vahid etemad | University of Tehran (original) (raw)

Papers by vahid etemad

Research paper thumbnail of Calibration of FARSITE fire area simulator in Iranian northern forests

Natural Hazards and Earth System Sciences Discussions, 2014

Wildfire simulators based on empirical or physical models need to be locally calibrated and valid... more Wildfire simulators based on empirical or physical models need to be locally calibrated and validated when used under conditions that differ from those where the simulators were originally developed. This study aims to calibrate FARSITE fire spread model considering a set of recent wildfires occurred in Northern Iran forests. Site specific fuel models in the study areas were selected by sampling the main natural vegetation type complexes and assigning standard fuel models. Overall, simulated fires presented reliable outputs that accurately replicated the observed fire perimeters and behavior. Standard fuel models of Scott and Burgan (2005) afforded better accuracy in the simulated fire perimeters than the standard fuel models of Anderson (1982). The best match between observed and modeled burned areas was observed on herbaceous type fuel models. Fire modeling showed a high potential for estimating spatial variability in fire spread and behavior in the study areas. This work represen...

Research paper thumbnail of Soil fauna communities and microbial activities response to litter and soil properties under degraded and restored forests of Hyrcania

iForest - Biogeosciences and Forestry, 2021

Biogeosciences and Forestry Biogeosciences and Forestry Soil fauna communities and microbial acti... more Biogeosciences and Forestry Biogeosciences and Forestry Soil fauna communities and microbial activities response to litter and soil properties under degraded and restored forests of Hyrcania Maryam Bazyari (1) , Vahid Etemad (2) , Yahya Kooch (3) , Anoushirvan Shirvany (2) Reforestation has long been the best practice to restore degraded forests due to human interventions. In this paper we investigated the effect of forest degradation (DNF) along with reforestation using 4 endemic species (Alnus subcordata, ASP; Acer velutinum, AVP; Cupressus sempervirens, CSP; Quercus castaneifolia Mey, QCP) on forest's soil chemical and biological indicators compared to a close-to-virgin natural forest (VNF). For this study, a total of 24 physico-chemical and 25 biological and microbial indicators were measured in soils of all 6 forest stands along with the litter properties. Results showed that the lowest soil quality was observed under DNF, CSP, and QCP which was the result of forest cover degradation in DNF and low litter quality, especially low pH and high C:N, in CSP and QCP. Soil fauna communities were significantly affected by tree species. We found two times higher density of earthworms in VNF compared to ASP, but in DNF the density was 5 times lower than VNF. We found no epigeic earthworms in QCP, CSP and DNF and no endogeic earthworms in DNF. Acarina and Collembola density was high in VNF and ASP, but they showed significant differences (VNF>ASP), and their density sharply decreased in other stands, especially in CSP (3 times lower than VNF) and DNF (8 to 10 times lower than VNF). Nematode density was statistically equal in VNF, ASP, and AVP, but significantly lower in other stands. Protozoa, bacteria and fungi densities were significantly higher in VNF and ASP (VNF>ASP) compared to each other and other forest stands. Basal respiration, substrate induced respiration, microbial biomass N and P, and carbon availability index was also higher in VNF and ASP compared to other stands. Although VNF has the best condition because of old forest cover and high diversity, ASP soil showed significant improvements, demonstrating the importance of litter quality in soil restoration. Restoration effectiveness ranking of the four tested species on soil improvement are therefore ASP>AVP>QCP>CSP. The significant improvement of soil quality under ASP compared to other reforestated stands, only after 3 decades, emphasizes the importance of tree species selection and litter quality on soil chemical and biological restoration.

Research paper thumbnail of Development of the Dead Trees Structural Legacy in the Dynamics Process of Pure Beech (Fagus orientalis Lipsky) Stands (Case study: Gorazbon District of Kheyrud Forest)

Ecology of Iranian Forests

Research paper thumbnail of Identification of optimum afforestation areas considering sustainable management of natural resources, using geo-environmental criteria

Research paper thumbnail of Assisted phytoremediation of Cd-contaminated soil using poplar rooted cuttings

International Agrophysics, 2012

To investigate the effect of amended substrates on cadmium uptake by one-year old poplar rooted c... more To investigate the effect of amended substrates on cadmium uptake by one-year old poplar rooted cuttings a pot culture was carried out. Pots were filled with three substrates. Four treatments of Cd supply including were organized. The results showed that higher biomass productions in substrates A and B compare to substrate C, led to an increase total Cd uptake two times more than that in substrate C, at 150 mg kg-1 concentration. Meanwhile maximum total uptake occurred in substrate B at 100 mg kg-1 concentration. Using synthetic chelators such as ethylenediaminetetraacetic acid in order to achieve high removal rate led to increased environmental impacts while they are not expected when such environmental friendly approaches are applied.

