Patch Scarification Research Articles

Современная практика искусственного лесовосстановления в таежной зоне европейской части России

The article presents an analysis of technologies and techniques for creating forest plantations used in the Arkhangelsk and Kirov Regions, as well as the Komi Republic, based on the materials of reforestation projects for 2020. The territories under consideration belong to 6 forest areas: the Northern taiga, the Dvina-Vychegda taiga, the Southern taiga, the coniferous- broad-leafed (mixed) forests, the Western Ural taiga and the area of tundra forests and sparse taiga. The database created on the basis of the data from reforestation projects includes 13 indicators: categories of reforestation areas, forest vegetation conditions (terrain, soil type, soil moisture, group of forest types, degree of turfing), as well as tillage methods, mechanisms and aggregates used for tillage and planting seedlings and saplings and planting stock type. It has been established that in the studied regions, reforestation is more often carried out in fresh (1–2-year-old) felling areas in place of spruce plantations of blueberry forests, with podzolic drained and poorly drained soils. When cultivating soil for forest plantations, excavators are widely used (44 %), replacing traditional tractors with ploughs (usually PL-1). In most areas, furrow tillage is prevalent (52 %), but strips, mounds and patch scarification are also common (40 %). Containerized spruce and pine planting stocks have become more widely used (more than 50 % of the area), though seedlings are extremely rare (7 % in the Kirov Region). The data obtained allow us to asses the real picture of the use of reforestation technologies in the taiga zone on the example of three subjects of the Russian Federation, which will help the subjects of the Russian Federation in making management decisions for exercising their powers in the reforestation field.

Environmental impact of mechanical site preparation on mineral soils in Sweden and Finland — a review

Mechanical site preparation (MSP) is deliberate soil disturbance which is undertaken to improve the conditions for forest regeneration. Disc trenching and mounding are the dominant MSP practices currently used in Sweden and Finland. In this paper, the impacts of MSP on the soil, water quality, greenhouse gas (GHG) emissions and ground vegetation of mineral soil sites in Sweden and Finland are reviewed. The practices considered are patch scarification, mounding, inverting, disc trenching, and ploughing, which together represent a wide range of soil disturbance intensity. The environmental effects of MSP in this region have not been studied extensively. The environmental impact of MSP derives from the process of creating microsites which involves horizontal and/or vertical redistribution of soil and soil mixing. This typically affects decomposition, element circulation and leaching, vegetation coverage and uptake of nutrients and water, and possibly erosion and sediment exports. Following disc trenching or mounding the effects on GHG emissions appear to be minor over the first two years. For a few years after disc trenching concentrations in soil water collected below ridges are higher than that below furrows for some elements (e.g., NO3-, NH4+, Mg2+, and total or dissolved organic C). The physical and chemical effects of ploughing remain detectable for several decades. There is little evidence about how the effects of forestry activities in upland areas on soil-water chemistry are transferred to adjacent surface water bodies, including what role streamside discharge areas play. MSP increases the tree biomass C store and may increase the total ecosystem C store. The impact of MSP on the cover and abundance of ground vegetation species depends on the composition of the original plant community, MSP intensity, and the establishment rate of different species. Species cover generally seems to decline for late succession understory species, while pioneer and ruderal species can benefit from the microsites created. Areas containing lichens which are used for reindeer forage require special consideration. More research is needed on the environmental effects of MSP, particularly regarding its long-term effects. Further efforts should be made to develop efficient site-preparation practices which better balance the disturbance intensity with what is needed for successful regeneration.

