Hormoz Sohrabi

Tarbiat Modares University | TMU · Department of Forest Science and Engineering

Accurate estimates of forest biomass are essential for several purposes, ranging from carbon accounting and ecological applications to sustainable forest management. There are, however, critical steps for mapping aboveground forest biomass (AGB) based on optical satellite data with an acceptable degree of accuracy, such as selecting the proper stat...

The use of freely accessible Sentinel-1 synthetic aperture radar (S-1 SAR) and Sentinel-2 multispectral instrument (S-2 MSI) data are currently a feasible way of mapping forest aboveground biomass (AGB) over large areas. Despite the extensive mapping of forest AGB by remote sensing, how to effectively combine different sensors data, selecting the p...

Sparse vegetation such as riparian forests and trees outside forests (TOF) cover only small areas but present various ecological advantages. The detection of these vegetation types in semi-arid mountainous areas is challenging as trees are heavily mixed with other land cover types. Their mapping requires therefore high-resolution imagery. We propos...

Unmanned aerial vehicles (UAVs) paired with a structure from motion (SfM) algorithm (UAV-SfM) can be used to derive canopy height models (CHMs) for individual tree crown delineation (ITCD). ITCD algorithms normally perform well in coniferous forests, but their capabilities in broadleaf or mixed forests are still challenging. In this study, we inves...

Accurate spatial modelling of forest characteristics is one of the most important challenges in remote sensing applications. In this study, we compared the ability of Multiple Linear Regression (MLR), Geographically weighted regression (GWR), and Random Forest (RF) to estimate different forest attributes based on field sample data and Landsat 8 ima...

Excessive tree mortality is a global concern and remains poorly understood as it is a complex phenomenon. We lack global and temporally continuous coverage on tree mortality data. Ground-based observations on tree mortality, e.g., derived from national inventories, are very sparse, not standardized and not spatially explicit. Earth observation data...

This paper develops two parametric median-based spatial regression models for geostatistical data defined on a bounded support. Specifically, these models resemble spatial generalized linear mixed models (SGLMMs), wherein the response variable is modeled using Kumaraswamy and Johnson-t distributions. The proposed models are more robust than the usu...

Mangrove forests are known as important sea carbon ecosystems because they play an important role in carbon sequestration among coastal ecosystems. This coastal ecosystem has 10 to 50 times more carbon sequestration capacity compared to terrestrial ecosystems, and among the most productive systems, they can effectively reduce climate change. Theref...

Mapping the distribution of species, especially those that are endemic and endangered like certain tree species, is a vital step in the effective planning and execution of conservation programs and monitoring efforts. This task gains even more significance as it directly contributes to forest conservation by highlighting the importance of species d...

Accurate information about the tree composition of a forest is required for many forest monitoring and conservation purposes. In recent years, the use of modern remote sensing methods and techniques based on unmanned vehicles have been used to regularly update information in the forest. In this research, different data sources including multi-spect...

Advances in remote sensing enable fast mangrove mapping the less need for intensive fieldwork, complex and heavy processing, and skill-based classification techniques. In this research, mangrove forest mapping was performed using Sentinel-2 satellite images in Google Earth Engine (GEE) in Hormozgan province in three ecosystems of Qeshm, Khamir, and...

Unmanned aerial vehicles (UAV) imagery has proved to be useful in the efficient protection and management of mangrove forests. However, there have been few attempts to show that UAV-RGB images may be used for mapping trees at the species level. Our objective, in this study, is to identify two mangrove species using object-based classification. Heig...

Poplar (Populus deltoides Bartr. ex Marsh.) produce a large amount of biomass per unit area and is important fast-growing species in different planting systems. However, the appropriate space between poplar trees is essential to high-performance productivity in diverse regions. The present study monitored the effect of different spacing configurati...

One of the requirements for achieving efficiency and maximum productivity is continuous monitoring and identifying of horticultural and agricultural products. Traditional plant monitoring and evaluation methods are time-consuming, labor-intensive, and costly. Unmanned aerial vehicles (UAVs) using real color imaging (red/green/blue) is an economical...

The sex ratio is the proportion of male to female trees, which has a substantial impact on reproductive success and conservation status. Appropriate sex-related differences in dioecious trees commonly result in leading to a robustly structured population. Fieldwork for sex discrimination is time-consuming and labor-required. Benefiting from the unm...

Canopy cover is an important structural trait that is frequently used in forest inventories to assess sustainability as well as many other important aspects of forest stands. Remote sensing data is more effective and suitable for canopy cover estimating than traditional field measurements such as sample plots, especially at broad scales. Measuremen...

Despite the low area coverage, riparian vegetation presents several ecosystem services. But there is no precise spatial information on these ecosystems in Iran. Considering the lack of such information, mapping and providing a spatial database is essential. Due to the mixture of these vegetation types and other land covers, the detection of these t...