Research paper thumbnail of Natural regeneration of oriental beech (Fagus orientalis Lipsky) trees in canopy gaps and under closed canopy in a forest in northern Iran

Journal of Forestry Research

Research paper thumbnail of Image texture indices and trend analysis for forest disturbance assessment under wood harvest regimes

Journal of Forestry Research

Research paper thumbnail of Soil texture and plant degradation predictive model (STPDPM) in national parks using artificial neural network (ANN)

Modeling Earth Systems and Environment

Research paper thumbnail of The importance of coarse woody debris in dynamic phases exposure in the beech (Fagus orientalis L.) stands of Hyrcanian forests

Journal of Forest Science

In a natural forest, phases of different dynamics are gradually replaced to create sustainability... more In a natural forest, phases of different dynamics are gradually replaced to create sustainability in the stands. Coarse woody debris is among the most significant structural elements of natural stands that perform an influential position in the identification of dynamic phases. Therefore, the focus of this study is on dead wood conditioning as one of the major structural components in determining the various dynamic phases in the northern forests of Iran as part of the temperate forests. For this study, compartment 326 of Gorazbon District was considered as one of the control parcels of Kheyroud Forest. In this parcel, 25 one-hectare sample plots were selected as permanent plots for a long-term forest structure and succession studies. The coarse woody debris by 100% sampling method was measured. The results showed that there are 8 main phases in this area (gap formation, understorey initiation, stem exclusion, volume accumulation, volume degradation, multiple, lighting, old-growth)....

Research paper thumbnail of Determining structural variation in a managed mixed stand in an old-growth forest, northern Iran

Journal of Forestry Research

Research paper thumbnail of Natural Regeneration Within Natural and Man-Made Canopy Gaps in Caspian Natural Beech (Fagus Orientalis Lipsky) Forest, Northern Iran

Journal of Sustainable Forestry

Research paper thumbnail of Study on some engineering attributes of pine nut (Pinus pinea) to the design of processing equipment

Research in Agricultural Engineering

Moisture-dependent engineering properties of pine nut were studied at 6.3, 8.2, 10.8, 14.5, 18.9,... more Moisture-dependent engineering properties of pine nut were studied at 6.3, 8.2, 10.8, 14.5, 18.9, and 20.1% moisture content (dry basis). The length, width, thickness, and geometric mean diameter increased significantly (P < 0.05) from 21.75 to 21.85 mm, 7.39 to 7.47 mm, 6.07 to 6.14 mm, and 9.89 to 9.98 mm, respectively, with an increase in moisture content from 6.3% to 20.1%, whereas the increase in sphericity from 45.49% to 45.69% was not significant. Similarly, thousand seed mass, true density, porosity, terminal velocity, and angle of repose increased (P < 0.05) from 0.85 to 0.93 kg, 1043.3 to 1071 kg/m3, 41.31% to 44.57%, 8.67 to 8.83 m/s, and 35.4° to 39°, respectively, with an increase in moisture content under the experimental condition. Moreover, the bulk density decreased significantly (P < 0.05) from 612.3 to 593.6 kg/m3. Coefficient of static friction increased (P < 0.05) from 0.251 to 0.292, 0.241 to 0.271, 0.227 to 0.262, and 0.218 to 0.247 on plyw...

Research paper thumbnail of Change in biochemical parameters of Persian oak (Quercus brantii Lindl.) seedlings inoculated by pathogens of charcoal disease under water deficit conditions

Research paper thumbnail of Modeling of forest soil and litter health using disturbance and landscape heterogeneity indicators in northern Iran

Journal of Mountain Science

Research paper thumbnail of Redescription of two species of Oplitis Berlese (Acari, Mesostigmata, Oplitidae) from Iran

ZooKeys, 2016

Two new species records of Oplitidae, Oplitis exopodi Hunter & Farrier, 1975 and Oplitis sarcinul... more Two new species records of Oplitidae, Oplitis exopodi Hunter & Farrier, 1975 and Oplitis sarcinulus Hunter & Farrier, 1976 are redescribed based on Iranian specimens from leaf-litter forest in Mazandaran province, northern Iran. A key to the Iranian species of Oplitis is presented.