Effects of Norway spruce shelter density and soil scarification method on mortality and height growth of underplanted European beech, European silver fir and Douglas fir

AbstractIn Europe, 6–7 million ha even-aged, pure stands of Norway spruce grown outside its natural range are prone to butt rot, windthrow, and bark beetle infestation. Climate change may well accelerate these problems and there is an urgent need to develop methods for converting Norway spruce plantations into more heterogeneous forest with larger resistance and resilience towards natural disturbances. Based on a field experiment located on former heathland on an outwash plain in western Denmark, we examined the mortality and height growth of European beech (Fagus sylvatica L.), European silver fir (Abies alba Mill.), and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) planted under a shelterwood of 17–19 m tall Norway spruce (Picea abies (L.) Karst.) at shelter densities initially ranging by basal area from 10 to 36 m2 ha−1 (271–1099 stems ha−1). Underplanting included plots of beech (100 per cent) and silver fir (100 per cent) as well as plots with two-species mixtures of silver fir/beech (66 per cent/33 per cent and 33 per cent/66 per cent) and Douglas fir/beech (66 per cent/33 per cent). The experiment also included two soil scarification methods (patch and strip scarification). The experiment was laid out in an unbalanced factorial split-plot design, replicated in time and space, and totaling 144 plots in four blocks. The experiment was followed for 19 years during which a gradual reduction in shelter density took place although in some plots the shelterwood was removed abruptly by windthrow and bark beetle infestation. Shelter densities larger than 10 m2 ha−1 had only a minor effect on the mortality of beech and silver fir, while shelter densities larger than 20 m2 ha−1 resulted in increased mortality of Douglas fir. Subsequent abrupt reduction in shelter density resulted in increased mortality, especially of silver fir. Height growth decreased with increasing shelter density, more for Douglas fir than for beech, and marginally more for beech than for silver fir. For shelter densities <15 m2 ha−1, height growth of silver fir was unaffected. Beech grew faster when mixed with Douglas fir. The soil scarification method did not influence mortality, but strip scarification resulted in marginally larger height growth than patch scarification. We hypothesize that the shelter effect was related mainly to competition for light, while late frost and browsing were important factors in open shelters (<10 m2 ha−1). Based on these results, recommended initial shelter densities are at or <10 m2 ha−1 for the establishment of Douglas fir, at ~15–20 m2 ha−1 for silver fir, and around 15 m2 ha−1 for beech.

Spatial variability of carbon and nitrogen stocks in integrated management systems and pasture in a cerrado region

The conversion of the native Cerrado into agricultural systems promotes a reduction in the input of organic residues on the soil, which can compromise the contents of soil organic carbon. The spatial distribution of carbon and nitrogen stocks in the soil is normally influenced by environmental and anthropogenic factors. This research aimed to map and evaluate the spatial variability of carbon and nitrogen stocks in the soil, in different integrated systems and pasture areas in the edaphoclimatic conditions of the Cerrado biome, in the state of Maranhão. The work was set up in a Red-Yellow Latosol with different management methods: crop-livestock integration with no-till farming, crop-livestock integration with patch scarification and harrowing, crop-livestock-forest integration, and pasture. The samples were removed at a depth of 0.0-0.20 m, in a grid with a regular interval of 50 m, totaling 193 points. The data were subjected to descriptive statistics, geostatistics, and kriging interpolation. The mean and median values are similar for the carbon and nitrogen stocks, in their respective management systems, indicating symmetric data distribution, confirmed by the asymmetry and kurtosis values close to zero. The spatial distribution of the carbon stocks is more homogeneous in the crop-livestock integration with no-till farming, whereas the crop-livestock integration with patch scarification and harrowing presents greater homogeneity in nitrogen distribution.

Influence of mechanical site preparation on regeneration success of planted conifers in clearcuts in Fennoscandia – a review

