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Abbas Banj Shafiei Moslem Akbarinia Gholamali Jalali Mohsen Hosseini 《Forest Ecology and Management》2010
Most of world's forests of different climates have a history of fire, but with different severities. Fire regimes for broadleaf deciduous forests have return intervals that vary from many decades (or less) to centuries (or more). Iran has a total of 1.2 million ha of temperate forest in the north, where fires burn about 300–400 ha annually. This study focused on the impact of fire on forest structure, tree species quality, and regeneration composition (specially beech) in the Chelir forest of northern Iran. The results showed that forest fires changed the structure and had different effects on tree species composition between burned and control areas. Thin barked species such as oriental beech (Fagus orientalis Lipsky) and coliseum maple (Acer cappadocicum Gled.) have been affected more than those with thick bark, like hornbeam (Carpinus betulus L.) and chestnut-leaved oak (Quercus castaneifolia C.A. Mey). The density of oriental beech regeneration in the unburned area was greater than in the burned area, while the quantity of regeneration of hornbeam, coliseum maple and velvet maple (Acer velutinum Boiss) was higher in burned area. Forest fire had a greater effect on oriental beech quality, and changed regeneration composition in the burned area. Fire prevention activities should be considered as a silvicultural treatment for preserving these valuable forests. 相似文献
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We investigated the influence of tree canopy composition and structure on the spatial and temporal variability of (i) concentrations of inorganic N (NH4+ and NO3−) and (ii) net N-mineralization and net nitrification, within the temperate forest floor. We compared a pure European beech stand (PS) with a mixed beech-hornbeam one (MS). Three sampling areas were chosen in each stand. Within the PS, the tree locations represented a decreasing gradient of light intensity reaching the forest floor. Within the MS they represented a gradient in the amount of hornbeam leaves present in the litter. In the field NH4+ and NO3− concentrations were measured in the upper mineral soil (UMS) and the overlying organic layers (OL and OF+OH). Field exposures using buried bags were carried out on UMS over 1 year to measure in situ net N-mineralization and net nitrification. Potential net N-mineralization and net nitrification were investigated in summer with UMS, OL and OF+OH incubated at 28 °C for 28 days in the laboratory. We hypothesize that with the presence of a mull-forming species (hornbeam) within a stand dominated by a moder-forming one (European beech), (i) the spatial and (ii) temporal patterns of soil inorganic N concentrations, net N-mineralization and net nitrification would be different in the two stands. Our main results show that tree species composition has an influence on both spatial and temporal patterns of nitrification. The PS exhibited its highest peaks of UMS NO3− concentration and net nitrification in spring and early summer while they were highest in the MS in winter. Furthermore, PS exhibited a higher rate of net nitrification than MS. We discuss this unexpected result and suggest that dissolved organic C may be the controlling factor for net nitrification in the MS. 相似文献
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Biomechanical characteristics of the root system of hornbeam (Carpinus betulus) were assessed by measuring Root Area Ratio (RAR) values and tensile strength of root specimens of eight hornbeam trees growing
on hilly terrain of Northern Iran. RAR values of the roots were obtained using profile trenching method at soil depth of the
top 0.1 m. In total 123 root specimens were analyzed for tensile strength. Results indicate that in general, RAR decreases
with depth, following a power function. The RAR values in up and down slopes have no significant statistical differences.
In most cases, the maximum RAR values were located in soil depth of the top 0.1 m, with maximum rooting depth at about 0.75
m. The minimum and maximum RAR values along the profiles were 0.004% and 6.431% for down slope and 0.004% and 3.995% for up
slope, respectively. The number of roots in the up and down slope trenches was not significantly different. In the same manner
as for RAR, number of roots distributing with depth was satisfactorily approximated a power function. The penetration depths
of above 90 percent of the roots were at soil depths of 50 cm and 60 cm for up and down slopes, respectively. Results of Spearman’s
bivariate correlation showed no significant correlation between the RAR value with tree diameter and gradient of slope and
number of roots. The mean value of root tensile strength was 31.51 ± 1.05 MPa and root tensile strength decreased with the
increase in root diameter, following a power law equation. Using ANCOVA, we found intraspecies variation of tensile strength.
Biography: Ehsan Abdi (1978– ), Male, Ph.D candidate, in the Department of Forestry, University of Tehran, Karaj 31585-3314,
Iran. 相似文献
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Belowground competition in a broad-leaved temperate mixed forest: pattern analysis and experiments in a four-species stand 总被引：1，自引：0，他引：1
We investigated fine root biomass and distribution patterns in a species-rich temperate Carpinus–Quercus–Fagus–Tilia forest and searched for experimental evidence of symmetry or asymmetry in belowground competition. We conducted extensive
root coring and applied the recently introduced in situ-root growth chamber technique for quantifying fine root growth under
experimentally altered intra- and interspecific root neighbourhoods in the intact stand. In 75% of all soil cores, fine roots
of more than two tree species were present indicating a broad overlap of the root systems of neighbouring trees. Quercus trees had more than ten times less fine root biomass in relation to aboveground biomass or productivity (stem growth) and
a much higher leaf area index/root area index ratio than Carpinus, Fagus and Tilia trees. The root growth chamber experiments indicated a high belowground competitive ability of Fagus in interspecific interactions, but a low one of Quercus. We conclude that (1) interspecific root competition is ubiquitous in this mixed stand, (2) root competition between trees
can be clearly asymmetric, and (3) tree species may be ranked according to their belowground competitive ability. Fagus was found to be the most successful species in belowground competition which matches with its superiority in aboveground
competition in this forest community. 相似文献
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Biomechanical characteristics of the root system of hornbeam (Carpinus betulus) were assessed by measuring Root Area Ratio (RAR) values and tensile strength of root specimens of eight hornbeam trees growing on hilly terrain of Northern Iran. RAR values of the roots were obtained using profile trenching method at soil depth of the top 0.1 m. In total 123 root specimens were analyzed for tensile strength. Results indicate that in general, RAR decreases with depth, following a power function. The RAR values in up and down slopes have no significant statistical differences. In most cases, the maximum RAR values were located in soil depth of the top 0.1 m, with maximum rooting depth at about 0.75 m. The minimum and maximum RAR values along the profiles were 0.004% and 6.431% for down slope and 0.004% and 3.995% for up slope, respectively. The number of roots in the up and down slope trenches was not significantly different. In the same manner as for RAR, number of roots distributing with depth was satisfactorily approximated a power function. The penetration depths of above 90 percent of the roots were at soil depths of 50 cm and 60 cm for up and down slopes, respectively. Results of Spearman's bivariate correlation showed no significant correlation between the RAR value with tree diameter and gradient of slope and number of roots. The mean value of root tensile strength was 31.51 ± 1.05 MPa and root tensile strength decreased with the increase in root diameter, following a power law equation. Using ANCOVA, we found intraspecies variation of tensile strength. 相似文献
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