Remote detection of aerial parasitic plants in forests is imperative in precision forestry, as it can help to manage tree stands and to monitor forest ecosystem health. The plain forests located in Noor and Hyrcanian forests (Iran), characterized by mixed broadleaved forests, host large populations of mistletoe (Viscum album). In this study, aiming...

Introduction Estimation of forest Carbon stocks plays an important role in assessing the quantity of carbon exchange between the forest ecosystem and the atmosphere. Direct methods of measuring carbon stock are not economically efficient. Optical remote sensing methodsalso have limited capability in predicting forest biomass, because the spectral r...

The present study aims to evaluate the effect of single-tree selection harvest intensity on biomass of hornbeam-Persian ironwood stand. For this purpose, information on all trees and dead trees were collected in 70 half-hectare plots. The 35 sample plots were in single-tree selection stands with three harvest intensities and the same sample plot...

The accuracy in estimating forest ecosystem above-ground biomass (AGB) has drawn extensive attention from researchers in the field of global climate change. Determination of suitable interpolation methods for the transformation of discrete samples into continuous maps is a disputable issue in environmental researches. On other hand, ignored spatial...

Background and Objective: Considering the increasing importance of forest ecosystems in climate change mitigation projects, reliable and cost-effective methods are required to estimate the aboveground biomass (AGB). Common methods used to estimate the aboveground biomass (AGB) include in-situ measurement, the biomass calculation using alometric equ...

In view of the important role played by roots against shallow landslides, root tensile force was evaluated for two widespread temperate tree species within the Caspian Hyrcanian Ecoregion, i.e., Fagus orientalis L. and Carpinus betulus L. Fine roots (0.02 to 7.99 mm) were collected from five trees of each species at three different elevations (400,...

This paper aims to conduct a model-based analysis of the spatial patterns of three tree species in a Hyrcanian forest and investigate their associations. There are many known and unknown mechanisms that influence the spatial forest structure and species associations. These complex and mainly unobservable mechanisms can be modeled by hidden Gaussian...

Knowing the tree species combination of forests provides valuable information for studying the forest’s economic value, fire risk assessment, biodiversity monitoring, and wildlife habitat improvement. Fieldwork is often time-consuming and labor-required, free satellite data are available in coarse resolution and the use of manned aircraft is relati...

Advances in Unmanned Aerial Vehicle (UAV) technology made it possible to collect very high-resolution images at an affordable cost. On the other hand, data processing capabilities have made it feasible to obtain three-dimensional (3D) data which can be used for measurement and estimation of different forest structural properties. In this research,...

Two-dimensional image conversion algorithms to 3D data create the hope that the structural properties of trees can be extracted through these images. In this study, the accuracy of biomass estimation in tree, plot, and hybrid levels using UAVs images was investigated. In 34.8 ha of Sisangan Forest Park, using a quadcopter, 854 images from an altitu...

Forest carbon stocks are a time-integrated manifestation of various phenomena and processes ranging from tree growth and mortality to natural and human disturbances. Understanding the effects of environmental and human activities is critically important in vulnerable ecosystems like arid and semi-arid forests, given climate variability coupled with...

Recent advances in unmanned aerial vehicles (UAVs) technology, as well as the development of lightweight sensors offer a great possibility for measurement of different tree features with relatively low costs compared to traditional methods. In this research, the precision and accuracy of tree height measurement and estimation using imagery by a low...

Investigating the tree's biomass can provide the basis information about forest carbon stock. The Biomass Expansion Factor (BEF) is a variable for estimating carbon stock of the forests. The aim of this study was to analyze the Above Ground Biomass (AGB) allocation, developing the BEF and carbon stock for two vegetation forms of Brant's Oak (Quercu...

Light is the most important physical variable that affects patterns of biomass allocation. A quantitative understanding of biomass allocation patterns is crucial to quantifying ecosystem dynamics and might have many practical uses in silviculture. In this research, we investigated the allocation of the aboveground biomass to leaves, branches, and bo...

The original version of this article was inadvertently published without the acknowledgements section.

The effect of digital preprocessing and modeling method on an estimation of aboveground carbon stock of Zagros forests using Landsat 8 imagery

This study was carried out to understand the dynamics of Lebanon oak coppice regeneration. In this regard, the effect of thinning on both individual sprouts and stools as well as estimation of sprout biomass using allometric equation were investigated. 45 Lebanon oak trees with different sizes (i.e. DBH from 25 to 65< cm) in five sites were cut and...

Evaluation of forest biomass is required for sustainable forest management, efficiency valuation and exploring variations in carbon resources. In this research, we studied the possibility of polarimetric synthetic aperture radar (PolSAR) features in order to approximation of forest biomass in Hyrcanian forests. Our study sought to resolve the follo...

