共查询到20条相似文献，搜索用时 31 毫秒
1.
《Scandinavian Journal of Forest Research》2012,27(2):225-236
The objective of the investigation was to describe moisture conditions and germination of Scots pine (Pinus sylvestris L.) seeds in different seedbed substrates (feather mosses, mineral soil, humus and ground organic material) with and without irrigation during 2 weeks, in a clearcut in northern Sweden. Without irrigation no seeds germinated, which could be explained as an effect of the low moisture conditions of the seedbed substrates. This was shown in the seeds' low moisture content, with highest values in mineral soil, 10-20%, and for the other seedbed substrates 5-15%. The moisture conditions were highest during the night and lowest in the afternoon. With irrigation, moisture conditions improved (seed moisture content 20-50%) and diurnal changes were moderated. Seeds germinated in all substrates with most seedlings in mineral soil (60% of sown germinable seeds). The moisture conditions of the seedbed substrates proved to be in poor agreement with the seeds' requirement for germination, especially during warm weather with no precipitation. 相似文献
2.
草珊瑚不同播种育苗方式效果研究 总被引：5，自引：0，他引：5
试验采用营养袋播种育苗和田间苗床播种育苗2种方式进行草珊瑚苗木生长量的比较研究,结果表明：2种育苗方式对苗木的出土时间没有影响,但对种子的发芽率具有极显著影响,前者比后者提高29.3%。2种不同育苗方式的高径生长量、根系生长量及总生物量（鲜重）差异极显著;营养袋有利于苗木的高径生长和主根生长,总生物量比田间苗床播种苗提高30.4%;但侧根生长相比较差。为提高移栽成活率,在生产上提倡营养袋育苗。 相似文献
3.
The spatial distribution of plant-available mineral nutrients in forest soils is often highly heterogeneous. To test the hypothesis that local nutrient enrichment of soil leads to increased root proliferation in the nutrient-rich soil zone, we studied the effects of nutrient enrichment on the growth and nutrient concentrations of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) roots. Three-year-old seedlings were grown for 9 months in split-root containers filled with nutrient-poor forest mineral soil, with one side supplemented with additional mineral nutrients. Root dry weight and root length in Scots pine and Norway spruce were increased in the nutrient-supplemented soil compared with the nonsupplemented side, whereas root growth in Douglas-fir was unaffected by nutrient enrichment. Of the three species examined, Norway spruce exhibited the highest root and shoot growth and the highest nutrient demand. Specific root length (m g(-1)) and the number of root tips per unit root length were not affected by local nutrient addition in any of the species. Despite increased root growth in Norway spruce and Scots pine in nutrient-supplemented soil, their root systems contained similar nutrient concentrations on both sides of the split-root container. Thus, coniferous trees may respond to local nutrient supply by increased root proliferation, but the response varies depending on the species, and may only occur when trees are nutrient deficient. As a response to local nutrient enrichment, increases in root dry matter or root length may be better indicators of pre-existing nutrient deficiencies in conifers than increases in root nutrient concentrations. 相似文献
4.
Göran Hallsby 《New Forests》1994,8(1):43-60
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
5.
The purpose of this study was to examine the effects of type and amount of ground vegetation and substrate on the germination and early survival of Norway spruce (Picea abies (L.) Karst) seedlings in uneven-aged stands on mineral soils in Southern Finland. The study was conducted on two permanent plots representing average site quality for spruce stands in the area. A gradient in selection cut intensity and residual stand density was imposed across each of the two permanent plots. Regeneration and vegetation surveys were repeated annually on a grid of unmanipulated microplots and on a set of soil treatment microplots. The results indicated that the number of spruce germinants per unit area was positively correlated with herb cover but negatively correlated with total plant cover. Germinant density was also related to vegetation-free seedbed conditions, high overstory competition index and presence of larger spruce seedlings. Regeneration microsites dominated by moss or with plants with a relatively high light demand were associated with low germinant numbers. Bare humus layer and decayed stumps seemed to promote germinant emergence. Exposure of mineral soil resulted in germination rates that were 4.3–6.9 times higher than in undisturbed conditions during the first growing season. 相似文献
6.
