Long-Term Effects of Timber Extraction by a Crawler Tractor on Soil Condition Recovery in a Mixed Forest

In this study, the physical, chemical and biological characteristics of compacted soil due to tracked skidding (LTT-100A) after 35 years (from 1986 to 2021) of clear cutting operation were investigated in an even aged mixed deciduous stand in Masal forests, Guilan province, northern Iran. Three levels of machine traffic intensity (TI) (low, LT; medium, MT; and high, HT), two levels of skid trail slope (SC) (Gentle, <10%, GS; and steep, ≥10%, SS), two sample locations(SL) (Between track, BT; and On tracks, OT), and two soil depths (SD) (0-5 cm, and 5-10 cm) were considered as independent variables affecting the process of soil profile recovery. The values measured from the abandoned skid trails were compared with those of undisturbed areas to estimate the soil profile recovery rates. Results showed that TI had significant effects on all soil physicochemical (except for soil moisture) and biological properties (i.e., leaf litter, above-and below-ground biomass); all physicochemical and biological properties (except for soil moisture and leaf litter) were affected by SC; the effect of SL on soil texture, density and moisture was significant; and soil texture and density were the only characteristics affected by SD. The values of soil bulk density and penetration resistance on the skid trails were 35% and 49% higher than those of the control area, respectively, while total porosity value was 17.5% lower than that of the control area. Furthermore, soil organic carbon on the skid trails was 20% less than that of the control area. The amount of soil biomass on the skid trails was not recovered after 35 years, so the above and below ground biomass on skid trails were 42% and 46% less than the control area, respectively. The value of leaf litter on the skid trails was 31% less than that of the control area. Overall, the results of this research revealed that the soil of the studied forest is sensitive to the activity of timber harvesting machines. Thus, sustainable forest management needs to reduce the impact of logging within the context of best management practices (BMPs)

Plant species diversity in the ecological species groups in the Kandelat Forest Park, Guilan, North of Iran

Pourbabaei H, Haghgooy T. 2012. Plant species diversity in the ecological species groups in the Kandelat Forest Park, Guilan, North of Iran. Biodiversitas 13: 7-12. Forest vegetation indicates conditions and productivity potential of forest habitat, because it reflects the interaction of climate, soil and topography. The aim of this research was to study the relationship between vegetation and topography factors. In order to do this research, type, number and percentage cover of trees, shrubs (sample plot with 1000 m2 area) and type and percentage cover of herbaceous species (sample plot with 64 m2 area) investigated and recorded. The coverage percent of species were estimated on the basis of Domin scale. Vegetation classified using Two-Way Indicator Species Analysis (TWINSPAN). The results revealed that there were 6 ecosystem units (ecological groups) in the region. The comparison of diversity indices and topographic factors between groups were performed with ANOVA test. Results also indicated that there were significant differences between groups in terms of biodiversity indices and topographic factors. The formation of a particular group is affected by a combination of environment variables. The aspect was the most important variable of topographic factors in this study

The influence of gap size on plant species diversity and composition in beech (Fagus orientalis) forests, Ramsar, Mazandaran Province, North of Iran

Pourbabaei H, Haddadi-Moghaddam H, Begyom-Faghir M, Abedi T. 2013. The influence of gap size on plant species diversity and composition in beech (Fagus orientalis) forests, Ramsar, Mazandaran Province, North of Iran. Biodiversitas 14: 89-94.This study was conducted to investigate the influence of gap size on plant species diversity and composition in beech (Fagus orientalis Lipsky.) forests, Ramsar, Mazandaran province. Fifteen gaps in small, medium, and large sizes were randomly selected. Abundance of tree saplings, shrubs and herbaceous species were counted on 4 m2 micro-plots within the gaps. Diversity indices including Shannon-Wiener, Simpson, Mc Arthur's N1, Hill's N2, species richness and Smith-Wilson’s evenness index were computed. The results revealed that there was significant difference among three gap categories in terms of diversity. The highest diversity values of tree and herbaceous species were obtained in the large gaps, while the highest diversity value of shrub species was in the medium gaps. Species composition of small gaps (28 species: 7 trees and 21 herbaceous), medium gaps (37 species: 7 trees, 5 shrubs and 25 herbaceous) and large gaps (40 species: 7 trees, 4 shrubs and 29 herbaceous) were recognized. Therefore, based on the results of this study, it is recommended that in order to maintain plant diversity and composition up to 400 m2 gap size cloud be used in this forests

Evaluation of fuel load following fire in Loblolly Pine (Pinus taeda L.) plantations using line sampling and of FLM method (Case study: Takhsam plantations in Guilan Province)

The occurrence of fire in natural ecosystems depends on the prevailing meteorological conditions, the availability of ignition material and the quantity and characteristics of fuel biomass. The rate at which fuels accumulate is a crucial determinant of fire regimes. Woody debris in the forest and herbaceous cover are also important determinants of the severity of the fire. Therefore particular fuel management is required for improved understanding and awareness on the amount of fuel, fuel diameter classes and required spatial and temporal fuel condition. Coniferous plantations located in Saravan and Lacan located in the vicinity of Rasht metropolitan area are amongst the most fire sensitive areas within Guilan province. To determine the amount of accumulated fuel and the degree of their proneness to fire risk, forest plantation area of Takhsam in Lakan was investigated. To this aim, we used the transect sampling and the FLM method. The results showed that the fuel load in loblolly pine plantation accounts for 3.89 tons per hectare and vary in different diameter classes. This amount of fuel is not presumable to impose high wildfire risks for severe fire events. However, if combined with the existing herbaceous cover, a higher proneness to severe wildfire can be expected