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1.
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2.
Since the mid-1970's new types of forest damage (of unknown origin) were observed in West Germany. Nonspecific foliage losses and foliar discolorations are the most common symptoms. This resulted in a comprehensive research program being initiated in the fall of 1983 to investigate the nutritional status of Norway spruce (Picea abies (L.) Karst.) stands in southwest Germany, growing on a variety of sites. Forests at these sites revealed light to moderate damage or acute site-and species-specific nutritional disturbances involving Mg, K, Ca, Mn, and Zn. Historical comparisons of needle-analysis data showed a dramatic change of the nutrient supply at many sites over the last one or two decades.

As a working hypothesis, the adverse impacts of air pollutants (e.g. photo-oxidants) and/or acidic atmospheric precipitation are seen as inciting factors causing increased leaching of nutrient elements. The tree's potential to compensate for the nutrient losses by increased uptake are limited by the often poor nutrient supply for forest soils. Accelerated soil acidification increase nutrient leaching from the soil, probably enhancing decline. Over a short period, fertilization led to a decrease or to the disappearance of the symptoms, and to the improvement in the nutrient composition of the foliage.

Microscopy investigation of Norway-spruce needles indicated the regeneration potential on a histological level for moderate yellowed needles after fertilization. Furthermore, needles of nutrient-deficient-trees reveal typical tissue damages different to those caused by SO2 or O3.

Acid mist increased the leaching of K, Ca, Mg, Mn, and Zn from the foliage. Even when nutrients are being leached from the foliage, nutrient uptake canbe increased by improving the nutrient supply in the soil.

Preliminary studies on the effects of damages caused by ozone (O3) on ponderosa pine suggest imbalance in micronutrient concentrations of foliage.  相似文献   


3.
A process-based ecosystem model was used to assess the impacts of changing climate on net photosynthesis and total stem wood growth in relation to water availability in two unmanaged Norway spruce (Picea abies) dominant stands with a mixture of Scots pine (Pinus sylvestris) and birch (Betula sp.). The mixed stands were grown over a 100-year rotation (2000-99) in southern and northern Finland with initial species shares of 50, 25 and 25% for Norway spruce, Scots pine and birch, respectively. In addition, pure Norway spruce, Scots pine and birch stands were used as a comparison to identify whether species' response is different in mixed and pure stands. Soil type and moisture conditions (moderate drought) were expected to be the same at the beginning of the simulations irrespective of site location. Regardless of tree species, both annual net canopy photosynthesis (P(nc)) and total stem wood growth (V(s)) were, on average, lower on the southern site under the changing climate compared with the current climate (difference increasing toward the end of the rotation); the opposite was the case for the northern site. Regarding the stand water budget, evapotranspiration (E(T)) was higher under the changing climate regardless of site location. Transpiration and evaporation from the canopy affected water depletion the most. Norway spruce and birch accounted for most of the water depletion in mixed stands on both sites regardless of climatic condition. The annual soil water deficit (W(d)) was higher on the southern site under the changing climate. On the northern site, the situation was the opposite. According to our results, the growth of pure Norway spruce stands in southern Finland could be even lower than the growth of Norway spruce in mixed stands under the changing climate. The opposite was found for pure Scots pine and birch stands due to lower water depletion. This indicates that in the future the management should be properly adapted to climate change in order to sustain the productivity of mixed stands dominated by Norway spruce.  相似文献   

4.
The aim of this study was to determine how soil chemistry and the distribution of fine roots (<1 mm) in the organic and upper mineral soil horizons were affected by an admixture of birch (Betula pendula Roth and B. pubescens Ehrh.) in Norway spruce (Picea abies (L.) Karst) stands. The surface organic horizons (LF and H) and mineral soil were characterized to a depth of 10 cm on three sites in southern and central Sweden. On these sites, replicated plots had been established that contained either ca. 30-year-old birch growing as a shelter over similar-aged spruce (mixed plots) or spruce only. The treatments had been created 8–11 years before this study was done. A fourth site, with plots containing ca. 90-year-old spruce or birch/spruce, and a fifth site, with 30-year-old spruce and a low admixture (12% by basal area) of birch, were also included in the study. Concentrations of Ca and Mg and pH in the LF layer were significantly higher in plots with a birch admixture. In the H-horizon, concentrations of K, Ca and Mg were significantly higher in mixed plots than in plots with pure spruce. Consequently, base saturation was higher in mixed plots than in pure spruce plots. A shelter of birch decreased the total amount of spruce fine roots (<1 mm), as revealed at one of the sites. Total fine root biomass (birch + spruce) in the organic and mineral soil horizons (to 10 cm) did not differ significantly between the pure spruce stands and the spruce stands with a birch shelter.  相似文献   

