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1.
The impact of winter harvesting on regeneration 50 years after an experimental diameter-limit cutting was examined in mixed deciduous–coniferous ecosystems of southern Quebec, Canada. The study was conducted in La Mauricie National Park, Quebec, Canada. Regeneration data in two balsam fir (Abies balsamea (L.) Mill.), red spruce (Picea rubens Sarg.), sugar maple (Acer saccharum Marsh.), and yellow birch (Betula alleghaniensis Britt.) ecosystem types were analyzed. Comparisons between uncut and cut stands were obtained from a total of 63 sample plots. For both ecosystems, there were no significant differences between uncut and cut plots for regeneration density and stocking. The most abundant regeneration species were balsam fir, red spruce, sugar maple, red maple (Acer rubrum L.), yellow birch and American beech (Fagus grandifolia Ehrh.). The type of diameter-limit cutting described in the study did not affect regeneration density and stocking but its impact on productivity, timber quality and genetics is still unknown.  相似文献   

2.
Careful logging around advance growth and tree planting following site preparation or not (fill planting) have been widely used to regenerate black spruce (Picea mariana) stands in the boreal forest of Canada. An experiment was established in 1990 to compare these regeneration modes and natural seeding over a 25-year period following two types of scarification (cone- or disk-trenching) that were applied at two intensities (single- or double-pass). Without scarification, the three types of regeneration had slow height growth during the first 10 years (3.4–5.8?cm/year). Thereafter, planted seedlings (6.1–9.8?cm/year) and pre-established layers (5.8–8.5?cm/year) had 2–3 times higher growth than natural seedlings (2.6–3.1?cm/year). Scarification improved height growth of the three types of regeneration, but planted seedlings responded much earlier, and more strongly over the 25 years (+9.4?cm/year) than layers (+2.8?cm/year) and natural seedlings (+2.7?cm/year). A shift in the proportion of layers and natural seedlings was observed following treatment. Long-term monitoring revealed that double-pass scarification was beneficial to layer growth from years 15 to 20, while no positive effect was observed on natural or planted seedlings. Our results suggest that decades may be required for natural regeneration to respond to scarification in cold soils of the boreal forest.  相似文献   

3.
Seedling growth is often hampered on sites dominated by Kalmia angustifolia. In June 2000, a trial was established on a clear-cut site in Quebec, Canada, with a high cover of Kalmia and Vaccinium species. The objectives were to evaluate how soil scarification and fertilization at the time of planting influence early growth and establishment of black spruce [Picea mariana (Mill.) BSP] and jack pine (Pinus banksiana Lamb.) seedlings. During the first 2 years, scarification reduced Kalmia cover three-fold and doubled the distance from seedlings to the nearest Kalmia stem. Scarification did not increase soil-extractable NH4-N concentration, and reduced soil potassium, calcium and magnesium. Scarification had no effect on seedling water stress. Seedling growth improved and foliar nutrient concentrations were generally higher in scarified plots than in unscarified control plots. No differences were observed between single- and double-pass scarification for any variables except for ground-level stem diameter of seedlings, which was greater with double-pass scarification (12.1 vs 13.1 mm). Spot fertilization increased seedling growth and foliar nitrogen concentrations. Jack pine growth was greater than black spruce growth, an effect enhanced when seedlings were fertilized.  相似文献   

4.
Composition, structure, and species-specific patterns of recruitment and growth were characterized in two yellow birch (Betula alleghaniensis Britt.)–conifer stands in Quebec, Canada, to improve our understanding of the dynamics of these complex ecosystems. The mixture of mid- and shade-tolerant species in the canopy, the inverse J-shape stem diameter distribution, and the age distribution were indicative that the two stands were in a late-successional stage. Recruitment of mid-tolerant species above 1.3 m in height appeared to be periodic and synchronized with historical spruce budworm (Choristoneura fumiferana Clem.) outbreaks, while the coniferous component of these mixedwood stands recruited continuously. Results suggest that recruitment of yellow birch and red maple (Acer rubrum L.) requires disturbances of a certain intensity that affect at least 25 % of the forest cover. In contrast, balsam fir (Abies balsamea (L.) Mill.) and red spruce (Picea rubens Sarg.) can recruit under the canopy without relying on moderate or large canopy disturbances. Results suggest that the historical disturbance regime, and differences in shade tolerance between species, largely govern the contemporary composition of these stands. This study improves the comprehension of mechanisms that regulate the dynamics of yellow birch-conifer stands and will be useful for the subsequent elaboration of forest management strategies.  相似文献   

