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1.
Experiments were carried out at four sites in Sweden to investigate the possibility of establishing hairy birch (Betula pubescens Ehrh.) and silver birch (Betula pendula Roth) on abandoned fields using natural regeneration and (or) direct seeding. The effects of six soil preparation methods (no preparation, ordinary ploughing, rotary cultivation, deep ploughing, inverted ground, removal of top-soil) and five additional treatments (no treatment, herbicide, peat litter, wood-ashes, slaked lime) on seedling emergence percentages (SEP) and vegetation cover percentages (VCP) were studied. SEP-values were estimated in June (SEP(J)) and October (SEP(O)). The experimental designs used were: 1) split-plot design with whole plots in a randomized complete block design (RCBD); 2) RCBD. The SEP-values observed with no preparation were close to 0% while the SEP-values obtained with mechanical soil preparation methods mostly were much higher (p0.014). Seedbeds with top-soil in the surface, created by ordinary ploughing or rotary cultivation, and seedbeds with mainly bare mineral soil in the surface, created by deep ploughing, inverted ground or removal of top-soil, obtained SEP-values of equal merit on silty soils, reaching SEP(O)-values up to 15%. The latter seedbeds obtained the best results on sandy soil, with as high SEP(O)-values as 47% after removal of top-soil. Seedbeds with top-soil in the surface were quickly colonized by ground vegetation, reaching VCP-values between 70% and 100%. Herbicide spraying with glyphosate and application of peat litter to the seedbed surface promoted seedling emergence. However, herbicide spraying before soil preparation was of little effect when followed by mechanical soil preparation.  相似文献   

2.
Interactions between scarification treatments and seedling types of Norway spruce were examined at two different locations in southern Sweden. The scarification treatments were not scarified control, mounding and soil inversion and the seedling types were a 10 week-old containerized seedling (mini seedling), a 2 year-old containerized seedling and a 2 year-old hybrid seedling, grown as a containerized seedling the first year and as a bare-root seedling the second year. Site preparation intensity had a greater effect on the mini seedlings. The results indicated that mini seedlings established faster in the soil inversion treatment compared to the larger seedling types. At the same seedling age, the mini seedlings had faster or similar growth rate as the containerized and the hybrid seedlings regardless of scarification treatment. Although mini seedlings grew as well as or even better than larger seedlings if they were successfully established, they were more sensitive to their planting environment and proper handling was critical. Problems with frost heaving and competing vegetation have to be taken into consideration when choosing site preparation method and seedling type.  相似文献   

3.
To clarify the establishment pattern of Cryptomeria japonica seedlings, the demography of current-year seedlings was studied under various micro-environmental conditions for 2 years in a cool-temperate old-growth forest in the snowy region of Japan. In both years, more than 70% of seedlings that emerged died within a year, and differences in the survival rate of seedlings with respect to micro-environmental conditions were similar. While a number of seedlings survived at the sites on fallen logs and in mineral soil, almost no seedlings survived at the sites with either broad-leaved or coniferous litters at the end of the first growing season. The negative litter effect may kill most small seedlings of C. japonica. In addition, we found that survival rates of the seedlings were greater as the distance from the nearest adult and canopy openness increased. An analysis using Quantification Theory I showed that, of the possible micro-environmental factors, substrate conditions had the strongest effect on the survival of seedlings. The analysis also indicated that distance from the nearest adult and canopy openness also affected seedling survival significantly and to almost the same extent, although the effects were weaker than those for the substrate condition. Given the limited establishment sites for C. japonica seedlings, layering is suggested to be the main mode of regeneration in this forest.  相似文献   