5.
Carbon (C) sequestration was studied in managed boreal forest stands and in wood products under current and changing climate in Finland. The C flows were simulated with a gap-type forest model interfaced with a wood product model. Sites in the simulations represented medium fertile southern and northern Finland sites, and stands were pure Scots pine and Norway spruce stands or mixtures of silver and pubescent birch.

Changing climate increased C sequestration clearly in northern Finland, but in southern Finland sequestration even decreased. Temperature is currently the major factor limiting tree growth in northern Finland. In southern Finland, the total average C balance over the 150 year period increased slightly in Scots pine stands and wood products, from 0.78 Mg C ha−1 per year to 0.84 Mg C ha−1 per year, while in birch stands and wood products the increase was larger, from 0.64 Mg C ha−1 per year to 0.92 Mg C ha−1 per year. In Norway spruce stands and wood products, the total average balance decreased substantially, from 0.96 Mg C ha−1 per year to 0.32 Mg C ha−1 per year. In northern Finland, the total average C balance of the 150 year period increased under changing climate, regardless of tree species: in Scots pine stands and wood products from 1.10 Mg C ha−1 per year to 1.42 Mg C ha−1 per year, in Norway spruce stands and wood products from 0.69 Mg C ha−1 per year to 0.99 Mg C ha−1 per year, and in birch stands and wood products from 0.43 Mg C ha−1 per year to 0.60 Mg C ha−1 per year.

C sequestration in unmanaged stands was larger than in managed systems, regardless of climate. However, wood products should be included in C sequestration assessments since 12–55% of the total 45–214 Mg C ha−1 after 150 years' simulation was in products, depending on tree species, climate and location. The largest C flow from managed system back into the atmosphere was from litter, 36–47% of the total flow, from vegetation 22–32%, from soil organic matter 25–30%. Emissions from the production process and burning of discarded products were 1–6% of the total flow, and emissions from landfills less than 1%.  相似文献   


6.
Conifer dominated plantations in central and northern Europe are associated with relatively low ecological values, and in some cases, may be vulnerable to disturbances caused by anthropogenic climate change. This has prompted the consideration of alternative tree species compositions for use in production forestry in this region. Here we evaluate the likely biodiversity costs and benefits of supplanting Norway spruce (Picea abies) monocultures with polycultures of spruce and birch (Betula spp.) in southern Sweden. This polyculture alternative has previously been evaluated in terms of economic, recreational, and silvicultural benefits. By also assessing the ecological implications we fill a gap in our understanding of the range of socio-ecological benefits that can be achieved from a single polyculture alternative. We project likely broad scale changes to species richness and abundance within production stands for five taxonomic groups including ground vegetation, tree-living bryophytes, lichens, saproxylic beetles, and birds. Our research leads us to three key findings. First, the replacement of spruce monocultures with spruce–birch polycultures in the managed forest landscapes of southern Sweden can be expected to result in an increase in biological diversity for most but not all taxa assessed, but it is unlikely to improve conditions for many red-listed forest species. Second, modification of other aspects of forest management (i.e. rotation length, dead wood and green tree retention, thinning regimes) is likely to contribute to further biodiversity gains using spruce–birch polycultures than spruce monocultures. Third, the paucity of empirical research which directly compares the biodiversity of different types of managed production stands, limits the extent to which policy relevant conclusions can be extracted from the scientific literature. We discuss the wider implications of our findings, which indicate that some climate change adaptation strategies, such as risk-spreading, can be readily integrated with the economic, environmental and social goals of multi-use forestry.  相似文献   

