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.     

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     

Long-term effect of fire on herbaceous species diversity in oriental beech (Fagus orientalis Lipsky) forests in northern Iran

We studied the long-term impacts of natural burning on herbaceous species diversity 37 years after a fire occurred in the Roudbar forests of Guilan Province, northern Iran. Numerous studies have examined short-term changes in understory vegetation following wildfire; however, very few long-term studies are available or changes inferred from retrospective studies based on chronosequences. For this study, 170 ha of forest (85 ha, burned areas; 85 ha, unburned areas) were surveyed. Because the 1000 m 2 plots were too large for detailed measurements of herbaceous species, we determined a sub-sample size according to the Whittaker’s nested plot sampling protocol and minimal areas method. Hence, sub-plots of 32 m 2 were used for herbaceous species measurements, which consisted of percent cover of each species based on the Domin criterion. We measured plant diversity (Shannon-Wiener index), species richness (Margalef’s index), and evenness (Smith-Wilson index). Mean percent cover, together with diversity, richness and evenness, increased markedly in burned areas compared to unburned controls. This suggests that the biodiversity of these forests could be restored within 37 years after fire. However, the abundance of invasive species such as Rubus fruticosus and Bromus benekenii increased significantly in burned areas, but these could be controlled by relevant silvicultural operations.     

Pit and mound influence on soil features in an Oriental Beech (Fagus orientalis Lipsky) forest

Windthrow, i.e. the felling of trees by wind, occurs continually in forest ecosystems. The uprooting of old trees creates multiple microsites (e.g. pit and mound landscape) that are the main source of soil heterogeneity. To determine the impact of pit and mound landscapes on soil features, a beech forest of the Langa district (Mazandaran province, Northern Iran) was studied. An area of 25 ha was considered for this study wherein three microsites were distinguished, including pit bottom (pit), mount top (mound) and level areas (closed canopy). In this area, 22 uprooted trees were also found. Soil samples were collected at different depths (i.e. 0–15, 15–30 and 30–45 cm) from all microsites and analysed. Our study shows that windthrow events should be considered as an important factor in influencing forest ecosystem, as they affect physical (i.e. density, texture and water content), chemical (i.e. pH, organic C, total N, cation exchange capacity and available nutrients) and biological (i.e. soil microbial respiration and earthworm density/biomass) characteristics of soil, thus resulting in pit and mound microsites that may strongly differ with respect to the closed canopy.     

Assemblages of wood-inhabiting fungi related to silvicultural management intensity in beech forests in southern Germany

Current silvicultural treatments in beech forests are aimed at achieving thick logs without discoloured hardwood. Therefore intensive thinning is applied already in younger stands with the objective of large-sized trunks at an age of 100 years. However, this approach bears the risk that dead wood structures and broken trees are completely removed from the forest. The impact of three different silvicultural management intensity levels on wood-inhabiting fungi over decades was investigated in a large beech forest (>10,000 ha) in southern Germany in 69 sampling plots: A Intensive Thinning and Logging with high-value trees, B Conservation-Oriented Logging with integration of special structures such as dead wood and broken trees and C Strict Forest Reserves with no logging for 30 years. The analysis of community showed marked differences in the fungus species composition of the three treatments, independent of stand age. The relative frequencies of species between treatments were statistically different. Indicator species for naturalness were more abundant at sites with low silvicultural management intensity. Fomes fomentarius, the most common fungus in virgin forests and strict forest reserves, is almost missing in forests with high-management intensity. The species richness seemed to be lower where intensive thinning was applied (P = 0.051). Species characteristic for coarse woody debris were associated to low management intensity, whereas species with a significant preference for stumps became more frequent with increasing management intensity. A total amount of dead wood higher than 60 m³/ha was found to enable significantly higher numbers of species indicators of naturalness (P = 0.013). In conclusion, when applying intensive silvicultural treatment, the role of dead wood needs to be actively considered in order to maintain the natural biocoenosis of beech forests.     