4.
This study investigated the intercropping of rattan, an important non-timber forest product, in coffee and cacao agroforests in Sulawesi, Indonesia. The viability of producing seedlings from seeds and vegetative cuttings with the large-diameter rattan, Calamus zollingeri Beccari, and initial seedling survival, growth and response to light and soil drainage were investigated in village nurseries and perennial farms. Over 96% of seeds and 61% of vegetative cuttings were raised to transplanting size (25 cm with two to three leaves) over 20 months. One hundred C. zollingeri seedlings produced from cuttings were transplanted into each of three coffee or cacao farms and one primary forest site and exhibited an overall survival rate of 96%, 12.7 cm of height growth and the production of 0.8 new leaves per plant after eight months. No significant differences were observed between the four sites with respect to seedling survival, growth, or leaf production and no significant differences were found between seedling survival, growth or leaf production and light intensity (based on multiple PAR measurements). However, poorly drained sites exhibited significantly reduced C. zollingeri seedling survival and growth. The cultivation of C. zollingeri rattan in coffee and cacao agroforests represents a potential means of intensifying and diversifying perennial cash crop farming systems.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

5.
The survival of bare-root and container-grown loblolly pine (Pinus taeda L.) seedlings exceeded 90% when outplanted in March at two sites in Lee County, Alabama. At both sites, soil moisture and seedling survival were greater in March than in May. A March herbicide application reduced weed biomass by 75–80% at both sites. At the moist site, herbicide application did not affect survival. However, at the drier site, a reduction in weed biomass increased both the percent soil moisture and the survival of May-planted bare-root seedlings. When soil moisture at planting time was less than 13% on a dry weight basis container-grown seedlings survived better than bare-root seedlings. At both sites, reduced weed competition resulted in greater seedling heights and diameters.Alabama Experiment Station Journal Series No. 9-85802.  相似文献   

6.
Effects of site preparation, shelterwood density and planting depth on the survival and growth of planted beech and oak seedlings were studied. Experiments were performed in one oak and one beech stand in southern Sweden. Two areas with different densities of shelterwood and one clearcut were established in each stand. Growth, damage and survival of the planted seedlings were observed for three years. Soil water potential was recorded weekly and radiation and soil temperatures were recorded continuously during the growing seasons.Neither site preparation methods nor planting depth affected oak seedling growth, when planting was carried out on fresh clearcuts or in shelterwoods, while growth of beech seedlings was positively affected by mounding. Growth of oak seedlings was inhibited by the shelterwood treatments. In beech seedlings, growth was lowest in dense shelterwood, while there was no difference in growth between seedlings on the clearcut area and in the shelterwood of low density. Differences in growth may be explained by differences in radiation and soil water potential.When planting was carried out on a one-year-old clearcut, site preparation improved the subsequent growth of oak and beech seedlings.  相似文献   

7.
Pine plantations on selected sites in the extensive zone of degraded oak coppice of northern Greece are deemed necessary for increasing wood production in the area and suitable site preparation may accelerate early tree growth. Seven site preparation treatments including raking (R), with sub-soiling (RS), disc harrowing (RD), tine ploughing (RT) and their combinations (RSD), (RDT) and (RSDT) were compared for the establishment of black pine (Pinus nigra Arn) in an oak coppice site, of conglomerate parent material at Anthrakia, northern Greece. The randomised blocks trial of three replications and 110 trees per treatment, half of which were fertilised with 150 g NPK per plant, was assessed at the age of 15 years for diameter, dominant tree height and survival. There was no significant difference between the treatments in any of the traits examined, nor did the fertilisation had any effect. Only the fertiliser × treatment interaction was found significant at p<0.001 for dominant height, accounting for 37% of the observed variation in this trait. The lack of response to site preparation treatments may be attributed to the hard Bt3 clay horizon, extending beyond cultivation depth (50 cm), that prevents the roots penetration into deeper moist soil layers. The F × T interaction, where the combination of (RSDT) treatment and fertiliser was found to accelerate tree height growth in relation to the same treatment without fertiliser, indicates that thorough soil cultivation is needed for fertilisation to be effective in such sites.  相似文献   

