جستجوی مقالات مرتبط با کلیدواژه « wildfire » در نشریات گروه « جنگلداری »

In recent years, many attempts have been made to manage and control wildfires. Modeling and mapping wildfire probability across fire-prone landscapes is one of the most important measures. In the present study, the capability of frequency ratio and weight-of-evidence models for predicting the probability of wildfires occurrence in the Kohgiluyeh and Boyer-Ahmad province were investigated. The modeling process and prediction of future fires were based on an analysis of the relationship between 271 historical fires occurred during the 2002-2014 period and 10 predictor variables including slope degree, aspect, altitude, temperature, wind speed, land use, NDVI, and proximity to rivers, roads, and human settlement. During the modeling process, the significance of each variable class on wildfire occurrence was quantified. The model results were used to produce distribution maps of wildfire probability. The results of the evaluation and comparison of the models, which were carried out using the receiver operating characteristic method, success rate, prediction rate, and Wilcoxon test showed that the weight-of-evidence model with success and prediction rates of 0.886 and 0.821 performed better than the frequency ratio model in both training and validation datasets. Overall, the results revealed that approximately 30% of the forests and rangelands of the province fall within the high and very high probability to wildfire occurrence, which requires prudent management measures to mitigate the risk of fire.

Forest fire and leaf litter is one of the effective factors influencing soil nutrient. Fire intensity and duration can affect the properties of ash and surface soil. The aim of this study was to investigate the physio- chemical properties of ash after the heating of Aleppo oak (Quercus infectoria Oliv.) litter at various temperatures under laboratory conditions. In order to collect litter, Khavmire Abad district in Marivan forest was selected such that litter samples were taken under the crown of the 8 Aleppo oak trees. Trees were selected on a transect parallel to the contour lines, 30 m interval. Leaf litter has milled first and then the samples were prepared in four treatments (milled litter and three treatments heated at 200, 400 and 600 °C). The results showed that the color of ash was dark brown, gray and light gray in temperatures of 200, 400 and 600 °C, respectively. The amount of pH, EC, P, Ca, K and Mg increased significantly with increasing temperature, while OC and TN first increased until 200°C and then decreased significantly. The reduction of nutrient concentrations in the ash of Aleppo oak was: N> C> P> K> Mg> Ca. In sum, temperature can significantly affect the availability of nutrients in ash of Aleppo oak after heating. In addition, different temperatures had significant effects on the amount of nutrients and ash color.

The forests located in Kurdistan province, in particular the Marivan forests, are assessed to be substantially vulnerable to wildfire hazard due to the Mediterranean climatic regime within the region. A research was designed here to explore the effects of periodic wildfires on soil nutrient. A total number of 40 soil samples were collected, consisting of 10 samples from 0-20 cm depth within 3 Persian oak (Quercus brantii) stands which were previously affected by fire in 2005, 2008 and 2010, as well as 10 samples from a fire-unaffected natural stand as control treatment. The soil properties were analyzed within the taken samples, which showed the Ca, Mg and EC content to be higher in the burned soils compared to those within the control treatment. Furthermore, the more currently-occurred fire resulted in a higher amount of the three nutrient elements. Concentration of potassium was also shown to be higher in the burned soils, with an exception of the burned soil of 2008 fire.