Using remote sensing data to estimate some biophysical parameters of trees at different levels, such as single tree leveling, is very important. the newest device that has been widely used in this field is unmanned aerial vehicles (UAVs). UAVs data is very efficient because of the high spatial resolution to detect single trees. In this study, which...

There are a wide variety of management and conservation applications which encourages remote sensing-assisted classification of tree species [1]. Information of dominant or subdominant tree species, as well as species composition, is needed for silvicultural practices [2]. Also, an accurate estimation of forest biomass or growing stock can be achie...

Recent advances in unmanned aerial vehicles (UAVs) technology and the parallel development of sensors that can be installed on them, made it possible to measurement tree features accurately with relatively low costs compared to traditional methods. In this research, UAV high-resolution imagery was used to estimate tree heights. The 2D images were t...

Replantation of degraded forest using rapid growth trees can play major roles in global carbon budget because it can store large quantities of carbon in live biomass, forest floor, and soil organic matter. Potential of 20-year old stands of three rapid gross tree species including Alnus subcordata, Populus deltoides and Taxodium distichum for carbo...

Mixed-forest plantation with native species have gradually become the focus of forest research. The need to better understand their performance and productivity is, nowadays, a matter of particular relevance to forestry practice. The objective of this study was a long-term analysis of the effects of species-mixing of Populus deltoides Bartr. ex Mar...

Available budgets for the inventory of non-commercial woodlands are small. Therefore, there has been increased interest in using distance methods, such as k-tree sampling, which are faster than fixed plot sampling. In low-density woodlands, large search areas for k nearest trees contradict any practical advantage over sampling with fixed area plots...

Remote sensing of low biomass forests has challenges related to the contribution of soil and understory reflectance recorded by sensors, hampering accurate forest aboveground carbon (AGC) quantification. To improve Landsat-based AGC estimates in forests with low biomass, this study explored the use of multi-temporal Landsat 8 Operational Land Image...

Background and objectives: Information on aboveground carbon (AGC) is important for managing forests at local level, land management at regional levels, and carbon emissions reporting at national and international levels; therefore, there is a critical need for low-cost and time-saving approaches for quantifying of AGC. According to this, the estim...

Forest roads alter the biotic and abiotic components of ecosystems, modifying temperature, humidity, wind speed, and light availability that, in turn, cause changes in plant community composition and diversity. We aim at investigating and comparing the diversity of herbaceous species along main and secondary forest roads in a temperate-managed horn...

Leaf area (LA) and leaf biomass (LB) are important variables for most physiological, horticultural and agronomic studies involving plant growth, development rate, radiation use efficiency, and water or nutrient use. Measuring these variables need destructive and aggressive sampling. Fortunately, evolving allometric equations can help for low cost a...

In this study, five biochemical traits obtained for seedlings of five different provenances of Quercus castaneifolia C.A. Meyer were used to evaluate the available light environment using instantaneous electronic readings as a standard. Experimental design was executed under controlled conditions at six different irradiance levels (10, 20, 30, 50,...

To understand the function of peroxidase (POD) in relation to a light gradient, changes in POD activity were studied in five different provenances of chestnut oak seedlings. An experiment was conducted in controlled conditions and six different irradiances (10, 20, 30, 50, 60, and 70% of full light) were considered. According to the results, POD ac...

The role of forests as a reservoir for carbon has prompted the need for timely and reliable estimation of aboveground carbon stocks. Since measurement of aboveground carbon stocks of forests is a destructive, costly and time-consuming activity, aerial and satellite remote sensing techniques have gained many attentions in this field. Despite the fac...

The role of forests as a reservoir for carbon has prompted the need for timely and reliable estimation of aboveground carbon stocks. Since measurement of aboveground carbon stocks of forests is a destructive, costly and time-consuming activity, aerial and satellite remote sensing techniques have gained many attentions in this field. Despite the fac...

In arid and semi-arid lands using industrial wastewater for irrigating tree plantations offers a great opportunity to fulfill the purpose of Clean Development Mechanism by sequestering carbon in living tissues as well as in soil. Selection of tree for plantation has a great effect on the goal achievements, especially when the managers deal with aff...

The increase of atmosphere carbon dioxide (CO 2) as a result of burning fossil fuel is becoming a global issue. Biomass fuels are an environmental friendly alternative for energy supply. Among the sources of biomass, forests are playing a significant role in supplying the biomass for energy. As a renewable source, tree branchwood can provide signif...

Background Nowadays, aquatic organisms are used as bio-indicators to assess ecological water quality in western regions, but have hardly been used in an Iranian context. We, therefore, evaluated the suitability of several indices to assess the water quality for an Iranian case study. Methods Measured data on biotic (fish and macroinvertebrates) an...

