sahar mokaram kashtiban

 Biochar is known as a widely-use amendment in improving phytoremediation efficiency through the increase of plant growth; whereas its influence (either individually or in combination with bacteria) on the reduction of heavy metals (HMs) bioavailability of soil is an important advantage. This study was planned to assess the effects of separately and combined of biochar produced by forest wood wastes of hornbeam at three levels of 0, 2.5 and 5% of soil dry weight and Pseudomonas fluorescens bacteria on growth properties of potted white willow (Salix alba L.) seedling in a HM contaminated soil (Pb, Cu, and Cd). The variation of bioavailability (BA) and removal efficiency (RE) indexes, and bioaccumulation (BCF) and translocation (TF) factors also were analyzed in the treatments. The experiment was conducted under greenhouse condition for a 160 days’ period. The results showed that the variation in most growth components of seedlings was significant in the separate and combined treatments. The combined treatment of bacteria-biochar (at 5% level) increased the dry weight of leaf, shoot, root and total plant about 59, 36, 142, and 85% in comparison to the control (without the biochar and bacteria). In the biochar treatments, the BA, RE (except Pb), BCF, and TF (only in 2.5% of biochar) for Pb, Cu, and Cd were 13-57, 4-47, 29-60, and 16-33% lower than those in control, respectively. These indexes were improved by up to 191, 79, 84, and 13% in the bacteria-biochar treatment in compared to the individual application of biochar. In overall, according to our findings, the combination of biochar-bacteria led to the HMs bioavailability and improving the white willow function to eliminate soil HMs. So that, co-application of biochar and bacteria as soil amendments can increase growth parameters in white willow seedling and improve HMs bioavailability of plant in phytoremediation process.

In order to investigate the effect of traditional utilization on the diversity and composition of woody species diversity in the western oak forest, two disturbed and less disturbed stands were selected with similar physiographic and floristic conditions. Therefore, 30 circularly shape plots with 1000 m2 surface area were established based on random-systematic sampling with 50×50 m network dimensions. In each sample plot, the frequency and type of woody species were recorded in the prepared sheets of inventory. The average Margalaf species richness indices, Pielo evenness, Shannon-Weiner and Simpson species diversity were calculated in each plot and normalized by Kolmogorov-Smirnov test. To test the significance of the difference between the mean of indices, t-student test was used for normal data and Mann-Whitney U test for abnormal data. Detrended Correspondence Analysis (DCA) was used for ordination of the woody species samples. The results of the study showed that the means of richness and diversity indices in the disturbed stand were significantly lower than in the less disturbed stand; however, the mean of evenness index did not show any statistically significant differences between two stands. High correlation of first axis of DCA proves the importance of destructive factors, such as cutting, branching, frequency of copping, grazing, and qualitative factors, such as basal area and number of trees. These factors plays an important role in differentiation of the forest stands.