A Consumer Grade UAV-Based Framework to Estimate Structural Attributes of Coppice and High Oak Forest Stands in Semi-Arid Regions

Semi-arid tree covers, in both high and coppice growth forms, play an essential role in protecting water and soil resources and provides multiple ecosystem services across fragile ecosystems. Thus, they require continuous inventories. Quantification of forest structure in these tree covers provides important measures for their management and biodiversity conservation. We present a framework, based on consumer-grade UAV photogrammetry, to separately estimate primary variables of tree height (H) and crown area (A) across diverse coppice and high stands dominated by Quercus brantii Lindl. along the latitudinal gradient of Zagros mountains of western Iran. Then, multivariate linear regressions were parametrized with H and A to estimate the diameter at breast height (DBH) of high trees because of its importance to accelerate the existing practical DBH inventories across Zagros Forests. The estimated variables were finally applied to a model tree aboveground biomass (AGB) for both vegetative growth forms by local allometric equations and Random Forest models. In each step, the estimated variables were evaluated against the field reference values, indicating practically high accuracies reaching root mean square error (RMSE) of 0.68 m and 4.74 cm for H and DBH, as well as relative RMSE < 10% for AGB estimates. The results generally suggest an effective framework for single tree-based attribute estimation over mountainous, semi-arid coppice, and high stands.

Zoning of Areas with Susceptibility to Oak Decline in Western Iran

Zagros forests have the greatest impact on soil and water protection in western Iran. Despite this, a significant part of these forests, especially in Ilam province, have suffered a lot due to the phenomenon of oak decline. The first and most fundamental thing a person must know when combating this issue is the distribution of these areas in forests. Therefore, using the parameters affecting the decline in the forests of Ilam province and based on fuzzy logic, a map of susceptible to oak decline areas was prepared. In this study, the parameters of temperature and precipitation, slope, aspect, altitude, distance from farmlands, roads and forest density were selected as effective parameters and fuzzy gamma overlap method was used. The results showed that more than 77% of the oak forests in the province are highly and extremely susceptible to the decline. This confirms the need for rapid action to plan and protect these forests. In addition, the fuzzy method is proposed, which is considered as a fast and efficient method in preparing such maps for other areas.

Wildfire Severity Zoning Through Google Earth Engine and Fire Risk Assessment: Application of Data Mining and Fuzzy Multi-Criteria Evaluation in Zagros Forests, Iran

The arid and semi-arid regions of Zagros forests in the Middle East are constantly exposed to wildfire due to ecological conditions, and support systems are inefficient in controlling wildfires due to managerial and social weaknesses. Remote sensing and assessment tools are suitable for rapid prevention and action to identify the severity and location of a wildfire. This study investigated the natural resource management of Zagros Forestry in terms of protecting wildfire and combating forest wildfires using the NASA fire spatial data and the wildfire severity in the Google Earth Engine (GEE) platform. The land-use of the study area is produced by applying the Random Forest (RF) classification method and data from the Sentinel 2 satellite imagery for 2019. To separate the types of cultivation and vegetation of the region, the method of extracting the average vegetation index of the seasons is extracted from GEE. To evaluate fire risk, eleven human and ecological factors and two assessment models are applied to classify the probability fire risk therein. Furthermore, the outcome of AUC confirmed the Logistic Regression (LR) model; the accuracy of the LR (AUC=0.875049) model is satisfactory and is suitable for fire risk mapping in Zagros Forestry. Six high-risk areas of the wildfire were identified by MOLA, which overlap with protected areas. Out of a total of 20469.17 Ha of wildfire, 10426.41 Ha belong to these protected areas. 3826 Ha of this area were in the forests of Amygdalus spp, Quercus brant ii, pistacia Atlantica, and Quercus Infectoria, and 6600.41 Ha of it were in rangelands. Accordingly, an executive order was developed for the decision support system that reduces the risk of wildfire and helps extinguish the wildfire.

Effect of site conditions on the properties of hawthorn (Crataegus azarolus L.) wood

This study investigated the influence of site conditions on the physical and morphological properties of hawthorn (Crataegus azarolus L.) wood grown in Zagros forests of Iran. Hawthorn is a valuable woody species in Iran’s Zagros forests with data deficiency in its wood properties. To our best knowledge, there is no study on the properties of hawthorn wood. Twenty-seven mature trees were randomly chosen and sampled at three altitude levels (1 800–2 000, 2 000–2 200, and 2 200–2 400 m) in the Bazoft region of Chaharmahal Va Bakhtiari, Iran. Dry wood density, volumetric shrinkage, fibre length, fibre diameter, cell wall thickness were then determined. Multivariate analysis of variance (MANOVA) was conducted to evaluate significant differences between the mean values of studied wood properties at different altitude levels and slope classes. Moreover, the relationships between the above-mentioned properties and some site conditions (temperature, precipitation, altitude, and slope) as well as growth parameters of trees (tree height, DBH, age, crown dimensions, volume, etc.) were studied by principal component analysis (PCA). The results indicated that trees growing at the second altitude level had the highest oven-dry density values, and those at the third altitude level had the lowest ones. Results also indicated a significant effect of altitude levels on fibre length, fibre diameter, and cell wall thickness. In contrast, a significant difference was found between the mean values of fibre diameter at different slope classes. PCA indicated that altitude, precipitation, and temperature are the most important environmental site variables affecting the wood characteristics.