Micropropagation of juvenile and mature american beech

The purpose of this study was to micropropagate juvenile and mature American beech (Fagus grandifolia Ehrh.) resistant to beech bark disease. Shoot tips (from juvenile seedlings and root sprouts of mature trees) and buds from branches of mature trees, were cultured and multiplied on aspen culture medium supplemented with 0.89 μM 6-benzyladenine, 0.27 μM α-naphthaleneacetic acid, 20 g l^-1 sucrose, and 7 g l^-1 Difco Bacto-agar. Rooting of shoots was achieved using a 1 minute dip in 12.3 mm indole-3-butyric acid, followed by culture in a Horticube saturated with half-strength aspen culture medium containing 20 g l^-1 sucrose. Thirteen of 33 mature genotypes were established from shoot tips taken from root sprouts, and six of 41 were established from mature buds. Plantlets of six genotypes were successfully acclimatized to a growth room for three months. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nutrient dynamics along a precipitation gradient in European beech forests

Precipitation as a key determinant of forest productivity influences forest ecosystems also indirectly through alteration of the nutrient status of the soil, but this interaction is not well understood. Along a steep precipitation gradient, we studied the consequences of reduced precipitation for the soil and biomass nutrient pools and dynamics in 14 mature European beech (Fagus sylvatica L.) forests on Triassic sandstone. We tested the hypotheses that lowered summer precipitation (1) is associated with less acid soils and (2) a reduced accumulation of organic matter on the forest floor, and (3) reduces nutrient supply from the soil and leads to decreasing foliar and root nutrient concentrations. Soil acidity, the amount of forest floor organic matter, and the associated organic matter N and P pools decreased to about a half from wet to dry sites; the C/P and N/P ratios, but not the C/N ratio, of forest floor organic matter were reduced as well. Net N mineralization and P and K pools in the mineral soil did not change with decreasing precipitation. Foliar P and K concentrations (beech sun leaves) increased while N remained constant, resulting in decreasing foliar N/P and N/K ratios. Estimated N resorption efficiency increased toward the dry sites. We conclude that a reduction in summer rainfall significantly reduces the soil C, N and P pools but does not result in decreasing foliar N and P contents in beech. However, the decreasing foliar N/P ratios towards the dry stands indicate that the importance of P limitation for tree growth declines with decreasing precipitation.     

Effects of Temperature on Bud-Sprouting and Early Growth of Cyperus esculentus in the Dark

Cyperus esculentus tubers and early growth of their sprouts. Percent sprouting increased with increasing temperature within the range of 12 to 38 C, while no sprouting occurred at 10 C and few tubers sprouted at 42 C. The rate of sprouting also increased with temperature up to 35 C. A base temperature of 11.4 C was determined for bud-sprouting of tubers in this species. Higher temperatures led to larger sprouts and greater survival rate. In particular, increased temperature favored root growth, and hence resulted in high root: shoot ratio of the sprouts. Larger tubers produced larger sprouts as a consequence of mobilizing a greater amount of their reserves, but they tended to utilize a smaller proportion of their reserves. The efficiency of reserve utilization significantly differed among the incubation temperatures, and its relation with temperature followed a quadratic pattern. This pattern is different from that documented for the bud-sprouting of rhizomes and stolons of other perennials. Our results demonstrate that temperature is crucial to the successful establishment of C. esculentus. Received 24 June 1999/ Accepted in revised form 14 December 1999     

Response of Japanese beech (Fagus japonica Maxim.) sprouts to canopy gaps

The response of Japanese beech (Fagus japonica Maxim.) sprouts to canopy gaps in natural beech forest in central Japan was studied using two contrasted gaps in which tree-ring chronologies of regenerating stems were analyzed. The gaps were created by uprooting of a single Quercus mongolica var. grosseserrata stem (diameter: 50 cm; gap size: 40 m²; 23 years old) and by concurrent uprootings of four F. japonica stools (gap size: 180 m²; 30 years old). Japanese beech sprouts emerged before and after the gap formation and dominated stem populations in both gaps. In gaps, growth of F. japonica sprouts was equal or lower than growth of stems of seed origin, but most sprouts (F. japonica, Acer mono var. marmoratum) appeared a few years before emergence of seedlings. The small gap created by single stem fall was dominated by some beech sprouts from stools adjacent to the gap. The multiple gap was not closed by beech sprouts from stools surrounding the gap, but some dominant beech stems were resprouts from the uprooted beech stools. The existence of a sprout bank under the canopy may play an important role in the closing process of gaps in natural Japanese beech forest.     