8.
In northern Europe, there are high risks of severe pine weevil (Hylobius abietis) damage to newly planted conifer seedlings. Site preparation is one of the most important measures for reducing these risks and as several studies have shown the damage is highly dependent on the amount of pure mineral soil around the seedlings. We investigated effects of three site preparation techniques: (1) disc trenching with a conventional Bracke T26, (2) MidiFlex unit and (3) soil inversion with a Karl Oskar unit on characteristics of the planting spots, growth and pine weevil damage and survival rates of untreated and insecticide treated planted Norway spruce (Picea abies) seedlings. All three site preparation techniques reduced pine weevil damage in comparison with no site preparation, and the proportion of spots with pure mineral soil they created was inversely related to the rate of mortality caused by pine weevil. The results indicate that the quality of the planting spots depends on the technique used. In areas where pine weevil is the major threat to seedling survival, the amount of mineral soil in the planting spots is the most important factor in order to protect the seedling from damage. Without site preparation most planting spots consisted of undisturbed humus. Generally, the Karl-Oskar created the most spots with pure mineral soil, but on very stony soils the Bracke T26 created more mineral soil spots than other methods. Site preparation is a valuable tool in order to improve survival in regeneration areas and it is of great importance to make the right choice of technique depending on the particular circumstances on the actual site.  相似文献   

9.
Unsuccessful colonization by indigenous tree species into established plantations has retarded the succession of artificial plantations to more natural, secondary forests in South China. To understand how to improve colonization by seedlings of indigenous species, we determined how performance of indigenous seedlings is affected by seedling species (the shade-intolerant Castanopsis chinensis, the moderately shade-intolerant Michelia chapensis, and the shade-tolerant Psychotria rubra), the site into which the seedlings were transplanted (a mixed-legume plantation, a eucalyptus plantation, a mixed-native plantation, a mixed-conifer plantation, and a shrubland), and site preparation (removal or retention of understory vegetation and litter). Seedling survival and growth were generally increased by removal of understory vegetation and litter. C. chinensis and M. chapensis grew better in the mixed-legume and mixed-conifer plantations, while P. rubra grew better in mixed-native and mixed-conifer plantations. Responses of the transplanted seedlings to environmental factors were species specific. The effects of light on seedling survival and growth were correlated with the shade tolerance of the species. Soil moisture was important; it was positively correlated with survival but negatively correlated with growth of C. chinensis seedlings. Growth of C. chinensis and M. chapensis was positively correlated with soil potassium, while growth of P. rubra was positively correlated with soil organic matter but negatively correlated with soil hydrolyzed nitrogen. These findings suggest that we should select suitable native species under the different plantations before improvement of plantations. Light and soil moisture are most important environmental factors for the selection of species specific. Site preparation and fertilizer are needed during the improvement of those plantations.  相似文献   

10.
We have experimentally investigated the impact of biotic factors, acting at the seed and seedling stages, on a Quercus pyrenaica forest in the Sierra Nevada mountains (SE Spain). We monitored the natural establishment of the oak for 3 years in two forest plots and two shrubland plots, by counting seedlings and juveniles. In addition, we established several experiments in these plots to examine acorn and seedling survival, while also considering the microhabitat effect on survival probability. Dispersed acorns were quickly consumed by several species of predators, particularly wild boar (Sus scrofa) and woodmouse (Apodemus sylvaticus). Less than 4% of the experimental acorns survived to produce seedlings, even when they were buried 4 cm in soil, simulating caches. No effect of microhabitat was found on predation, and thus no safe site appears to exist for Q. pyrenaica acorns in the study area. Some 98% of the 1000 experimental seedlings were killed by herbivores, notably woodmice, wild boar, and domestic and wild ungulates. Seedling survival varied spatially, being significantly higher under shrubs (4%) than in any other microhabitat (less than 0.5%). Both acorn and seedling survival were much lower in the shrublands than in the forests. In shrubland plots, the main agent of seedling mortality was trampling by domestic ungulates foraging in herds. This study suggests that the regeneration of Q. pyrenaica forests in Mediterranean mountains can be limited by herbivores acting at several life-history stages.  相似文献   

