Category: Research article
article id 9948, category Research article
Co-variation relations of physical soil properties and site characteristics of Finnish upland forests. Silva Fennica vol. 52 no. 3 article id 9948. https://doi.org/10.14214/sf.9948
Highlights: Atmospheric temperature sum is related to site index H100 as a covariate;Soil pH and water retention at field capacity (FC) are also closely related to H100;Fine fraction is related to water retention at FC, soil layer and site type;Fine fraction co-varies also with temperature sum, H100 and slope.
Physical soil properties have a marked influence on the quality of forest sites and on the preconditions for forest growth and management. In this study, water retention characteristics (WRC) and related physical soil properties in addition to vegetation coverage and tree stand data were studied at upland forest sites in Finland. Fixed and mixed models between soil and site characteristics were formed to estimate physical and hydrologic soil characteristics and the site quality with indirect co-varying variables. In the present data, the site quality index (H100) shows a high coefficient of determination in respect to the temperature sum. It is also related to soil fine fraction content, topsoil pH and water retention at field capacity. The thickness of the humus layer is predictable from the pH and cover of xeric and mesic plant species. The soil fine fraction content (clay + silt) is closely related to water retention at field capacity, the soil layer and site type, and without WRC to the temperature sum and site index and type, as well as the slope angle. The soil bulk density is related to organic matter, depth (layer) or alternatively to organic matter, slope and field estimated textural class (fine, medium, coarse). Water retention characteristics were found to be best determinable by the fine fraction content, depth and bulk density. Water content and air-filled porosity at field capacity are closely related to the fine fraction. This study provides novel models for further investigations that aim at improved prediction models for forest growth, hydrology and trafficability.
article id 1219, category Research article
Diversifying clearcuts with green-tree retention and woody debris structures: conservation of mammals across forest ecological zones. Silva Fennica vol. 48 no. 5 article id 1219. https://doi.org/10.14214/sf.1219
Highlights: Species diversity of small mammals increased with structural complexity left on clearcut sites; Productivity of red-backed vole populations was higher in sites with green-tree retention (GTR) and windrows of woody debris; GTR and windrows may provide additive effect for providing habitat to conserve mammals on clearcuts.
We tested the hypotheses (H) that on newly clearcut-harvested sites, (H1) abundance and species diversity of the forest-floor small mammal community, and (H2) abundance, reproduction, and recruitment of red-backed voles (Myodes gapperi Vigors), would increase with higher levels of structural retention via green-tree retention (GTR) and woody debris (dispersed and constructed into windrows). Study areas were located in three forest ecological zones in southern British Columbia, Canada. For H1, mean total abundance did generally increase with the gradient of retained habitat structure. Mean species richness and diversity were similar among treatment sites but did show an increasing gradient with structural compexity. For H2, mean abundance, reproduction, and recruitment of M. gapperi were higher in GTR and windrow sites than those without retained structures. There was a positive relationship between mean abundance of M. gapperi and total volume of woody debris across treatments. This study is the first investigation of the responses of forest-floor small mammals to an increasing gradient of retained habitat structure via GTR and woody debris on clearcuts. Our assessment of a combination of these two interventions suggested a potentially strong additive effect that could be cautiously extrapolated across three forest ecological zones. With the advent of low levels of GTR on clearcuts, woody debris structures should help provide some habitat to conserve forest mammals on harvest openings.
article id 933, category Research article
Effects of clear-cutting and slash removal on soil water chemistry and forest-floor vegetation in a nutrient optimised Norway spruce stand. Silva Fennica vol. 47 no. 2 article id 933. https://doi.org/10.14214/sf.933
Fertilisation with nutrient optimisation has in Sweden resulted in large increases in volume growth in young stands of Norway spruce. There are, however, environmental concerns about repeated fertilisation and one is the risk of nutrient leakage to ground water resources and aquatic ecosystems after clear-cutting of such forests. The present study followed soil-water chemistry in optimised fertilised stands after clear-cutting, as well as effects of harvest of slash on nutrient leakage. Parts of a 30-year-old stand of Norway spruce, which had been subject to a nutrient optimisation experiment for 17 years, were clear-cut. A split-plot design with whole-tree harvesting as the sub-plot treatment was applied. Lysimeters were installed and soil-water sampled at nine occasions during the following four years. No significant effects of fertilisation on nitrate leaching were found, while harvest of slash reduced the concentration of Ca, DOC, DON, K, Mg, ammonium and nitrate, as well as pH in the soil solution. While no effects of fertilisation could be seen on the soil water concentration of N, the results indicate an interaction between fertilisation and harvest of slash on the concentration of nitrate in the soil solution. The results indicate that forest-floor vegetation plays an important role in the retention of N after clear-cutting of fertilised forests.