7.
Phosphorus is an essential nutrient for forest growth. In this study, we assessed the impact of soil extractable phosphorus using two simple extraction methods on nutrition and productivity of Norway spruce in sixteen mature forest stands on different bedrocks and soils in Bavaria, Southern Germany. Representative trees were sampled for needles, twigs, branches, stem bark, and stem wood. Total phosphorus content in the tree parts and soil phosphorus stock extractable with citric acid and sodium bicarbonate up to a soil depth of 80 cm were determined. We found that easily soil extractable phosphorus is a suitable indicator for estimating phosphorus uptake and stand productivity in Norway spruce. In contrast, organic layer phosphorus showed no significant correlation with aboveground biomass phosphorus contents. In the biomass, the highest phosphorus contents were measured in young needles and twigs, but the highest correlation with soil phosphorus was detected for phosphorus contents in needles and bark. The stock of phosphorus extracted by citric acid down to 40 cm soil depth revealed the best correlation with phosphorus in needles and bark. Therefore, as a supplemental or alternative method to needle analysis, our study suggests the use of phosphorus contents in stem bark to evaluate tree phosphorus nutrition. These results highlight the suitability of the citric acid soil extraction method to characterize plant available phosphorus in Norway spruce ecosystems.  相似文献   

8.
For several reasons the conversion of mono-species into mixed-species forests is presently a major concern of forest management and policy in Central Europe. Although it is possible to show a clear trend in favour of mixed-species forests, private forest owners and some forest economists have often not favoured mixed forests, assuming that they are less profitable. The trend towards mixed forests seems mainly for ecological reasons, while sound economic analysis of mixed forests is still rare. Based on this background the objective of the study is to answer the following four questions: (1) Does the yield of mixed-species forests differ from that of pure forests? (2) Does the mixing of tree species influence the ecological stability of forests? (3) Is the economic value of a mixed forest less than that of a monoculture? (4) How do forest economic models integrate the findings on yield and ecological stability of mixed forests? To answer these questions a literature review was conducted on the possible impacts of mixed-species forests. In comparison to pure stands a greater yield is not necessarily given in mixed stands. Yet, mixed-species stands are better able to compensate disturbances than monocultures. Moreover, there is substantial evidence that mixed-species stands are more resistant against biotic and abiotic disturbances. Applying an extended forest economic model, it was possible to demonstrate that mixing large blocks of native broadleaf species into pure conifer forests may lead to a significant reduction of financial risk. From a risk-averse perspective the economic value of a mixed-species forest may thus be greater than that of a mono-species forest. Yet, it became clear that forest economists do not often integrate the research findings on yield and ecological stability of mixed stands in modelling, but rather apply simple bioeconomic modelling. Moreover, in the context of mixed forests economists also largely ignore even classical financial approaches, which consider risk and risk preferences. We concluded that forest economics has to close substantial research gaps. Firstly, the knowledge of how to integrate biophysical properties of mixed forests in bioeconomic modelling is still an open question. Secondly, forest economists have to adopt the modern approaches of financial theory and management science to value mixed forests.  相似文献   

9.
A storm in January 2005 in southern Sweden (Gudrun) caused large damage to forests, archaeological sites, buildings, power supply, telecommunications, and infrastructure. In this work, we analyzed the factors affecting the probability of windthrow at stand level (i.e. tree- and stand characteristics) in southern Sweden. We selected a sub-sample (1721 plots) of existing plots from the Swedish National Forest Inventory (inventoried in 2003 and 2004). To assess whether these plots had suffered damage or not, aerial photographs were taken in summer 2005. In order to analyze the effects of measured characteristics on damage, field data for each sub-sample plot were merged with the corresponding result of the aerial photo interpretation.We found that the plots damaged were typically well stocked mature stands, dominated by Norway spruce (Picea abies (L.) Karst.), and often also recently thinned. Probability of damage increased with increase in stand height. In mixed stands, decrease of proportion of Norway spruce decreased the probability of damage. An admixture of deciduous trees, leafless in this winter storm, showed larger effect in this sense than that of Scots pine.  相似文献   