In the Nordic countries Finland, Norway and Sweden, the most common regeneration method is planting after clearcutting and, often, mechanical site preparation (MSP). The main focus of this study is to review quantitative effects that have been reported for the five main MSP methods in terms of survival and growth of manually planted coniferous seedlings of Norway spruce ( (L.) Karst.), Scots pine ( L.) and lodgepole pine ( var. Engelm.) in clearcuts in these three countries. Meta analyses are used to compare the effects of MSP methods to control areas where there was no MSP and identify any relationships with temperature sum and number of years after planting. In addition, the area of disturbed soil surface and the emergence of naturally regenerated seedlings are evaluated. The MSP methods considered are patch scarification, disc trenching, mounding, soil inversion and ploughing. Studies performed at sites with predominately mineral soils (with an organic topsoil no thicker than 0.30 m), in boreal, nemo-boreal and nemoral vegetation zones in the three Fenno-Scandinavian countries are included in the review. Data from 26 experimental and five survey studies in total were compiled and evaluated. The results show that survival rates of planted conifers at sites where seedlings are not strongly affected by pine weevil ( L.) are generally 80–90% after MSP, and 15–20 percent units higher than after planting in non-prepared sites. The experimental data indicated that soil inversion and potentially ploughing (few studies) give marginally greater rates than the other methods in this respect. The effects of MSP on survival seem to be independent of the temperature sum. Below 800 degree days, however, the reported survival rates are more variable. MSP generally results in trees 10–25% taller 10–15 years after planting compared to no MSP. The strength of the growth effect appears to be inversely related to the temperature sum. The compiled data may assist in the design, evaluation and comparison of possible regeneration chains, i.e. analyses of the efficiency and cost-effectiveness of multiple combinations of reforestation measures.Picea abiesPinus sylvestrisPinus contortalatifoliaHylobius abietis

Nine-year physiology, nutrition and morphological development of Picea glauca reintroduced by planting in a high-graded yellow birch–conifer stand

ABSTRACTDepletion of white spruce (Picea glauca) in mixedwood forest is a frequent problem, particularly in stands that were high-graded as a result of inadequate silviculture and spruce budworm (Choristoneura fumiferana) epidemics. To provide information that will help guide restoration efforts, we assessed the effect of four seed-tree retention (STR: 0, 10, 40 and 60 trees/ha) levels and two scarification (SC: patch scarification and disk-trenching) types on white spruce reintroduced by planting in a high-graded yellow birch (Betula alleghaniensis)–conifer stand. We present the 9-year results from the seedling physiology, nutrition and morphology. Physiology and nutrition changed with years, but did not vary with STR levels and SC types. Significant increases in the number of internodal branches, height growth, and total height at the two lowest STR levels and after release suggest that the performance of white spruce in terms of morphology and growth is sensitive to small variations in available light. Because seedling morphology and growth were similar between SC types, a moderate disturbance of the forest floor by disk-trenching would be sufficient at a relatively low cost. Our findings highlight that the STR levels influenced the morphology and growth of planted white spruce seedlings more than the SC types.

Soil respiration after slash and stump removal in three clear-cut areas with patch scarification and mounding

ABSTRACTWe studied the soil carbon dioxide respiration (Rs) at three clear-cut mesic forest sites in south, central and north central Finland, which had been treated with different intensities of stump lifting and slash removal and then patch mounded and planted with spruce. The follow-up period after the initial calibration lasted for five consecutive years. Throughout the study the Rs remained at fairly steady levels according to the study site and soil disturbance level. Based on a split-plot test using the general linear model there were no significant differences in the Rs between the different stump and slash removal treatments at the three study sites, but unaffected and moderately affected soil surfaces had significantly higher Rs than mounds and wheel ruts. We conclude that the removal of stumps and slash have minor direct effects on Rs, but large indirect effects through soil disturbance.

Natural regeneration after gap cutting in Scots pine stands in northern Finland

ABSTRACTThe objective of the study was to examine the success of regeneration in gaps of variable size in pine-dominated stands in terms of seedling density. It was based on an experiment in central Lapland containing circular clear-cut gaps of 20, 40 and 80 m in diameter on typical sub-xeric and xeric pine sites with site preparation (patch scarification). The observation period covered the first five years after cutting. The average number of seedlings that had emerged after gap cutting was about 22 000 ha−1 for pine and 7 000 ha−1 for birch. The proportion of regeneration sample plots without any pine seedlings was less than 10%. The seedling density diminished constantly with greater distance from the edge stand but indicating sufficient density up to the largest gap size in the study (diameter 80 m, area ca. 0.5 ha). Site preparation promoted regeneration remarkably, and we conclude that successful regeneration would be achieved in most cases with soil scarification exposing just 10–20% of the soil surface.

