فهرست مطالب کامبیز براری

The present study aimed to compare the rate of net nitrogen mineralization as one of the most important biological properties of soil in managed and control forests of Khalilmahle series 1, Behshahr. Net N mineralization was measured using the buried bag method. Four points from each forest were selected for sample preparation. At each point, three samples (samples of A, B, C) were taken at 0-10 cm depth. Sample A was placed in a plastic bag and transferred to the laboratory. Samples B and C in plastic bags were buried at the same spot. Sample B and sample C were taken after 30 and 60 days, respectively. Results showed that the net rate of nitrogen mineralization in the managed plot (0.15) was significantly higher than the control plot (0.05) for the entire study period. The net rate of ammonium production was less than zero (-0.03) in control plot while it was greater than zero (0.04) in the managed plot. The net rate of nitrate production in control and managed plots was 0.08 and 0.11, respectively. Knowing the net rate of nitrogen production in addition to studies about nutritional requirements could be an appropriate strategy in optimal management of forests. Our finding suggested that appropriate forest management can result in increasing net N mineralization as one of the important features at site productivity.

This study was undertaken to investigate the role of forest management in tree diversity، regeneration and vegetation in control and managed parcels of series No. 1 of forestry plan in Khalil-Mahale، Behshahr. Thirty samples with an area of 1000 m2 were systematically and randomly taken with a 100 × 75 m grid in both parcels. In each plot، tree number and species type were recorded. In order to study the vegetation، five micro-plots (1 m2)، one in the center and four others in four main directions (half radius from the center of the plot) were taken in each plot. The type and percentage of herbaceous species were recorded in each microplot. To count the regeneration in the center of the main plot، circular sample plots with an area of 100 m2 were used. To study and compare the biodiversity in the two plots and to calculate the richness and evenness، the Simpson and Shannon-Wiener diversity indices، Margalef and Menhinic indices and the Pilo index were used، respectively، using PAST software. The results showed that the number of plant species was more in managed plots. The biodiversity of woody and herbaceous plants richness indices and regeneration of tree species were higher in managed plots. In fact، the results showed that forest management using single selection method had different effects on woody species regeneration and diversity of herbaceous and tree species.