【目的】比较秦岭辛家山林场云杉和红桦天然林土壤有机碳密度的估算结果,检验新方法通过扣除根系体积而提高的估算精度。【方法】分别估算矿质土层(表土层、心土层和底土层)和有机土层(凋落物的未/半分解层和完全分解层)的有机碳密度。在现有方法的基础上通过扣除林木根系体积含量来提高矿质土层有机碳密度的估算精度。各层林木根系体积含量的估算方法为:首先,使用前人提出的回归方程估算出单株林木根系生物量,乘以林木生长密度得到单位面积林地的根系总生物量;其次,通过采集部分根系样品测定其生物量和体积,并计算出根系样本的密度以代表整体根系的密度;然后,通过单位面积林地的根系总生物量除以根系的密度计算出单位面积林地的根系总体积;最后,利用前人研究得出的根系沿深度的分布规律,将单位面积根系总体积分配到各土层,计算出根系体积含量。对有机土层有机碳密度的估算,使用林木平均地径估算林木根基部所占面积,将有机土层中含有的林木体积扣除。此外,由于有机土层的各组分分布极不均匀,本研究依据来源器官和物理形态对凋落物(有机土层)中的不同成分进行了细致的分组,分别测定各组分的有机碳密度。【结果】云杉林表土层、心土层和底土层的厚度分别为19.10、14.20和31.03 cm,红桦林则分别为18.57、15.13和28.13 cm;云杉林表土层、心土层和底土层的有机碳含量分别为(44.56±3.72)、(25.63±1.77)和(10.79±2.28)g ·kg^-1 ,红桦林的分别为(34.11±5.46)、(19.06±4.95)和(11.02±3.86)g·kg^-1;2种林分有机土层各组分有机碳含量差异显著(P<0.05),凋落物中枝条、根系、云杉球果和苔藓的有机碳含量均大于600 g·kg^-1 ,叶片次之,云杉林和红桦林分别为(458.90±46.81)和(420.72±55.66)g·kg^-1 ,其余难以分辨的细颗粒含量最低均小于300 g·kg^-1;在矿质土层,云杉林各层每公顷根系体积(及体积比例)分别为表土层66.81(3.5%)、心土层20.69(1.5%)以及底土层9.18(0.3%)m^3,红桦林则分别为50.57(2.7%)、31.75(2.1%)和17.22(0.6%)m^3;使用改进公式估算的云杉林矿质土层有机碳密度为16.58 kg ·m^-2 ,有机土层有机碳密度为4.26 kg ·m^-2 ,完全分解层和半分解层分别占84%和16%,矿质土层和有机土层有机碳密度分别较原方法降低2.13%和0.73%;使用改进公式估算的红桦林矿质土层有机碳密度为 14.06 kg ·m^-2 ,有机土层碳密度为3.49 kg ·m^-2 ,分解层和半分解层分别占90%和10%,矿质土层和有机土层有机碳密度分别较原方法降低1.61%和0.48%。【结论】去除根系体积含量后,云杉林与红桦林的土壤总有机碳密度估算值分别降低1.85%和1.39%,这意味着目前预测的林地土壤碳储量可能普遍偏高。 相似文献
7.
The objective of this investigation was to comparemoisture conditions and Scots pine (Pinussylvestris L.) seed germination percentages in fourtypes of seedbed substrates, (i.e., feather mosses,mineral soil, humus, and ground organic material). Twoexperiments were conducted, with and withoutirrigation, in the summer of 1996 in a stand innorthern Sweden. The moisture conditions weredetermined by periodically weighing seedsamples. When plots were not irrigated, no seedsgerminated, probably because conditions were too dryin the seedbeds, as indicated by the low seed moisturecontent (under 15%). However, during rainy days, seedmoisture contents were relatively high (20–45%). Onthe irrigated plots the seeds germinated on allseedbed substrates, with the best germinationoccurring in humus (about 40%). Seed moisturecontents were high and relatively consistent in allirrigated seedbed substrates (35–55%). Inirrigated plots temperature rather than moisture, wasa limiting factor, and germination was highest in thewarmest seedbed types which are generally regarded aspoor germination substrates. We suggest that seedbedsin areas scheduled for harvesting be prepared in thestand before clear-cutting, and that the preparationshould enhance not only the substrates's water-holdingcapacity, but its thermal conductivity as well. 相似文献
8.
