Over-mature beech trees (Fagus orientalis Lipsky) and close-to-nature forestry in northern Iran

Oriental Beech is the most important commercial tree species in northern Iran. In recent years wood production companies interested in felling large beech trees for profit have challenged advocates of close-to-nature silviculture who favor conservation. Our study objective was to assess the economic value of over-mature beech trees by relating tree diameter (DBH) to amount of decay. Based on the location of onset of decay, we categorized three types of decay as stump, stem, and crown decay. Trees of greater diameter (age) typically showed greater decay in the stem. Percent of decayed volume, diameter of decayed tissue, and length of decay in tree stems varied between 0.5%?64.3%, 15 cm?75 cm, and 2.0?19.5 m, respectively. With increasing trunk diameter, the proportion of truck decay increased. Red heart and dark red heart constituted 25% and 14.3% of sampled trees, respectively. However, we found no correlation between intensity of stem decay and morphological characteristics of trees. Seedlings were not abundant around the bases of over-mature trees, suggesting that the trees did not contribute to regeneration of the stand. Beech trees of diameter >1 m do not provide valuable round wood for industries and cause to raise wood production costs. We recommend that these trees >1 m DBH should be retained in forest stands because of their low commercial value but high ecological and conservational values such as maintaining biodiversity in forest ecosys-tems.     

Aboveground biomass and net primary production of semi-evergreen tropical forest of Manipur, north-eastern India

The aboveground biomass dynamics and net primary productivity were investigated to assess the productive potential of Dipterocarpus forest in Manipur, Northeast India. Two forest stands (stand I and II) were earmarked randomly in the study site for the evaluation of biomass in the different girth classes of tree species by harvest method. The total biomass was 22.50 t·ha-1 and 18.27 t·ha-1 in forest stand I and II respectively. Annual aboveground net primary production varied from 8.86 to 10.43 t·ha-1 respectively in two forest stands (stand I and II). In the present study, the values of production efficiency and the biomass accumulation ratio indicate that the forest is at succession stage with high productive potential.     

Notes on beech (Fagus crenata Blume) seed and seedling mortality due to rodent herbivory in a northernmost beech forest, Utasai, Hokkaido

We investigated the mortality of post-dispersal seeds and current-year seedlings of a beech species (Fagus crenata Blume) at the northernmost extent of its geographical range at Utasai (Kuromatsunai), Hokkaido, Japan. Introduced seeds that were protected from rodent predation by wire cages had a higher survival rate from winter to the following spring (mean ± SD: 84 ± 16.7%,n = 10) than controls without cages (mean ± SD: 12 ± 17.9%,n = 10). Unprotected transplanted current-year seedlings with almost fully opened primary leaves never survived more than three days (0%,n = 30), while more than 80% (n = 30) of seedlings within cages survived to the end of the growing season. These results indicate that rodent herbivory is a major mortality factor that strongly prevents the establishment of beech seedlings. In a natural population, we observed that 90% of seedlings (n = 197) disappeared within 10 days after their emergence and rodent herbivory caused this heavy mortality. A herbivorous rodent, the gray-backed vole,Clethrionomys rufocanus bedfordiae, was remarkably abundant in late June (101.5 voles/ha), suggesting that this species strongly affects the formation of the seedling bank. The presence ofC. rufocanus bedfordiae may be one of the reasons for the scarcity of beech seedlings and saplings and the rarity of recruitment in this northernmost beech forest.     

Natural regeneration of oriental beech(Fagus orientalis Lipsky)trees in canopy gaps and under closed canopy in a forest in northern Iran

For developing nature-based silvicultural practices in a beech forest to promote, abundance, height,vitality, and preferred growth form, regenerated trees growing in gaps were compared with those under closed canopies.A systematic 50×50 m grid was plotted in a beech stand in the Kheyrud Experimental Forest for selecting trees to measure variables in gaps and under closed canopies.Abundance and mean height of regenerated beech trees were significantly higher in closed canopies than in canopy gaps.Beech seedlings with excurrent growth were significantly taller within regeneration patches under closed canopy.Moreover, regenerated trees with high vitality were more abundant in closed canopy areas than in gaps.Thus, beech regeneration should improve under closed canopies; hence, gaps in a near natural forest should be created only after adequate regeneration and appropriate growth under the parent tree in a closed canopy area is ensured.The results of this research have profound implications for the sustainable management of the forest and for ensuring sustainable beech regeneration.The presence of a closed canopy cover likely will reduce potential stresses on oriental beech regeneration.     

