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1.
Average tree height and basal area growth for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) in Sweden were studied as functions of species, age, stand density, location and year of inventory in the period 1953–1992, on the basis of sample tree data from the National Forest Inventory. A highly significant annual increase of both height and basal area growth was found, of the magnitude 0.5–0.8%, during the 40 yr period. Possible reasons for the trend are discussed. The altered way of cutting in the early 1950s, from selective cutting to clear felling and thinning from below, has had a large impact. Also, improved regeneration methods, nitrogen fertilization and ditching have increased growth. The increasing atmospheric deposition of nitrogen is another possible factor.  相似文献   

2.
Correlations between root growth capacity (RGC), at the time of planting, and field performance were studied for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings. Before planting a gradient in seedling viability was generated through exposure to low root temperatures and different winter storage regimes. The hypothesis that high RGC values would improve field performance was to some extent verified for pine seedlings while no correlations could be registered for spruce. Reasons for these results are discussed.  相似文献   

3.
In single‐tree selection, trees removed by harvest or lost through mortality are replaced by ingrowth from the seedling/sapling bank. Because the level of ingrowth is governed not only by the recruitment rate of new seedlings, but also by mortality and growth rates within the seedling/sapling stratum, knowledge of how these processes are related to the tree stratum is important for successful application of single‐tree selection. Therefore, Norway spruce (Picea abies (L.) Karst.) regeneration (0.1 m ≤ height ≤ 2.0 m) was measured on seventy 100 m2 circular subplots at each of two sites in central and northern Sweden. Both sites had previously been selectively logged, but the time elapsed since the last harvest was at least 30 yrs. Basal area of trees of at least 2 m height within three different radii from the subplot centres was measured. Measurements on regeneration included height and leader length. Influence of local stand basal area on density and growth of regeneration was analysed by ordinary least‐squares linear regression for each of four height intervals. Regeneration was significantly aggregated at both sites, but number of Norway spruce seedlings and saplings per circular subplot was not correlated to local stand basal area. Out of 36 regressions, only eight showed a significantly (p < 0.05) negative correlation between seedling and sapling height growth and local stand basal area. In five of these cases, removal of one point (subplot) made p > 0.05. The results suggest that density and growth of Norway spruce regeneration in selectively logged uneven‐aged Norway spruce stands is affected more by ground conditions than by local stand basal area.  相似文献   

4.
The study was focused on severe forest regeneration problems that are typical for highly productive peatlands. The aim of the study was to give recommendations for practical forestry on how to renew the forests. Experiments with different forest regeneration methods on highly productive peatlands were set up in nine mature Norway spruce (Picea abies (L.) Karst.) forests in northern, central and southern Sweden. The treatments in the study were natural regeneration in shelterwoods (at densities of 140 and 200 stems ha‐1), planting of bare‐root spruce seedlings after site preparation (mounding) in the shelterwoods and on clearcuts, and planting without site preparation on clearcuts.

Judging from the extent of windthrow in the denser shelterwoods and the stocking of natural regeneration under remaining shelter trees 4–5 years after final cut, shelterwood regeneration is a promising method. On clearcuts, planting without site preparation resulted in poor seedling survival, large extent of damage to the seedlings and small height increment. Planting in mounds on the clearcuts was much more successful. The best survival of planted seedlings was observed in the shelterwoods. Both the denser and the sparse shelterwoods seemed to give satisfactory protection to the seedlings.

Final recommendations on the most suitable forest renewal method(s) will be made in about five years after the removal of the shelter trees.  相似文献   

5.
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6.
In the Nordic countries, Norway spruce (Picea abies) is a major species in tree breeding. In order to facilitate breeding work and availability of highly bred forest regeneration material, the time required for breeding and implementation of results should be shortened. This could be done by accelerating production of clonal material for field testing, and possibly for planting stock, by combining production of rooted cuttings with somatic embryogenesis (SE). This would allow efficient production of numerous plants of the same genotype, with equal age and propagation history between genotypes. In the present work, we studied the rooting potential of cuttings from Norway spruce emblings. Altogether 36 clones from 12 families representing elite breeding materials and ornamental forms were examined under different rooting conditions (container type and rooting media) in 2015 and 2016. Our results show that Norway spruce emblings are good donors for cuttings. Best combination (peat–vermiculite mixture and Plantek 81f containers) resulted in 91% rooting, variation among the tested clones of elite breeding materials being 55–100% per treatment. The rooting variation between families is acceptable for breeding purposes. High rooting (87–96%) of ornamental forms indicates propagation potential with the combination of SE and rooted cuttings.  相似文献   

