نوع مقاله : مقاله پژوهشی
1 دانشیار پژوهش، مؤسسۀ تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران
2 کارشناس ارشد پژوهش، مؤسسۀ تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران
عنوان مقاله [English]
Plotless or distance sampling methods, also known as k- tree sampling, are practical field sampling methods for forest inventories and ecological surveys. In this research, in order to test the efficiency of Continues Nearest Neighbor (C-nn) distance sampling method a 220 ha forest area was selected in Kheyroud forests of northern Iran. Then field sampling was performed using: 1- circular sample plots of 1000 m2 which is conventional in these forests and 2- C-nn samples with k = 15 trees, both based on a 150 m×200 m systematic grid. In total, we measured 77 circular sample plots and 77 C-nn samples in the study area. Results showed that there was no significant difference between estimation of forest stem basal area using the two methods and even among different values of k (6 to 15). However, sampling precision decreased significantly by decreasing the amount of k from 7 to 6 trees. Furthermore, time cost in the C-nn method was significantly lower than the other one. Therefore, regarding to the ease of implementation and the statistical precision of the C-nn sampling method, we concluded when sampling using plotless methods is needed to apply in these kind of forest, the C-nn sampling method can be implemented with k =7 trees based on cost and precision of inventory.