article id 47, category Research article
A comparison of residual forest following fires and harvesting in boreal forests in Quebec, Canada. Silva Fennica vol. 46 no. 3 article id 47. https://doi.org/10.14214/sf.47
Residual forests are a key component of post-burned areas creating structure within burns and providing habitat and seed sources. Yet, despite their importance to biodiversity and ecosystem processes there is little information on how similar or different residuals in burned landscape are to harvested landscapes. Our goal was to examine and compare the density, size, shape, and spatial arrangement of residual forest vegetation after fire and clearcutting. We evaluated residual forest in two locations within the boreal mixedwood region of Quebec, Canada using aerial photo interpretation and ArcGIS 9.1 software. We found residual stands to be larger and more abundant in harvested zones relative to sites affected by fire. Differences with respect to shape and spatial arrangement of residual forest were also observed among disturbance types. Factors such as proximity to watercourses, watercourse shape, and physiography affected residual abundance and spatial distribution. Residual forest in harvested zones tended to be more elongated with greater edge due to rules governing forest operations. Despite greater quantity of residual forest in harvested areas than fires, managers should still be prudent as the surrounding forest matrix is reduced in many managed landscapes.
article id 451, category Research article
Green-tree retention and life after the beetle: stand structure and small mammals 30 years after salvage harvesting. Silva Fennica vol. 44 no. 5 article id 451. https://doi.org/10.14214/sf.451
We report on a retrospective investigation of the impacts of salvage harvesting of lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.), killed by an outbreak of mountain pine beetle (Dendroctonus ponderosae Hopk.) in the 1970s, with variable retention of Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco). Our inference to biodiversity was coniferous stand structure and four mammal species: the southern red-backed vole (Myodes gapperi Vigors), common shrew (Sorex cinereus Kerr), red squirrel (Tamiasciurus hudsonicus Erxleben) and northern flying squirrel (Glaucomys sabrinus Shaw). We tested hypotheses that, at 30 years after salvage harvest of beetle-killed lodgepole pine trees, (1) abundance and diversity of stand structure, and (2) abundance of mammal species, will increase with higher levels of green-tree retention (GTR). Stand structure attributes and small mammals were sampled during 2005–2008 in young pine stands, with a range of GTR seed-trees (none, dispersed, and aggregated Douglas-fir), and uncut forest in south-central British Columbia, Canada. Diameters and heights of Douglas-fir and lodgepole pine and basal area of total conifers supported hypothesis (1). Mean abundance of the red-backed vole was consistently higher (2.3 to 6.4 times) in the uncut forest than other stands. Overall mean patterns of abundance for common shrews, red squirrels, and northern flying squirrels were similar among treatment stands. Mean abundance of the red-backed vole supported hypothesis (2), but numbers of the other three species did not. There is “life after the beetle” at 30 years after salvage harvesting, and this was enhanced by GTR.
article id 253, category Research article
Retention of phosphorus in peatland buffer zones at six forested catchments in southern Finland. Silva Fennica vol. 42 no. 2 article id 253. https://doi.org/10.14214/sf.253
Our current knowledge of the P retention efficiency of peatland buffer zone areas used to reduce sediment and nutrient leaching from forestry areas is insufficient. Especially the role of P sorption by soil in buffer zones needs closer examination as there is considerable variation in the efficiency of P retention. Six sites in southern Finland were chosen for the study. The buffer zone areas varied between 0.1–4.9% of the catchment area. A total of 10 kg of solute PO4–P was added to the inflow of the buffer zone areas and the concentrations of PO4–P in inflow and outflow were measured for 2–4 years. P retention characteristics of the surface peat were determined with sorption-desorption isotherms before and after PO4–P addition and the effective buffer zone area over which the added P was spread was determined from soil water samples. P retention in the two largest buffer zone areas was complete (100% retention), and the third largest buffer retained 94%. Retention in the three smallest buffer zones was 24%, 95% and 95% of the added P. As a result of P addition reduction in peat P retention capacity was detected in three out of four cases. The effective buffer zone area varied from 67% to 100% of the total buffer zone area. Factors contributing to efficient P retention were large buffer size and low hydrological load whereas high hydrological load combined with the formation of preferential flow paths, especially during early spring or late autumn was disadvantageous. High P retention capacity in peat contributed to the sustainability of P retention. The study showed that even relatively small buffer zone areas are able to efficiently reduce P load.