5.
Most of world's forests of different climates have a history of fire, but with different severities. Fire regimes for broadleaf deciduous forests have return intervals that vary from many decades (or less) to centuries (or more). Iran has a total of 1.2 million ha of temperate forest in the north, where fires burn about 300–400 ha annually. This study focused on the impact of fire on forest structure, tree species quality, and regeneration composition (specially beech) in the Chelir forest of northern Iran. The results showed that forest fires changed the structure and had different effects on tree species composition between burned and control areas. Thin barked species such as oriental beech (Fagus orientalis Lipsky) and coliseum maple (Acer cappadocicum Gled.) have been affected more than those with thick bark, like hornbeam (Carpinus betulus L.) and chestnut-leaved oak (Quercus castaneifolia C.A. Mey). The density of oriental beech regeneration in the unburned area was greater than in the burned area, while the quantity of regeneration of hornbeam, coliseum maple and velvet maple (Acer velutinum Boiss) was higher in burned area. Forest fire had a greater effect on oriental beech quality, and changed regeneration composition in the burned area. Fire prevention activities should be considered as a silvicultural treatment for preserving these valuable forests.  相似文献   

6.
Effects of enhanced nitrogen deposition on nutrient foliar concentrations and net photosynthesis of sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Ehrh) and red spruce (Picea rubens Sarg.) were evaluated at the Bear Brook Watershed in Maine (BBWM). The BBWM is a paired-watershed forest ecosystem study with one watershed treated since 1989 with bimonthly dry ammonium sulfate ((NH4)2SO4) additions at a rate of 25.2 kg N ha−1 year−1, while the other watershed serves as a reference. The (NH4)2SO4 treatment resulted in significant increases in foliar N concentrations for all three species and significant reductions in foliar Ca, Mg and Zn concentrations for American beech and red spruce. Treatment effects on foliar concentrations of other nutrients were not significant in any species. Despite higher N concentrations in all species, only treated sugar maple showed significantly higher photosynthetic rates. The non-response in net photosynthesis to higher foliar N in American beech and red spruce might be attributed to their low foliar Ca and/or Mg concentrations. Higher net photosynthetic rates in sugar maple might be explained by the higher foliar N and by the ability of this species to maintain an adequate Ca and Mg supply. Results suggested that nutrient imbalances due to inadequate supply of Ca and Mg might have counteracted a potential increase in net photosynthesis induced by higher N concentrations in American beech and red spruce.  相似文献   

7.
Survival and growth of planted white spruce was assessed under partial harvest treatments and different site preparation techniques in mixedwood forests of two compositions prior to logging: deciduous dominated (d-dom) – primarily comprised of mature trembling aspen (Populus tremuloides Michx.) and coniferous dominated (c-dom) – primarily comprised of mature white spruce (Picea glauca (Moench) Voss). Levels of overstory retention were 0% (clearcut), 50% and 75% of original basal area, and site preparation techniques were inverted mounding, high speed mixing, scalping and control (no treatment). The survival and growth of white spruce were assessed seven years after planting. The experiment was established as a part of the Ecosystem Management Emulating Natural Disturbance (EMEND) experiment located in northern Alberta, Canada. In the c-dom, the 50% and 75% retention of overstory resulted in reduced growth and survival of white spruce seedlings compared to clearcuts. In contrast, in the d-dom, the seedlings performed best in sites that had 50% of the overstory retained. For the c-dom, the mounding and mixing treatments yielded the best growth of spruce seedlings, while scalping yielded the worst. In the d-dom, spruce growth was highest in sites with the mixing treatment. In the d-dom, growth and survival of the planted spruce was greater than in the c-dom. The natural regeneration of deciduous trees was suppressed by the retention of canopy regardless of original composition.  相似文献   

8.
Due to the exceptional sweetness of its sap, sugar maple (Acer saccharum Marsh.) is economically exploited at a commercial scale for maple syrup production in northeastern North America. Approximately 80% of world production is realised in the province of Quebec, Canada, where it is economically important for rural communities. Despite important financial investments in industrial infrastructure over recent decades, the maple syrup yield (ml of sap/tap/year) has followed a general declining trend over the last 15 years, presumably because of unfavourable climatic conditions. In this study, the relationship between climate and maple syrup yield by tap for the whole province was investigated.  相似文献   