Research paper thumbnail of Biochemical Composition and Analytical Characterization of Iranian Moringa peregrina Seed Oil: An Excellent Source for Oils Blend Formula

Research paper thumbnail of Effects of different treatments on the germination of wild pear (Pyrus glabra) seeds and their peroxidase, amylase, and catalase reactions

Journal of Medicinal Plants Research, Nov 25, 2012

Wild pear (Pyrus glabra) is an endemic and medicinally important endangered plant species of Zagr... more Wild pear (Pyrus glabra) is an endemic and medicinally important endangered plant species of Zagros Mountain. Interventions on behalf of conservation are necessary to protect this species. The seeds show very low germination (%), and these low rates represent a major obstacle to successful regeneration. In this study, the viability, germination (%), germination rate, pattern of germination and enzymes activities during seed germination under cold stratification were assessed. The experimental treatments used were cold stratification (CS), CS with cool water for 24 h, CS with gibberellic acid at 1000 ppm and at 1500 ppm for 48 h. The mean seed viability was 42.25 ± 1.9%. The highest germination rate was obtained under cold stratification for a period of 50 days. The activity of catalase was low during germination. Peroxidase activity increased with increasing periods of CS. Amylase activity was always high compared to the other enzymes, which showed a limited range of variation. The best time for germination could be inferred by determining the time at which the enzymatic activities are equal. The study found that the seed dormancy of the wild pear is of the morphological type. The embryo needs a 50-day cold period at a temperature of 5°C to begin germination. The study demonstrated that the low regeneration rate of this species is caused by the low percentage of viable seeds.

Research paper thumbnail of Study of tree regeneration in the grazed and non-grazed areas in the Iran-o-Turanian Ecological Zones

International Journal of Advanced Biological and Biomedical Research, Jan 30, 2013

Research paper thumbnail of Elevational gradient and vegetation-environmental relationships in the central Hyrcanian forests of northern Iran

Nordic Journal of Botany, 2016

Research paper thumbnail of Rainfall interception in a Pinus eldarica plantation in a semiarid climate zone: An application of the gash model

Journal of Agricultural Science and Technology

ABSTRACT

Research paper thumbnail of Calibration of FARSITE fire area simulator in Iranian northern forests

Natural Hazards and Earth System Sciences Discussions, 2014

Wildfire simulators based on empirical or physical models need to be locally calibrated and valid... more Wildfire simulators based on empirical or physical models need to be locally calibrated and validated when used under conditions that differ from those where the simulators were originally developed. This study aims to calibrate FARSITE fire spread model considering a set of recent wildfires occurred in Northern Iran forests. Site specific fuel models in the study areas were selected by sampling the main natural vegetation type complexes and assigning standard fuel models. Overall, simulated fires presented reliable outputs that accurately replicated the observed fire perimeters and behavior. Standard fuel models of Scott and Burgan (2005) afforded better accuracy in the simulated fire perimeters than the standard fuel models of Anderson (1982). The best match between observed and modeled burned areas was observed on herbaceous type fuel models. Fire modeling showed a high potential for estimating spatial variability in fire spread and behavior in the study areas. This work represen...

Research paper thumbnail of Soil fauna communities and microbial activities response to litter and soil properties under degraded and restored forests of Hyrcania