article id 331, category Research article
Height distributions of Scots pine sapling stands affected by retained tree and edge stand competition. Silva Fennica vol. 40 no. 3 article id 331. https://doi.org/10.14214/sf.331
The paper focused on the height structure of Scots pine saplings affected by (1) retained solitary pine trees or (2) a pine-dominated edge stand. The study material in (1) and (2) consisted of ten separate regeneration areas in southern Finland. In (1) 2-m radius study plots were located at 1, 3, 6 and 10 m distances from 10 systematically selected, solitary retained trees in each stand. In (2) the study plots were systematically located within 20 m from the edge stand. Competition of the individual trees was modelled using ecological field theory. The 24th and 93rd sample percentiles were used for estimating the height distribution using the two-parameter Weibull function. The models incorporated the effect of varying advanced tree competition on the predicted percentiles. Competition free dominant height was used as a driving variable for the developmental phase. Competition resulted in retarded height development within a radius of about 6 m from the retained tree, while it extended up to roughly half of the dominant height of the edge stand. The height distribution without external competition was relatively symmetrical, but increasing competition resulted in a more peaked and skewed distribution. Slight differences were found between northern sunny and southern shaded stand edges, while the least retarded height occurred at the north-western edge receiving morning sunlight. Kolmogorov-Smirnov goodness-of-fit tests showed acceptable and equal fit for both data sets; 2% and 8% of the distributions did not pass the test at the alpha 0.1 level when the Weibull distribution was estimated with the observed or predicted percentiles, respectively.
article id 360, category Research article
Defoliation by the common pine sawfly (Diprion pini) and subsequent growth reduction in Scots pine: a retrospective approach. Silva Fennica vol. 39 no. 4 article id 360. https://doi.org/10.14214/sf.360
The foliage status in the main stem of Scots pines (Pinus sylvestris) was studied retrospectively using the needle trace method (NTM) on a stand, seriously defoliated by the pine sawfly (Diprion pini) in the 1980s. Needle density increased abruptly in the seasons following the defoliation. The strongest reduction in annual needle production occurred one year later. As a consequence of lower needle production, the annual number of attached needles decreased three to five years after the defoliation. Needle retention and the average age of attached needles tended to increase after defoliation. In analyses of covariance with the NTM variables, needle density (logarithmic transformed values) and average age of attached needles, had the highest, significant, negative relationship with radial and height increments both in the period prior to the defoliation and in the time when the trees were suffering from defoliation. The relationships between height increment and the number of needles and needle loss were positive and significant. Also radial increment had a positive relationship with the number of needles but not with needle loss. Interestingly, an abrupt increase in the needle density gave a good indication of the effects of a sudden defoliation in pines.
article id 502, category Research article
Relation between soil properties and tree species composition in a Scots pine–Norway spruce stand in southern Finland. Silva Fennica vol. 37 no. 2 article id 502. https://doi.org/10.14214/sf.502
It is commonly known in Finland that Scots pine (Pinus sylvestris L.) is a tree of dry soils and Norway spruce (Picea abies (L) Karst.) is a tree of fresh soils. However, the concepts of dry and fresh soils still lack a precise definition. Consequently, the discussion on which soil/site is a pine or spruce habitat has continued over several decades. Moreover, in forest regeneration, the practice of tree species selection between the pine and the spruce has varied. We investigated the relationship between soil properties and pine–spruce species composition in a mature, naturally regenerated stand in southern Finland. We applied spatial analysis to divide the stand area up into 3–7 classes based on selected soil properties and then investigated the variations in species composition among those classes. The pine–spruce basal area ratio (BA of pines / BA of spruces) increased along with increasing mean particle size and proportion of coarse sand and gravel particle size fraction (0.6–20 mm) of mineral soil, and was lowest in classes, with the highest proportions of fine texture fractions. The results suggest that in southern Finland on sorted soils, pine is more competitive in regeneration and growth than spruce when mean particle size is above 0.44 mm or percentage of coarse sand and gravel is higher than 50%.