Soil temperature is a main factor limiting root growth in the boreal forest. To simulate the possible soil-warming effect of future climate change, 5-year-old Norway spruce (Picea abies (L.) Karst.) seedlings were subjected to three simulated growing seasons in controlled environment rooms. The seedlings were acclimated to a soil temperature of 16 degrees C during the first (GS I) and third growing seasons (GS III), but were assigned to random soil-temperature treatments of 9, 13, 18 and 21 degrees C during the second growing season (GS II). In GS II, shoot diameter growth was lowest in the 21 degrees C treatment and root growth was lowest in the 9 degrees C treatment. In GS III, shoot height and root length growth improved in seedlings that had been kept at 9 degrees C during GS II, indicating compensatory growth in response to increased soil temperature. The temporary decrease in soil temperature had no long-lasting significant effect on seedling biomass or total nutrient uptake. At the end of GS III, fine roots of seedlings exposed to a soil temperature of 21 degrees C in GS II were distributed more evenly between the organic and mineral soil layers than roots of seedlings in the other treatments. During GS II and GS III, root growth started earlier than shoot growth, decreased during the rapid shoot elongation phase and increased again as shoot growth decreased. 相似文献
9.
Bigras FJ 《Tree physiology》1997,17(5):311-318
Root systems of 6-month-old, cold-hardened, container-grown black spruce seedlings (Picea mariana (Mill.) B.S.P.) were exposed to 0, -5, -10, -15, -20, or -22.5 degrees C. Freezing-induced damage to fine roots, coarse roots and the whole root system was assessed by various viability tests including leakage of electrolytes, leakage of phenolic compounds, water loss, root and shoot water potentials, and live root dry mass. To assess the long-term effects of freezing-induced root damage, seedling survival and regrowth were measured. Leakage of both electrolytes and phenolic compounds differed among fine roots, coarse roots, and whole root systems. In coarse roots and the whole root system, but not in fine roots, leakage of electrolytes, leakage of phenolic compounds, water loss, and root and shoot water potentials were correlated with percentage of live root dry mass which, in turn, was highly correlated with seedling survival and regrowth. Compared with live root dry mass, electrolyte and phenolic leakage, water loss, and root and shoot water potentials were less well correlated with seedling survival and regrowth. Among the viability tests, electrolyte leakage of the whole root system correlated most closely with seedling survival and regrowth. Under freezing conditions that destroyed less than 50% of each seedling's root system, about 70% of the seedlings survived and subsequent growth was little affected, whereas under freezing conditions that destroyed 70% of each seedling's root system, only about 30% of the seedlings survived and subsequent growth was reduced compared with that of undamaged plants. 相似文献
10.
Black spruce (Picea mariana (Mill.) BSP) and tamarack (Larix laricina (Du Roi) K. Koch) are the predominant tree species in the boreal peatlands of Alberta, Canada, where low nutrient availability, low soil temperature and a high water table limit their growth. Effects of flooding for 28 days on morphological and physiological responses were investigated in greenhouse-grown black spruce and tamarack seedlings in a growth chamber. Flooding reduced root hydraulic conductance, net assimilation rate and stomatal conductance, and increased water-use efficiency (WUE) and needle electrolyte leakage in both species. Although flooded black spruce seedlings maintained higher net assimilation rates and stomatal conductance than flooded tamarack seedlings, flooded tamarack seedlings were able to maintain higher root hydraulic conductance than flooded black spruce seedlings. Needles of flooded black spruce developed tip necrosis and electrolyte leakage after 14 days of flooding, and these symptoms were subsequently more prominent than in needles of flooded tamarack seedlings. Flooded tamarack seedlings exhibited no visible injury symptoms and developed hypertrophied lenticels at their stem base. Application of exogenous ethylene resulted in a significant reduction in net assimilation, stomatal conductance and root respiration, whereas root hydraulic conductivity increased in both species. Thus, although flooded black spruce seedlings maintained a higher stomatal conductance and net assimilation rate than tamarack seedlings, black spruce did not cope with the deleterious effects of prolonged soil flooding and exogenous ethylene as well as tamarack. 相似文献
11.