10.
Carbon and nitrogen stocks and their medium-term and readily decomposable fractions in topsoils were compared in relation to soil microbial biomass and activity along sequences from coniferous to deciduous stands. The study was carried out in the Ore Mountains and the Saxonian lowland, representing two typical natural regions in Saxony, Germany. In accordance with current forest conversion practices, the investigation sites represent different stands: mature conifer stands of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) (type A); Norway Scots spruce and pine with advanced plantings of European beech (Fagus sylvatica L.) or European beech/Common oak (Quercus petreae Liebl.) (type B); and mature deciduous stands of European beech and European beech/Common oak (type C). The investigated forest sites can be grouped into three silvicultural situations according to the development from coniferous stands to advanced plantings and finally mature deciduous forests (chronosequence A–B–C). The organic layer (L, F and H horizons) and uppermost mineral soil (0–10 cm) were analysed for potential C mineralisation, microbial biomass, concentrations of total C and N (TOC and TN) and for medium-term and readily decomposable C and N fractions, obtained by hot- and cold-water extraction respectively. The results showed an increase in organic layer thickness and mass as well as TOC and TN stocks along the forest sequences in the lowland. Yet, underplanted sites with two storeys revealed higher organic layer mass as well as TOC and TN stocks as compared to coniferous and deciduous stands. Stocks of hot- and cold-water-extractable C and N in relation to microbial biomass and its activity revealed a high turnover activity in deeper organic horizons of deciduous forests compared to coniferous stands. The stand-specific differentiation is discussed in relation to microbial biomass, litter quantity and quality and forest structure, but also with respect to the site-specific climatic factors and water budget as well as liming and fly-ash impacts. Results indicate higher dynamics in deciduous stands in the lowland especially during the initial turnover phase. The elevated microbial activity in deeper organic horizons of deciduous litter-influenced sites in spring is discussed as a specific indicator for long-term C sequestration potential as besides C mineralisation organic compounds are humified and thus, can be stored in the organic layer or in deeper soil horizons. Due to liming activities, stand-specific effects on organic matter turnover dynamics have evened out today in the Ore mountain region, but will presumably occur again once base saturation decreases. Here, the stand-specific effect on microbial biomass can currently be seen again as Cmic in the L horizon increased from spruce to beech. Our study sites in the lowland revealed no significant fly-ash impact. Differences between sites were evaluated by calculating the discriminance function. TOC and TN as well as medium-term degradable C and N were defined in this study as indicators for turnover dynamics along forest conversion sites.  相似文献   

11.
Increasing use of forest fuels for energy production is generating greater quantities of wood ash. In Sweden, it is recommended that this ash should be returned to the forest to counter soil acidification and avoid potential future nutrient deficiencies, but the effects on tree growth require clarification. Thus, 10 field experiments were established in Sweden in 1990–2006 to study the effects of adding wood ash of various origins, doses and combinations of both ash and nitrogen on stem growth in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) stands on mineral soil. Observations after 5–15 years show that growth responses were strongest when N was added, either alone or with wood ash. Growth responses to additions of wood ash without N were small and variable and statistically insignificant at all study sites. However, there were indications that adding wood ash may increase stem-wood growth at fertile sites and decrease it at less fertile sites. Hence, at fertile sites, it may compensate for the growth reductions that normally follow whole-tree harvests, at least temporarily, presumably due to its effects on soil N turnover. At less fertile sites, adding N is probably essential to counteract these growth reductions.  相似文献   

12.
To test the direct regeneration hypothesis and support natural disturbance-based forest management we characterized the structure and composition of boreal mixedwood forests regenerating after large wildfires and examined the influence of pre-fire stand composition and post-fire competing vegetation. In stands which had been deciduous (Populus sp.)-dominated, conifer (white spruce)-dominated, or mixed pre-fire we measured regeneration stocking (presence in 10 m2 plots), density and height 10–20 years post-burn in five wildfires in Alberta, Canada. Most plots regenerated to the deciduous or mixed stocking types; plots in the older fire and in stands that were pure conifer pre-fire had higher amounts of conifer regeneration. Surprisingly, regeneration in pre-fire ‘pure’ white spruce stands was most often to pine, although these had not been recorded in the pre-fire inventory. Pre-fire deciduous stands were the most resilient in that poplar species dominated their post-fire regeneration in terms of stocking, density and height. These stands also had the highest diversity of regenerating tree species and the most unstocked plots. High grass cover negatively affected regeneration density of both deciduous and conifer trees. Our results demonstrate the natural occurrence of regeneration gaps, pre- to post-fire changes in forest composition, and high variation in post-fire regeneration composition. These should be taken into consideration when developing goals for post-harvest regeneration mimicking natural disturbance.  相似文献   