Mixed-forest plantation with native species have gradually become the focus of forest research. The need to better understand their performance and productivity is, nowadays, a matter of particular relevance to forestry practice. The objective of this study was a long-term analysis of the effects of species-mixing of Populus deltoides Bartr. ex Mar...

The carbon stored in small diameter trees of temperate forests has been ignored in most studies and there is a lack of biomass equations for this component of forests. We harvested nine main tree species at sapling stage (dbh < 8 cm) across different site conditions (from 100 to 1700 m a.s.l). For each species, 10–12 individuals were selected rando...

Biomass equations are essential for evaluating the climate change mitigation potential of forests through biomass accumulation and carbon sequestration. In northern Iran’s Hyrcanian forests, topographic relief is so extreme that developing biomass equations from destructive sampling of trees is physically challenging. In this paper, allometric biom...

The objectives of this study were to assess the biological water of the Iranian Tajan River using different metrics, i.e., a Multimetric Macroinvertebrate Index (MMI) and a traits-based method. Twenty-eight physico-chemical parameters, 10 habitat factors, and abundance of macroinvertebrates were obtained for 17 sites. The Shahid-Rajaie dam divides...

Abstract2 Background and objectives: Estimation of forest carbon stocks essentially needs accurate estimation of biomass. During last decade, many regression models have been developed, while biomass estimation of the small diameter trees as a missing part of forest measurements is highly significant. The main objective of this study is to devel...

One of the most important factors in determining the volume of trees is selection of appropriate form factor. In the present study, four different method of form factor calculation were evaluated for two rapid growth species including Populus deltoides and Taxodium distichum. For this purpose, in each stand, 12 trees per 4 diameter class ranging fr...

We assessed the potential of white poplar (Populus alba L.) and its inter-sectional hybridization with euphrates poplar (P. euphratica Oliv.) for carbon storage and sequestration in central Iran. Trials were established at planting density of 2,500 trees per hectare in block randomized design with three replicates. After 6 years, we measured the ab...

In the present research using a simple square grid idea, the height and crown radius of the total target and adjacent coppice shoots was measured reliably and precisely. To determine statistical differences between the other devices and introduced idea, height of the 30 coppice shoots of the oak species (Quercus persica J.&.Sp.) as the dominate spe...

Throughfall (TF) has a large spatial variability due to the heterogeneous canopy structure and variable rainfall patterns. In this study, the aim was to estimate the optimum number of collectors needed to obtain a mean cumulative TF value within certain error limits for five individual Brant’s oak trees (Quercus brantii) in the Zagros forests of Il...

Estimates of tree biomass are useful in assessing forest structure and evaluating ecological and economic processes such as nutrient cycle, forest productivity and fuel inventories. The information on tree biomass is required to assess the amount of carbon held in trees. This research was conducted in order to measure biomass and Carbon stocks of t...

Biomass factor is one of the efficient methods for non-destructive estimation of biomass and carbon storage in forest stands. To fulfill the existing lack of biomass data in plantations of Northern Iran, this study derived biomass factor (BF), crown biomass to aboveground biomass ratio (R) and biomass expansion factor (BEF) coefficients for three t...

Patterns of biomass allocation were determined for seedlings of five provenances of Quercus castaneifolia from west to east of the Hyrcanian forest along a rainfall gradient. Experimental design was executed under controlled conditions at seven different light levels (10, 20, 30, 40, 50, 60, 70 and 100% full light). We quantified the biomass alloca...

To provide the initial database of this study, a 53-ha forest reserve in central Zagros was 100% surveyed by recording the location, height and crown coverage of the entire trees and shrubs including Brant`s oak (Quercus brantii), Syrian ash (Fraxinus rotundifolia), Persian juniper (Juniperus polycarpos), hawthorn (Crataegus Spp.) and Montpellier m...

Forest Canopy density is a major factor in evaluation of forest status and is an important indicator of possible management interventions. Forest canopy cover, also known as canopy coverage or crown cover, is defined as the proportion of the forest floor covered by the vertical projection of the tree crowns. Estimation of forest canopy cover has re...

The use of global positioning systems (GPS) has increased in recent years, including for urban forestry management, as a result of its wide range of applications, ease of use and direct use of GPS data in geographic information systems. This study was conducted in an urban green space to assess the accuracy and precision of two consumer-grade GPS r...

Tree growth has a great ecological and economic importance and stem analysis is one of the reliable and widely used methods which is used to study the growth of different attributes of the trees. In the present study, we evaluated diameter, basal area, and height and volume growth of two fast growing species (namely Populus deltoides and Taxodium d...

Carbon sequestration into plant biomass is an easiest and economically most practical way for dropping off CO2 from atmosphere. The current study was made for four poplar species, consisting of two natives (Populus alba and P. nigra) and two exotics (P. alba×euphratica and P. euphratica× alba), planted at Boldaji Experimental Station in province of...