Genetic variation of beech (Fagus sylvatica L.) in Rodopi (N.E. Greece)

The recent taxonomic classification of beech in Europe considers existence of one species (Fagus sylvatica L.) with two subspecies: F. sylvatica ssp. sylvatica and F. sylvatica ssp. orientalis. Four beech populations growing on the Greek part of the Rodopi Mountains were studied using morphological traits as well as DNA molecular markers (AFLPs and chloroplast DNA SSR). The aim of the study was to describe the variation patterns of beech in the Rodopi Mountains and to test the hypothesis of possible introgression between the beech subspecies’ sylvatica and orientalis in this area. Both morphological traits and gene markers revealed a possible influence of F. orientalis on the east side of Rodopi and at the low elevations, while characters resembling F. sylvatica were observed mainly on the western part of the mountains and in higher altitudes. There was a clinal increase of genetic diversity from the west to the east, reaching a level firstly reported for beech populations. These results can be explained either by the existence of a main refugial area for beech during the last glaciation or by the occurrence of a recent hybridization among the subspecies, which were spatially isolated during the last glaciation and came into reproductive contact during their postglacial remigration. These two scenarios are not necessarily mutually exclusive.     

Photosynthesis and biomass allocation of beech (Fagus crenata) and dwarf-bamboo (Sasa kurilensis) in response to contrasting light regimes in a Japan Sea-Type beech forest

Regeneration of beech (Fagus crenata) forests depends on the formation of canopy gaps. However, in Japan Sea-type beech forests, a dwarf bamboo (Sasa kurilensis) conspicuously occupies sunny gaps. Therefore,F. crenata seedlings must escape the severe interference ofS. kurilensis in the gaps and persist beneath a closed canopy of the beech forest. We hypothesized that the growth ofF. crenata seedlings in the understory would be favored by their being more plastic thanS. kurilensis in photosynthetic and morphological traits, which would support the matter production ofF. crenata seedlings in a wide range of light availabilities. To examine this hypothesis, the photosynthetic-light response of individual leaves and the biomass allocation in aboveground parts (i.e., the culm/foliage ratio) were surveyed at sites with contrasting light availabilities in a Japan Sea-type beech forest in central Japan. InF. crenata, photosynthetic light utilization efficiency at relatively low light was greater, and the dark respiration rate was smaller in the leaves of seedlings (10 cm in height) beneath the closed canopy than in the leaves of saplings at the sunny forest edge. The culm/foliage (C/F) ratio of theF. crenata seedlings at the shady site was small, suggesting effective matter-production beneath the beech canopy. On the other hand,S. kurilensis both in the gap and beneath the beech canopy showed low plasticity in photosynthesis and the culm/foliage ratio. Because the shoot density ofS. kurilensis was smaller beneath the beech canopy than in the gap, the light availability at the bottom of theS. kurilensis layer was greater beneath the beech canopy. These results suggest that the photosynthetic productivity of theF. crenata seedlings would be enough for the seedlings to survive in the understory with a low density ofS. kurilensis shoots beneath the closed beech canopy.     

Assessment of biomass and net primary productivity of a dry tropical forest using geospatial technology

This study quantifies biomass, aboveground and belowground net productivity, along with additional environmental factors over a 2-3 year period in Barnawapara Sanctuary of Chhattisgarh, India through satellite remotesensing and GIS techniques. Ten sampling quadrates20×20, 5×5 and 1×1 m were randomly laid for overstorey (OS), understorey (US) and ground vegetation(GS), respectively. Girth of trees was measured at breast height and collar diameters of shrubs and herbs at 0.1 m height. Biomass was estimated using allometric regression equations and herb biomass by harvesting. Net primary productivity (NPP) was determined by Ssumming biomass increment and litter crop values. Aspect and slope influenced the vegetation types, biomass and NPP in different forests. Standing biomass and NPP varied from 18.6 to101.5 Mg ha^-1 and 5.3 to 12.7 Mg ha^-1 a^-1, respectively,in different forest types. The highest biomass was found in dense mixed forest, while net production recoded in Teak forests. Both were lowest in degraded mixed forests of different forest types. OS, US and GS contributed 90.4, 8.7and 0.7%, respectively, for the total mean standing biomass in different forests. This study developed spectral models for the estimation of biomass and NPP using Normalized Difference Vegetation Index and other vegetation indices.The study demonstrated the potential of geospatial tools for estimation of biomass and net productivity of dry tropical forest ecosystem.     