Foliar δ15N is affected by foliar nitrogen uptake, soil nitrogen, and mycorrhizae along a nitrogen deposition gradient

Foliar nitrogen isotope (δ¹⁵N) composition patterns have been linked to soil N, mycorrhizal fractionation, and within-plant fractionations. However, few studies have examined the potential importance of the direct foliar uptake of gaseous reactive N on foliar δ¹⁵N. Using an experimental set-up in which the rate of mycorrhizal infection was reduced using a fungicide, we examined the influence of mycorrhizae on foliar δ¹⁵N in potted red maple (Acer rubrum) seedlings along a regional N deposition gradient in New York State. Mycorrhizal associations altered foliar δ¹⁵N values in red maple seedlings from 0.06 to 0.74 ‰ across sites. At the same sites, we explored the predictive roles of direct foliar N uptake, soil δ¹⁵N, and mycorrhizae on foliar δ¹⁵N in adult stands of A. rubrum, American beech (Fagus grandifolia), black birch (Betula lenta), and red oak (Quercus rubra). Multiple regression analysis indicated that ambient atmospheric nitrogen dioxide (NO₂) concentration explained 0, 69, 23, and 45 % of the variation in foliar δ¹⁵N in American beech, red maple, red oak, and black birch, respectively, after accounting for the influence of soil δ¹⁵N. There was no correlation between foliar δ¹³C and foliar %N with increasing atmospheric NO₂ concentration in most species. Our findings suggest that total canopy uptake, and likely direct foliar N uptake, of pollution-derived atmospheric N deposition may significantly impact foliar δ¹⁵N in several dominant species occurring in temperate forest ecosystems.     

Effects of elevated CO2 concentration on photosynthesis, respiration and carbohydrate status of coppice Populus hybrids

To determine how increased atmospheric CO₂ will affect the physiology of coppiced plants, sprouts originating from two hybrid poplar clones ( Populus trichocarpa × P. deltoides - Beaupre and P. deltoides × P. nigra - Robusta) were grown in open-top chambers containing ambient or elevated (ambient + 360 μmol mol⁻¹) CO₂ concentration. The effects of elevated CO₂ concentration on leaf photosynthesis, stomatal conductance, dark respiration, carbohydrate concentration and nitrogen concentration were measured. Furthermore, dark respiration of leaves was partitioned into growth and maintenance components by regressing specific respiration rate vs specific growth rate. Sprouts of both clones exposed to CO₂ enrichment showed no indication of photosynthetic down-regulation. During reciprocal gas exchange measurements, CO₂ enrichment significantly increased photosynthesis of all sprouts by approximately 60% ( P < 0.01) on both an early and late season sampling date, decreased stomatal conductance of all sprouts by 10% ( P < 0.04) on the early sampling date and nonsignificantly decreased dark respiration by an average of 11%. Growth under elevated CO₂ had no consistent effect on foliar sugar concentration but significantly increased foliar starch by 80%. Respiration rate was highly correlated with both specific growth rate and percent nitrogen. Long-term CO₂ enrichment did not significantly affect the maintenance respiration coefficient or the growth respiration coefficient. Carbon dioxide enrichment affected the physiology of the sprouts the same way it affected these plants before they were coppiced.     

Relationships between tree dimension and coarse root biomass in mixed stands of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies[L.] Karst.)

