Effect of wide spacing on increment and branch properties of young Norway spruce

The effects of stand density on increment and branch properties were studied in three spacing experiments of Norway spruce [Picea abies (L.) Karst.]. The stand densities ranged from 350 stems ha⁻¹, regarded as open-grown trees, up to 1,600 stems ha⁻¹, corresponding to the density recommended for forestry practice. Properties of all the branches were measured from the stem apex downwards. The study material included a total of 5,661 branches from 45 trees. Increasing stand density resulted in a decrease in radial increment as well as shorter and narrower crowns, but it had no effect on height increment. The average number of spike knots per tree was 0.87, 0.27, and 0.33 in densities of 350, 700 and 1,600 ha⁻¹, respectively. Additionally, in the widely spaced stands of 350 stems ha⁻¹, the fraction of trees having spike knots was high (over 50%). At a density of 1,600 ha⁻¹, the sample trees had somewhat less branches in a whorl compared with the more widely spaced plots. The most pronounced effect of stand density was the increase in branch diameter with decreasing stand density. At a density of 350 ha⁻¹, the maximum branch diameter of all the sample trees exceeded the diameter limit of quality class B in the European quality requirements for round wood. The results give some indication that trees subjected to severe competition would produce smaller branches per unit of crown projection area. However, the possibilities for reducing branch dimensions relative to stem and crown size through competition appear quite restricted.     

Effects of Long-Term Aerial Pollution on Soil Seed Banks in Drained Pine Mires in Southern Finland

The effects of pollution on thecomposition of soil seed banks in four drained pinemires located along a pollution gradient in southernFinland were studied using the emergence method. Thespecies composition of the seed bank was compared withthe above ground vegetation. Dominant species in theseed banks were Calluna vulgaris, Betulaspp. and Ledum palustre. Seeds seemed to beviable despite a heavy pollution load. Especially inthe vicinity of the pollution source, seed bank andabove ground vegetation were weakly correlated.     

Nitrate uptake by Eriophorum vaginatum controls N2O production in a restored peatland

The clear dependence of N₂O production through denitrification on available nitrate in soil has been shown in many studies. Since N availability similarly limits the growth of plants, the resource competition with vegetation limits the activity of denitrifying microbes and may consequently moderate the N₂O emissions from peatlands. We used uptake by Eriophorum vaginatum L. as a vegetation competition factor for microbes. The species was selected for the experiment because it has high nutrient use efficiency in low-nutrient conditions and high nutrient uptake efficiency in luxuriant nutrient conditions. We measured gaseous N flux as N₂O (end product of denitrifier activity) in a restored peatland in central Finland with acetylene inhibition technique over a growing season from sample plots with varying addition levels and E. vaginatum cover. The resource competition effects were analysed with a model that used exponential decay dependence of N₂O flux on the leaf area of E. vaginatum, and saturating response of N₂O flux to addition level. The model explained the variation in N₂O fluxes well (R²=0.86). The model simulation showed that the increasing nutrient uptake of E. vaginatum decreased the N₂O fluxes exponentially. Simultaneously, denitrification appeared to saturate even in conditions with high availability of and low level of competition by vegetation. Thus, E. vaginatum is an effective competitor for in sedge-dominated peatlands that controls the availability of for denitrification, and consequently moderates the N₂O emissions from peatlands.     

Road and railway verges serve as dispersal corridors for grassland plants

The role of linear habitat strips as dispersal corridors is a disputed topic. Reports concerning their significance for animals have been contradictory, and the functions of corridors have been difficult to study in the case of sedentary organisms such as plants. Previous studies on dispersal of plants along corridors have concentrated on a single or a few species at a time. We developed a general method, a generalisation of the binomial test, for considering dispersal or spatial relations of a large group of species. Particularly, we studied the ability of grassland plants to spread along road and railway verges. Our data set consists of plant lists collected at study plots scattered irregularly along road and railway networks. The dispersal ability was assessed by testing whether the species composition at neighbouring sites – measured along roads and railways – reflects spatial dependence within each species. Our result showed that similar combinations of grassland species occurred at neighbouring sites more often than expected in a spatially independent case. We argue that management of verges and spatial autocorrelation of environmental factors were not responsible for the result and thereby we conclude that grassland plants use road and railway corridors for dispersal. This result is encouraging in regards to preservation of grassland plant populations. Although semi-natural and natural grasslands have become scarce, road and railway embankments may partly compensate for this loss, serving as substitute habitats and dispersal routes.     

Airborne small-footprint discrete-return LiDAR data in the assessment of boreal mire surface patterns, vegetation, and habitats

Boreal mires encompass high diversity in species and habitats, many of which are endangered. In Finland, extensive use of peatlands has resulted in habitat fragmentation. A need for accurate and cost-efficient vegetation mapping and monitoring of habitat changes exists in mire conservation, restoration and peatland forestry. LiDAR is an emerging and excellent tool for probing the geometry of vegetation and terrain. Modern systems measure the backscattered signal accurately and also provide radiometric information. Experiments were carried out in a complex minerotrophic–ombrotrophic eccentric raised bog in southern Finland (61°47′N, 24.18′E). First, we tested discrete-return LiDAR for the modeling of mire surface patterns and the detection of hummocks and hollows, as well as the effect of mire plants on the Z accuracy of the surface echoes. Secondly, the response of different mire vegetation samples in LiDAR intensity was examined. Thirdly, we tested area-based geometric and radiometric features in supervised classification of mire habitats to discover the meaningful variables. The vertical accuracy of LiDAR in mire surface modeling was high: 0.05–0.10 m. A binary hummock-hollow model that was estimated from a LiDAR-based elevation model matched flawlessly in aerial images and had moderate explanatory power in habitat classification trials. The intensity of LiDAR in open-mire vegetation was mainly influenced by the surface moisture, and separation of vegetation classes spanning from ombrotrophic to mesotrophic vegetation proved to be difficult. Area-based features that characterize the height distribution of LiDAR points in the canopy were the strongest explanatory variables in the classification of 21 diverse mire site types. Actual qualifying differences in the ground flora were unattainable in the LiDAR data, which resulted in inferior accuracy in the characterization of ecohydrological conditions and nutrient level of open mires and sparsely forested wet sites. Mire habitat classification accuracy with LiDAR surpassed earlier results with optical data. The results suggested that LiDAR constitutes an efficient aid for monitoring applications. We propose the co-use of images and LiDAR for enhanced mapping of open mires and tree species. In situ calibration and validation procedures are required until invariant geometric and radiometric features are discovered.     