Rehabilitation silviculture in a high-graded temperate mixedwood stand in Quebec, Canada

Vast areas of hardwood and mixedwood forests of eastern North America have been high-graded in the past and need silvicultural treatments to increase their value and productivity. To rehabilitate a high-graded temperate mixedwood stand, in Quebec, Canada, we used a split–split-split plot design with three replicates to assess different seed-tree and strip cutting systems, in combination with scarification and planting. The experiment consisted of three regeneration cuts in main plots: 10 seed-trees/ha, 40 seed-trees/ha and a 40-m wide strip clearcut (0 seed-tree/ha) with 60 seed-trees/ha in leave strips, thereby resulting in four levels of tree retention, and all included understory brushing. We applied two types of scarification (patch scarification or disk-trenching) to subplots, two regeneration modes (natural regeneration or planting with white spruce [Picea glauca]) to sub-subplots and two mechanical release treatments (softwood or mixedwood production) to planted sub–sub-subplots. Density of seed-trees did not affect the natural regeneration dynamics after 5 years, but disk-trenching was more efficient for the establishment of yellow birch (Betula alleghaniensis) and sugar maple (Acer saccharum). Few seed-trees of desirable white spruce were present and most died standing, confirming the importance of supplemental planting. Height growth of planted seedlings was 15% higher in the 0 and 10 (26–27 cm/year) than in the 40 and 60 (23 cm/year) seed-trees/ha treatments, and release doubled mean height growth (33.1 vs. 16.6 cm/year). Despite intensive site preparation, pre-established beaked hazel (Corylus cornuta) and mountain maple (Acer spicatum) were present at high densities in the regeneration stratum. Controlling this recalcitrant layer might be the greatest challenge for rehabilitating degraded stands of the mixedwood forest, especially since the use of herbicides is prohibited on Quebec’s public lands.

The demand of hybrid aspen (<i>Populus tremula</i> × <i>P. tremuloides</i>) on site conditions for a successful establishment on forest land

Hybrid aspen ( L. × Michx.) is a deciduous tree species suitable for producing large amounts of renewable biomass during short rotations. Its potential under North European conditions could be largely extended if not only agricultural land but also forest land was used for cultivation. Unfortunately, the knowledge of appropriate forest site conditions and effects of site preparation methods on hybrid aspen establishment is limited. In this paper, two studies that explore these questions are presented. In the first study, the sensitivity to acid soils was tested under greenhouse conditions in two type of soils: a) peat soil limed to certain pH levels (3.4–5.7) and b) collected forest soils where pH varied from 3.9 to 5.3. The lowest pH level resulted in reduced growth, elsewhere no significant differences were found. The second study was applied in the field and investigated the effect of four site preparation methods on survival and growth. The methods were: 1) control with no site preparation, 2) patch scarification, 3) mounding and 4) soil inversion. While no differences were found for survival, mounding was generally the method with the highest growth and patch scarification was least successful. The result was probably an effect of good soil aeration and less competition from vegetation after mounding. The field study also revealed clonal differences in growth performance, which stresses the importance of clone selection prior to planting. The results of these studies indicate that hybrid aspen is less sensitive to variation in pH and site preparation methods compared with other poplar species, as have been found in similar studies.Populus tremulaP. tremuloides

Effects of soil preparation methods and plant types on the establishment of poplars on forest land