7.
Abstract

An experiment was established in 1978 in two Norway spruce [Picea abies (L.) Karst.] plantations in southern Sweden to study yield after mortality in patches with and without supplementarily planted (SP) seedlings. Gaps of different sizes were created by removing the originally planted seedlings. The gaps were either left unplanted or a supplementary planting was performed with one of four species [Norway spruce, Scots pine (Pinus sylvestris L.), lodgepole pine (Pinus contorta Dougl.) or hybrid larch (Larix deciduas Mill×L. Leptolepis Gord.)] 2 (at Knäred) or 6 years (at Ullasjö) after the original plantation. In 2002, most of the SP Scots pine, lodgepole pine and hybrid larch seedlings were dead or severely damaged by roe deer and moose. Survival was high among SP Norway spruces, but they had slower growth than the originally planted spruces. Growth was lower at Ullasjö than at Knäred. In Ullasjö, growth was lower in small gaps than in large gaps. Trees in original regeneration in areas surrounding unplanted gaps were larger than trees surrounding gaps with SP seedlings, which in turn were larger than originally planted trees in plots without gaps. In conclusion, because the original plantation surrounding unplanted gaps used a large part of the open space and growth of SP seedlings was slow, supplementary planting resulted in an insignificant growth increase. However, supplementary planting may increase the timber quality of trees surrounding the gaps, although this effect remains to be quantified.  相似文献   

8.
The single-tree selection system is an important option for management of Norway spruce (Picea abies (L.) Karst.) and silver fir (Abies alba Mill.) forests because it provides continuous cover, requires low investments for tending, and promotes natural regeneration as well as high stand resistance and elasticity. It is often regarded as a very conservative system that usually results in only minor spatiotemporal changes in forest structure and composition. We studied management history, structural changes, regeneration dynamics, and light climate of a traditional single-tree farmer selection silver fir-Norway spruce forest (site typology Bazzanio-Abietetum). Stand structure was analyzed on five 0.25 ha permanent plots in 1994, 2001, and 2008. Regeneration density and height growth, forest floor vegetation, and light climate were also assessed on 1.5 × 1.5 m regeneration subplots in 2001 and 2008. Tree cores extracted from dominant trees from both species in two plots were used for reconstructing stand history and age structure of the canopy layer. We documented the forest response to three types of selection management regimes: excessive, normal, and conservative. Excessive management with harvest intensity significantly above the increment was documented until the late 1950s, including two peaks of heavy fellings (diameter limit cut) in the 1880s and 1930s, which favoured establishment of Norway spruce and released regeneration. The period that followed was characterized by normal selection management, but was nevertheless marked by a decline of silver fir as a result of air pollution and several droughts. This led to sanitary fellings that were carried out from the late 1970s to the early 1990s. In the last two decades conservative management followed, which led to suppression and decline of regeneration, especially of Norway spruce, and loss of selection structure. Although we recorded lower regeneration potential of silver fir compared with Norway spruce within the seedling category, silver fir outcompeted Norway spruce within the small-sized tree category (1 cm < dbh ? 10 cm) because of its superior height growth in low light levels (diffuse light <6%) and occupied a greater share of the canopy. Nevertheless, we anticipate that over the long-term the low light regime will also cause regeneration decline of silver fir and broadleaves. Our research revealed significant structural changes in a single-tree farmer selection forest during the last 150 years. These were a result of variable management regime and environment. A farmer single-tree selection system could better mimic the natural disturbance regime if spatiotemporal combinations of diverse felling regimes would be used.  相似文献   

