Ali Salehi

Structure, composition and regeneration of riparian forest along an altitudinal gradient in northern Iran

In order to protect and understand the regeneration of riparian forests, it is important to understand the environmental conditions that lead to their vegetation differentiation. We evaluated the structure, composition, density and regeneration of woody species in forests along the river Safaroud in Ramsar forest in northern Iran in relation to elevation, soil properties and distance from the river. Using 60 transects located perpendicularly to river and 300 quadrats, we examined forests 0, 50, 100, 150 and 200 m from the stream along an elevation gradient spanning from 350 to 2,400 m a.s.l. We found that total density, regeneration, diameter and basal area of trees were significantly higher in the interior of the forest whereas shrub density was higher close to the river. The uneven-aged forest structure showed no significant differences among gradient from the river to the forest interior. Hydro-geomorphic processes, flooding, the elevation gradient, distance from the river and soil properties were the most important factors that influenced plant community distribution in relation to the river.

Response curves of seventeen woody species to soil factors along a riparian forest in northern Iran

The aim of this study was to determine type of response curves for seventeen woody species (10 tree and 7 shrub species) to soil factors in an intact riparian forest in Safaroud River in northern Iran using HOF function. Data were collected along transects established perpendicular to the water flow on both sides of the river. Results indicated different responses for different woody species. The most common were symmetricunimodal response curves and curves showing an increase in occurrence probability after a certain value in form of a plateau. Bimodal curves were four times more frequent in riverside than forest interior area. It seems that river flow disturbances through frequent floods effect on species tolerance and optimum in riversides.

Effects of rubber-tired skidder and farm tractor on physical properties of soil in plantation areas in the north of Iran.

Physical properties of soil can be affected by machines that are used for skidding which have the potential to impact soil sustainability and forest productivity. The present study evaluated the effect of timber skidding by a rubber-tired skidder and farm tractor on the soil physical properties. The study site was located in Hafdaghanan plantation region in the north of Iran. Two treatments that consisted of skidding by HSM 904 skidder and ITM285 farm tractor equipped with trailer were applied. The trails were included in three traffic levels: primary, secondary and tertiary. Treatment effects were tested using analysis of variance (ANOVA) with skidding machine types and traffic levels. Results indicated that machine type and traffic intensity are the effective factors on soil physical properties. The results showed that with an increase of traffic frequency, bulk density increased but total porosity and soil water content decreased. The results of the study provide clear evidence that farm tractor is a more environmentally friendly machine than rubber-tired skidder in the plantation area.

Earthworms as indicators for different forest management types and human disturbance in Ilam oak forest, Iran

Abstract There has been observed widespread destruction of natural ecosystems around the world due to population growth, land use change and clear cutting which have affected soil properties. Different management strategies have been so far implemented to reduce this crisis in various regions of the world, such as e.g. short-term and long-term conservation management in the Zagros region. However, any management approach should be evaluated with appropriate measures to determine how managed areas respond. The main objective of the present study was to evaluate the potential of earthworms as an indicator for different forest management strategies and human disturbances in Zagros oak (Quercus persica Jaub. and Spach) forest. The sites selected included undisturbed one as the control (Un), the sites under five-year conservation management (FCM) and twenty-year conservation management (TCM) as well as the disturbed site (D). The results of principal component analysis (PCA) showed that different regions separated into the components: PC1 and PC2. Un and TCM sites gathered together and represented higher values of the factors such as pH, Kavailable, OC, clay content, Pavailable, CEC, overstory tree canopy, Ntot, biomass and abundance of earthworms. The positive direction of the first axis reflected a gradient of EC, BD and Ptot. According to the logistic model, NH4-N and EC played the most important role in earthworm presence and absence in Zagros forest ecosystem. Earthworm abundance and biomass could be a good indicator to evaluate different forest management strategies in the study area.