The success of poplar plantations on forest land was affected by soil preparation, plant type, site, and clone. Mounding in combination with large plant types (rooted plants or long cuttings) of site-adapted clones achieved the highest survival and growth. Poplars (Populus species and hybrids) are fast-growing trees used to make various products. In north European countries, they are mainly grown on agricultural land, but interest in planting poplars on forest land has increased. Plant damage and mortality problems occur on forest land, probably due to soil conditions and competing vegetation. It is therefore of interest to investigate whether combinations of soil preparation methods and plant materials can improve establishment. At three sites in southern Sweden, the effects of four soil preparation treatments (no soil preparation, patch scarification, mounding, soil inversion) in combination with three plant types (short cuttings, long cuttings, rooted plants) were studied. Survival and growth were significantly influenced by site, soil preparation method, plant type, and their interactions. Mounding resulted in the best overall performance on all sites. Interactions between site and plant type revealed differences in growth dependent on site conditions, but rooted plants and long cuttings were in general most successful. Patch scarification and short cuttings were associated with lower survival and growth. Soil preparation is needed to support survival and early growth, but the combination of method and plant type must be adapted to site conditions. The choice of clones should also be considered.

Soil-surface CO2 flux during the first 2 years after stump harvesting and site preparation in 14 Swedish forests

ABSTRACTStumps are a source of renewable energy (bioenergy) that can mitigate climate change. We aimed to determine whether conclusions from recent studies could be generalized for other sites by monitoring the in situ soil respiration (Rs) by a portable soil-respiration system of 14 clear-cut experimental sites during the first 2 years after stump extraction and site preparation. The sites were established all over Sweden in 2013 and 2014 and were subjected to no disturbance (Control), patch scarification (PatchS), disc trenching (DiscT), and stump harvesting (StumpH). During year 1, Rs from sites treated with PatchS and StumpH were 11% and 13% lower than Rs from Control sites. DiscT-treated sites were apt to produce lower Rs than the Control (−9%, p = .09). In the second year, there were no significant differences in Rs between treatments, as no soil disturbance type occurring after stump harvest and site preparation had higher Rs than untreated, intact soil. Our results suggest that soil disturbances resulting from stump harvest and site preparation do not generally increase Rs and thus, from this perspective, provide support for the use of stumps for bioenergy.

Long-term effects of stump harvesting and site preparation on pools and fluxes of soil carbon and nitrogen in central Sweden

ABSTRACTClear-cutting and subsequent site preparation is a common forest management practice in the Nordic countries. Slash and stumps have been suggested to replace fossil fuels in district heating plants. Stump/root removal from clear-cuts will reduce the amount of decomposable substrate in the soil and thus decrease soil CO2 emission, but stump lifting is also supposed to stimulate CO2 efflux and counteract CO2 reduction. To determine the effects of stump/root harvesting in relation to site preparation (stumps retained) on pools and fluxes of carbon (C) and nitrogen (N) after a period of 20–30 years, soil sampling was performed in four pairs of stump/root harvesting (S) and patch scarification (P) stands in central Sweden in 2009. Stump/root harvesting resulted in a significantly lower soil C pool in the humus layer. Annual heterotrophic respiration (RH) in the whole soil profile was significantly lower after the S than after the P treatment, the mean difference being 38 ± 23 g CO2–C m−2 year−1 (95% CI). This difference was larger than corresponding data from stump/root decomposition models (11–18 g CO2–C m−2 year−1), but both empirical and model data showed that stump/root harvesting will reduce heterotrophic soil CO2 emissions to the atmosphere during the actual period.

Negative effects of stem and stump harvest and deep soil cultivation on the soil carbon and nitrogen pools are mitigated by enhanced tree growth