基于CASA模型的瓦屋山林场植被净初级生产力估算

在地理信息系统和遥感技术支持下,利用改进的CASA模型,并结合Landsat TM遥感影像、气象数据和林班数据,估算出瓦屋山林场2008—2009年的植被净初级生产力(PNPP),并通过实测植被生物量和生产力的关系,验证CASA模型在研究地区估算结果。结果表明:CASA模型估测植被PNPP与实测结果有较好的一致性,能够适用于瓦屋山林场植被净生产力估算;CASA模型估算结果主要植被类型年均PNPP区别明显,从高到低依次是:中国山杨、麻栎、板栗、马尾松、湿地松、灌木、杉木和池杉;瓦屋山林场植被PNPP季节变化显著,夏季贡献率最大,其次是春季和秋季,冬季最少,主要由于不同季节环境因素不同,其中又以太阳辐射最为重要。     

The receptivity of powdered beech wood (Fagus crenata) to cyanuric chloride

Summary The chemical modification of powdered beech wood by reaction with cyanuric chloride (2,4,6-trichloro-s-triazine) is discussed in terms of the reaction time and temperature, as well as the concentration of the aqueous sodium hydroxide solutions used in the preparation of alkali-treated wood powders. The influence of the surface structure of wood on the receptivity of alkali-treated wood powders to this reagent is also discussed. The amount of cyanuric chloride taken up by the wood powder treated with the highest concentration of aqueous sodium hydroxide (18% NaOH) is about 0.8 mmol/g. This exceeds the theoretical amount of cyanuric chloride which can be reacted with the primary surface in the void model previously proposed. the extent of cross-linking at longer reaction times is minimal in case of the treatment of wood with 0.8% sodium hydroxide. On the other hand, the hydrolysis of C–Cl bonds of the second and third chlorine on the s-triazine ring and/or the internal cross-linking reactions are accelerated by increases in the concentration of sodium hydroxide. However, these reactions (the hydrolysis of C–Cl bonds and the internal cross-linking) are independent of the change in the structure of wood caused by the mercerizing alkalinity.The authors are thankful to K. Sakurai of the Forestry and Forest Products Research Institute for his elemental analyses for nitrogen and chlorine     

Spatial and seasonal variations in photosynthetic properties within a beech (Fagus crenata Blume) crown

The light response curve and the intercellular CO₂ concentration response curve of CO₂ assimilation rate were investigated together with the light conditions at the four different heights within the beech crown from 1995 to 1997 on Mt. Fuji in Japan. On the seasonal fluctuation, the CO₂ assimilation rate at light saturated condition increased rapidly in May, and attained to the maximum between the end of June and July, thereafter, slightly decreased until the middle of August and rapidly decreased in September and October. The daily sum of photosynthetic photon flux density attenuated with deeping within the crown, and particularly, the relative value on 2nd position dropped to only 30%. TheA _max decreased from 10 to 5μmol m⁻² s⁻¹, approximately, with deeping within the crown. The light saturation point, quantum yield, light compensation point and dark respiration rate also varied with deeping. These results suggest that the photosynthetic properties vary gradually from sun to shade leaves along the light attenuation within a beech crown. At light saturated condition, the stomatal conductance and mesophyll conductance were strongly correlated withA _max among the four different heights (r > 0.96, respectively). TheC _i/C _a ratio was around 0.8, and there were no remarkable differences among the four different heights. These results suggest that the vertical gradient ofA _max depends on the variation of mesophyll conductance. The stomatal conductance may be also one of the major factor in the vertical gradient ofA _max. However the intercellular CO₂ concentration doesn’t influence the vertical gradient ofA _max within the crown. This work is supported by the Sasagawa Scientific Research Grant from The Japan Science Society and Grant-in-Aid for Scientific Research (C).     

The receptivity of graft-polyacrolein on powdered beech wood (Fagus crenata) to hydroxylamine

Summary The receptivity of graft-polyacrolein on wood to hydroxylamine is discussed in terms of a geometric model for the voids and surfaces formed in wood by the swelling action of water. The receptivity of the carbonyl group of graft-polyacrolein varies inversely with the number of graft sites. This relationship is a consequence of decrease in the spacing between graft chains on the primary surface. The receptivity increases gradually with an increase in the amount of graft polymer, and this is a result of the swelling action of graft-polyacrolein which extends to the microscopically visible macropores of wood.     