Relationships between tree parameters above ground and the biomass of the coarse root system were examined in six mixed spruce-beech stands in the Solling Mountain region in northwest Germany. The selected stands were located on comparable sites and covered an age range of 44 to 114 years. Coarse roots (d?\ge?2 mm) of 42 spruce and 27 beech trees were sampled by excavating the entire root system. A linear model with logarithmic transformation of the variables was developed to describe the relationship between the coarse root biomass (CRB, dry weight) and the corresponding tree diameter at breast height (DBH). The coefficients of determination (R ²) attained values between 0.92 for spruce and 0.94 for beech; the logarithmic standard deviation values were between 0.29 and 0.43. A significantly different effect of tree species on the model estimates could not be detected by an analysis of co-variance (ANCOVA). For spruce, the derived relationships were similar to those reported in previous studies, but not for beech. Biomass partitioning in the tree compartments above and below ground differs significantly between spruce (coarse root/shoot ratio 0.16±0.06) and beech (coarse root/shoot ratio 0.10±0.03) in the mixed stands. These results are similar to those given in other studies involving pure spruce and beech stands on comparable sites in the region, although the ratios of pure stands in other regions growing under different site conditions are somewhat higher. Comparing trees of the same DBH classes, root/shoot ratios of spruce are 1.2 to 3 times higher than those of beech. Dominant spruce trees (DBH>60 cm) attained the highest ratios, suppressed beech trees (DBH<10 cm) the lowest. Site conditions of varying climate and soils and interspecific tree competition are likely to affect root/shoot ratio and DBH-coarse root biomass relationships. The greater variability in beech compared with spruce indicates a high 'plasticity' and adaptability of beech carbon allocation. Thus, the derived equations are useful for biomass estimates of coarse roots involving trees of different ages in mixed stands of spruce and beech in the Solling Mountains. However, application of these relationships to stands in other regions would need further testing.     

SPATIAL DISTRIBUTION AND DEVELOPMENT OF ROOT SPROUTS IN FAGUS GRANDIFOLIA (FAGACEAE)

Root sprouts around 31 Fagus grandifolia parent trees, some declining due to beech bark disease, were studied to describe the pattern of sprout distribution, the ecological importance of this pattern, and the relationship between sprout patterns and parent vigor. Microtome sections of roots were studied to determine the histological origin of sprouts. Sprout distribution was circular and usually centered on the parent tree. Most sprouts were within 8 m of the parent and remained attached to the parent root system even after the sprouts reached 10 yrs of age. Root sprouting in F. grandifolia may be effective in replacing dead parent trees, but the potential for clones to spread is limited. Spatial distribution of sprouts was mostly unaffected by tree vigor. Root sprouts originated from callus tissues associated with wounds on superficial woody roots.     

Effects of Calcium on the Rate and Extent of Litter Decomposition in a Northern Hardwood Forest

Cross-site syntheses of litter decomposition studies have shown that litter calcium (Ca) concentration may have a role in controlling the extent of decomposition of tree foliage. We used an ongoing watershed CaSiO₃ addition experiment at the Hubbard Brook Experimental Forest in New Hampshire, USA, to test the hypotheses that increased Ca in litter would have no effect on the initial rates of litter decay but would increase the extent or completeness (limit value) of foliar litter decomposition. We tested these hypotheses with a 6-year litter decomposition experiment using foliar litter of four tree species that are prominent at this site and in the Northern Hardwood forest type of North America: sugar maple (Acer saccharum Marsh), American beech (Fagus grandifolia Ehrh.), yellow birch (Betula alleghaniensis Britt.), and white ash (Fraxinus americana L.). The experiment used a reciprocal transplant design with the Ca-treated watershed and a control site providing two sources of litter and two placement sites. The litter from the Ca-treated site was 10–92% higher in Ca concentration, depending on species, than the litter from the control site. After about 3 years of decomposition, the Ca concentrations in the litter reflected the placement of the litter (that is, the site in which it was incubated) rather than the source of the litter. The source of the litter had no significant effect on measures of initial decomposition rate, cumulative mass loss (6 years), or limit value. However, the placement of the litter had a highly significant effect on extent of decomposition. Some litter types responded more than others; in particular, beech litter placed in the Ca-treated site had a significantly higher limit value, indicating more complete decomposition, and maple litter in the Ca-treated site had a marginally higher limit value. These results indicate that Ca may influence the extent of litter decomposition, but it is the Ca at the incubation site rather than the initial litter Ca that matters most. The results also suggest that loss of Ca from the soil due to decades of acid deposition at this site may have impeded late-stage litter decomposition, possibly leading to greater soil C storage, especially in forest stands with a substantial component of beech. Likewise, de-acidification may lead to a reduction in soil C.     