9.
The effects on seedling survival and growth of a new scarification method, inverting, were evaluated over 10‐yrs after planting lodgepole pine and Norway spruce on a 2‐yr‐oId clear‐cut in northern Sweden. Inverting, which provides planting spots containing humus turves covered in loose mineral soil without making mounds or ridges, was compared with ploughing, mounding, disc trenching, and no scarification. Subplots with high or low planting positions were used to assess small‐scale topographical effects. For both species, the treatment ranking according to stem volume production after 10‐yrs was inverting > ploughing ≥ mounding = disc trenching > no scarification. Inverting improved seedling height growth by approximately 35% compared with mounding or disc trenching and by more than 100% compared with no scarification. High survival rates were also found following inverting, but only the no‐scarification treatment resulted in a statistically significant reduction in survival rates (ca. 25%) for both species. Further development of the inverting technique might give environmental advantages compared with conventional mechanical site preparation.  相似文献   

10.
A general model for comparing the profitability of natural regeneration in beech (Fagus sylvatica L.) with planting of Norway spruce (Picea abies L.) is developed. The model is basically a method of comparing a series of net present values. An example of using the model is given: BEECH (90–110) denotes a cyclic regime in which regeneration is initiated at age 90 of a stand, and the canopy trees are cleared at age 110. This regime is compared with the alternative of planting Norway spruce. Economic data used for the comparison are representative of the southeastern regions of Denmark. The conclusion of the comparison is as follows: BEECH (90–110) is superior to planting of Norway spruce for required real rates of return up to 3–4%. For higher required rates of return planting of Norway spruce is preferable.  相似文献   

11.
Manipulation of the canopy cover and site preparation are the most important silvicultural measures to enhance the conditions for natural regeneration of Norway spruce (Picea abies (L.) Karst.). During the early regeneration phase however, seedling mortality may be high, so it is important to study how different combinations of stand-level treatments and site preparation methods affect seedling establishment. We studied emergence, 1st winter and 2nd summer mortality for naturally regenerated spruce seedlings in a field experiment that combined four harvest treatments (shelterwoods of high (SH), medium (SM) and low (SL) residual basal area, and a 50 × 50 m clear-cut (CC)) and two site preparation methods (patch scarification and inverting). The CC had significantly fewer seedlings the 1st fall than the SL and SH (p = 0.0377), and in all harvest treatments, fewer seedlings emerged in inverted than in patch scarified spots (p = 0.0351). Mortality was also lower with patch scarification than inverting (1st winter: p = 0.0565, 2nd summer: p = 0.0377), but was not affected by harvest treatment (1st winter: p = 0.9211, 2nd summer: p = 0.1896). On average, mortality from 1st to 2nd fall reached 38% and 27% after inverting and patch scarification, respectively. First winter mortality accounted for approximately two thirds of the accumulated mortality, regardless of the harvest treatment and site preparation method.  相似文献   

12.
To restore non-wooded stands dominated by dwarf bamboo species (Sasa kurilensis or S. senanensis) into forests, mechanical soil scarification has been applied in northern Japan since the 1960s. The treatment is followed both by natural regeneration and artificial planting. In this study, we quantified the total carbon stock (plants plus 0.3 m depth of soil) of these stands over 35-year age-sequences. The natural regeneration stands were gradually dominated by Betula ermanii. The carbon stock increased linearly to 215.1 ± 35.2 Mg C ha−1 for a 37-year-old stand formerly dominated by S. kurilensis, and 181.1 ± 29.8 Mg C ha−1 for a 34-year-old stand formerly dominated by S. senanensis. The latter was similar to that of a Picea glehnii plantation, formerly dominated by S. senanensis, with comparable stand age (160.3 ± 6.7 Mg C ha−1 for 35-year-old stands). Although the carbon stock in plants quickly offset the untreated level, that in the soil remained depressed even in the older stands. This resulted in small differences in carbon stock of these stands with untreated dwarf bamboo stands. We conclude that natural regeneration following scarification could be a prime option for carbon sink management in the region. However, we should take a long rotation period (i.e., >50 years) to ensure a carbon sink state. A potential of further improvements of the practice, including that reduce intensity of soil disturbance, was presented.  相似文献   

