Simplified forest structures following even-age management have been associated with the loss of biodiversity, which may be avoided through disturbance-inspired silviculture. Here, we ask how much do gap characteristics in a managed old-growth differ from those in unmanaged old-growth subject only to natural dynamics? In this study, we compared important characteristics of gaps (e.g. canopy gap fraction, distribution of gap sizes) and gapmakers (e.g. size classes, frequency, decay classes) between a managed and an adjacent unmanaged old-growth Oriental beech (Fagus orientalis Lipsky) compartment in the Keladarsht region of northern Iran 10 years after a single harvest entry using single-tree selection. Canopy openings >100 m2 with visible remnants of gapmakers (i.e. stumps) were included in this study. Gap characteristics of both compartments were within typical ranges for old-growth beech. Nonetheless, small but potentially important differences between the two areas were observed. In the managed compartment, harvesting poor quality trees with structural defects and typical diameters at breast height >52.5 cm plus natural mortality resulted in 102 canopy gaps (1–6 gapmakers, averaging 3.5 gaps/ha, gap fraction 9.8 per cent) compared with 59 natural canopy gaps (1–7 gapmakers, averaging 2.6 gaps/ha, gap fraction 13.7 per cent) in the unmanaged compartment. In both compartments, medium-sized gaps (200–500 m2) were most prevalent. In the managed compartment, 60 per cent of gapmakers were large or very large (typically cut) compared with 39 per cent in the unmanaged compartment where large trees typically snapped and became snags. Uprooting, particularly of small and medium sized gapmakers, was less common in the managed than the unmanaged compartment. Our results indicate that even one single-tree selection harvest may lead to a short-term divergence in stand structure compared with the unmanaged forest. While such managed forests may no longer be considered as old-growth, divergences in canopy gap characteristics indicate that a more nuanced harvesting scheme that includes cutting some larger gaps may more closely mimic the canopy dynamics of this old-growth forest.
Parhizkar P., sagheb-talebi K., shahini y., teimouri M. (2017): introduction of suitable species for planting in gaps of different size (case study: loveh forest, Golestan, iran). J. for. sci., 63: 9-15.this study was carried out in loveh forest, north of iran. We measured the quantitative characteristics of seedlings including collar diameter (measured at 1 cm above the soil surface), height, and current annual height increment and calculated the mean annual increments of height and diameter. ten gaps with the same climatic, edaphic and topographic conditions were selected. in each gap, two transects, 2 m wide, were laid along the longest (north-south) and the shortest (West-east) axis. nine sampling microplots, 4 m 2 area, were established: one at the centre, four at the edges and four under the canopy within the transects. results showed that the highest frequency of seedlings was seen in medium-size gaps (200-500 m 2 ). Quantitative characteristics of oak seedlings were better in small and medium-size gaps. there was a significant difference in the length of spring shoots, mean annual increment of height and mean annual increment of diameter between the species. Hornbeam, wild service and wild cherry seedlings are recommended for faster gap recovery, as the results showed that these species had the highest values of studied variables.
This study was carried out to evaluate gap characteristics and gapmakers for different development stages of an oriental beech forest in northern Iran. Development stages of 1 ha square-shaped mosaic patches were identified using 100 × 100 m sampling grid and all gaps within these mosaics were recorded. Gap areas were calculated and classified into four classes and gapmakers were counted and classified into 4 decay and 4 diameter classes as well. Results showed that gaps comprised 13.7, 9.1 and 17.6% of the study area in initial, optimal and decay stages, respectively. There was a significant difference between development stages with respect to gap size and the highest amount was observed in decay stage. Medium-sized gaps were the most frequent in all three stages. Frequency distribution of gapmakers varied among development stages. Our findings revealed that 200–500 m<sup>2</sup> is the most preferable gap size for close-to-nature silvicultural approaches in Hyrcanian beech forests. To achieve this gap size 1–2 trees should be marked for harvesting operations.
The predominant natural disturbance regime within an old-growth Oriental beech (Fagus orientalis Lipsky) forest has been imitated in order to continue the forest cover. It is unclear how much the silvicultural characteristics of regeneration in a managed forest differ from those in an unmanaged old-growth forest subject only to natural dynamics. In this study, we compared important quantitative (e.g. height, collar diameter, crown width, length of spring shoot on the main stem and length of the uppermost internodes) and qualitative (e.g. healthy, mode of branching and stem form) silvicultural characteristics of beech saplings within the gaps between an unmanaged old-growth Oriental beech compartment and a managed forest in the northern Iran ten years after a single harvest entry using a single-tree selection. Canopy gaps larger than 100 m<sup>2</sup> with visible remnants of gapmakers (i.e. stumps) were included in this study. The saplings’ characteristics of both compartments were within typical ranges for an old-growth beech forest. Small, but important differences were also observed. The value of beech saplings’ density in the managed compartment (4.9 ± 0.7 SE) was significantly (P < 0.05) higher than the unmanaged one (3.4 ± 0.6 SE). Conversely, the value of the Menhinick Richness index in the unmanaged one (0.96 ± 0.05 SE) was significantly (P < 0.01) higher than the managed compartment (0.80 ± 0.04 SE). The sapling spring shoot length in the unmanaged compartment (13.3 ± 1.7 SE) was also significantly (P < 0.01) higher than the managed one (7.3 ± 0.7 SE). Relying on beech trees in a managed compartment will hamper the stability of future forest stands. The imitation of the old growth forest must be complete. To increase the resistance of the forest stands to adverse conditions, pay attention to the tree species richness at the time of marking.
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