9.
In the absence of reliable and representative data on the frequency of seed years, seed amounts, germination and survival of seeds, the data of the observation period 1992–1996 of the permanent national forest inventory of Austria are used to develop a model describing the probability for the occurrence, density and height of Norway spruce (Picea abies (L.) Karst) natural regeneration in the forests of Austria. The forest inventory provided data on natural regeneration (saplings between 10 and 130 cm height) on clusters within a 3.89 km square sampling grid. A logistic equation is used to predict the probability for natural regeneration occurrence. Input parameters for this equation are the variables that describe the site, with slope and azimuth as continuous variables, and growth districts and vegetation types as discrete variables; the crown competition factor describes density and the quadratic mean diameter describes the stage of development of the stand. The same equation type is used to predict the probability for the occurrence of Norway spruce, conditional on the occurrence of some regeneration. An additional variable in this species specific model is a dummy variable which is set to 1 if Norway spruce occurs in the overstory and otherwise zero. Additional site variables entering this model are elevation and vegetation types characterizing soil fertility and moisture. Because the density and height of spruce regeneration depends on the stand's susceptibility to browsing, the probability for browsing is also modelled as a logistic equation depending on elevation, vegetation type, and stand density. Finally the probability distribution for height and density of the regeneration is described by two bivariate Weibull-distributions, each one describing browsed and unbrowsed Norway spruce regeneration respectively.  相似文献   

10.
This study explores the economic feasibility of several long-rotation afforestation scenarios for southern Ontario, Canada. Three species, red pine (Pinus resinosa Ait.), Norway spruce (Picea abies L.) and black walnut (Juglans nigra L.) are examined. We integrate growth and yield models, site suitability maps, and several management scenarios to investigate the investment attractiveness of these species inclusive and exclusive of carbon sequestration values. We report net present values (NPV), internal rates of return (IRR) and two break-even price metrics. For wood value only scenarios the IRRs range from 4.3 to 4.6% for red pine and 3.4–3.6% for Norway spruce (for the most attractive 10,000 ha, in a single rotation scenario). Black walnut had rates of return 3.5–3.7% for the most attractive 10,000 ha area. Adding carbon valued at Cdn $3.4 per metric ton CO2 − e (roughly 2005 prices in the Chicago Climate Exchange) increases rates of return by about 0.6% for red pine and Norway spruce and 0.4% for black walnut scenarios. Perhaps surprisingly these returns are comparable and better than 20-year rotation hybrid poplar plantations. To achieve a 6% real rate of return break-even carbon prices were $10.7/t CO2 − e for red pine, $12.6/t CO2 − e for Norway spruce and $17.2/t CO2 − e for black walnut (again for the “best” 10,000 ha). Although somewhat unremarkable, the results suggest that these longer-rotation species may be a better investment than perhaps previously expected if landowners have the appropriate site conditions.  相似文献   

11.
Roots of 1‐year‐old containerized seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) were experimentally frozen in December. The seedlings were then grown for 3 weeks in a growth chamber and evaluated with regard to root growth capacity (RGC) and shoot elongation. The subsequent RGC of Scots pine declined as root zone temperatures were lowered from ‐6°C to ‐11°C and from ‐11°C to ‐16°C. Almost no root growth was observed after exposure to ‐20°C. Shoot growth was also negatively affected by low root temperatures but less than root growth. Low root temperatures did not affect Norway spruce as much as Scots pine, although root and shoot growth of Norway spruce were reduced after exposure to the lowest test temperatures (‐16°C and ‐20°C). The length of exposure, ranging between 1 and 8 hours had no effect on subsequent growth.  相似文献   

12.
Mean diameter by basal area (dg) is an important stand variable for long‐term economic forecasts of forest holdings. In order to use stand‐by‐stand surveys based on aerial photo interpretation as the data basis for forecasts, dg has to be determined. The objective was to develop and test a regression function for dg in mature stands of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) applicable in southeastern Norway. A study of 700 plots was used to estimate a function for dg . An additive model was found to be most suitable. The independent variables were potential yield capacity, Lorey's mean tree height, crown closure determined by ocular estimation by means of aerial photographs, and the product of potential yield capacity and crown closure. The R2 value was 0.604 and the coefficient of variation was 10.8%. The regression fitted most parts of the calibration data quite well, but it may overestimate the mean diameter in pure spruce stands by 1–2%, and underestimate the diameter in pure pine stands by 3%. For mixed coniferous stands the regression seems satisfactory. Testing by means of an independent data set showed systematic errors of 3–23%. The systematic errors were due partly to calibration problems in connection with the ocular crown closure estimation.  相似文献   