花榈木不同播种育苗方式效果研究 总被引：6，自引：0，他引：6
试验采用营养袋播种育苗和田间苗床播种育苗2种方式进行花榈木苗木生长量的比较研究,结果表明,2种不同育苗方式的种子的发芽率、高径生长量、根系生长量差异极显著;营养袋有利提高花榈木种子的发芽率及苗木的高径生长和主根生长,但侧根生长较差;为提高移栽成活率,在生产上提倡采用营养袋育苗。 相似文献
12.
Black spruce (Picea mariana (Mill.) BSP) is the most important commercial tree species in the eastern boreal forest of Canada. Only limited work has
been conducted to assess the quality of the various substrates that are found on post-disturbed sites prone to paludification
having an effect on black spruce seedling growth. The objectives of this study were (1) to use a pot test to assess black
spruce seedling performance on substrates found at the soil surface, in the rooting zone of undisturbed soil, at depths that
become available to spruce roots after soil disturbance by wildfire or through management; and (2) to determine the nutritional
quality of these substrates when constraints of poor drainage are artificially removed. Black spruce growth was greatest with
fibric Pleurozium in the rooting zone, and with burned fibric Pleurozium and living Sphagnum at the soil surface. Good seedling growth on different substrates found in the rooting zone was associated with higher N
and P foliar concentrations. Based on these results, we recommend targeted planting of black spruce seedlings in substrates
of Pleurozium origin and the development of management techniques that promote Pleurozium schreberi.
The Canadian Crown’s right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged. 相似文献
13.
P. -O. Brandtberg Hel ne Lundkvist Jan Bengtsson 《Forest Ecology and Management》2000,130(1-3):253-264
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
14.
We studied the influence of temperature and near- and sub- optimal mineral nutrition of black spruce seedlings (Picea mariana [Mill.] B.S.P.) during their second growing period on bud set, bud development, growth, mineral content and cold tolerance. Bud break and growth after bud break were also studied. Seedlings were grown for 106 d in growth chambers under three temperature regimes in combination with three concentrations of a fertilizer. They were then cold hardened for 56 d and dehardened for 66 d.Under these near- and sub-optimal N levels, bud formation occurred during the growing season. Bud formation was accelerated with decreasing fertilization, but was not affected by temperature treatments. Needles from seedlings with 0.64% N (dry mass basis) before hardening did not harden. Those with 0.87% N showed a lesser degree of hardiness than those with 1.28% N. Stem diameter increased at the beginning of the hardening period. During this acclimation period, shoot dry mass decreased with time at a constant rate and at the same rate over time for all treatments whereas root dry mass was more variable. Total number of needle primordia was low and no difference was observed among growing conditions. Bud break was similar in all treatments. Following bud break, shoot height and stem diameter increases were small but their magnitude varied with the nutritional regimes applied during the previous growing period. During hardening, nitrogen concentration of shoot tissues first increased and then decreased; phosphorus concentration first increased and then remained stable; potassium concentration remained stable. Concentration of these three elements generally decreased in the roots during this hardening. 相似文献
15.
