är på väg att göra det. I ett av delprojekten har projektledaren flyttat utomlands, varför ambitionen i det projektet minskats något. Projektets medarbetare har också lyckats hitta kompletterande finansiering under 2013, och deltagarna har kopplat upp sig mot internationella nätverk finansierade av EU. Projektets mål ser ut att kunna nås vid slutet av 2014, men eftersom forskningssatsningen är relativt liten är det knappast troligt att målen nås om det utvärderas enskilt. Utvärderat tillsammans med liknande forskningssatsningar på temat lövskog där projektdeltagarna är inblandade i är det däremot troligt att målen nås. Flera av projektets deltagare kommer under 2014 att behöva lägga ned mer arbete på att finna ny finansiering eftersom flera delprojekt redan har förbrukat en relativt stor del av sin finansiering. Slutligen vill vi som deltar i projektet tacka finansiärerna till denna forskningssatsning

Monitoring and control of forest seedling quality in Europe

The relationship between the quality of forest seedlings and their outplanting survival and growth has long been recognized. Various attributes have been proposed to measure the quality of planted seedlings in forest regeneration projects, ranging from simple morphological traits to more complex physiological and performance attributes, or a combination thereof. However, the utility and meaning of seedling quality attributes can differ significantly among regions, nursery practices, site planting conditions, species and the establishment purpose. Here, forest scientists compiled information using a common agreed questionnaire to provide a review of current practices, experiences, legislation and standards for seedling quality across 23 European countries.Large differences exist in measuring seedling quality across countries. The control of the origin of seed and vegetative material (genetic component of plant quality), and control of pests and diseases are common practices in all countries. Morphological attributes are widely used and mandatory in most cases. However, physiological attributes are hardly used at the operative level and mainly concentrated to Fennoscandia. Quality control legislation and seedling quality standards are less strict in northern European countries where seedling production is high, and quality control relies more on the agreements between producers and local plant material users. In contrast, quality standards are stricter in Southern Europe, especially in the Mediterranean countries.The control of seedling quality based on plantation and reforestation success is uncommon and depends on the conditions of the planting site, the traditional practices and the financial support provided by each country. Overall, European countries do not apply the "target seedling concept" for seedling production except for seed origin. Seedling production in many countries is still driven by traditional "know-how" and much less by scientific knowledge progress, which is not adequately disseminated and transferred to the end-users.Our review highlights the need for greater harmonization of seedling quality practices across Europe and the increased dissemination of scientific knowledge to improve seedling quality in forest regeneration activities

Silviculture of Mixed-Species and Structurally Complex Boreal Stands

Understanding structurally complex boreal stands is crucial for designing ecosystem management strategies that promote forest resilience under global change. However, current management practices lead to the homogenization and simplification of forest structures in the boreal biome. In this chapter, we illustrate two options for managing productive and resilient forests: (1) the managing of two-aged mixed-species forests; and (2) the managing of multi-aged, structurally complex stands. Results demonstrate that multi-aged and mixed stand management are powerful silvicultural tools to promote the resilience of boreal forests under global change

Halvtid för uthålligt skogsbruk i ädellövskog

Rapporten har tagits fram på initiativ av styrgruppen i programmet och skall fungera som bas för den utvärdering som skall ske då programmet pågått i tre år. Rapporten täcker verksamhet från 8 september 2003 fram till 1 september 2006. Styrgruppen hade fram till det senare datumet beslutat starta 12 delprojekt. Ytterligare fyra delprojekt hade redan funnit finansiering vid programmets start. Det återstår för programmet att hitta finansiering för tre delprojekt, vilka ännu inte startat. Delprojekten löper ungefär enligt plan, men några är tidsmässigt förskjutna. Huvudsakligen beror det på att det tagit längre tid än beräknat att finna eller frigöra nödvändig kompetens. Ett delprojekt skall omorganiseras. Det finns en god chans att nå de flesta delmål i programmet. Dock behöver de tre ofinansierade delprojekten då komma igång. Vidare behövs en planering och strategi för kunskapsöverföring från programmet till dess avnämare. Det tionde delmålet ”Att inom sex år öka antalet ämnesexperter i samhälle och näringsliv genom att meritera totalt sex doktorer och tre docenter inom ramen för programmet” kommer inte att nås under programperioden. Inom ramen för programmet har hittills totalt 34 vetenskapliga samt 67 övriga manuskript producerats (Tabell 1). Emellertid befinner sig programmet bara i början av en process som kommer att leda till en mängd ytterligare publikationer

Current and future drought vulnerability for three dominant boreal tree species

Climate change is projected to increase the frequency and severity of droughts, possibly causing sudden and elevated tree mortality. Better understanding and predictions of boreal forest responses to climate change are needed to efficiently adapt forest management. We used tree-ring width chronologies from the Swedish National Forest Inventory, sampled between 2010 and 2018, and a random forest machine-learning algorithm to identify the tree, stand, and site variables that determine drought damage risk, and to predict their future spatial–temporal evolution. The dataset consisted of 16,455 cores of Norway spruce, Scots pine, and birch trees from all over Sweden. The risk of drought damage was calculated as the probability of growth anomaly occurrence caused by past drought events during 1960–2010. We used the block cross-validation method to compute model predictions for drought damage risk under current climate and climate predicted for 2040–2070 under the RCP.2.6, RCP.4.5, and RCP.8.5 emission scenarios. We found local climatic variables to be the most important predictors, although stand competition also affects drought damage risk. Norway spruce is currently the most susceptible species to drought in southern Sweden. This species currently faces high vulnerability in 28% of the country and future increases in spring temperatures would greatly increase this area to almost half of the total area of Sweden. Warmer annual temperatures will also increase the current forested area where birch suffers from drought, especially in northern and central Sweden. In contrast, for Scots pine, drought damage coincided with cold winter and early-spring temperatures. Consequently, the current area with high drought damage risk would decrease in a future warmer climate for Scots pine. We suggest active selection of tree species, promoting the right species mixtures and thinning to reduce tree competition as promising strategies for adapting boreal forests to future droughts

