RESUMO
Light requirements and spatial distribution of major forest tree species in Turkey hasn’t been analyzed yet. Continuous surface solar radiation data, especially at mountainous-forested areas, are needed to put forward this relationship between forest tree species and solar radiation. To achieve this, GIS-based modeling of solar radiation is one of the methods used in rangelands to estimate continuous surface solar radiation. Therefore, mean monthly and annual total global solar radiation maps of whole Turkey were computed spatially using GRASS GIS software “r.sun” model under clear-sky (cloudless) conditions. 147498 pure forest stand point-based data were used in the study for calculating mean global solar radiation values of all the major forest tree species of Turkey. Beech had the lowest annual mean total global solar radiation value of 1654.87 kWh m-2, whereas juniper had the highest value of 1928.89 kWh m-2. The rank order of tree species according to the mean monthly and annual total global solar radiation values, using a confidence level of p < 0.05, was as follows: Beech < Spruce < Fir species < Oak species < Scotch pine < Red pine < Cedar < Juniper.The monthly and annual solar radiation values of sites and light requirements of forest trees ranked similarly.
RESUMO
Previous studies have been able to successfully detect changes in gently-sloping forested areas with low-diversity and homogeneous vegetation cover, using medium-resolution satellite data such as landsat. The aim of the present study is to examine the capacity of multi-temporal landsat data to identify changes in forested areas with mixed vegetation and generally located on steep slopes or non-uniform topography. landsat thematic mapper (TM)and landsat enhanced thematic mapper plus (ETM+) data for the years 1987-2000 was used to detect changes within a 19,500 ha forested area in the Western Black sea region of Turkey. The data comply with the forest cover type maps previously created for forest management plans of the research area. The methods used to detect changes were: postclassification comparison, image differencing, image rationing and NDVI (Normalized Difference Vegetation Index) differencing methods. Following the supervised classification process, error matrices were used to evaluate the accuracy of classified images obtained. The overall accuracy has been calculated as 87.59% for 1987 image and as 91.81% for 2000 image. General kappa statistics have been calculated as 0.8543 and 0.9038 for 1987 and 2000, respectively. The changes identified via the post-classification comparison method were compared with other change detetion methods. Maximum coherence was found to be 74.95% at 4/3 band rate. The NDVI difference and 3rd band difference methods achieved the same coherence with slight variations. The results suggest that landsat satellite data accurately conveys the temporal changes which occur on steeply-sloping forested areas with a mixed structure, providing a limited amount of detail but with a high level of accuracy. Moreover, it has been decided that the post-classification comparison method can meet the needs of forestry activities better than other methods as it provides information about the direction of these changes.
RESUMO
This study introduces the monitoring system to be established within this project, it aims to determine changes occurring within forested areas, settlement areas and other land use forms located at the peripheral area of Istanbul during consecutive decades. The first phase of the study was completed in 1998 and published, covering the period from 1984 to 1994. This study is the second phase of the first one and implemented to determine land use changes which have occurred on the same site from 1994 to 2000. Standard topographic maps with 1/25 000 scale, forest management maps with the same scale, results of the previous study, orthophoto maps of the year 2000 that were produced from aerial color photographs of the site with 1/5 000 scale, and 4-band IRS_LISS III multispectral satellite data for July 2000 were used as data. The changes in land use within the study area occurring during a six year period were studied.