11.
Successful regeneration of conifer forests by planting is, in large parts of Europe, highly dependent on the effective suppression of damage caused by the pine weevil Hylobius abietis. We investigated the effectiveness of various combinations of control measures against pine weevil damage under boreal forest conditions in Sweden. In particular, we aimed to determine whether satisfactory regeneration could be obtained without the use of insecticides. The experimental study was established on ten new clear-cuts in each of three consecutive years. We studied the use of chemical and physical methods to protect seedlings directly, and investigated the influence of seedling type, age of clear-cut, and a number of soil factors as affected by preparation of the planting site, on the mortality and level of damage suffered by protected and unprotected seedlings. After two seasons, mortality due to pine weevil was 16% among unprotected seedlings, 6% for seedlings treated with the insecticides cypermethrin or imidacloprid, and less than 1% for those physically protected by a coating of Conniflex. However, the Conniflex, which consists of fine-grained sand embedded in a flexible acrylate matrix, was applied manually, and this may have enhanced its effectiveness compared to that achieved during large-scale, commercial application. Two types of containerized Norway spruce seedlings, which differed mainly in their stem diameter (average 2.6 mm and 3.5 mm), were used in the experiments. Among the unprotected seedlings, the narrower stemmed type was more frequently attacked (34% vs. 28%) and killed (19% vs. 12%) by pine weevil. Mortality caused by pine weevil among unprotected seedlings was higher on 1-year-old than on 2-year-old clear-cuts (20% vs. 12%). Soil preparation around unprotected seedlings had a substantial effect on the proportion attacked and killed by pine weevil as well as on the total mortality, with the highest level of feeding damage and mortality occurring on seedlings in undisturbed humus, and the lowest levels occurring on seedlings planted in pure mineral soil (26% vs. 7% for unprotected seedlings). This study demonstrates that acceptable levels of seedling survival can be achieved in regenerations of North European boreal forest without the use of insecticides. Mortality of unprotected seedlings can be reduced to acceptable levels if they are mostly planted in pure mineral soil. Damage can be further reduced by using seedlings with a somewhat larger stem diameter. Insecticides or a physical barrier of Conniflex alone appear to provide a sufficient level of protection.  相似文献   

12.
On three sites in coastal northwestern Oregon, USA, seedling root and shoot development were assessed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western red-cedar (Thuja plicata Donn ex D. Don) container seedlings under varying sulfometuron methyl (Oust XP®) herbicide application treatments. Treatments consisted of application of 0.16 kg active ingredient (ai) ha?1 as a site preparation in fall 2003, a release application in fall 2004, or a control treatment with no application. Seedlings were planted in winter 2004 and measurements recorded in summer 2004, winter 2005, and summer 2005. During first season growth, western red-cedar seedlings showed the greatest negative impact to site preparation compared to the control with overall average new root length outside the root plug reduced by 67%. Significant reductions in root length also occurred for western hemlock (47%) and Douglas-fir (40%) seedlings. About 9 months after the release treatment, and 21 months after the site preparation application, there were no significant differences between treatments for any measured parameter. These findings suggest that seedlings under the site preparation treatment recovered from initial damage incurred to the root system. Lack of seedling response under the release treatment may be the result of opposing influences from the herbicide application associated with seedling phytotoxicity and enhanced seedling development resulting from effective vegetation control. Although our study was limited to 21 months following planting, reduced vegetation cover in the site preparation and release treatments suggests that these treatments may benefit future seedling growth.  相似文献   