香果树根萌苗生长特性及影响因子分析

香果树(Emmenopterys henryi)为我国Ⅱ级野生保护植物,由于生境遭到破坏、过度开发利用以及种群自然更新能力差等原因,导致自然环境下香果树种群数量迅速衰减。运用方差分析、多重比较、主成分分析等方法,对自然环境下香果树种群的根萌苗生长状况及其主要影响因子进行了研究。结果表明:香果树根萌苗的数量随着苗龄的增长逐渐减少,1a根萌苗的死亡率最高;苗高和基径均随苗龄的增大呈指数增长;香果树根萌苗主要生长在母树东南方120°~150°(以正北方为0°按顺时针方向旋转,下同)位置、距母树树干2 m以内及直径2 cm、长度30 cm的露根上;根萌苗苗高受母树方位影响较小,受露根直径、露根长度以及与母树间距离的影响稍大;母树南向(168.75°)根萌苗的基径显著大于其它方向的根萌苗基径;与北向和南向相比,母树东向和西向根萌苗的冠幅较大;根萌苗苗高、基径和冠幅等形态指标均随着与母树树干间距离的增加而降低,但随着露根直径的增加各形态指标均呈先升高后降低的趋势(露根直径6.5 cm时苗高和基径达到最大值),随着露根长度的增加各形态指标呈先降低后升高的趋势;与树冠内根萌苗相比,香果树母树树冠外根萌苗的死亡率较高。主成分分析结果表明,随着林内光照条件的改善、土壤中有机质含量的增加、砾石覆盖率的增加以及适度的人为干扰均有利于香果树根萌苗的生长。因此,减小林冠郁闭度、增加人工抚育措施对维持香果树的种群发展、实现其种群自然更新具有重要作用。     

Emergence, Growth and Nutrient Composition of Sugarcane Sprouts Under NaCl Salinity

The changes induced by 80 and 120 mM NaCl during emergence and growth of sprouts in salt-tolerant (CPF-213) and sensitive (L-116) genotypes of sugarcane were determined. The rate and percentage of emergence of sprouts, length and dry mass of shoot and root, and number of nodal roots decreased under salinity. Concentrations of Na and Cl increased and those of K, Ca, N and P decreased with a rise in substrate salinity. A greater salinity tolerance ability of CPF-213 than L-116 was attributable to greater root mass and higher nutrient concentrations in the sprouts of the former genotype.     

Analysis of seedling banks of a climax beech forest: ecological importance of seedling sprouts

Most of the common and dominant tree species in gaps of a climax Japanese beech (Fagus crenata) forest have large seedling banks on the forest floor. These seedlings were classified into “true seedlings” and “seedling sprouts”, each of which was further classified into two and three subtypes, respectively. Each species had a characteristic seedling form spectrum. The seedling bank of beech was composed almost solely of true seedlings, whereas, seedling sprouts predominated in the seedling banks of lower tree species such as Prunus grayana Maxim. and some species of Acer. The age structures suggested that seedling sprouts had longer life spans and had been recruited more constantly than true seedlings. The habit of sprouting and creeping seemed to enable seedlings of these species to persist for long periods, thus increasing their chance for eventual success in canopy gaps.     