13.
Heiskanen  Juha 《New Forests》2004,27(2):101-114
Norway spruce (Picea abies (L.) Karst.) is shade-tolerant and sensitive to high irradiance, summer frosts and winter desiccation, which can impair its reforestation success. In this study, artificial pre- and post-planting shading was examined to determine their effects on post-planting shoot and root growth as well as the vigor of one- and two-year-old Norway spruce seedlings. Three planting experiments were carried out on open nursery fields (Exp. 1, 2) and on a mounded forest clearcut in central Finland (Exp. 3). Before planting, the seedlings were stored over winter either in a freezer or on open fields under snow cover. For two weeks prior to planting, half of the seedlings were placed in the open and the other half under a horizontal shade netting (light transmittance 56 %) (Exp. 1, 2). All seedlings were planted with or without a vertical post-planting shade, which was located on the southern side. Post-planting shading enhanced shoot growth and reduced damage (better visual vigor and needle color and less pine-weevil damage) on Norway spruce seedlings for at least two years after planting (Exp. 2, 3). Those seedlings, that had been stored over winter in the open and kept in shade prior to planting seemed to benefit most from post-planting shading (Exp. 2). However, post-planting shading may give variable results, depending on the seedling quality and weather conditions after planting, and may even reduce shoot growth if no pre-planting shading is used (Exp. 1). Shoot growth may also be improved at the expense of root growth (Exp. 3). The costs of manufacturing and installing post-planting shades may limit their use in practice, for example, to selected regeneration sites where there is high risk of frost damage but where no alternative silvicultural procedure (shelterwood or nurse crop) has been used.  相似文献   

14.
Incoming shortwave global radiation (Q g) and photosynthetically active radiation (PAR; Q pa as a fraction of full daylight, relative irradiance (%Q), were measured at the same time in young stands of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). Measurements were made on three levels above ground: 20 cm above ground and 50 and 15 % of stand height. Stands of three heights (75, 150 and 300 cm) were studied during two months. The stands were created by arranging young trees cut from natural stands, in nine quadratic spacings: 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0, 1.4 and 2.0 m. The leaf area index (L) was estimated. Differences in %Q‐values for Q pa and Qg in the same species and at the same stand height and level of light measurements above ground were significant only in 150 and 300 cm stands. In 75 cm high stands of Scots pine, the %Q was <60% at spacings <0.2 m and in 75 cm high stands of Norway spruce, the %Q was <60% at spacings <0.3 m. Only at 0.1x0.1–0.3x0.3 m, %Q was <20% in Norway spruce stands. In 150 cm stands %Q<20% was measured at spacings <0.7 m in Norway spruce and <0.5 in Scots pine. In 300 cm stands of Norway spruce it was measured up to 1.2 and in Scots pine <1.1 m. Light extinction coefficients, K and Kg for spruce and pine stands were 0.17–0.40 and 0.16–0.31 respectively. Some practical implications of the study are presented. Lack of light (%Q<10%) as a single factor of seriously suppressed growth and development of broad‐leaved plants and suckers by competition in young stands of spruce and pine only occur in dense stands 0.3x0.3 m‐1.1xl.l m (8000–100000 stems/hectare). Competition by light on a regenerated area generally occurs in the level of 50% of tree height (150–300 cm) and higher due to the rapid growth of broad‐leaved trees (sprouts) compared with planted conifers but the light intensity at these levels %Q>10%.  相似文献   

15.

Artificial regeneration of Scots pine (Pinus sylvestris L.) has been applied to a variety of forest site in Lapland. Occasional failures in regeneration have been observed on sites with high soil moisture contents and originally dominated by Norway spruce (Picea abies (L.) Karst). Understorey vegetation was studied on four naturally pine-dominated and eight spruce-dominated sites to determine suitable indicator plants for assessing soil moisture regimes. Soil moisture contents were estimated using the in situ dielectric measurements with radar surface arrival detection targeted to a depth of 0-50 cm. The abundance and frequence of plant species were analysed using logistic regression. The most reliable indicators were found to be Stereocaulon and Cladonia lichens for the dry regime (θv<25%), and Polytrichum commune Hedw. and Carex globularis L. for the wet regime (θv>25%). It was concluded that the indicator plants found in this study provide an alternative to the traditional Finnish forest site type approach in recognizing high soil moisture regimes.  相似文献   

