عنوان مقاله [English]
Background and Objectives:
Studying the structure of the landscape based on the principles of ecology and the spatial indicators of the landscape as its components is considered a suitable tool for mapping and quantifying the spatial characteristics of each land use. Ecological functions, the structure of the landscape, and landscape patterns have undergone unwelcome changes due to the increasing expansion of human activities. Therefore, to monitor and control these changes, quantifying and studying the landscape is important. This study aims to quantify the landscape pattern of regions with different development levels using the line intersect sampling (LIS) method to estimate the metrics of the total length of the forest edge, and the point sampling method was conducted to estimate the metric of contagion. In this regard, the preserved region of Sefidkuh and the manipulated region of Qaleh Gol in Lorestan province were considered.
Materials and Methods:
For this purpose, we selected two 200-hectare areas from the two mentioned regions on Google Earth images and in a GIS environment. To perform the line intersect method, 16 transects with lengths of 100 and 200 m were fitted on the study area using systematically randomized directions. For the paired point sampling method, paired points with 100 and 200 m were systematically and randomly implemented on the selected images, and then metrics were calculated. The outcomes show that in both measured transects, the total length of the forest edge in the Qaleh Gol region is greater than in the Sefidkuh region, and the numerical value of the contagion metric in the Qaleh Gol region is less than in Sefidkuh. Also, the t-student method was applied to compare the regions with different line intersect lengths and paired point lengths. Then, spatial indices were calculated. The paired t-test was also used to compare the different distances in the two regions.
The findings show that there is more disturbance and fragmentation in Qaleh Gol. Moreover, the results indicate that the sampling methods used in this study are a suitable alternative for more detailed vegetation cover maps. The landscape patterns can be quantified by spending less cost and time and with higher accuracy. The obtained results can be used in planning and management at different levels (local, regional, and national), especially in areas with a high rate of change. Also, in this study, it was found that sampling methods are a suitable alternative for vegetation maps with many details. The results of the total length of the forest edge are also consistent with the results of the contagion estimation, and the Qaleh Gol area, which has less contagion, has a longer total length of the forest edge, indicating more destruction and fragmentation of this area compared to the less disturbed Sefidkuh area. Among the reasons for the disturbances in the Qaleh Gol area, we canmention the presence of artificial and man-made disturbances such as numerous villages, agricultural activities, horticulture, livestock grazing, and other rural activities. These have caused the thinning of the forest cover in the area.
Linear intercept sampling (LIS) can be used to estimate the total edge length of forests, while paired-point sampling can be used to estimate the spatial coverage index. These methods can be effective alternatives to detailed vegetation cover maps for downsizing the pattern of land cover in different regions with varying degrees of development. They can also provide a more accurate comparison of land cover patterns with lower costs and in less time.