New energy policies in many forest rich countries have promoted the utilization of industrial and logging residues for energy purposes. This practice is, however, questioned from a climate change mitigation point of view, particularly when it comes to the harvest of coarse woody biomass like stem wood and stumps.Stump harvest removes slowly decomposing biomass with its carbon (C) and nutrients. The harvest operations also cause soil disturbance that may stimulate mineralization of the soil organic pool, and thereby further increase the C and nutrient loss from the site. However, increased mineralization and expected decrease in amount of competing vegetation could make more nutrients available that stimulates growth of the new tree generation and thereby compensates for the soil C loss.Based on two field experiments, located in southern and northern Sweden, we present C and nitrogen (N) pool data in soil (0–70cm depth) and tree biomass 22 and 24years after stem and stump harvest and deep soil cultivation (SS-DSC) in comparison to conventional stem-only harvest and a manual patch scarification (S-PS). The SS-DSC management practice represents a “worst case” in terms of potential C and N loss.We tested the hypotheses that SS-DSC (i) will reduce C and N pools in the soil; (ii) will increase C and N pools in the planted trees; (iii) will not have any effect on the total C and N pools (soil and tree biomass) as compared to S-PS.Soil C and N pools were lower following SS-DSC in line with hypothesis (i) but only statistically different for C at the northern site. Tree biomass C and N pools were significantly increased by the SS-DSC treatment in line with hypothesis (ii). As a result, the total C and N pools were not significantly affected by SS-DSC in line with hypothesis (iii).The main conclusion from these results is that judgments on the effects of silvicultural measures on the forest C and N balances or net greenhouse gas emissions cannot be based on measurements of single C or N pool changes (i.e. in the soil or in the trees only) – it has to be based on changes in the total C or N pool. The trade-off between soil and tree biomass C and N pools is discussed in terms of possible causes, current forestry practices, and the climate change mitigation potential of soil vs. tree biomass C.

Black spruce growth and survival in boreal open woodlands 10 years following mechanical site preparation and planting

Since 1950, the creation of open woodlands has increased in Canada's northeastern continuous boreal forest and recent studies have demonstrated that the mechanisms underlying their creation are similar to those found in the lichen woodland zone. Since no natural re-densification of open woodlands has been observed to date, afforestation is necessary to counteract an increase of these types of stands in the continuous boreal forest. The aim of this study was to test the operational feasibility and success of afforestation efforts in open woodlands, 10 years after planting. The experimental design included different containerized seedling stocks and site preparation approaches, such as patch and disk scarification, and covered most of the geographical range of accessible continuous boreal forest in Quebec. In open woodlands, regardless of black spruce stock size, disk scarification increased planted seedling survival and growth compared with patch scarification and direct planting, possibly due to a beneficial effect on seedling nutrition. However, even if seedling growth in open woodlands and feathermoss stands submitted to disk scarification was comparable, growth was higher in the latter stands. Nonetheless, we conclude that disk scarification followed by planting is an appropriate method to afforest boreal open woodlands.

Regeneration result of excavator-mounted rototiller in direct seeding of Scots pine on forestry-drained peatland

The need to regenerate peatland forests is expected to increase in the near future in Finland due to harvest of large amounts of peatlands drained during the 1950s and 1960s. In anticipation of this, a new type of excavator-mounted rototiller for soil scarification in peatlands has been developed in Finland to improve the moisture conditions of the seedbed by mixing the ground vegetation, raw humus layer, and peat. The regeneration result of the new rototiller was compared with traditional patch scarification (i.e. scalping) in direct seeding of Scots pine in three forestry-drained peatland sites in eastern Finland. After two growing seasons, rototilling offered no advantage over scalping in terms of the number of established seedlings, probability of empty patches, or seedling height. Seedling establishment was on average higher on scalping (10%) than on rototilling (8%). The main problem in rototilling may have been the loose and porous structure of the seedbed resulting in drought and frost damages.

Soil-CO2 flux after patch scarification, harrowing and stump harvest in a hemi-boreal forest

Stump harvesting is one way of increasing the amount of bioenergy, but little is known about the consequences of tree-stump harvesting on the carbon balance in the forest. Therefore, soil-surface CO2 flux (soil respiration, R s) was determined two years after clear-cutting for common soil disturbances occurring after patch scarification, harrowing and stump harvest in southern Sweden. R s from intact soil was found to be of the same magnitude as emissions from areas of mixed humus, indicating only small effects of disturbance. Elevated mounds produced lower emissions than in the intact soil during the second year despite larger amounts of organic matter, probably due to low soil moisture. The lowest R s was found in soil surfaces with exposed mineral soil. The treatment effects on R s were estimated considering the actual area of different disturbances. During the first year, there was no difference in R s among the treatments, whereas in the second year the flux was 10% higher after harrowing and stump harvesting than after patch scarification, implying that the effects on CO2 flux after stump harvest were comparable to conventional harrowing. However, it is unclear whether this finding basically applies to regions where decomposition is limited by soil moisture during the summer.