iForest - Biogeosciences and Forestry, 2021

Biogeosciences and Forestry Biogeosciences and Forestry Soil fauna communities and microbial acti... more Biogeosciences and Forestry Biogeosciences and Forestry Soil fauna communities and microbial activities response to litter and soil properties under degraded and restored forests of Hyrcania Maryam Bazyari (1) , Vahid Etemad (2) , Yahya Kooch (3) , Anoushirvan Shirvany (2) Reforestation has long been the best practice to restore degraded forests due to human interventions. In this paper we investigated the effect of forest degradation (DNF) along with reforestation using 4 endemic species (Alnus subcordata, ASP; Acer velutinum, AVP; Cupressus sempervirens, CSP; Quercus castaneifolia Mey, QCP) on forest's soil chemical and biological indicators compared to a close-to-virgin natural forest (VNF). For this study, a total of 24 physico-chemical and 25 biological and microbial indicators were measured in soils of all 6 forest stands along with the litter properties. Results showed that the lowest soil quality was observed under DNF, CSP, and QCP which was the result of forest cover degradation in DNF and low litter quality, especially low pH and high C:N, in CSP and QCP. Soil fauna communities were significantly affected by tree species. We found two times higher density of earthworms in VNF compared to ASP, but in DNF the density was 5 times lower than VNF. We found no epigeic earthworms in QCP, CSP and DNF and no endogeic earthworms in DNF. Acarina and Collembola density was high in VNF and ASP, but they showed significant differences (VNF>ASP), and their density sharply decreased in other stands, especially in CSP (3 times lower than VNF) and DNF (8 to 10 times lower than VNF). Nematode density was statistically equal in VNF, ASP, and AVP, but significantly lower in other stands. Protozoa, bacteria and fungi densities were significantly higher in VNF and ASP (VNF>ASP) compared to each other and other forest stands. Basal respiration, substrate induced respiration, microbial biomass N and P, and carbon availability index was also higher in VNF and ASP compared to other stands. Although VNF has the best condition because of old forest cover and high diversity, ASP soil showed significant improvements, demonstrating the importance of litter quality in soil restoration. Restoration effectiveness ranking of the four tested species on soil improvement are therefore ASP>AVP>QCP>CSP. The significant improvement of soil quality under ASP compared to other reforestated stands, only after 3 decades, emphasizes the importance of tree species selection and litter quality on soil chemical and biological restoration.

Research paper thumbnail of Development of the Dead Trees Structural Legacy in the Dynamics Process of Pure Beech (Fagus orientalis Lipsky) Stands (Case study: Gorazbon District of Kheyrud Forest)

Ecology of Iranian Forests

Research paper thumbnail of Identification of optimum afforestation areas considering sustainable management of natural resources, using geo-environmental criteria

Research paper thumbnail of Assisted phytoremediation of Cd-contaminated soil using poplar rooted cuttings

International Agrophysics, 2012

To investigate the effect of amended substrates on cadmium uptake by one-year old poplar rooted c... more To investigate the effect of amended substrates on cadmium uptake by one-year old poplar rooted cuttings a pot culture was carried out. Pots were filled with three substrates. Four treatments of Cd supply including were organized. The results showed that higher biomass productions in substrates A and B compare to substrate C, led to an increase total Cd uptake two times more than that in substrate C, at 150 mg kg-1 concentration. Meanwhile maximum total uptake occurred in substrate B at 100 mg kg-1 concentration. Using synthetic chelators such as ethylenediaminetetraacetic acid in order to achieve high removal rate led to increased environmental impacts while they are not expected when such environmental friendly approaches are applied.

Research paper thumbnail of Natural regeneration of oriental beech (Fagus orientalis Lipsky) trees in canopy gaps and under closed canopy in a forest in northern Iran

Journal of Forestry Research

Research paper thumbnail of Image texture indices and trend analysis for forest disturbance assessment under wood harvest regimes

Journal of Forestry Research

Research paper thumbnail of Soil texture and plant degradation predictive model (STPDPM) in national parks using artificial neural network (ANN)

Modeling Earth Systems and Environment

Research paper thumbnail of The importance of coarse woody debris in dynamic phases exposure in the beech (Fagus orientalis L.) stands of Hyrcanian forests

Journal of Forest Science

In a natural forest, phases of different dynamics are gradually replaced to create sustainability... more In a natural forest, phases of different dynamics are gradually replaced to create sustainability in the stands. Coarse woody debris is among the most significant structural elements of natural stands that perform an influential position in the identification of dynamic phases. Therefore, the focus of this study is on dead wood conditioning as one of the major structural components in determining the various dynamic phases in the northern forests of Iran as part of the temperate forests. For this study, compartment 326 of Gorazbon District was considered as one of the control parcels of Kheyroud Forest. In this parcel, 25 one-hectare sample plots were selected as permanent plots for a long-term forest structure and succession studies. The coarse woody debris by 100% sampling method was measured. The results showed that there are 8 main phases in this area (gap formation, understorey initiation, stem exclusion, volume accumulation, volume degradation, multiple, lighting, old-growth)....