13.
Bauer G  Schulze ED  Mund M 《Tree physiology》1997,17(12):777-786
Mineral nutrition of Norway spruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.) was investigated along a transect extending from northern Sweden to central Italy. Nitrogen (N) concentrations of needles and leaves in stands growing on acid soils did not differ significantly between central Italy and southern Sweden (1.0 +/- 0.1 mmol N g(-1) for needles and 1.9 +/- 0.14 mmol N g(-1) for leaves). In both species, foliar N concentrations were highest in Germany (1.2 mmol N g(-1) for needles and 2.0 mmol N g(-1) for leaves) and decreased by 50% toward northern Sweden (0.5 mmol N g(-1)). Both species showed constant S/N and P/N ratios along the transect. Calcium, K and Mg concentrations generally reflected local soil conditions; however, Mg concentrations reached deficiency values in Germany. Leaf area per unit dry weight varied significantly along the transect with lowest values for Norway spruce recorded in northern Sweden and Italy (3.4 m(2) kg(-1)) and a maximum in central Europe (4.7 m(2) kg(-1)). A similar pattern was observed for beech. Despite the low variation in foliar N concentrations on the large geographic scale, local and regional variations in N concentrations equalled or exceeded the variation along the entire continental transect. Furthermore, nutrient contents (i.e., nutrient concentration x dry weight per needle or leaf) showed a greater variation than nutrient concentrations along the transect. Nitrogen contents of Norway spruce needles reached minimum values in northern Sweden (2.4 micro mol N needle(-1)) and maximum values in Denmark (5.0 micro mol N needle(-1)). The N content of beech leaves was highest in Denmark (242 micro mol N leaf(-1)). At the German site, foliar N content rather than N concentration reflected the seasonal dynamics of foliar growth and N storage of the two species. During foliage expansion, there was an initial rapid increase in N content and a decrease in N concentration. This pattern lasted for about 2 weeks after bud break and was followed by 6 weeks during which dry weight and N content of the foliage increased, resulting in a further decrease in N concentration. During summer, dry weight and N content of mature needles of Norway spruce increased further to reach a maximum in autumn, whereas N concentration remained constant. In spring, reallocation of N from 1- and 2-year-old needles was 1.5 and 1.0 micro mol N needle(-1), respectively. This remobilized N was a major source of N for the development of new needles, which had an N content of 1.5 micro mol N needle(-1) after bud break. The seasonal remobilization of N from old foliage decreased with increasing needle age. Needle N content and dry weight decreased progressively with age (1 micro mol N needle(-1) between age classes 2 and 5), whereas N concentrations remained constant. For Norway spruce, annual stemwood production was correlated with needle N content but not with foliar N concentration or with the total amount of N in the canopy. Interspecific and geographical differences in plant nutrition are discussed on the basis of competitive demands for C and N between growth of foliage and wood.  相似文献   

14.
Using a representative sample of stands from a cross section through the Bavarian portion of the northern Calcareous Alps, this study evaluates the plausibility and significance of causal hypotheses for an explanation of the poor crown condition of Norway spruce in mountain forests: (1) ozone exposure in conjunction with (a) drought and (b) ample water supply; (2) soil-borne nutrient deficiency; (3) drought; and (4) tree age. Site index and, in a subset of stands, foliar nutrient concentrations are considered as additional indicators of tree vigour. According to principal component analysis and multiple regression, crown condition was controlled by soil chemistry (transparency increased towards shallow calcareous soils), stand age and, to a smaller degree, by an interaction between ozone exposure and drought. Site index was best explained by a model including elevation, soil chemistry and drought. Tree nutrition clearly reflected the main soil chemical gradient, and P, N and Fe deficiencies were found in transparent stands, which had markedly smaller needles. The similar distributions of crown transparency, site index and nutrition present a strong argument for the hypothesis that soil chemistry has constrained the vigour of spruce trees in the Calcareous Alps for a long time. By leaving unproductive stands to age naturally, forest management has accentuated the pattern of crown condition. In the heterogeneous alpine landscape, possible effects of recent increases in ozone exposure have to be viewed extremely carefully against the background of these natural and anthropogenic covariables.  相似文献   