Regeneration and tree growth dynamics of Picea abies, Betula pendula and Betula pubescens in regeneration areas treated with spot mounding in southern Finland

This study addresses the dynamics of young stands established in areas of southern Finland which have been site prepared with spot mounding and planted with Norway spruce. The principal attributes investigated were the density of natural birch on the major soil surface types associated with the method (mounds, patches and undisturbed soil) and the growth rate of the planted spruces compared with natural birches. The study material included 18 regeneration areas treated with spot mounding and planted with Norway spruce container seedlings, around three, six or nine growing seasons before measurement. Rather than permanent plots that would have constituted a genuine time series, the data collected for the study originated from a sample of stands of different ages. The results indicated that there were comparatively few birches on the mounds after 3 years, but greater average densities were evident at 6 and 9 years than on the patches and undisturbed soil. Compared with methods such as patch scarification and disc trenching, the observed delay in the emergence of birch probably gives spruce a competitive advantage during the most susceptible, earliest stages of development in spot mounding.

Effects of granivorous rodents on direct seeding of oak and beech in relation to site preparation and sowing date

Planting bare-rooted seedlings is a rather expensive method to regenerate oak ( Quercus robur) and beech ( Fagus sylvatica). Direct seeding could reduce artificial regeneration costs substantially, but the method currently suffers from a number of problems, one of which is seed consumption by rodents. In the present study clear-cut areas in southern Sweden were prepared using one of four different mechanical site preparation methods – disc trenching, patch scarification, topsoil removal or mounding – then manually sown with acorns and beech nuts. Acorns were sown in May and July 2006, and both acorns and beech nuts were sown in May 2007. Three years following sowing, best seedling establishment from viable acorns, 60–70%, was achieved after sowing in mounds in May, and the subsequent survival reached 90–100%. After the first growing season for beech, both seedling establishment and subsequent survival was lower than for oak, which coincides with a higher number of lost beech nuts at the excavation to investigate the fate of seeds. Granivorous rodents ( Apodemus flavicollis, A. sylvaticus, Mus musculus, and Myodes glareolus) were live-trapped more frequently in the vicinity of slash piles compared to other micro-site features, such as uprooted stumps, snags and stones. In 2006, no connection was found between number of rodents captured and proportion of lost seeds, while in 2007 the two were in good accordance. No clear relationship was found between number of captured rodents, vegetation cover class and mechanical site preparation method. More rodents were captured in 2007 than in 2006, and there was an increase in captures from spring until late summer/autumn for both years, which was mirrored in the seedling establishment result from the three different times of sowing. Based on experiences from the present study the recommendation for successful direct seeding of oak on clear-cuts is a combination of mounding site preparation, removal of slash and sowing in May rather than July. However, the results indicate that successful direct seeding of beech is more difficult to achieve.

Scots pine stand establishment with special emphasis on uncertainty and cost-effectiveness, the case of northern Finland

The effect of uncertainty on the cost-effectiveness of alternative chains of stand establishment in northern Finland was examined. The data were from a reforestation study of Scots pine (Pinus sylvestris L.) consisting of 288 sample plots, which were measured with respect to regeneration success. The study design included four site-preparation methods (patch scarification, ploughing, prescribed burning and disk trenching) combined with three reforestation methods (sowing, planting with containerized seedlings and planting with bare-rooted transplants). Initial reforestation density was 2,500 spots or seedlings per hectare, and the regeneration success was modeled as probability with two thresholds, namely 500 and 1,100 saplings. On formerly spruce-dominated as well as pine-dominated sites the most cost-effective chain was ploughing and planting with containerized seedlings, when threshold was 1,100 saplings per hectare. However, with threshold of 500 saplings the best performer was ploughing and direct sowing on both sites.