article id 654, category Research article
Needle chronologies on Pinus sylvestris in northern Estonia and southern Finland. Silva Fennica vol. 33 no. 3 article id 654. https://doi.org/10.14214/sf.654
A needle trace method was used to reveal the chronology of needle retention on Scots pine (Pinus sylvestris L.) in southern Finland (two stands) and northern Estonia (two stands). The average annual summer needle retention along the main stem varied from 2.2 to 3.1 in Estonian stands and between 3.4 and 4.2 in Finnish stands during the period 1966–1990. The 23-year-mean needle age was 3.0 and 2.1 years in Finland and Estonia, respectively. In all stands, the mean needle age decreased sharply in 1980s.
Category: Review article
article id 553, category Review article
Natural fire regime: a guide for sustainable management of the Canadian boreal forest. Silva Fennica vol. 36 no. 1 article id 553. https://doi.org/10.14214/sf.553
The combination of certain features of fire disturbance, notably fire frequency, size and severity, may be used to characterize the disturbance regime in any region of the boreal forest. As some consequences of fire resemble the effects of industrial forest harvesting, conventional forest management is often considered as a disturbance that has effects similar to those of natural disturbances. Although the analogy between forest management and fire disturbance in boreal ecosystems has some merit, it is important to recognise that it also has its limitations. Short fire cycles generally described for boreal ecosystems do not appear to be universal; rather, important spatial and temporal variations have been observed in Canada. These variations in the fire cycle have an important influence on forest composition and structure at the landscape and regional levels. Size and severity of fires also show a large range of variability. In regions where the natural matrix of the boreal forest remains relatively intact, maintenance of this natural variability should be targeted by forest managers concerned with biodiversity conservation. Current forest management tends to reduce this variability: for example, fully regulated, even-aged management will tend to truncate the natural forest age distribution and eliminate over-mature and old-growth forests from the landscape. We suggest that the development of strategic-level forest management planning approaches and silvicultural techniques designed to maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain this variability. Although we use the boreal forest of Quebec for our examples, it is possible to apply the approach to those portions of the boreal forest where the fire regime favours the development of even-aged stands in burns.
Category: Discussion article
article id 573, category Discussion article
Boreal carabid beetles (Coleoptera, Carabidae) in managed spruce forests – a summary of Finnish case studies. Silva Fennica vol. 36 no. 1 article id 573. https://doi.org/10.14214/sf.573
article id 5503, category Article
Variation in water retention characteristics of peat growth media used in tree nurseries. Silva Fennica vol. 27 no. 2 article id 5503. https://doi.org/10.14214/sf.a15664
The water retention characteristics and their variation in tree nurseries and related physical properties were determined for commercially produced growth media made of light slightly humified Sphagnum peat. A total of 100 samples of peat media were collected from filled seedling trays in the greenhouses of four Finnish nurseries in 1990. In addition, the physical properties were determined for two growth media made of compressed peat sheets and chips. The variation in water retention characteristics in nurseries was described using linear models with fixed and random effects. The sources of variation in the mixed linear models were producer, grade, batch (greenhouse) and sample (tray).
The water retention of the peat media at different matric potentials was comparable to that given in the literature. The media shrank an average of 0–16% during desorption. The peat grades were finer than the Nordic quality standards for peat growth media. Particles < 1 mm increased and particles 1–5 mm decreased the water retention characteristics measured. The greatest total variation in water retention was at -1 kPa. The water retention of the peat media differed least at -5 and -10 kPa. The water retention characteristics of media from different producers usually differed significantly. The grades, on the other hand, did not differ from each other in their water retention characteristics nor were there significant interactions between producer and grade. The batch effect was marked but was lower than the effect within batches, where the sample (tray) effect was greater than the effect due to random measurement error. At -10 kPa, the measurement error was, however, clearly greater than the sample effect. The random measurement error was comparable to the batch effect. Aeration of the growth media is dependent on the water content retained between saturation and -1 kPa. The water availability to seedlings at the nursery phase is affected mainly by water retention between -1 and -10 kPa.
The PDF includes an abstract in Finnish.
article id 5438, category Article
Maan vesipotentiaali paljasjuuristen männyntaimien taimitarhakasvatuksessa. Silva Fennica vol. 25 no. 1 article id 5438. https://doi.org/10.14214/sf.a15592
English title: (1991). Soil water potential during the production of bare-rooted Scots pine seedlings.
