جستجوی مقالات مرتبط با کلیدواژه "سرشاخه زنی" در نشریات گروه "جنگلداری"

In order to investigate the effect of traditional utilization on the diversity and composition of woody species diversity in the western oak forest, two disturbed and less disturbed stands were selected with similar physiographic and floristic conditions. Therefore, 30 circularly shape plots with 1000 m2 surface area were established based on random-systematic sampling with 50×50 m network dimensions. In each sample plot, the frequency and type of woody species were recorded in the prepared sheets of inventory. The average Margalaf species richness indices, Pielo evenness, Shannon-Weiner and Simpson species diversity were calculated in each plot and normalized by Kolmogorov-Smirnov test. To test the significance of the difference between the mean of indices, t-student test was used for normal data and Mann-Whitney U test for abnormal data. Detrended Correspondence Analysis (DCA) was used for ordination of the woody species samples. The results of the study showed that the means of richness and diversity indices in the disturbed stand were significantly lower than in the less disturbed stand; however, the mean of evenness index did not show any statistically significant differences between two stands. High correlation of first axis of DCA proves the importance of destructive factors, such as cutting, branching, frequency of copping, grazing, and qualitative factors, such as basal area and number of trees. These factors plays an important role in differentiation of the forest stands.

Tree felling، delimbing and bucking includes all activities undertaken to fell standing trees and prepare them for extraction. The study was conducted in Gorazbon district in the Hyrcanian forests. In this study، the objectives were to discover the special characteristics in the time consumption of manual tree delimbing and bucking، productivity and costs، and develop regression model. The continuous time study was conducted with professional operators for chain-saw delimbing and bucking and the cycles were broken down into time elements. Tree delimbing time of working crew is the most time-consuming element in delimbing and bucking، followed by bucking and rest and meal time. The operational and personal delay is the most time-consuming delay time in tree delimbing and bucking. Result showed that time consumption for delimbing and bucking was increased with increasing diameter. Labor costs accounted for 37% of the hourly cost while only 1. 5% was related to machine cost. A significant linear relationship was found between delimbing and bucking cycle time and diameter. Productivity of chainsaw delimbing and bucking was increasing related to tree DBH as power. The costs of chainsaw delimbing and bucking with and without delay time were 203710 and 179796 Rial/m3، respectively. The cost of delimbing and bucking was increased as simple exponential equation when DBH of harvested tree was decreased. However، the unit delimbing and bucking cost for chainsaw operation decreased as tree size increased. Total delimbing and bucking cycle time without delay averaged 25. 31 minutes and with delay time were averaged 22. 34 minutes.

Tree felling is one of the most important component among tree harvesting components which consists of cutting and felling, limbing and bucking sub-stages. Tree limbing using chainsaw in hardwood forest is much effective and important. This research was carried out in two compartments of Namkhaneh district, in Kheyrud Forest for assessment of limbing sub-stage. The objectives of this study were time study of tree limbing operation, estimating the productivity and costs of chainsaw and developing regression model. Factor affecting total limbing time regression model was dbh of harvested tree. The hourly production of chainsaw limbing with and without delay time were 11.1 m3/h (4 tree/h) and 14.8 m3/h (5 tree/h), respectively. Productivity of chainsaw tree limbing is increasing with dbh as power. The unit cost of chainsaw limbing with and without delay time were 14710 and 11020 Rials/m3, respectively. Total tree limbing cycle time without delay averaged 12.37 minutes and with delay time averaged 16.51 minutes and also with reducing personal delay, work efficiency can be increased.