Integrating bilberry yields into regional long-term forest scenario analyses

In many areas, picking wild berries constitutes an important forest commodity offering food, recreational services, and revenues. Intensified forest management has negatively affected bilberry yields. In this study, regional-level scenario analyses were conducted to investigate the effects of four approaches to the inclusion of bilberry yields on the economics, management, and resulting forest structures in North Karelia. The current approach ignoring bilberries resulted in decreasing bilberry yields and increasing younger forests. When bilberries were valued at market price (1.72?€?kg^?1), bilberry yields still decreased despite the fact that forest management were slightly modified to favour bilberry. Adding non-declining sustainability constraints to bilberry yields resulted in a slightly lower total net present value of timber and bilberry since forest management favoured longer rotation lengths, which increased bilberry yields. Similar effects occurred when the bilberry price was tripled to include the implicit ecosystem benefits of bilberries. When forests were managed only for bilberries (timber zero-priced), bilberry yields started to increase immediately resulting in 1.5-fold difference in 50 years as compared to timber only scenario. In conclusion, managing forests for both timber and bilberry production has rather minor effects on economics, but it can have clear positive effect on bilberry yields.     

Breeding habitat preferences of 15 bird species on south-western Finnish archipelago coast: Applicability of digital spatial data archives to habitat assessment

Knowledge about the importance of physical habitat characteristics to the breeding site selection of birds is a prerequisite for understanding their breeding habitat ecology and distribution, as well as managing their habitats. Geographical information systems (GIS) and existing digital data archives provide new possibilities for the quantitative and cost-effective assessment of coastal breeding habitats of birds. We tested the applicability of GIS and digital data archives for the analysis of coastal bird habitats by conducting a multivariate analysis on the relationship between physical island characteristics and the breeding site selection of 15 species of ducks, waders, larids and alcids in 2001-2005 in the fragmented archipelago coast of south-western Finland. We used GIS and environmental databases containing shoreline, bathymetry and elevation data to calculate five physical parameters for 71 small islands and their vicinity. Island area was generally the most important factor determining the presence of the species, but also water depth, shore openness, and island elevation were important for some species. The differences and similarities in habitat preferences within and between species groups seem to reflect the breeding habitat ecology of the species. GIS and spatial data archives are becoming increasingly valuable for research and development, as well as administrative tasks. Our results indicate that physical island characteristics affect the breeding site selection and the distribution of our target species, and that GIS and digital data archives provide applicable information on the breeding habitats of coastal birds and thus function as a tool for conservation and management.     

Added value from an added chromosome: Potential of producing large fillet fish from autumn to spring with triploid rainbow trout,Oncorhynchus mykiss

Three‐summers‐old all‐female triploid and diploid rainbow trout were compared after one on‐growing season in sea net cages. Slaughter traits of round weight, gutted weight, fillet weight, carcass% and fillet% were measured at three times in November 2017, January and April 2018. The triploid group had lower daily growth coefficient mean (4.25) and higher feed conversion ratio (1.18) than diploids (4.48 and 1.05, respectively) during on‐growing (June–November). In November, no difference of means was found between mature or immature diploids and triploids for any of the weight traits when the effect of vertebrae defects was statistically removed. However, the triploids had attained higher means than mature or immature diploids in gutted and fillet weight by January, suggesting that the loss of muscle mass during early winter was lower in triploids. Sexually maturing diploids (46%) had lower slaughter yield means compared to triploids or immature diploids at each measurement time, and these differences also increased during overwintering. Instead, the means of yield traits remained similar between the triploid and immature diploid groups through the winter. Likewise, fillet redness remained at equally high level in triploids and immature diploids, whereas in maturing diploids this attribute decreased substantially during overwintering. The triploid group had a higher incidence of vertebral defects (12.0%) than diploids (5.3%). The present results demonstrate the potential of triploid trout in producing large‐sized (>2 kg) fillet fish until spring markets. However, more detailed investigations are needed, particularly regarding the animal health and growth efficiency in triploids, relative to their diploid counterparts.     

Constructing forest plans interactively based on owner-driven evaluation of the holding- and stand-level alternatives

In this study, an interactive forest planning process corresponding to the practical demands was developed and further tested in a challenging forest planning situation in northeastern Finland. The process includes prior preparation of alternative stand-level treatments and a small amount of holding-level forest plans; an interactive planning session consisting of the primary choice of the forest owner's profile; the owner's selection of the best holding-level plan; and finally a local improvement of this plan. The method as a whole aims to bridge the gap between the prevailing planning culture that has developed for private forest planning over three decades in Finland and the planning approach suggested by multiobjective forest planning theory. The usability and characteristics of the process were evaluated through an exercise set given to both forestry students and forest professionals. Tests of the process indicated, among other things, that comparison particularly of stand-level alternatives and offering owners the possibility to make changes and truly affect the end-result of the planning process are seen as important characteristics of the process.