Abstract

Variability of light and soil physics indicators following gap formation in the Caspian forest, Iran

Author(s): Yahya Kooch, Seyed Mohsen Hosseini, Jahangard Mohammadi, Seyed Mohammad Hojjati

To improve our understanding of the role of a canopy opening on the variability of light and soil physics indicators in a natural forest, a case study was undertaken in and around a gap in a natural beech - dominated (Fagus orientalis Lipsky) forest. This research carried out in twenty hectare areas of Experimental Forest Station of Tarbiat Modares University that is located in a temperate forest of Mazandaran province in the north of Iran. After field trip, twenty one canopy gaps with different areas were found in studied areas and classified as small (85.12 m2), medium(325.21 m2), large (512.11 m2) and very large (723.85 m2) gaps. Measurements of the light transmittancewere collectedwith a ceptometer (LI 250USA), at 1.00mabove the ground,with the instrument held horizontally. Soil sampleswere taken at 0 - 15, 15 - 30 and 30 - 45cm depths from gap center, gap edge and closed canopy using core soil sampler with 81cm2 cross section. Bulk density, soil texture andmoisturemeasured in the laboratory.With considering to analysis of variance, light transmittance amounts had ascending trend with increasing of canopy gaps areas. Also, this character showed significantly increasing fromgap edge to center position.Bulk density had no significantly difference among canopy cover areas. But, the most amounts of this character devoted in 30 - 45cm depth, gap center and edge positions. The higher amounts of sand found in very large areas of canopy gaps, gap center and edge positions and also soil upper layers. Significant statistical difference werenÂ’t showed for silt character in different areas of canopy gaps, but the most were found in closed canopy and beneath depths.Mediumareas of canopy gaps, closed canopy and 30 - 45cm soil depth had the higher amounts of clay. Greater values of soil moisture devoted in small areas of canopy cover and closed canopy, but significant differenceswerenÂ’t found in soil depths. These results further our understanding of the abiotic and consequent biotic responses to gaps in broadleaved deciduous forests created by natural treefalls, and provide a useful basis for evaluating the implications of forest management practices.