13.
In this study we integrated digital terrain models, forest inventory maps, optical remote sensing and field data to analyze the spatial structure of a 4850 km2 boreal mixedwood forest landscape in northeastern British Columbia. We built independent maps of forest cover and landform using a Bayesian classification algorithm and quantitative surface analysis. These data were used to test the strength of the association between topographic position and forest cover using a modified electivity index. We then used logistic regression to test whether the probability of a site being occupied by either mixedwood or hardwood is correlated to its distance from white spruce (Picea glauca) seed sources. The relationship between forest cover and topography showed significant departures from randomness, with white spruce preferentially associated with channels and concave slopes, and hardwoods preferentially associated with ridges and convex slopes. The analysis of mixedwood and hardwood stand distribution showed a positive correlation between hardwood occurrence and distance from spruce stands, suggesting that the dispersal limitations of white spruce is a significant influence on landscape vegetation dynamics. Overall, the results support the hypothesis that mixedwood dynamics are the product of ecological processes at multiple scales. Furthermore, these dynamics are only revealed by taking a varied approach to both data gathering and analyses.  相似文献   

14.
Abstract

The success of natural regeneration on patch clear-cuts in Norway spruce stands in Southern Finland was examined in terms of stocking and tree height. The experiment was established in mature spruce stands in the submesic Myrtillus (MT) site type. In each of the eight study sites, three plots were treated with clear-cutting and planting, clear-cutting with partial tree retention and planting, and patch clear-cutting without site preparation, respectively. In three of the study sites, one plot with patch clear-cutting and site preparation was established. Each plot was 1 ha, out of which three patches of 40×40 m were clear-cut in the patch treatments. 10–11 years after cutting, the patches had on average 1316 crop trees ha–1, of which 91% were spruces. Some 27% of the stands were up to the target stocking level (≥1600 ha?1), and 36% were at least satisfactory (≥1300 ha?1). Site preparation did not yield greater stocking levels on patches, but that result is ambiguous due to a difference in initial stocking. The average spruce tree height in the patches (0.76 m) was much smaller than in the case of clear-cutting and planting (2.42 m). In conclusion, the patches had been restocked tolerably well with spruce and birch for practical purposes during the 10- to 11-year period, but the regeneration process had been very slow compared to clear-cutting and planting.  相似文献   

15.
Differences in sensitivity to soil conditions across tree species and developmental stage are important to predicting forest response to environmental change. This study was conducted to compare elemental concentrations in leaves, stems, and roots of (1) sugar maple (Acer saccharum Marsh.) seedlings vs. mature trees and (2) mature sugar maple vs. mature American beech (Fagus grandifolia Ehrh.) in two sites that differ in soil base saturation and pH. Both sites are located in Huntington Forest, NY, USA; one site (hereafter ‘H’) has higher soil pH and Ca, Mg, and Mn concentrations than the other site (hereafter ‘L’). Sugar maple growth at H (14.8 cm2 year−1 per tree) was much greater than at L (8.6 cm2 year−1 per tree), but the growth of beech was not different between the two sites. Leaves, roots, and stem wood of mature beech trees and sugar maple seedlings and mature trees were sampled for nutrient analysis. Foliar Ca, K, and Al concentrations were positively correlated with soil elements, but Mn concentrations were negatively correlated. Sugar maple differed more than beech between sites in foliar K and Mn concentrations. Root Mg and P concentrations reflected soil chemistry differences, in contrast to foliar concentrations of Mg and P, which were indistinguishable between the sites. In sugar maple, seedlings differed more than in mature trees in nutrient concentrations in roots, especially for Mg and Mn. Although beech was not as responsive to nutrient availability as sugar maple in foliar and root nutrient concentrations, Ca and Mg concentrations in beech wood were higher in H (52% higher for Ca and 68% higher for Mg), while sugar maple did not differ between sites. Sugar maple regeneration failure on acidic soils in the same region is consistent with our finding that sugar maple seedlings were very sensitive to nutrient availability. This sensitivity could ultimately contribute to the replacement of sugar maple by American beech in regions of low pH and base cations if base cation leaching by anthropogenic deposition and tree harvesting continues.  相似文献   