Response of oriental beech (Fagus orientalis Lipsky) seedlings to canopy gap size

The response of nursery seedlings and wildings of oriental beech(Fagus orientalis Lipsky) to canopy gap size was studied ina climax beech forest in northern Iran with respect to seedlingsurvival, shoot growth and vitality. These parameters were followedfor 2 years after planting in gaps of 50, 200 and 600 m², aswell as in the open field. Foliage coloration was used as acriterion for vitality. The survival rate of nursery seedlingsand wildings dropped rapidly with increasing gap size from 84per cent in 50-m² canopy openings to     

Induced response of the Siebold's beech (Fagus crenata Blume) to manual defoliation

Siebold's beech (Fagus crenata) was manually defoliated for two successive years. The beech caterpillar (Quadricalcarifera punctatella) was used in a bioassay to determine insect performance. Survival and body size were low on foliage from defoliated trees. Reduced foliar nitrogen and increased tannin content were probably the main causes of the low insect performance. Leaves were less tough on defoliated trees than in controls. Two sucessive years of manual defoliation caused stronger induced resistance than one year defoliation. The quality, as well as the quality of the foliage, decreased the year following manual defoliation; total weight of leaves on a tree was less than one half of that before treatment. Severe defoliation may cause a decrease of leaves the following year and starvation may limit populations. Delayed induced resistance of beech trees is proposed as a possible cause of the cyclical population dynamics ofQ. punctatella. The delayed induced response also affected folivorous insects other thanQ. punctatella.     

Japanese beech (Fagus crenata) plantations established from seedlings of non-native genetic lineages

In order to examine whether seedlings of non-native genetic lineages had been planted, we compared chloroplast DNA haplotypes in plantations and neighboring natural populations of Fagus crenata in Nagano Prefecture, Japan. This region was chosen for study because there are abundant natural F. crenata populations with different haplotypes, and because the species is also frequently used for afforestation in the area. We sampled 159 trees from 30 populations of the species across most of its natural range in the region, and 136 trees from 20 plantations of the species, ranging in age from 3 to 17 years. Six single nucleotide polymorphisms and four insertions/deletions in two chloroplast DNA regions (trnL–trnF and trnK) were analyzed in each of the sampled individuals in order to determine their haplotypes. Four haplotypes (B, D, E and F) were detected in the natural populations, and these exhibited a clear geographical structure; in contrast, only two haplotypes (A and B) were found in the plantations. We found that 15 out of the 20 plantations—located in central and southern areas on the Pacific side of Honshu, where the natural populations contain haplotypes D, E, and F, and where the climate is characterized by dry, cold winters—had been established using seedlings with haplotypes A and B derived from the Sea of Japan side of the Japanese Islands, where it snows heavily. The risks associated with planting seedlings of inappropriate lineages are discussed.     

Interaction of lignin and polysaccharides in beech wood (Fagus sylvatica) during drying processes

Summary ¹³C CP MAS NMR spectroscopy was used to characterize the structural changes of cell wall polymers in beech wood Fagus sylvatica during drying processes. The analysis of five wood samples, namely, untreated, untreated dried, pre-treated by steam and/or NaOH subjected to drying showed partial depolymerization of lignin component as well as the change of the ratio of the crystalline and of the amorphous parts of cellulose as the consequence of wood pre-treatment. In addition, T_1ρ(¹H) relaxation times were determined in beech wood sample pre-treated with steam at 135 °C and the lignin isolated from this sample. The magnitudes of the relaxation times were found comparable in both samples as well as in the lignin-cellulose model compound. These unique T_1ρ (¹H) values indicate that spin diffusion is complete and homogeneous due to spatial proximity of spins and confirmed the formation of lignin-cellulose complex during thermal treatment of wood. Received 30 June 1997     

Effects of selective thinning on growth and development of beech (Fagus sylvatica L.) forest stands in south-eastern Slovenia

