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, K available , OC, clay content, P available , CEC, overstory tree canopy, N tot , biomass and abundance of earthworms. The positive direction of the first axis reflected a gradient of EC, BD and P tot . According to the logistic model, NH 4 -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.
ABSTrACT:To clarify the effect of shelterwood silvicultural method on the diversity of plant species in a beech (Fagus orientalis) forest in the north of Iran, we compared the plant species diversity in three compartments (treatments) where regeneration cuttings were performed with that in a primary compartment. The sampling procedure was a systematic random method and the tree, tree regeneration, shrub and herbaceous species were identified and measured within sampling plots. Results indicated that the mean tree richness in compartment No. 1 (only with one seed cutting) was higher than in the other compartments. The mean richness of understorey species in compartment No. 4 (with all regeneration cuttings) was higher than in the other compartments. The mean evenness (E Var ) of tree species in compartment No. 4 was higher than in the other compartments. The mean evenness of understorey species in compartment No. 1 was higher than in the other compartments. The mean tree diversities (i.e. 1-D, N 2, H´ and N 1 ) in compartment No. 1 were higher than in the other compartments. In addition, the mean diversities of understorey species in compartment No. 1 were higher than in the other compartments.
The lime tree is one of the rare and valuable species that found in the Hyrcanian moist forests with economic as well as ecological value. Identification of the quantitative and qualitative features of this species is important. In order to investigate the stem form of this species in the Shafaroud forests of Guilan Province, 141 lime trees in 39 plots were analyzed during the four stages of small pole, pole, saw-timber, and maturity. In each plot, stem-diameter at different heights was measured by using the Spiegel Relaskop. Measurements and analyses included diameter at breast height (d.b.h.) and total height. Same parameters was calculated: stem form factor based on diameter, stem form factor based on volume, form quotient, slenderness factor, ratio of stem height to total height, ratio of stem volume to total volume, correlation, and coefficient of determination to describe stem form factor. The results showed that the average stem form factor based on diameter was 0.554. The average stem form factor based on volume was 0.576, average form quotient was 2.32 and slenderness factor was 35.04%. The average ratio of stem height to total height was 82.45. In addition the results indicated a strong relationship between diameter at breast height and trunk coefficient. The ratio of stem volume to total volume revealed that 64.44 of lime volume is located in the bottom half of the trunk. The value of the parameters described here is towards a better description of stand characteristics. Obtained results indicating stability for natural lime tree in Iran.
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