16.
Jari Miina  Timo Saksa 《New Forests》2006,32(3):265-283
This study predicts the regeneration establishment on 3-year-old Norway spruce (Picea abies (L.) Karst.) plantations in southern Finland using regeneration survey data. Regeneration establishment was described by seven response variables: number of planted spruces, natural Scots pines (Pinus sylvestris L.), natural spruces, natural seed-origin birches (Betula pubescens Ehrh. and B. pendula Roth.) and other broadleaves (i.e. sprout-origin birches and other broadleaves than birch), as well as height of crop-tree spruce and dominant height of broadleaves. Due to the multivariate (several responses for each plot) and multilevel (plot, stand, municipality, forest centre) structure, regeneration establishment was modelled by fitting a multivariate multilevel model with explanatory variables such as temperature sum, site fertility, soil quality and method of site preparation. In the model, the numbers of tree seedlings were modelled using over-dispersed Poisson distributed equations, and the tree heights were modelled using normally distributed linear equations. The estimated fixed and random parameters of the equations were logical, and there was no serious bias in predicting the regeneration establishment in the independent test data set. This modelling approach can be used to predict the regeneration establishment stochastically by taking into account the large unexplained variation in regeneration models.  相似文献   

17.
Abstract

The economic outcomes of stump treatment against spore infections of the root rot pathogen Heterobasiodion annosum s. l. were analysed based on simulations in four stands typical of Swedish forestry and forest management: (A) Norway spruce [Picea abies (L.) Karst.] stand on former agricultural soil (SI?=?32), (B) Norway spruce stand (SI?=?26) on forest land; (C) Mixed stand of Norway spruce and Scots pine (Pinus sylvestris L.) (SI?=?24) with only H. parviporum present, i.e. no infection of Scots pine and no possibility of interspecies spread of disease between hosts; and (D) same as C, but H. annosum s. str. (Fr.) Bref and H. parviporum Niemelä & Korhonen present, i.e. interspecies spread of disease possible. Models for disease development, growth and yield and cross-cutting were used in the simulations. The simulated decay frequency in Norway spruce trees ranged between 2 and 90%. Stump treatment at the previous final felling and in all thinning operations was profitable at interest rates 1 and 3% in stands A, B and D, but not in stand C. In stand C, no stump treatment at all or treatment in thinnings only gave the highest net future value. Implications for stump treatment in practical forestry are discussed.  相似文献   

18.
A stage‐structured model for projecting stand growth and yield is coupled with a gradient‐based algorithm to determine optimal treatment regimes for Norway spruce (Picea abies Karst.) plantations. The growth model forecasts the movement of trees between 3 cm diameter classes using a growth matrix that includes nonlinear equations for diameter growth. Because harvest treatments may be specified by tree diameter class, the model allows the determination of the optimal thinning timing, thinning intensity, and thinning type simultaneously with planting density and clearfelling age. The optimization model is used to determine treatment regimes with and without thinning for a wide range of values for economic and biological parameters. Results show that the optimal economic planting density is highly sensitive to interest rate, logging costs, planting costs and site class. For a given set of economic parameters, the optimal planting density is not sensitive to the number of thinnings performed or the thinning intensity. Top thinning is the optimal method for every regime in which thinning is scheduled. Results indicate that managers have great flexibility in choosing thinning schedules: few thinnings and shorter rotations give almost the same economic results as more frequent thinnings and longer rotations. Major uncertainties in these results and areas for further research are discussed.  相似文献   

19.
Damage by the large pine weevil, Hylobius abietis (L.), is a major threat to conifer plantations throughout Eurasia, but damage is usually less severe in northern areas. However, pine weevil damage seems to increase if the sites are burnt. The aim of this study was to determine the effects of variations in the time of planting (with respect to the total age of the clear-cut and the time since burning) on pine weevil damage to seedlings on burnt sites in northern Sweden. The study also explored whether there is an optimal time for planting at which damage levels are reduced to acceptable levels. Ten sites were selected in an inland area of northern Sweden where pine weevils are normally scarce. The sites were dry–mesic and represented a range of times since clear-cutting and since burning. The sites were planted in June 1998, 1999 and 2000 with 1-year-old container-grown seedlings of Norway spruce [Picea abies (L.) Karst.]. Pine weevil damage was reduced if planting was done no earlier than 3 years after clear-cutting and no earlier than 2 years after burning. Planting too soon after burning, irrespective of the age of the clear-cut, resulted in unacceptably high damage levels.  相似文献   

20.
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