Effect of livestock grazing and human uses on herbaceous species diversity in oriental beech （Fagus orientalis Lipsky） forests,Guilan, Masal,northern Iran

Plant diversity plays key ecological roles in forest ecosystems, including influencing succession, resilience and nutrient cycling. This study was conducted to investigate the effect of livestock grazing and human uses on herbaceous species diversity. We surveyed 50 ha of protected area and 50 ha of unprotected area to evaluate herbaceous species diversity in oriental beech （Fagus orientalis Lipsky） forests in northern Iran. We calculated and compared three indices each of diversity and evenness, and species richness between the two areas. Herbaceous cover was higher in the unprotected area while leaf litter depth and tree canopy cover were higher in the protected area. The diversity indices, H （Shan- non-Wiener index ）, N~ （McArthur index）, N2 （Hill＇s index）, EQ （Modified Nee index）, E,ar （Smith-Wilson index）, E5 （modified index of Hill） and R=S （species richness） and species richness R=S were greater in the protected area than in the unprotected area, suggesting that protection from grazing results in increased numbers of plants and species. The effect of land protection on plant diversity was more pronounced for evenness than for species richness and the positive correlation between diversity and evenness indices was higher than that between diversity and richness.     

Control of rhododendron (Rhododendron ponticum and R. flavum) in the eastern beech (Fagus orientalis) forests of Turkey

Because purple-flowered rhododendron (Rhododendron ponticum L.) and yellow-flowered rhododendron (R. flavum Don.) significantly reduce seedling growth and regeneration of eastern beech (Fagus orientalis Lipsky) as well as local floristic diversity in northern Turkey, effective and cost-efficient woody control is needed. Various manual (cut and grub) and herbicide (foliar and cut-stump spray) woody control techniques were used in two different beech-rhododendron sites in the Black Sea Region (BSR) of Turkey. Two years later, biological and economic effectiveness were substantially greater with foliar-applied herbicide and grubbing treatments than with the cutting, cut-stump, and check treatments. Yet, grubbing showed a great potential for sprout crown reduction. Cut-stump spray was intermediate in effectiveness. Cutting had the least woody control and economic effectiveness among all of the treatments. Foliar-applied Arsenal SL (imazapyr) had significantly greater rhododendron control than foliar-appliied Garlon 4 (triclopyr ester). Increasing rates did not enhance herbicide efficacy. Reducing rates further may provide the same level of control at less cost.     

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.     

Three-year storage of oriental beechnuts (<Emphasis Type="Italic">Fagus orientalis</Emphasis> Lipsky)

Oriental beech (Fagus orientalis) is one of the main tree species in Turkey. In this study, 3-year storage of oriental beechnuts from eight Turkish provenances was researched. Beechnuts were stored at −6°C in sealed containers. The average germination percentages of over all provenances were 91.67, 75.92, and 76.75%, prior to initial storage, after 1 year in storage, and after 3 years in storage, respectively. There were significant decreases in the germination percentages of seven provenances while one provenance retained its high initial germination ability over a 3-year storage period. The loss of viability initiated from the radicle and the plumula in stored beechnuts. The average mean germination times were 10.43, 10.22, and 11.89 weeks prior to storage, after 1 year in storage, and after 3 years in storage, respectively. The beechnuts stored for 3 years germinated significantly later than both fresh beechnuts and beechnuts stored for 1 year in terms of average mean germination time. This study showed that oriental beechnuts can be stored in a dormant state for at least 3 years at low temperature (−6°C) with a low moisture content (about 6–7%).     

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.     