The matrix potential, measured with tensiometers, and its effect on the soil air-water ratio were examined during the production of bare-rooted Scots pine (Pinus sylvestris L.) seedlings in nursery fields. Soil water potential was monitored during the growing season of 1983 at three nurseries in Finland, and from fields growing various seedling types at depths of 10 and 20 cm. In 1986, soil core samples were collected in order to assess the water desorption characteristics of the soil. In addition, the effect of polypropylene gauze covering (Agryl P 17) on the soil water potential was examined during the growing season of 1985 at two nurseries in Finland at depths of 5, 10 and 15 cm.
The soil water potential was relatively high in all the fields studied. In fields growing one- and two-year-old seedlings, the median potential was higher than -10 kPa. The potential did not fall below the limit of the measured scale (ca. -85 kPa) of the tensiometers. Soil aeriation may have been periodically insufficient in the rooting zone, as a result of high water content. The favourable water potential is below -5 to – 6 kPa. The gauze covering slightly (1–4 kPa) increased the soil water potential, an effect which could be harmful if the soil air space is low. During the second growing season, the soil water potential was lower in the fields covered by the gauze during the first year than in the fields without the covering.
The PDF includes an abstract in English.
article id 7631, category Article
Taimitarhamaiden fysikaalisia ja kemiallisia ominaisuuksia sekä niiden suhde orgaanisen aineksen määrään. Acta Forestalia Fennica no. 184 article id 7631. https://doi.org/10.14214/aff.7631
English title: (1983). Physical and physio-chemical properties of forest tree nursery soils and their relation to the amount of organic matter.
The aims of the present study were to determine physical and physio-chemical properties of some Finnish forest tree nursery soils, and to examine relationships between these properties and the amount of organic matter in the soil.
The following soil tillage layer properties of 33 fields belonging to 8 forest tree nurseries were determined: soil particle size distribution, organic matter content, bulk density and density of solids, total pore space, soil water volume at potentials pF 2.0 and 4.2, available water content and air space at potential pF 2.0, active acidity, electrical conductivity index and cation exchange capacities at pH 4.5 and 8.0. The soil texture class of the tillage layer parent material was sand, only in a few cases did higher percentage of silt and clay indicate a morainic nature of parent material. The amount of organic material in the soils varied within wide limits, reflecting differences in amelioration policy between the single nurseries.
Relationships between the physical properties of the soil parent material and those related to fertility were in most cases strongly influenced by the amount of soil organic matter. Soil density values decreased as the organic matter content increased from 2 to 25%, giving rise to the increase in the total pore space. However, the amount of water held at potential pF 2.0 and the available water content did not increase with increasing organic matter content. This was due to the absence of the particle fraction in the sand. Nursery soil amelioration, involving in most cases a mixture of Sphagnum peat with sand, thus gives rise to an increase in the content of drainable water.
Cation exchange capacities were positively correlated with the organic matter content. However, the absolute number of exchange sites expressed as equivalents in the tillage layer did not increase in accordance with the increase in organic matter content due to the influence of the organic matter content upon the ratio of solids in the voids.
The PDF includes a summary in English.
article id 7563, category Article
Hydraulic conductivity and water retention in peat soils. Acta Forestalia Fennica no. 129 article id 7563. https://doi.org/10.14214/aff.7563
The paper is a part of a larger study of the basic hydrologic properties of peat. This part of the study deals with the hydraulic conductivity and water retention capacity of peat and with their dependence on some of its structural properties. The data of the study was collected in Central Finland (61°50'N; 24°20'E) from drained peatlands. The limits of the quantitative range of variation in the hydraulic conductivity of peat can be put at 2.0 x 10-6 and 1.1 x 1O-2 cm/sec. The variation occurring in the hydraulic conductivity of peat is extremely large. At saturation peat contains 82–95 volume per cent of water. The bulk density of peat seemed to be the factor best able to explain its water retention capacity. The quantity of water which can be removed from a site by draining decreases with increasing bulk density in such a way that it, in the case of well decomposed peat (bulk density 0.20 g/cm3) is slightly less than one third of that for slightly decomposed peat (bulk density 0.05 g/cm3). Also, the possibilities to estimate the quantities of water superfluous, available and unavailable to the plant cover is discussed.
The PDF includes a summary in Finnish.