جستجوی مقالات مرتبط با کلیدواژه « forest cover changes » در نشریات گروه « جنگلداری »

Monitoring of land use changes in forest areas provides acceptable information for better planning and management on forest resources. In this study, to assess the changes of the forest cover in the central part of Boyer-Ahmad County in Kohgiluyeh and Boyer-Ahmad Province in southwest of Iran, satellite imageries of two different Landsat time series including Landsat 5, TM satellite data (30.6.1987), and Landsat 8, OLI-TIRS data (23.7.2013) were used. Supervised classification was carried out by applying the Maximum Likelihood Algorithm and LMM model (Matrix Multiplication pictures). Moreover, Logistic regression and Geomod model were used to provide validation map and prediction of forest cover changes in 2039, respectively. Land cover maps achieved from the study area showed that there is a reduction of about 8395 hectares in the forest area during the past 26 years (1987-2013). Moreover, it is predicted that the forest area will decrease around 9938 hectares during the coming 26 years. The results showed that the kappa coefficient obtained from the supervised classification on the satellite imageries in 1987 and 2013 were 0.89 and 0.88, respectively. Moreover, the results of Logistic regression with pseudo R2 and ROC were 0.24 and 0.73, respectively, which indicate that the obtained model is relatively adapted to the real changes and there is an appropriate ability for the model to estimate the forest changes in the last 26 years. Results of simulation of the forest cover changes in 2013 reveal that the Geomod model is a good tool for forecasting the forest cover changes. The accuracy and precision of the obtained forest cover maps is about 90 percent.

Monitoring of the changes in land uses and forest degradation is an important issue in evaluation and management of the natural resources. In order to investigate the forest cover degradation trends and determination of the main environmental factors on forest degradation in Sirvan county of Ilam province, satellite images for the years 1987 and 2014 of MMS (80 m spatial resolution) and OLI (30 m spatial resolution) were used. To survey the spatial relationship of forest cover reduction with the main environmental factors, regression logistic statistics method was used. The results revealed that about 5910.15 ha of the forest cover has been reduced Sirvan county during 27 years. In addition, the results of modelling demonstrated that altitude, slope and aspect variables (α≤0.01) were the most affecting factors on forest degradation in the studied area, respectively. While distance to road and distance to villages had no significant effects (α>0.01) on forest degradation in this area. Assessment of regression model fitted with ROC (0.9045) and Pseudo-R2 (0.3275) indices indicated the ability of the model to describe the changes and to identify the areas prone to change.

In order to investigate the spatial pattern of forest cover changes for the county of Malekshahi in Ilam province during 1976 to 2014, logistic regression modeling technique were used. Logistic regression model is able to well determine the relationship between forest cover change (dependent variable) and its influencing factors (independent variables).
To survey the forest cover changes, the images of Landsat 1 satellite from MSS sensor relating to 1976 and the images of Landsat 8 from OLI sensor relating to 2014 were processed and classified. The surveyed images were classified into two classes of forest and non forest. To investigate the causes of degradation, forest cover changes map with physiographic and human spatial variables were integrated into model.
The evaluation of regression model with ROC (0.8210) and Pseudo-R2 (0.2514) indices indicated the ability of the model to describe the changes and to identify the areas prone to change. The results showed that approximately 26491.9 ha of forest areas were reduced during 38 years.
According to the results of modeling, it was found that altitude, soil depth, distance to the forest edge, aspect, slope, distance to drainage, population distribution, distance to the road and village had the greatest impact on the reducing of forest cover in the county of Malekshahi, respectively. The results of study can be considered in the future planning for the area that are related to the vegetation / land use changes.