جستجوی مقالات مرتبط با کلیدواژه « جنگلهای هیرکانی » در نشریات گروه « جنگلداری »

Plant distribution in forest ecosystems is not accidental and influenced by various factors. This study was done to investigate the structure, physiognomy and site requirements of Mediterranean cypress species (Cupressus sempervirens var. horizontalis) in order to achieve the basic structure, physiognomy and site requirements information of this species relative to soil and physiographic factors in Eshkevar, Rahimabad, Rudsar. For this purpose, 25 circular plots, each one with 1000-m2, were located according to random sampling. In each plot, type of tree and shrub species were designated; then, diameter at breast height (DBH) of trees more than 7.5 cm was measured. In each plot, soil sample were taken from 0 to 10 cm depth. The results indicated that stand structure was uneven-aged. Physiognomy studies showed that in tree, shrub, and herbaceous layers, broad- leaved and need-leaved trees, deciduous shrubs, and forbs were, respectively, dominance life forms. Between environmental factors, aspect and soil textures were effective on diameter, height and individual number of Mediterranean cypress. Number of species had a positive and negative correlation with sand percentage and aspect, respectively.

Determination of the spatial pattern of trees is one of the important structural parameters of the forest for identifying changes in forest communities and it's monitoring in recent years. On the one hand, extracting this structural parameter using satellite data has a significant impact on reducing cost of inventory and makes it easy to evaluate forests of forest managers. In this study, the spatial pattern of trees in the natural forest of Farim of Mazandaran province was determined by using SPOT7 satellite data. Thus, some tree`s characteristics such as species, diameter at breast height, the diameter of canopies, gaps and the position of each tree were measured in 12 plot with area about one ha (100 m x 100 m). On the other hand, after radiometric and geometric corrections of satellite data, the tree`s canopy and gaps were classified, using the object-based method, and tree position per plot also was determined by canopy gravity center. Then, the spatial distribution pattern of the trees and structure, distinguished and extracted by field inventory and satellite data was compared by O-ring function. The results showed that the overall accuracy of canopy and gaps extracted from satellite data by object-based classification was about 91% and kappa coefficient equaled 0.7. The spatial pattern of trees were random except of the small radius and similar to the pattern of trees in-ground inventory. In total, results showed that SPOT-7 data and the object-based classification have an acceptable potential for determining the spatial pattern of forest stands.

The Hyrcanian forests are typical deciduous broadleaf forests characterized by an important role in providing moisture to vegetation by fog precipitation (FP). The importance of FP on vegetated surfaces as a source of moisture has been acknowledged for a long time. The aim of this study was to quantify FP and water interception in a natural oriental beech (Fagus orientalis) stand in the Hyrcanian forests. Event-based measurements were carried out on 2016 and 2017 during the full leaf period. The rain-collectors used for measuring throughfall and gross-rainfall were n=122 and 10, respectively. During the measurement period 22 rainfall events occurred (total rainfall = 648 mm). The amount of throughfall and interception were 99.4% and 0.2%, respectively. Due to considerable amount of fog (3.5%) throughfall was found to be greater than 100% of GR in 14 rainfall event with negative interception (total=-22.6 mm) and 8 rainfall event were found with positive interception (total=25.5 mm). Maximum of FP was measured in September of 2016. Results indicated the role of FP on increasing of throughfall and decreasing interception. Because of the various bioclimatic condition in the Hyrcanian forests, interception is extremely different in oriental beech stands. Then, Fagus orientalis would have significant influence on the local hydrological processes of the mountain forests of Hyrcanian and its water demand would supply by FP in dry seasons. So, the maintenance of beech stands would help to increase of FP by capturing of fog droplets which would provide groundwater and water demand supply of these ecosystems.

Due to the lack of comprehensive policies for the Hyrcanian forests of Iran, formulating policies which encompass sustainable approach to forest management is essential. Therefore, in this research, we develop basic policymaking categories for the Hyrcanian forests of Iran. In order to get the objective, 47 national and international documents, including conventions, statements, policy documents, acts, programs, and reports related to the international dialogues, summits, conventions and forums and national vision, sectorial policy documents, international approved conventions, concerning forest and forestry issues were investigated by using of qualitative content analysis. Finally, 124 categories including 61 opportunities, 23 threats, 27 strengths and 13 weaknesses were extracted. Most of the opportunities come from international dialogues, while major threats are non forest sectorial legislations that challenge the mission of the forest management organization. The strengths are legal authority, resources and infrastructure, and the weaknesses are mainly related to the organizational structure and available financial facilities. According to the opinions of 78 experts of various stakeholder groups, all mentioned categories scored "partly high" to "high" in a 10 points scale. According to the results, Forest, Rangeland, and Watershed Organization efforts to use the strengths and opportunities to cover the weaknesses and threats were insufficient and more research suggested elaborating the situation