Iwan Wästerlund 《Forest Ecology and Management》1985,11(3):171-189
Five of the most common soils in forest areas in Sweden, viz., coarse sand, fine sand, coarse sandy till, medium sandy till and fine sandy till soil, were compressed at different loadings for 10 min. In the soils studied, it was found that the more fine material there was in the soil, the easier it compacted, and that till soils compacted much more than sediments of the same main particle class. The chosen compression time seemed to correspond well with an equilibrium level of static compaction. Influence of wall friction in compression tubes was found to be negligible for till soils.After compaction the soil cores were sown with Norway spruce (Picea abies (L.) Karst.) or Scots pine (Pinus sylvestris L.) and 16–20 days later the root lengths were recorded. Lengths of primary roots in per cent of the control were found to be almost inverse to the compaction of the soils; Norway spruce was more impeded than Scots pine. Thus, the bulk density alone is a poor indicator of the impact of soil compaction. Growth to 26, 33 and 120 days showed that the extension of secondary roots might be more impeded by compaction than the primary roots. Fertilization increased growth but did not decrease the growth difference between seedlings on unloaded and loaded soil cores. 相似文献
16.
为了解巨桉内含物对牧草的化感作用,试验选用浓度为1∶10、1∶50、1∶100的巨桉根浸提液(母液浓度为1∶10,w/v),以蒸馏水为对照,按照培养皿水培和盆栽土培的生物检测方法,探讨巨桉根系对黑麦草、紫花苜蓿、高羊茅3种牧草的化感作用。结果表明:在水培试验中,对黑麦草表现为高浓度抑制其根和苗生长,低浓度促进其根和苗生长;对紫花苜蓿根和苗生长均表现为促进作用。在盆栽试验中,对黑麦草和高羊茅表现为抑制其根长和促进其茎高生长,随着浓度的增加,对根的抑制作用逐渐增强;对紫花苜蓿根和地上部分干重表现为促进作用,随浓度的增加,促进作用减弱。 相似文献
17.
The aim of the study was to investigate dynamics and pattern of natural regeneration and the influence of seedbed and light
on germination and initial seedling survival of Scots pine (Pinus sylvestris L.) during three growing seasons. Four 5-m2 plots in a natural Scots pine forest in central Spain were randomly established at the beginning of the regeneration process.
Germination and seedling survival were recorded in 100 regeneration sampling subplots (0.25 m2) per plot, while seedbed type and the relative light intensity reaching the forest floor was characterised in 1-m2 subplots. The spatial correlations between survival, light conditions and organic matter depth were analysed through cross-variograms.
Germination and survival were highly variable both within and between plots (ranging from 0 to 89%) and affected by high summer
temperatures (33–35°C) in 2003. The spatial pattern characterisation of survival by Ripley’s K function showed a dominant cluster distribution. Occurrence tended to be clumped when abundance was greater than 15 seedlings,
whereas for lower densities, seedlings were randomly distributed. Seedlings and herbs occupied the same sites where environmental
conditions were appropriate for them to live. Spatial association occurred frequently for light and organic matter depth.
Results suggested that the Scots pine seedlings in our study in central Spain preferred moderate light conditions (Global
Site Factor <0.40). Thus, if this forest is to be naturally regenerated with Scots pine, the shelterwood system (whereby some
mother trees are left to provide shelter for at least 5 years), along with mechanical disturbance of the seedbeds, would promote
seed germination, as long as a seed source is present. However, regeneration success is affected by year-to-year conditions. 相似文献
18.