13.
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   

14.
A properly selected stocktype can greatly enhance reforestation success through increased survival and growth following outplanting. Implementing a robust stocktype trial using stocktypes of equal quality can ensure results lead to the best choice. Six container types, differing primarily in depth and volume, were used to evaluate the performance of ponderosa pine (Pinus ponderosa Laws. var. ponderosa) seedlings outplanted on two sites that varied in volumetric soil moisture content (θ), average temperature, and total precipitation (mesic and xeric). Seedlings in each container type were cultured specifically to achieve uniform seedling quality. After two growing seasons, seedlings planted at the mesic site showed high survival (>99%) and incremental growth gains of 147, 100, and 794% for height, root-collar diameter (RCD), and stem volume, respectively; container types exhibited differences in total height, RCD, and stem volume with larger containers generally yielding the largest seedlings. Seedlings planted at the xeric site experienced 83% survival, smaller growth gains (25, 46, and 220% for height, RCD, and stem volume, respectively), and also exhibited differences in height, RCD, and stem volume. Regression analysis revealed that for each site, initial seedling morphological characteristics were better at predicting absolute height, RCD and stem volume after the first year than after the second year, with initial seedling height offering the best predictive power (R2 = 0.66, mesic site; and R2 = 0.70, xeric site). Second-year absolute growth prediction was poorest on the mesic site (R2 < 0.21). Regression analysis indicates that initial seedling characteristics lost predictive value with time, especially on the mesic site, as seedlings grew out of their initial, container-induced characteristics and become more limited by current environmental and genetic factors. Conversely, on a xeric site, where absolute growth was reduced, traits determined by the container type persisted longer. Selecting stocktypes for mesic site conditions may only be limited by the minimum growth gains desired. Conversely, xeric sites may benefit from deep-planted quality seedlings or carefully planted long-rooted, large container seedlings.  相似文献   

15.
鹅掌楸容器育苗轻基质配方研究   总被引：2，自引：1，他引：1  
选用泥炭、稻壳、森林表土、黄心土混合配制成5种轻基质配方,开展鹅掌楸容器育苗技术研究。结果表明:不同轻基质配方之间的重量,容器苗苗高、地径、根系、单株干物质重量达到极显著差异;4号轻基质配方(泥炭50%+稻壳20%+森林表土20%+黄心土10%)育苗效果最好,苗木粗壮、根系发达、基质重量较轻;1号轻基质配方(泥炭20%+稻壳50%+森林表土20%+黄心土10%)效果最差。研究认为:在鹅掌楸容器育苗生产上宜选用4号轻基质配方。  相似文献   

16.
Seasonal and substrate effects on first-year seedling establishment of major conifer species (Abies mariesii, Abies veitchii, Picea jezoensis var. hondoensis, and Tsuga diversifolia) were assessed in an old-growth subalpine forest in central Japan. Older seedlings (≥1 year) were more abundant on woody debris (WD), such as fallen logs, than on soil. It is known that this preferential seedling establishment on WD is determined by the first-year seedling establishment. The present results indicate that first-summer seedling survivorship clearly contributes to the creation of such seedling–substrate associations, because mortality during the first-summer was greater on soil than WD but that during the first-autumn/winter was not different. Although the standardized mortality rate of current-year seedlings on WD was not so different among the three seasons, that on soil significantly decreased in the winter; indicating that soil is not an unsuitable substrate for seedling survivorship during snow-covered winter. Thus, it can be concluded that biotic and abiotic factors enhancing seedling mortality on soil are most active during summer, and seedling–substrate associations seem to be determined mainly during the first-summer soon after seedling emergence. Furthermore, the first-year survivorship of P. jezoensis var. hondoensis, which has smaller-sized seeds/seedlings that are disadvantageous for early survival, decreased with progressing WD decay toward soil. This suggests that the properties of WD also affect current-year seedling survivorship, especially for species sensitive to substrate properties. In conclusion, initial survivorship affects seedling bank dynamics, and such early dynamics are greatly regulated by the highly heterogeneous substrate availability on forest floors.  相似文献   

