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Planning of forest road network is the most important issue for sustainable management of northern forests in Iran. This study represented a technical method of forest road planning by using GIS (Geographic Information Systems) in Vatan forestry plan of Golestan province, Iran. The aim of this study was to find out options for the optimization of skid trail length and for decreasing the negative effects of redundant skid trail length. Results of this study showed that the total length of forest road and the road network density was 36745 m and 8.68 m ha−1, respectively. 54% of the area was covered by these roads. 98.06 km skid trail was planned from road verge into the forest interior. The density of this skidding trail was 23.17 m ha−1. The suggested road network length measured using GIS was 47.23 km. Road density was 10.87 m ha−1, with 79% coverage. Skid trail length was 81.04 km, and skid trail density was 19.15 m ha−1. On the basis of GIS measurements, the skid trails on new road network system had shorter length and more frequency. This causes to decrease the cost of primary transportation. Moreover, in this plan the roads with suitable coverage passed from stable slopes. Santrauka Miško kelių tinklo planavimas – viena svarstomų problemų, siekiant užtikrinti tvarią miškotvarkos sistemą šiaurinėje Irano dalyje esančiuose miškuose. Šiame straipsnyje pristatomas miško kelių planavimo techninis metodas, taikant GIS (geografinės informacinės sistemos) programą ir naudojant Vatan miško, Golestan provincijoje, Irane, planus. Šio tyrimo tikslas – išsiaiškinti galimybes, kaip optimizuoti miško keliukų ilgį ir sumažinti neigiamą poveikį miškui, mažinant perteklinį šių keliukų trasos ilgį. Pirminiai rezultatai parodė, kad bendras esamų kelių ilgis siekia 36 745 km, kelių tinklas aprėpė 54% visos tiriamosios teritorijos, tankis siekė 8,68 m ha−1, o optimalus miško kelių tinklas buvo rengiamas pagal esamą 98,06 km ilgio miško keliukų tinklą, kurio tankis – 23,17 m ha−1. Bendras siūlomo kelių tinklo ilgis siekia 47,23 km, tankumas – 10,87 m ha−1, jis aprėpia 79% teritorijos. Miško keliukų ilgis – 81,04 km, tankumas – 19,15 m·ha−1. Remiantis GIS matavimais, naujo miško keliukų tinklo keliukai buvo trumpesni, tačiau jų tinklas tankesnis. Dėl šios priežasties mažėja pirminės transporto išlaidos ir sukuriama optimali miško keliukų aprėptis, pagerinamas prieinamumas. Резюме Планирование сети лесных дорог является одним из важнейших вопросов при создании упорядоченной системылесохозяйствования в северной части Ирана. В статье представлен технический метод планирования лесохозяйственной деятельности (прокладки дорог) с использованием ГИС и плана леса Ватан в провинции Гулистан Ирана. Целью исследования было выяснить возможности оптимизации длины лесных дорог и уменьшениянегативных последствий их избыточной длины. Результаты исследования показали, что общая протяженность существующих лесных дорог составляет 36 745 км, сеть дорог охватывает 54% всей исследованной территории,ее плотность – 8,68 м га−1. Оптимальная сеть лесных дорог создавалась на основании имеющейся сети лесных дорог, протяженность которой 98,06 км, плотность – 23,17 м гa−1. Протяженность предлагаемой сети дорог составит 47,23 км, плотность – 10,87 м гa−1, она охватит 79% территории. Длина лесных дорог составит 81,04 км, а плотность – 19,15 м·гa−1. На основании измерений, проведенных с использованием ГИС, длина дорог лесной сети стала короче, а сеть более густой. В связи с этим снижаются первичные затраты на транспорт, охват леснымидорогами становится более оптимальным, увеличивается доступность.

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Average skidding distance for forest stands is an important parameter for the determination of the optimum road density and spacing. In this research the real mean skidding distance and theoretical mean skidding distance were measured to calculate the correction factor of skidding distance for Chafrood forest in Hyrcanian zone. The length and azimuth of skid trails from road and depot junction to forest interior were measured. Moreover, the position of skid trail was recorded by GPS. These skid trails with a buffer of 140 m were designed on a topographical map using Arc GIS software. Results indicated that the road spacing of 500 m in the study area resulted in a theoretical mean skidding distance of 125 m. For a real mean skidding distance of 525.9 m and for the mean slope of 40%, the correction factor was estimated to be 4.2.

Calculation of Skid Trail Spacing (STS) is an important option to minimize the total costs of skidding. Construction of many skid trails increases the construction cost, it also results in more degradation on different levels in forests. On the other hand, by constructing less skid trails, winching cost will increase, and in many cases, the skidders will exit from skid trails. This research was carried out in four districts under management of Mazandaran Wood and Paper Industry Company with the aim of determination of Optimum Skid Trail Spacing (OSTS) for an HSM skidder. In this study, a continuous time study method to the nearest second with stop watch was used. The results indicated that the time modelling of winching was mainly affected by load volume and winching distance. By using the time modelling of winching, the winching cost is estimated and then by combining that with the skid trail cost graph, the OSTS graph is calculated. Finally, 95 meters is calculated as optimum skid trail density in this study.

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A study was carried out to evaluate the effect of shelterwood cutting methods on stand structure and regeneration density. Data were collected from a northern hardwood forest stands in Iran with Fagus orientalis Lipsky as dominant species, with/without shelterwood cutting operation. Results clearly demonstrate that the management of Fagus orientalis Lipsky with shelterwood cutting system affected the frequency and diversity of the understory herbaceous species. The frequency of Viola silvestris Lam., Asperula odorata L., Carex spp. and Rubus hyrcanus Juz increased significantly after shelterwood cutting. The DBH (diameter at breast height) of commercial species in control stands (57.50±2.15 cm) was greater than that in treated stands (50.67±1.88 cm), whereas the total height of trees was similar between treated and control plots (21±0.5 m). The number of Parrotia persica seedlings increased by 13.2% from 1995 to 2005 whereas the number of Fagus orientalis and Carpinus betulus seedlings significantly decreased from 1995 to 2005. In conclusion, it confirms that instead of shelterwood cutting method other silvicultural practices such as selection cutting method should be applied for the mountainous beech stands of Hyrcanian forests.

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