Relationship between branch-scar parameters and knot features of oriental beech (Fagus orientalis Libsky)

The classification of roundwood is inextricably linked to the measurement of a particular single wood defect. The appearance, location, and number of defects are important in the quality evaluation of logs and sawn timber, and the most important defects are knots. The purpose of this study was to investigate the relationship between the appearance of branch scars and features of the related knot inside oriental beech logs, and to model the relationship between well-defined branch-scar and knot parameters. One hundred and fifty knots in 15 stems of oriental beech trees were studied. Image analysis software was used to measure the branch-scar and knot features. The results showed a significant positive correlation between the branch-scar parameter “moustache length” and the knot length. The ratio of branch-seal length to width was found to be a good estimator of the stem diameter at the time of knot occlusion and the amount of clear wood between the knot occlusion and the bark. The relationship obtained for the oriental beech stem radius at time of knot occlusion confirms relationship reported for European beech (Fagus sylvatica L.).     

Ectomycorrhizal communities within beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) forests that naturally regenerate from clear-cutting in northern Spain

The objectives of the work described here were to evaluate the diversity of ectomycorrhizal (ECM) fungi within Spanish beech (Fagus sylvatica L.) forests subjected to clear-cutting and natural regeneration and to elucidate the extent to which the carbohydrate concentration in roots of trees of different ages and sizes is related to ECM colonization. The study concerned an unmanaged forest, a stand clear-cut in 1996 and another clear-cut in 2001. ECM colonization of beech roots showed seasonal dynamics in the disturbed areas, but the percentage of roots colonized by ECM was not always related to the accumulation of non-structural carbohydrates. The composition of ECM communities differed between different stands and 40% of ECM morphotypes only occurred in disturbed ecosystems. However, comparable numbers of different ECM morphotypes (24, 25) were found in the three beech stands. This finding indicates that ECM diversity was quite high and similar within disturbed and unmanaged areas. This finding suggests that (1) ECM diversity was not affected by the size and age of trees and (2) the potential of ECM inocula remained high within clear-cut areas. Consequently, the introduction of ECM inocula by silvicultural practices would not be needed to improve the regeneration of clear-cut areas described in our study.     

Canopy gaps and regeneration in old-growth Oriental beech (Fagus orientalis Lipsky) stands, northern Iran

Virgin beech Fagus orientalis forests in northern Iran provide a unique opportunity to study the disturbance regimes of forest ecosystems without human influence. The aim of this research was to describe characteristics of natural canopy gaps and gap area fraction as an environmental influence on the success of beech seedling establishment in mature beech stands. All canopy gaps and related forest parameters were measured within three 25 ha areas within the Gorazbon compartment of the University of Tehran’s Kheyrud Experimental Forest. An average of 3 gaps/ha occurred in the forest and gap sizes ranged from 19 to 1250 m² in size. The most frequent (58%) canopy gaps were <200 m². In total, canopy gaps covered 9.3% of the forest area. Gaps <400 m² in size were irregular in shape, but larger gaps did not differ significantly in shape from a circle. Most gaps (41%) were formed by a single tree-fall event and beech made up 63% of gap makers and 93% of gap fillers. Frequency and diversity of tree seedlings were not significantly correlated with gap size. The minimum gap size that contained at least one beech gap-filling sapling (<1.3 m tall) was 23.7 m². The median gap size containing at least one beech gap-filling sapling was 206 m² and the maximum size was 1808 m². The management implications from our study suggest that the creation of small and medium sized gaps in mixed beech forest should mimic natural disturbance regimes and provide suitable conditions for successful beech regeneration.     

The influences of log storage and kiln drying climate on the colour of non-steamed beech (Fagus sylvatica L.) wood

Abstract

Discolouration during the drying of non-steamed beech is a major industrial concern. The generally preferred yellow-white colour can easily develop a reddish or dull grey appearance during drying. In this study, the influences of log storage time and kiln drying climate on the colour of non-steamed sawn beech have been investigated and quantified. Samples 27×87 mm in cross section were dried in laboratory kilns and the average colour, in CIELAB colour space was measured on dry planed surfaces using a photoelectric colorimeter. Log storage for 13 weeks under low-temperature conditions had no visible effect. The reddish discolouration is mainly temperature related while the greyish discolouration is mainly controlled by the equilibrium moisture content (EMC) during the initial drying. Within the investigated climate interval, the EMC was twice as important as temperature for the final colour. Regression models developed show that, as long as the EMC is kept below 15%, a temperature of up to 37°C can be allowed without any visually detectable discolouration.     