Fear effects on bank voles (Rodentia: Arvicolinae): testing for repellent candidates from predator volatiles

BACKGROUND Arvicolinae rodents are known pests causing damage to both agricultural and forest crops. Today, rodenticides for rodent control are widely discouraged owing to their negative effects on the environment. Rodents are the main prey for several predators, and their complex olfactory system allows them to identify risks of predation. Therefore, the potential use of predators' scents as repellents has gained interest as an ecologically based rodent control method. In a two-choice experiment, we investigated the potential repellent effects of five synthetic predator compounds: 2-phenylethylamine (2-PEA), 2-propylthietane (2-PT), indole, heptanal and 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), at 1% and 5% doses, using the bank vole (Myodes glareolus) as a rodent model. RESULTS The compound 2-PEA reduced both the food contacts and the time spent by voles in the treatment arm compared to the control arm. Likewise, 2-PT-treated arms reduced the food contacts, and the voles spent less time there, although this latter difference was not significant. Indole also showed a tendency to reduce the time spent at the treatment arm; however, this result was not significant. Unexpectedly, TMT had the reverse effect in showing attractive properties, possibly due to odor cues from differently sized predators and intraguild predation in nature. We found no dose-related effects for any compounds tested. CONCLUSION Our results suggest that the 2-PEA and 2-PT are both effective odor stimuli for triggering reduced food contacts and area avoidance, and they may be good repellent candidates. We suggest further testing of 2-PEA and 2-PT in field experiments to further determine their dose-efficiency as repellents against rodents in more natural environments

European Mixed Forests

We aim at (i) developing a reference definition of mixed forests in order to harmonize comparative research in mixed forests and (ii) briefly review the research perspectives in mixed forests. Area of study: The definition is developed in Europe but can be tested worldwide. Material and methods: Review of existent definitions of mixed forests based and literature review encompassing dynamics, management and economic valuation of mixed forests. Main results: A mixed forest is defined as a forest unit, excluding linear formations, where at least two tree species coexist at any developmental stage, sharing common resources (light, water, and/or soil nutrients). The presence of each of the component species is normally quantified as a proportion of the number of stems or of basal area, although volume, biomass or canopy cover as well as proportions by occupied stand area may be used for specific objectives. A variety of structures and patterns of mixtures can occur, and the interactions between the component species and their relative proportions may change over time. The research perspectives identified are (i) species interactions and responses to hazards, (ii) the concept of maximum density in mixed forests, (iii) conversion of monocultures to mixed-species forest and (iv) economic valuation of ecosystem services provided by mixed forests. Research highlights: The definition is considered a high-level one which encompasses previous attempts to define mixed forests. Current fields of research indicate that gradient studies, experimental design approaches, and model simulations are key topics providing new research opportunities

Direct seeding for restoration of mixed oak forests: Influence of distance to forest edge, predator-derived repellent and acorn size on seed removal by granivorous rodents

Restoration of mixed oak forest in northern temperate regions is important for biodiversity and for adaptation of forest management to climate change. Direct seeding has been considered as a cost-effective method for the assisted regeneration of oaks. However, removal of acorns by granivorous rodents hinders its application. Patterns of acorn removal can vary with habitat type, presence of predators, and acorn size. In this field study, we tested the effects of distance to forest edge, predator excrement as a repellent, and acorn size on the performance of direct-seeded oak in southern Sweden. The experiment was carried out at two different sites. Our hypotheses were: (i) in clear-cuts, acorn removal is higher closer to the forest edge compared to open areas, (ii) treatment with predator excrement reduces acorn removal without affecting germination, and (iii) larger acorns will be removed more readily than smaller acorns. Finally, we also investigated if seedlings from larger acorns survive better and grow taller compared to smaller acorns in relation to habitat structure and predator excrement as repellent. Acorn removal differed at the two sites. At Skrylle (older clear-cut), no forest edge effects were found. At Klåveröd (new clear-cut site), our results suggest that removal of acorns was higher in the open clear-cut due to the presence of large slash piles. Less vegetation coverage correlated with lower rates of acorn removal, except near slash piles. Our results therefore suggest that forest managers should reduce understory vegetation and avoid slash piles during direct seeding of oak. Mink excrement failed to protect acorns against removal, but did not reduce acorn germination. Bigger acorns produced taller seedlings but did not enhance overall woodland establishment due to their higher removal rate. Our results further suggest a potential food satiation effect due to an extra supply of additional food. Satiation manipulation might potentially be a method of mitigating the impact of seed predation by granivorous rodents during the direct seeding of oak, but such an approach requires further research before it could be recommended