Ozone effects on visible foliar injury and growth of Fagus sylvatica and Viburnum lantana seedlings grown in monoculture or in mixture

Seedlings of Fagus sylvatica (beech) and Viburnum lantana (Viburnum) grown in monoculture and mixture were exposed to ambient and sub-ambient (charcoal-filtered) ozone concentrations in open-top chambers over the course of the 2003 and 2004 growing seasons at the WSL Lattecaldo open-top chamber facility in southern Switzerland. The aim of the study was to determine how the sensitivity to ozone in ambient air of these two species would differ between monocultures and mixtures in terms of growth and visible foliar injury development. Ambient ozone concentrations were consistently higher from the end of April to the middle of October in 2003 than in 2004 with seasonal peaks and means reaching 147 and 50 parts-per-billion (ppb) in 2003 compared to 124 and 40 ppb in 2004. Ambient AOT40 (ozone concentration accumulated over a threshold of 40 ppb during daylight hours with global radiation >50 W m^?2) values from the end of April to the middle of October reached 48.3 and 26.8 parts-per-billon hours (ppm h) in 2003 and 2004, respectively. In general, Viburnum was a stronger competitor than beech over the course of this 2-year study. Seedlings of Viburnum benefited from interspecific competition in terms of both height growth and above-ground biomass accumulation at the expense of beech seedlings, which showed significantly reduced growth in the mixture as compared to the monoculture. However, as this was only the case for Viburnum growing in the charcoal-filtered treatment, ozone seemed to counteract the beneficial effect of interspecific competition on above-ground biomass accumulation in Viburnum, while at the same time decreasing relative biomass allocation to roots. Foliar sensitivity of the two species was also altered under interspecific competition suggesting that results based on seedlings of single species grown in monocultures may significantly over- or under-estimate foliar sensitivity to ozone. These results demonstrate that competition is an important factor affecting plant responses to ozone stress, but the direction and severity of these effects depend on the interacting species.     

The phosphorus status of northern hardwoods differs by species but is unaffected by nitrogen fertilization

Northern hardwood forests in the eastern US exhibit species-specific influences on nitrogen (N) cycling, suggesting that their phosphorus (P) cycling characteristics may also vary by species. These characteristics are increasingly important to understand in light of evidence suggesting that atmospheric N deposition has increased N availability in the region, potentially leading to phosphorus limitation. We examined how P characteristics differ among tree species and whether these characteristics respond to simulated N deposition (fertilization). We added NH₄NO₃ fertilizer (50 kg ha^?1 year^?1) to single-species plots of red oak (Quercus rubra L.), sugar maple (Acer saccharum Marsh.), eastern hemlock (Tsuga canadensis (L.) Carr.), American beech (Fagus grandifolia Ehrh.), and yellow birch (Betula alleghaniensis Britt.), in the Catskill Mountains, New York from 1997 to 2007. Species differences were observed in foliar, litter and root P concentrations, but all were unaffected by a cumulative N fertilization of 550 kg/ha. Similarly, measures of soil P availability and biotic P sufficiency differed by species but were unaffected by N fertilization. Results suggest species exhibit unique relationships to P as well as N cycles. We found little evidence that N fertilization leads to increased P limitation in these northern hardwood forests. However, species such as sugar maple and red oak may be sufficient in P, whereas beech and hemlock may be less sufficient and therefore potentially more sensitive to future N-stimulated P limitation.     

CO(2)-Enhanced Yield and Foliar Deformation among Tomato Genotypes in Elevated CO(2) Environments

Yield increases observed among eight genotypes of tomato (Lycopersicon esculentum Mill.) grown at ambient CO₂ (about 350) or 1000 microliters per liter CO₂ were not due to carbon exchange rate increases. Yield varied among genotypes while carbon exchange rate did not. Yield increases were due to a change in partitioning from root to fruit. Tomatoes grown with CO₂ enrichment exhibited nonepinastic foliar deformation similar to nutrient deficiency symptoms. Foliar deformation varied among genotypes, increased throughout the season, and became most severe at elevated CO₂. Foliar deformation was positively related to fruit yield. Foliage from the lower canopy was sampled throughout the growing season and analysed for starch, K, P, Ca, Mg, Fe, and Mn concentrations. Foliar K and Mn concentrations were the only elements correlated with deformation severity. Foliar K decreased while deformation increased. In another study, foliage of half the plants of one genotype received foliar applications of 7 millimolar KH₂PO₄. Untreated foliage showed significantly greater deformation than treated foliage. Reduced foliar K concentration may cause CO₂-enhanced foliar deformation. Reduced K may occur following decreased nutrient uptake resulting from reduced root mass due to the change in partitioning from root to fruit.     