17.
Growth of graded sweetgum 3 years after root and shoot pruning   总被引：1，自引：0，他引：1  
Nursery grown 1–0 bareroot sweetgum seedlings were lifted and graded into two diameter classes (12–16 and 4–8 mm) during the dormant season. Large and small grades were top and/or root pruned and then outplanted on two sites in the lower Coastal Plain of the southeastern United States. Seedling shoots were pruned to 50% of tree height, a 5 cm stump, or no pruning. Seedling roots were pruned to a 15 cm length or left unpruned. Site affected survival but not growth. Smaller, top pruned seedlings performed worse on one site, probably due to greater weed competition. Large seedlings increased survival and growth which increased 3 year average plot volumes by 89%. Top pruning stimulated height growth, but reduced diameter growth and decreased third year seedling volumes. Root pruning did not affect seedling growth. Diameter growth may better indicate treatment impact that height, which has been most commonly used in previous studies.  相似文献   

18.
The Rothwald forest in Lower Austria represents one of the few never logged old growth forests in Central Europe. Here, the influence of windthrow pits and mounds on tree regeneration in a spruce-fir-beech mountain forest was studied. Two main factors for recolonisation of sites after disturbance were investigated: (i) the trapping ability of microsites for seeds and (ii) the ability of particular tree species to establish and grow on different microsites. On two one hectare permanent sample plots, pits resulting from windthrow with existing tree trunks were recorded. At each windthrow three microsites were determined: pit, pitwall and undisturbed forest floor. If the windthrow plate already collapsed and formed a mound, this microsite was recorded as well. Furthermore, a control site was established at each windthrow. For two years the development of seedlings at four different microsites and the according control sites were monitored. To describe the variability of environmental factors possibly influencing seedling establishment and survival, litter, humus and soil attributes, herb vegetation cover as well as light availability (GSF) were assessed. In addition, soil temperature, chemical soil properties and water content were recorded at randomly selected windthrows. The distribution of the seedlings was assessed with a Redundancy Analysis, its occurrence modelled with a logistic regression and the mortality analysed with the Kaplan-Maier lifetime function. In contrast to the assumption of seed accumulation in concave microsites because of secondary dispersal, the pit microsites show comparable seed rain to the control site. However, pits have the lowest seedling numbers and by far the highest mortality rates of seedlings. The thickness of leaf litter was identified as a major driver of suitability of a microsite for recolonisation. Through its thickness, it inhibits germination and smothering of seedlings poses a particular high hazard during the winter period. Also different establishment patterns of the investigated tree species were detected. The results indicate that windthrows create microsite heterogeneity and plant species richness but limit tree population size and spatial distribution of the occurring tree species.  相似文献   

19.
Each link in initial process of artificial regeneration ofPinus koraiensis in clear cutting site was researched. The seedling recovery processes after transplantation, the affecting seedlings survival factors in different time, and the characters of seedling growth were analyzed. Results of this study suggest that the root recovery of Korean pine seedlings after transplanting is the key link in the artificial regeneration management. The synthetically management was proposed on basis of seedling root recovery process. The project was surpported by Natural Science Fund of Heilongjiang Province  相似文献   

20.
The dynamics of the seedling population of the pioneer tree, Betula maximowicziana, were studied for 6 years under various site conditions, with special reference to mortality and mortality factors, in order to better understand their seedling bank formation process. We found that current year seedlings suffered high annual mortality of more than 80%, but that mortality fell with age. Canopy covers and cohorts maintained strong influences on seedling mortality during the first 3 years after emergence. The open site with disturbed soil surface was best suited for 3-year seedling survival. Since the seedlings of B. maximowicziana emerged regardless of canopy covers, high seedling mortality was thought to be the main factor that interrupted their regeneration under a canopy. The occurrence of various hazards together caused high seedling mortality. The major mortality factors, regardless of site conditions, were drought, cold hazard and debilitation, though occurrence of the three factors varied, dependent upon the climate of that particular year. Annual mortality and the occurrence of each mortality factor at a fine scale of 0.2 m2 quadrate each showed certain spatio-temporal variations within the same site condition. The extremely high mortality of B. maximowicziana seedlings should be attributed to their inherently small, initial size. The poor root system of the small seedlings may be responsible for their low resistance to various hazards, such as drought and frost heaving.  相似文献   

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