15.
Tree growth and carbon dynamics are important issues especially in the context of climate change. However, we essentially lack knowledge about the effects on carbon dynamics especially in mixed stands. Thus, the objective of this study was to test the effects of climatic changes on the above and below ground carbon dynamics of a mixed stand of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) by means of scenario simulations. To account for the typical tree interactions in a mixed-species stand a spatial explicit tree growth model based on eco-physiological processes was applied. Three different climate scenarios considering altered precipitation, temperature, and radiation were calculated for an unthinned and a thinned stand. The results showed significant changes of above and belowground biomass over time, especially when temperature and radiation were increased additionally to decreased precipitation. The reduction in biomass increments of Norway spruce were more attenuated above than below ground. In contrast, the results for beech were the opposite: The belowground increments were reduced more. These results suggest a shift in the species contribution to above and belowground biomass under dryer and warmer conditions. Distinct effects were also found when thinned and unthinned stands were compared. A reduced stand density changed the proportions of above and below ground carbon allocation. As a main reason for the changed growth reactions the water balance of trees was identified which lead to changed biomass allocation pattern. This article belongs to the special issue “Growth and defence of Norway spruce and European beech in pure and mixed stands”.  相似文献   

16.
Where natural production capacity permits, modern silvicultural management in Central Europe frequently aims at the development of mixed broadleaved stands, instead of pure European beech (Fagus sylvatica) stands. It is crucial to study the effects of these tree-layer diversity variations on herb-layer vegetation, since herb-layer vegetation contributes significantly to ecosystem functioning in forests. In Hainich National Park (Thuringia, Germany), we conducted observational research in deciduous stands to investigate whether herb-layer diversity was related to canopy-layer diversity, and to ascertain possible causal mechanisms. We found that herb-layer vegetation of deciduous forest stands rich in canopy species appeared to be more diverse than herb-layer vegetation of beech-dominated stands. We surmise that herbaceous understorey diversity was indirectly influenced by canopy tree species through the medium of the altered environmental factors soil pH and litter layer thickness. Apparently, lower beech proportion had a more profound effect than the number of secondary tree species. There were no correlations between herb-layer diversity and light transmissibility of the canopy layer, indicating that the light factor was not crucial for herb-layer diversity. At least for the Hainich research sites, our results indicated that small-scale light and soil heterogeneity is insignificant for herb-layer diversity. We found several herb-layer species whose occurrence was particularly correlated with tree-layer diversity and environmental factors. Remarkably, all species positively correlated with soil pH were important for the phytosociological classification of the research sites. Beech-dominated research sites showed high tree-layer volumes, whereas research sites with high tree-layer diversity tended to feature lower tree-layer volumes. These findings could be the result of differing former silvicultural systems and varying soil clay contents affecting tree species composition. In contrast, herb-layer biomass was positively correlated with tree-layer diversity. Herb-layer productivity might be promoted in more diverse research sites by increased nutrient supply and base saturation. It is also possible that greater beech proportion interfered with herb-layer productivity. However, herb-layer biomass was also positively correlated with herb-layer diversity. Hence, our study hints that positive diversity-functioning relationships might occur in the herb-layer of the deciduous forest under investigation.  相似文献   

17.
A greenhouse trial was carried out to improve the knowledge of how forest organic matter could be utilized in site preparation and the choice of planting spot for Picea abies (L.) Karst. One-year old Norway spruce seedlings were grown for 26 weeks in pots containing pure mineral soil, forest organic matter in three different states of decomposition and combined treatments where the organic matter was mixed with or placed on the surface of the mineral soil (volume proportions of organic:mineral of 1:2). Watering was adapted to the water retention characteristics of each growing medium in order to keep the soil water potential between -4 and -5 kPa in all pots.In its pure form as well as combined with mineral soil, the moderately decomposed mor organic matter gave a higher seedling dry weight increment than the corresponding growing media containing the more decomposed humus. Adding mor or humus to mineral soil increased the seedling dry weight increment by 30–140% and 10–40%, respectively. The largest seedlings grew in the pure mor and humus. Mixing these forms of organic matter with mineral soil appeared to reduce seedling growth as compared to placing them on the mineral soil surface. The increment increase compared to plain mineral soil mostly consisted of proleptic growth and was probably due to the improved nutrient availability of the growing media. Fresh organic matter (chopped needles and twigs) seemed to impair seedling root function and reduced the dry weight increment by 30–50% as compared with pure mineral soil.The results suggest that as long as the water and temperature requirements are fulfilled planting Norway spruce seedlings without scarification and/or gathering extra mor and humus to the planting position should improve seedling growth as compared to the growth following scarification. Unmixed fresh needles and twigs or fresh needles and twigs combined with plain mineral soil should be avoided when planting Norway spruce seedlings.  相似文献   