Gap formation in Danish beech (Fagus sylvatica) forests of low management intensity: soil moisture and nitrate in soil solution

Soil moisture content (0–90 cm depth) and nitrate-nitrogen (NO₃-N) concentrations in soil solution (90 cm depth) were monitored after gap formation (diameter 15–18 m) in three Danish beech-dominated forests on nutrient-rich till soils. NO₃-N drainage losses were estimated by the water balance model WATBAL for one of the sites. Two forests were non-intervention forests (semi-natural and unmanaged), the third was subject to nature-based management. The study was intended to assess the range of effects of gap formation in forests of low management intensity. In the unmanaged and the nature-based managed forest, soil solution was collected for 5 years and soil moisture measured in the fourth year after gap formation. Average NO₃-N concentrations were significantly higher in the gaps (9.9 and 8.1 mg NO₃-N l⁻¹, respectively) than under closed canopy (0.2 mg l⁻¹). In the semi-natural forest, measurements were carried out up to 29 months after gap formation. Average NO₃-N concentrations in the gap were 19.3 mg NO₃-N l⁻¹. Gap formation alone did not account for this high level, as concentrations were high also under closed canopy (average 12.4 mg NO₃-N l⁻¹). However, the gap had significantly higher N concentrations when trees were in full leaf, and NO₃-N drainage losses were significantly increased in the gap. No losses occurred under closed canopy in growing seasons. Soil moisture was close to field capacity in all three gaps, but decreased under closed canopy in growing seasons. In the semi-natural forest, advanced regeneration and lateral closure of the gap affected soil moisture levels in the gap in the last year of the study.     

The effect of forest management on trace gas exchange at the pedosphere–atmosphere interface in beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) forests stocking on calcareous soils

The effect of forest management (thinning) on in situ carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) trace gas exchange between soil and atmosphere was studied in three consecutive years at three beech forest sites, which differ in aspect [southwest (SW), northeast (NE), northwest (NW)]. At all sites adjacent thinning plots (“T”) and untreated control plots (“C”) were established. Measurements at the SW and NE sites covered the years 4–6 after thinning while at the NW site measurements covered the year before and the first 2 years after thinning. Mean N₂O fluxes were <3 μg N₂O–N m⁻² h⁻¹ at all plots except for the newly thinned NWT plot. CH₄ uptake was rather low, too. Very low CH₄ oxidation rates during dry periods are explained by physiological drought stress for CH₄ oxidizers. Heterotrophic litter decomposition constitutes the largest part of total soil respiration. On the whole, no significant positive or negative effects of the silvicultural treatment on the magnitude of CO₂-, CH₄- and N₂O-trace gas exchange could be observed at the SW site 4–6 years after thinning. Also at the NE site, no effects of thinning on CO₂ and N₂O fluxes could be demonstrated. However, at this site a significant moisture-induced lower CH₄ uptake could be shown. At the NW site forest management led to a dramatic increase in N₂O emissions in the first two summers after thinning and to distinct effects on CO₂ emissions and CH₄ uptake in the first year after the felling. The unambiguous effects of thinning at the NW site are mainly related to higher C input by dead residues leading to enhanced mineralization activity, to a shift in the competition for nutrients favoring microorganisms as compared to trees and to changes in the soil water availability at the thinned plot. Considering the data obtained from the NE and SW site we expect that with the development of an understorey vegetation at the NW site the observed effects on the magnitude of trace gas exchange due to thinning will continue to decline in the following years. Our results implicate that it is indispensable to take account of the effects of forest management in order to accurately calculate trace gas emission inventories for the investigated forest ecosystem in case thinning took place immediately before.     

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.