Effects of liming on rhizosphere chemistry and growth of fine roots and of shoots of sessile oak (Quercus petraea)

Soil acidification can be detrimental to root growth and nutrient uptake, and liming may alleviate such acidification. In the following study, seedlings of sessile oak (Quercus petraea Liebl. M.) were grown in rhizotrons and subjected to liming (L) or gypsum (G) treatments and compared with the control (C). In order to study and interpret the impact of these calcium rich treatments on fine root development and tree growth, the following parameters were assessed: fine root biomass, fine root length, seedling development (height, diameter, leaves), seedling biomass, nutrient content of roots and seedlings, bulk soil and soil solution chemistry and rhizosphere soil chemistry. The results show that liming increased bulk soil pH, exchangeable Mg, Ca and the Ca/Al molar ratio, and decreased exchangeable Al, mainly in the A-horizon. Gypsum had a similar but smaller impact on exchangeable Al, Ca, H⁺ and the Ca/Al molar ratio in the A-horizon, but reacted with depth, so that exchangeable Mn, Mg and Ca were increased in the B-horizon. In the rhizosphere, the general pattern was determined by the treatment effects of the bulk soil. Most elements were more concentrated in the rhizosphere than in bulk soil, except for Ca which was less concentrated after liming or gypsum application. In the B-horizon rhizosphere pH was increased by the treatments (L > G,C) close to the root tips. Furthermore, the length of the zone with a positive root-induced pH increase was greater for the limed roots as compared with both the other treatments. Fine root growth was stimulated by liming (L > G,C) both in terms of biomass and length, whereas specific root length was not obviously affected apart from the indication of some stimulation after liming at the beginning. The live:dead ratio of fine roots was significantly higher in the limed rhizotrons as compared to the control (G not assessed), indicating lower mortality (higher longevity). Shoot growth showed greater lime-induced stimulation (L > G,C) as compared to root growth. As a result the shoot:root ratio was higher in the limed rhizotrons than in the control (L > G,C). Liming induced a higher allocation of P, S, Mg, Ca and K to the leaves, stem and twigs. Gypsum showed similar effects, but was only significant for S. Liming increased the foliar Ca/Al ratio by both increasing foliar Ca and decreasing foliar Al, whereas gypsum did not clearly improve foliar nutrition. This study suggests that a moderate application of lime can be successful in stimulating seedling growth, but that gypsum had no effect on seedling growth. It can be concluded that this lime-induced growth stimulation is directly related to the improved soil fertility status, and the alleviation of Al toxicity and acid stress, resulting in better foliar nutrition. The impact of liming on fine roots, as a consequence, was not limited to a stimulation of the total amount of fine roots, but also improved the root uptake performance. This revised version was published online in June 2006 with corrections to the Cover Date.     

Do chronic aboveground O3 exposure and belowground pathogen stress affect growth and belowground biomass partitioning of juvenile beech trees (Fagus sylvatica L.)?

The impact of chronic free air ozone (O₃) exposure and belowground pathogen stress on growth and total biomass development of young beech trees (Fagus sylvatica L.) was investigated in a lysimeter study. Plants were growing during four years under ambient or elevated atmospheric O₃ concentrations. Additionally, in the last vegetation period the root rot pathogen Phytophthora citricola was introduced to study the interaction of ozone exposure and pathogen stress in the soil-plant system. A complete harvest at the end of the experiment enabled for the first time the assessment of fine and coarse root biomass of individual trees with a high vertical resolution down to two meter depth. Plant growth was significantly reduced by elevated ozone but not affected by P. citricola. Biomass partitioning between fine and coarse roots as well as vertical root distribution were significantly affected by both factors, whereas changes in root/shoot biomass ratio were not observed.     