Stem cuttings of Eucalyptus globulus are used within tree improvement programs and for mass deployment. To be successful, cuttings must perform as well or better than seedlings. The root systems of cuttings are fundamentally different from those of seedlings. If these differences influence growth, the differences and their consequences must be identified and the propagation system manipulated to improve performance of the propagules.Cuttings are only a viable alternative to seedlings as planting stock if the method of propagation does not affect their growth and development adversely. Full-sibling cuttings and seedlings of Eucalyptus globulus were compared under controlled environmental conditions to minimise extraneous sources of variation, and to establish whether changes in growth or development were induced by propagation. On three occasions over a period of eight weeks root-collar diameter, shoot height, leaf and stem weight, shoot/root ratios and root system morphology were measured on cuttings and seedlings. Seedlings were taller than cuttings throughout the experiment, but both plant types had similar height growth rates. Diameter growth rates were lower in cuttings than seedlings, and there were differences in both height and diameter growth rates between families. Root system configuration differed between the plant types. Seedlings had strongly gravitropic tap-roots, with two types of primary roots from which secondary roots emerged. Cuttings had no tap roots, and the main structural components of their root systems were adventitious roots formed during propagation. Cuttings did not develop further structural roots during the experiment, whereas seedlings continued to develop primary roots. Individual primary roots of cuttings were longer and had larger mid-point diameters than those of seedlings, but the total length of primary roots was greater in seedlings. Seedlings also had a greater number and total length of secondary roots. Shoot/root ratios, calculated from a range of functional measures, were higher in cuttings than seedlings. 相似文献
19.
One-year old seedlings of trembling aspen (Populus tremuloides Michx.), black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss), and jack pine (Pinus banksiana Lamb.) were subject to seven soil temperatures (5, 10, 15, 20, 25, 30 and 35 °C) for 4 months. All aspen seedlings, about 40% of jack pine, 20% of white spruce and black spruce survived the 35 °C treatment. The seedlings were harvested at the end of the fourth month to determine biomass and biomass allocation. It was found that soil temperature, species and interactions between soil temperature and species significantly affected root biomass, foliage biomass, stem biomass and total mass of the seedling. The relationship between biomass and soil temperature was modeled using third-order polynomials. The model showed that the optimum soil temperature for total biomass was 22.4, 19.4, 16.0 and 13.7 °C, respectively, for jack pine, aspen, black spruce and white spruce. The optimum soil temperature was higher for leaf than for root in jack pine, aspen and black spruce, but the trend was the opposite for white spruce. Among the species, aspen was the most sensitive to soil temperature: the maximum total biomass for aspen was about 7 times of the minimum value while the corresponding values were only 2.2, 2.4 and 2.3 times, respectively, for black spruce, jack pine and white spruce. Soil temperature did not significantly affect the shoot/root (S/R) ratio, root mass ratio (RMR), leaf mass ratio (LMR), or stem mass ratio (SMR) (P>0.05) with the exception of black spruce which had much higher S/R ratios at low (5 °C) and high (30 °C) soil temperatures. There were significant differences between species in all the above ratios (P<0.05). Aspen and white spruce had the smallest S/R ratio but highest RMR while black spruce had the highest S/R but lowest RMR. Jack pine had the highest LMR but lowest SMR while aspen had the smallest LMR but highest SMR. Both LMR and SMR were significantly higher for black spruce than for white spruce. 相似文献
20.
《Forest Ecology and Management》1996,88(3):227-235
The nature of interference of bracken with Scots pine and Norway spruce seedling establishment was considered in three field experiments. In a seeding experiment, it was found that Scots pine germination was highest on exposed mineral soil and lowest when intact bracken litter and humus were present, suggesting adverse effects of litter and humus on pine regeneration probably due to phytotoxicity. In a second experiment, smothering by bracken caused high mortality of Scots pine seedlings while Norway spruce seedlings were relatively unaffected. Mortality for both Scots pine and Norway spruce seedlings was low when planted in a adjacent Scots pine-bilberry stand with no bracken. Annual shoot growth of Norway spruce was higher in bracken than in Scots pine-bilberry vegetation while no differences in shoot growth between these two vegetation types occurred for Scots pine. In a third experiment, activated carbon was added to the ground under Norway spruce seedlings planted in bracken to adsorb possible phytotoxic compounds released by bracken. The addition of carbon had no effect on seedling mortality or growth rate, indicating that the seedlings were not susceptible to allelochemicals released by bracken. Since large Norway spruce seedlings were relatively unaffected by bracken interference in this study, artificial regeneration with containerized Norway spruce seedlings is suggested to achieve an acceptable conifer tree establishment on clear-cuts invaded by bracken. 相似文献