18.
Stemwood growth, needle weight and nutrient concentrations in needles after liming and nitrogen fertilization were studied in two randomized block trials. The treatments were a single application of 500 kg lime per hectare, 1000 kg limer per hectare, 150 kg N per hectare and combinations of the two compounds. The trials are situated in the southern part of Sweden on mesic mineral soils. One of the experiments was located in 32–55-year-old highly productive Picea abies stands and the other in a 31-year-old Pinus sylvestris stand.As calculated by growth-ring analysis, liming alone did not significantly affect the growth during a 10-year period following treatment. Nitrogen fertilization increased growth in pine, but not in spruce. Lime in combination with N gave about the same effect in pine as the pure N treatment, whereas lime and N interacted in spruce and resulted in increased stemwood growth.Current-year needles were sampled during the winter, weighed and analysed for nutrient concentrations. In the N-treated plots the N concentration increased in both tree species, whereas the needle weight increased only in pine. In two cases, lower concentrations were indicated. In the first, there was a tendency of decreased N concentrations in spruce needles after liming. In the second, the magnesium concentrations decreased in needles of both species, especially in the treatments that included nitrogen. The concentrations of the measured nutrients were never below levels considered to imply a severe deficiency.  相似文献   

19.
Variability in short root morphology of the three main tree species of Europe's boreal forest (Norway spruce (Picea abies L. Karst.), Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth)) was investigated in four stands along a latitudinal gradient from northern Finland to southern Estonia. Silver birch and Scots pine were present in three stands and Norway spruce was present in all stands. For three fertile Norway spruce stands, fine root biomass and number of root tips per stand area or unit basal area were assessed from north to south. Principal component analysis indicated that short root morphology was significantly affected by tree species and site, which together explained 34.7% of the total variability. The range of variation in mean specific root area (SRA) was 51-74, 60-70 and 84-124 m(2) kg(-1) for Norway spruce, Scots pine and silver birch, respectively, and the corresponding ranges for specific root length were 37-47, 40-48 and 87-97 m g(-1). The range of variation in root tissue density of Norway spruce, Scots pine and silver birch was 113-182, 127-158 and 81-156 kg m(-3), respectively. Sensitivity of short root morphology to site conditions decreased in the order: Norway spruce > silver birch > Scots pine. Short root SRA increased with site fertility in all species. In Norway spruce, fine root biomass and number of root tips per m(2) decreased from north to south. The differences in morphological parameters among sites were significant but smaller than the site differences in fine root biomass and number of root tips.  相似文献   

20.
Variations in fine root biomass of trees and understory in 16 stands throughout Finland were examined and relationships to site and stand characteristics determined. Norway spruce fine root biomass varied between 184 and 370 g m(-2), and that of Scots pine ranged between 149 and 386 g m(-2). In northern Finland, understory roots and rhizomes (< 2 mm diameter) accounted for up to 50% of the stand total fine root biomass. Therefore, the fine root biomass of trees plus understory was larger in northern Finland in stands of both tree species, resulting in a negative relationship between fine root biomass and the temperature sum and a positive relationship between fine root biomass and the carbon:nitrogen ratio of the soil organic layer. The foliage:fine root ratio varied between 2.1 and 6.4 for Norway spruce and between 0.8 and 2.2 for Scots pine. The ratio decreased for both Norway spruce and Scots pine from south to north, as well as from fertile to more infertile site types. The foliage:fine root ratio of Norway spruce was related to basal area and stem surface area. The strong positive correlations of these three parameters with fine root nitrogen concentration implies that more fine roots are needed to maintain a certain amount of foliage when nutrient availability is low. No significant relationships were found between stand parameters and fine root biomass at the stand level, but the relationships considerably improved when both fine root biomass and stand parameters were calculated for the mean tree in the stand. When the northern and southern sites were analyzed separately, fine root biomass per tree of both species was significantly correlated with basal area and stem surface area per tree. Basal area, stem surface area and stand density can be estimated accurately and easily. Thus, our results may have value in predicting fine root biomass at the tree and stand level in boreal Norway spruce and Scots pine forests.  相似文献   

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