© Ecologia Balkanica
http://eb.bio.uniplovdiv.bg
Union of Scientists in Bulgaria – Plovdiv
University of Plovdiv Publishing House
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1 Ph.D. Candidate of Forestry, IRAN
2 Associate Professor of Forestry, Tarbiat Modares University. IRAN
Email: hosseini@europe.com, hosseini@modares.ac.ir
3 Associate Professor of Soil Sciences, Shahrekord University. IRAN
4 University of Natural Resources and Agriculture Sciences of Sari. IRAN
The present study aimed to examine the impacts of small (85.12 m
2
), medium (325.21 m
2
),
large (512.11 m
2
) and very large (723.85 m
2
) gaps on soil properties in a mixed beech – hornbeam
stand of northern Iran. As well as the value of pH, organic matter and carbon, total nitrogen, cation
exchange capacity (CEC), phosphorus, potassium, calcium, nitrogen mineralization, microbial
respiration, earthworms density and biomass of soil samples (0 – 15, 15 – 30 and 30 45 cm depths
from gap center, edge and closed canopy positions) were measured in laboratory. Significantly
effects of gaps size were found on soil properties as the highest values of CEC, density and biomass
of earthworms observed in small gaps. The highest values of carbon to nitrogen ratio, phosphorus,
potassium and calcium were detected in medium gaps. The most amounts of organic matter and
carbon, nitrogen mineralization devoted in very big gaps. Greater amounts of pH, total nitrogen
and microbial respiration were detected in big and very big gaps. It was found that gap position
had a profound effect on soil characters as the highest values of pH, organic matter and carbon,
total nitrogen, phosphorus, potassium, calcium, nitrogen mineralization, microbial respiration
observed in gap center. The greatest amounts of carbon to nitrogen ratio, CEC, density and biomass
of earthworms were detected in closed canopy. According to the results, soil upper layers showed
the highest values organic matter and carbon, soil nutrition elements and biochemical activities,
whereas the highest amounts pH, carbon to nitrogen ratio, CEC and density and biomass of
earthworms were observed in deeper soil. It is concluded that opening areas of canopy cover
should be less than 400 m
2
in beech forests of northern Iran with considering of soil properties.
gap size, gap position, nutrient availability, earthworm, soil.
Beech ( Lipsky) is one of the
most important forest species in the temperate
broad leaf forest biome and represents an
outstanding example of the re colonization
and development of terrestrial ecosystems and
communities after the last ice age, a process
which is still ongoing (MOSADEGH, 2000;
MARVIE MOHADJER, 2007). In the north of Iran,
pure and mixed oriental beech forests cover
17.6 per cent of the surface land area and
represent 30 per cent of the standing biomass.
Beech is the most valuable wood – producing
species in the Caspian forests (RESANEH
2001). The beech trees are found in small
groups up to 500 m a.s.l. while individuals
have been reported from 110 m up to 2650 m.
At low altitudes, they occur mixed with
hornbeam ( L.) (MARVIE
MOHADJER, 2007).