Contrasting ozone × pathogen interaction as mediated through competition between juvenile European beech (Fagus sylvatica) and Norway spruce (Picea abies)

Based on the growth-differentiation balance theory (GDB) and the influence of tropospheric ozone (O₃) on plants, we hypothesized that pre-conditioning with elevated O₃ reduces adverse effects of the root rot pathogen Phytophthora citricola Sawada. To this end a 2-year phytotron study with juvenile European beech (Fagus sylvatica L.) and (Picea abies [L.] Karst.) grown in mixture was performed. The hypothesis was tested on phenological, leaf and root morphological as well as physiological aspects of plant performance. Contrasting with spruce, elevated O₃ limited leaf and root biomass development, photosynthetic performance and N uptake of beech. The growth limitation by O₃ conveyed increased resistance in beech against the pathogen. Conversely, spruce displayed enhanced susceptibility in the combined O₃/P. citricola treatment. The hypothesis was supported in the case of beech rather than spruce. Nevertheless, conclusions support GDB regarding the trade-off between growth and stress defense, although compliance appears to be species-specific.     

Analysis of natural Fagus sylvatica L. s.l. regeneration in low elevation stands located in the central part of the Evros region in northeastern Greece: Is sprout origin regeneration significant for species maintenance?

Abstract

The aim of this study was (a) to analyse natural Fagus sylvatica L. s.l. regeneration in low elevation stands located in the central part of Evros region in northeastern Greece in relation to factors such as site productivity, type of silvicultural treatment and regeneration origin and (b) to determine whether or not sprout origin regeneration is significant for the maintenance of beech stands. One hundred and twenty plots (3 m × 3 m) were established in areas where thinnings and regeneration fellings had taken place, and in two site productivity regimes. In each plot, the number of beech seedlings, saplings, and stump or root sprouts (regeneration plants) with a height of up to 3 m was counted, and their height measured. Our findings indicate that even though reproduction by seed is the predominant regeneration mechanism in our stands, in the medium productivity sites sprouts represent a significant percentage of the total number of plants. Moreover, sprouting functions as a mechanism of maintenance of beech stands in medium productivity sites. During the regeneration fellings practised in this area, it is advisable to cut the seedlings and saplings of the advanced regeneration in order to supplement the seed-derived plants with seedling sprouts.     

Juvenile sprouting ability of the endangered maple, <Emphasis Type="Italic">Acer pycnanthum</Emphasis>

Japanese red maple, Acer pycnanthum, is an endangered species having a limited distribution of central Honshu, Japan. Sprouting is an important part of its natural history, and many remnant populations contain high number of multiple-stem clones. However, knowledge of sprout formation and growth is lacking, which has hampered understanding of the reestablishment process after major disturbance. My research objectives were to characterize the formation and growth of basal sprouts in the juvenile stage and determine the effects of light intensity and stump diameter on these characteristics. Twenty sprouting clones were investigated at a natural site in Nagano Prefecture during a four-year period after cutting. Japanese red maple exhibited abundant and vigorous sprouting from the root collar of cut trees. Many sprouts arose immediately after cutting. Average number of sprouts per stump was 12.2. Number of sprouts per stump was negatively correlated with relative light intensity. The two dominant sprouts (sprouts 1 and 2) of each clone were selected to analyze their growth. The average extension growth of sprout 1 (i.e., the tallest and most vigorous) was 173.3 cm at the end of first growing season. At the end of fourth growing season, average height and diameter at breast height (dbh) of sprout 1 were 377 and 2.1 cm, respectively. Relative light intensity and stump diameter significantly and positively affected D²H (diameter at breast height squared × height) of sprout 1. Because the growth rate of sprouts is much faster than that of seedlings, regeneration by sprouting is more significant than seedling regeneration to maintain populations after disturbances.