Research paper thumbnail of Determining structural variation in a managed mixed stand in an old-growth forest, northern Iran

Journal of Forestry Research

Research paper thumbnail of Natural Regeneration Within Natural and Man-Made Canopy Gaps in Caspian Natural Beech (Fagus Orientalis Lipsky) Forest, Northern Iran

Journal of Sustainable Forestry

Research paper thumbnail of Study on some engineering attributes of pine nut (Pinus pinea) to the design of processing equipment

Research in Agricultural Engineering

Moisture-dependent engineering properties of pine nut were studied at 6.3, 8.2, 10.8, 14.5, 18.9,... more Moisture-dependent engineering properties of pine nut were studied at 6.3, 8.2, 10.8, 14.5, 18.9, and 20.1% moisture content (dry basis). The length, width, thickness, and geometric mean diameter increased significantly (P < 0.05) from 21.75 to 21.85 mm, 7.39 to 7.47 mm, 6.07 to 6.14 mm, and 9.89 to 9.98 mm, respectively, with an increase in moisture content from 6.3% to 20.1%, whereas the increase in sphericity from 45.49% to 45.69% was not significant. Similarly, thousand seed mass, true density, porosity, terminal velocity, and angle of repose increased (P < 0.05) from 0.85 to 0.93 kg, 1043.3 to 1071 kg/m3, 41.31% to 44.57%, 8.67 to 8.83 m/s, and 35.4° to 39°, respectively, with an increase in moisture content under the experimental condition. Moreover, the bulk density decreased significantly (P < 0.05) from 612.3 to 593.6 kg/m3. Coefficient of static friction increased (P < 0.05) from 0.251 to 0.292, 0.241 to 0.271, 0.227 to 0.262, and 0.218 to 0.247 on plyw...

Research paper thumbnail of Change in biochemical parameters of Persian oak (Quercus brantii Lindl.) seedlings inoculated by pathogens of charcoal disease under water deficit conditions

Research paper thumbnail of Modeling of forest soil and litter health using disturbance and landscape heterogeneity indicators in northern Iran

Journal of Mountain Science

Research paper thumbnail of Redescription of two species of Oplitis Berlese (Acari, Mesostigmata, Oplitidae) from Iran

ZooKeys, 2016

Two new species records of Oplitidae, Oplitis exopodi Hunter & Farrier, 1975 and Oplitis sarcinul... more Two new species records of Oplitidae, Oplitis exopodi Hunter & Farrier, 1975 and Oplitis sarcinulus Hunter & Farrier, 1976 are redescribed based on Iranian specimens from leaf-litter forest in Mazandaran province, northern Iran. A key to the Iranian species of Oplitis is presented.

Research paper thumbnail of Biochemical Composition and Analytical Characterization of Iranian Moringa peregrina Seed Oil: An Excellent Source for Oils Blend Formula

Research paper thumbnail of Effects of different treatments on the germination of wild pear (Pyrus glabra) seeds and their peroxidase, amylase, and catalase reactions

Journal of Medicinal Plants Research, Nov 25, 2012

Wild pear (Pyrus glabra) is an endemic and medicinally important endangered plant species of Zagr... more Wild pear (Pyrus glabra) is an endemic and medicinally important endangered plant species of Zagros Mountain. Interventions on behalf of conservation are necessary to protect this species. The seeds show very low germination (%), and these low rates represent a major obstacle to successful regeneration. In this study, the viability, germination (%), germination rate, pattern of germination and enzymes activities during seed germination under cold stratification were assessed. The experimental treatments used were cold stratification (CS), CS with cool water for 24 h, CS with gibberellic acid at 1000 ppm and at 1500 ppm for 48 h. The mean seed viability was 42.25 ± 1.9%. The highest germination rate was obtained under cold stratification for a period of 50 days. The activity of catalase was low during germination. Peroxidase activity increased with increasing periods of CS. Amylase activity was always high compared to the other enzymes, which showed a limited range of variation. The best time for germination could be inferred by determining the time at which the enzymatic activities are equal. The study found that the seed dormancy of the wild pear is of the morphological type. The embryo needs a 50-day cold period at a temperature of 5°C to begin germination. The study demonstrated that the low regeneration rate of this species is caused by the low percentage of viable seeds.

Research paper thumbnail of Study of tree regeneration in the grazed and non-grazed areas in the Iran-o-Turanian Ecological Zones

International Journal of Advanced Biological and Biomedical Research, Jan 30, 2013

Research paper thumbnail of Elevational gradient and vegetation-environmental relationships in the central Hyrcanian forests of northern Iran

Nordic Journal of Botany, 2016

Research paper thumbnail of Rainfall interception in a Pinus eldarica plantation in a semiarid climate zone: An application of the gash model

Journal of Agricultural Science and Technology

ABSTRACT