16.
In 2015 and 2016, the North American maple tree pathogen Eutypella parasitica was identified in Bohemian and Polish Silesia. To date, the pathogen has been recorded in 35 locations over an area of approximately 400 km2. It has been found primarily in natural stands in Silesia in several types of ravine and alluvial forests, in other natural or commercial forests, in riparian stands and in open landscapes. The proportion of diseased maples ranged between approximately 1% and 50% in certain locations. Acer pseudoplatanus was confirmed as the main host but infections were also detected on A. platanoides and A. campestre. E. parasitica damages the most valuable sycamore timber and represents a clear risk for maple cultivation in the region.  相似文献   

17.
This paper deals with the determination of the pore-size distribution of untreated and thermally modified twin samples of Norway spruce (Picea abies (L.) Karst.) and sycamore maple (Acer pseudoplatanus L.) by means of mercury intrusion porosimetry. The investigations considered oven-dried and at 22 °C and 95 % relative humidity-conditioned samples. A special sample holder and a novel method for evacuation were developed for the measurements. This was necessary both to ensure that samples were positioned at a defined distance and the conditioned samples did not dry in an uncontrolled manner. The results clearly show that the climatic state influences the results. Thermal modification greatly alters the pore-size distribution of spruce. This can be largely attributed to the formation of intercellular spaces in the middle lamella as a result of cell-wall compression due to thermal modification. The alteration of the pore structure of maple due to thermal modification is not as pronounced as that of spruce.  相似文献   

18.
Gap-associated spruce (Picea abies (L.) Karst.) regeneration in Sphagnum-Myrtillus stands of south taiga forests (Central Forest Biosphere reserve, Tver region, Russia) was studied to evaluate the role of different disturbances in spruce dynamics. Sampled gaps (n=70) ranged from 40 m2 to 1.7 ha in size, and from 1 to 70 years since disturbance moment. Formation of gaps lead to increase in the number of stems per ha in all gap size classes (small: 40–200 m2, medium: 200–3000 m2, and large: >3000 m2 gaps). Spruce was the most important species in gap refilling, although its role was not the same in different gap classes. The highest values of relative abundance (compared to other species) were recorded in small gaps, and much lower values – in middle and large gaps. However, as refilling of gaps proceeded, spruce showed rather active regeneration in middle and large gaps and partly regained its abundance in middle-age disturbances. In general, all types of gaps studied supported spruce regeneration into the forest canopy. Almost perfect correlation between predicted outcome of spruce dynamics in gaps and its current role in the canopy of Sphagnum-Myrtillus stands suggests a good adaptation of this species to the current disturbance regime and a steady state of the these forests.  相似文献   

19.
Abstract

The effects of mulch and scarification on the establishment and growth of six clones of Norway spruce [Picea abies (L.) Karst.] were examined in a study in southern Sweden. Mulch and scarification reduced the amount of competing vegetation and tended to improve soil moisture and soil temperature. Budbreak occurred earlier for cuttings planted in the scarification treatment in comparison with the control and mulching treatment. Scarification increased survival and the combination of scarification and mulch resulted in the best growth. Gas exchange and the number of new roots were higher in planting spots covered with mulch. Clonal differences regarding gas exchange and growth were significant. Clones with a poor height growth also had a low gas exchange and a small number of new roots. In contrast, the clone with the best height growth had high gas exchange and a large number of new roots. Clonal effects on growth were greater than site preparation effects.  相似文献   

20.
Research on natural regeneration is crucial for the development of sustainable forestry practices, in light of the global climate changes taking place. In this study, 151 plots were sampled in six Pinus pinaster stands that were naturally regenerated by the seed-tree method in Mediterranean forests in central Spain. The objectives of the survey were to study the suitability of different forest stands designated for natural regeneration as well as to analyse seedling establishment and the relationship between regeneration and different site factors. Analysis of variance and multivariate analysis with canonical ordination techniques were employed. Full and partial redundancy analyses on a correlation matrix were used to carry out a direct gradient analysis of regeneration density as a function of site factors. Nearly all stands presented seedling densities over 2,000 seedlings ha−1 and were thus found to be suitable for natural regeneration of Pinus pinaster by the seed-tree selection method. Significant variables that best explained total seedling and viable seedling density were spring and autumn precipitation of the year prior to establishment, spring and summer precipitation of the year of establishment and percentage cover of litter. There were no signs of competition between shrubs and seedlings, but a negative significant correlation with grass cover was observed. Pinus pinaster natural regeneration was successful with the seed-tree method, although it appeared to be highly dependent on climate and stand conditions.  相似文献   

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