We studied the effects of two types of selective thinning on beech stands formed by a shelterwood cut in 1910 — with lower number of crop trees and higher thinning intensity (T1) and higher number of crop trees with lower thinning intensity (T2). The stands were thinned in 1980, 1991 and 2001. Despite a lower stand density after thinning, the annual basal area increments of thinned stands in both thinning periods (1980–1991 and 1991–2002) were around 20% higher compared to those of the control (unthinned) stands. The mean annual basal area increment of dominant trees was 30–56% larger in the thinned plots compared to the control plots. Of 176 initial crop trees in the T1, 72% were chosen again during the last thinning. In the T2, 258 crop trees were chosen in the first thinning, and only 62% of these trees were chosen again during the last thinning. Only crown suppression and diameter classes of crop trees significantly influenced their basal area increment when diameter classes, crown size, crown suppression, and social status were tested. In the thinned stands, the dominant trees are more uniformly distributed if compared to the dominant trees in the control plots. Finally, the herbaceous cover and the species diversity were higher in the thinned plots.     

Interannual variability of net ecosystem production for a broadleaf deciduous forest in Sapporo, northern Japan

To estimate net ecosystem production (NEP), ecosystem respiration (R _E), and gross primary production (GPP), and to elucidate the interannual variability of NEP in a cool temperate broadleaf deciduous forest in Sapporo, northern Japan, we measured net ecosystem exchange (NEE) using an eddy covariance technique with a closed-path infrared gas analyzer from 2000 to 2003. NEP, R _E, and GPP were derived from NEE, and data gaps were filled using empirical regression models with meteorological variables such as photosynthetic active radiation and soil temperature. In general, NEP was positive (CO₂ uptake) from May to September, either positive or negative in October, and negative (CO₂ release) from November to the following April. NEP rapidly increased during leaf expansion in May and reached its maximum in June or July. The four-year averages (±?standard deviation) of annual NEP, GPP, and R _E were 443?±?45, 1,374?±?39, and 931?±?11?g?C?m^?2?year^?1, respectively. The lower annual NEP and GPP in 2000 may have been caused by lower solar radiation in the foliated season. During the foliated season, monthly GPP varied from year to year more than monthly R _E. Variations in the amount of incoming solar radiation may have caused the interannual variations in the monthly GPP. Additionally, in May, the timing of leaf expansion had a large impact on GPP. Variations in GPP affected the interannual variation in NEP at our site. Thus, interannual variation in NEP was affected by the incoming solar radiation and the timing of leaf expansion.     

Changes in net ecosystem productivity with forest age following clearcutting of a coastal Douglas-fir forest: testing a mathematical model with eddy covariance measurements along a forest chronosequence

We hypothesized that changes in net ecosystem productivity (NEP) during aging of coastal Douglas-fir (Pseudotsuga menziesii Mirb. Franco) stands could be explained by (1) changing nutrient uptake caused by different time scales for decomposition of fine, non-woody and coarse woody litter left after harvesting, (2) declines in canopy water status with lengthening of the water uptake pathway during bole and branch growth, and (3) increases in the ratio of autotrophic respiration (R (a)) to gross primary productivity (GPP) with phytomass accumulation. These hypotheses were implemented and tested in the mathematical model ecosys against eddy covariance (EC) measurements of forest CO(2) and energy exchange in a post-clearcut Douglas-fir chronosequence. Hypothesis 1 explained how (a) an initial rise in GPP observed during the first 3 years after clearcutting could be caused by nutrient mineralization from rapid decomposition of fine, non-woody litter with lower C:N ratios (assart effect), (b) a slower rise in GPP during the next 20 years could be caused by immobilization during later decomposition of coarse woody litter, and (c) a rapid rise in GPP between 20 and 40 years after clearcutting could be caused by nutrient mineralization with further decomposition of coarse woody litter and of its decomposition products. During periods (a) and (b), heterotrophic respiration (R (h)) from decomposition of fine and coarse litter greatly exceeded net primary productivity (NPP = GPP - R (a)) so that Douglas-fir stands were large sources of CO(2). During period (c), NPP exceeded R (h) so that these stands became large sinks for CO(2). Hypothesis 2 explained how declines in NPP during later growth in period (c) could be caused by lower hydraulic conductances in taller trees that would force lower canopy water potentials and hence greater sensitivity of stomatal conductances and CO(2) uptake to vapor pressure deficits. Enhanced sensitivity to vapor pressure deficits was also apparent in the EC measurements over the post-clearcut chronosequence. Hypothesis 3 did not contribute to the explanation of forest age effects on NEP.