Hamidreza Keshtkar

University of Tehran | UT · Faculty of Natural Resources

Various statistical techniques have been used for species distribution modeling that attempt to predict the occurrence of a given species with respect to environmental conditions. The current study was conducted to compare the performance of three regression-based models (multivariate adaptive regression splines, generalized additive models, and ge...

The SWAT model is widely used to simulate watersheds and evaluate the impact of conservation watershed management practices. In this model, the simulation of the watershed processes is based on hydrological response units (HRUs) which are created by overlaying land use /land cover, soil and slope maps. Meanwhile, in the HRUs definition steps, these...

Mangrove forests play a valuable role in maintaining the coastal ecosystem. Global warming alongside human activities has caused reduced extent and health of these ecosystems in recent years. This study aimed to examine the variability of the extent of mangrove forests and the sea surface area in response to changes in climatic parameters in the so...

The analysis of forest cover change at different scales is an increasingly important research topic in environmental studies. Forest Landscape Restoration (FLR) is an integrated approach to manage and restore forests across various landscapes and environments. Such restoration helps to meet the targets of Sustainable Development Goal (SDG)–15, as o...

Restoring degraded forest is essential if we are to reduce human pressure on natural ecosystems and their biodiversity. Forests were nationalized in 1957 in Nepal and as a consequence, forest cover declined from 45% in 1964 to just 29% in 1994. However, as its response, sectoral plans and policies, particularly introduction of community-based fores...

Separating the effects of human activities/climate change on lotic ecosystems is one of the important components of environmental management as well as water resources maintenance. A Mann-Kendall analysis of hydro-climatic parameters and vegetation cover (VC), calculated using normalized difference vegetation index (NDVI), during the period 1985-20...

Land change simulation for highly water-demanding crops may prove a valuable tool to guide integrated land-and-water management in semi-arid regions facing water scarcity. We explored this premise by mapping and modelling past (1985–2015) and future (2015–2030) orchard development relative to water resources and other factors in Iran. We employed a...

Wetlands are one of the most important aquatic ecosystems that are vulnerable to various factors, including human activity or natural events such as drought. Remote sensing technology is an effective technique for managing and monitoring changes in these ecosystems caused by natural events and human activities. The present study evaluated the effec...

Species diversity is a combination of species richness with species evenness. It helps us differentiate between communities or areas that have the same number of different species, but not in the same abundance. The spatial distribution pattern of plant species is an important topic in plant ecology, the assessment of which is an essential part of...

Land use change simulation is an important issue for its role in predicting future trends and providing implications for sustainable land management. Hybrid models have become a recognized strategy to inform decision-makers, but further attempts are needed to warrant the reliability of their projected results. In view of this, three hybrid models,...

Globally, urbanization is increasing at an unprecedented rate at the cost of agricultural and forested lands in peri-urban areas fringing larger cities. Such land-cover change generally entails negative implications for societal and environmental sustainability, particularly in South Asia, where high demographic growth and poor land-use planning co...

Urbanization is developing unprecedentedly on a global scale. One of the chief repercussions of urbanization, caused by man-made alterations in land-use/land-cover (LULC), is the formation of urban heat islands. Albeit, differences among landscape structures and its accompanied effects on the environment are mostly neglected. Accordingly, the main...

In this study, land use/cover change was systematically investigated in the Qeshm Island to understand how human and nature interact in the largest island of Persian Gulf. Land-use maps were prepared for 1996, 2002, 2008, and 2014 using Landsat satellite imagery in six classes including agriculture, bare-land, built-up, dense-vegetation, mangrove,...

The provision of ecosystem services is directly related to the type of land use and land cover and management practices in a given area. Changes in land use and land cover can alter the supply of ecosystem services and affect the well-being of both humanity and nature. This study analyses the spatiotemporal variations of land use and land cover and...

Understanding the spatiotemporal dynamics of urbanization and predicting future growth is now essential for sustainable urban planning and policy making. This study explores future urban expansion in the rapidly growing region of eastern lowland Nepal. We used the hybrid cellular automata-Markov (CA-Markov) model, which utilizes historical land use...

A crucial part in designing a robustwater qualitymonitoring network is the selection of appropriatewater quality sampling locations. Due to cost and time constraints, it is essential to identify and select these locations in an accurate and efficient manner. The main contribution of the present article is the development of a practical methodology...

This study explored the past and present land-use/land-cover (LULC) changes and urban expansion pattern for the cities of the Kathmandu valley and their surroundings using Landsat satellite images from 1988 to 2016. For a better analysis, LULC change information was grouped into seven time-periods (1988–1992, 1992–1996, 1996–2000, 2000–2004, 2004–2...

The present study utilized time-series Landsat images to explore the spatiotemporal dynamics of urbanization and land use/land-cover (LULC) change in the Kaski District of Nepal from 1988 to 2016. For the specific overtime analysis of change, the LULC transition was clustered into six time periods: 1988–1996, 1996–2000, 2000–2004, 2004–2008, 2008–2...

Spatial–temporal analysis of land-use/land-cover (LULC) change as well as the monitoring and modeling of urban expansion are essential for the planning and management of urban environments. Such environments reflect the economic conditions and quality of life of the individual country. Urbanization is generally influenced by national laws, plans an...

Frequent human activity and rapid urbanization have led to an assortment of environmental issues. Monitoring land-cover change is critical to efficient environmental management and urban planning. The current study had two objectives. The first was to compare pixel-based random forest (RF) and decision tree (DT) classifier methods and a support vec...

Drought in recent years has made high losses to the country that must be reduced by using logical management as much as possible. For this purpose, it is necessary to compare the affected areas by the disaster and locate priority management actions. The aim of this study is determining the spatial and temporal patterns of drought risks and providin...

Regarding the role of rangelands in natural ecosystems and protection of water and soil, precise and principled management of these arenas seems necessary. Sustainable rangeland management practices are considered to be a solution to manage forage and rangeland degradation. In this study, plant production of arid and semi-arid rangeland in the nort...

Climate change and landscape fragmentation are considered to be the main treats to biodiversity. In this study, probable alteration of future species distribution was tested based on the association of landscape fragmentation and climate change scenarios compared to the classical approach that assumed an unchanged landscape. Also, projected range s...

Climate change and landscape fragmentation are considered to be the main treats to biodiversity. In this study, probable alteration of future species distribution was tested based on the association of landscape fragmentation and climate change scenarios compared to the classical approach that assumed an unchanged landscape. Also, projected range s...

Drought monitoring is a fundamental component of drought risk management. It is normally performed using various drought indices that are effectively continuous functions of rainfall and other hydrometeorological variables. In many instances, drought indices are used for monitoring purposes. Geostatistical methods allow the interpolation of spatial...

Spatially land-cover models are necessary for sustainable land-cover planning. The expansion of human-built land involves the destruction of forests, meadows and farmlands as well as conversion of these areas to urban and industrial areas which will result in significant effects on ecosystems. Monitoring the process of these changes and planning fo...

Abstract Land cover is one of basic data layers in geographic information system for physical planning and environmental monitoring. Digital image classification is generally performed to produce land cover maps from remote sensing data, particularly for large areas. In the present study the multispectral image from IRS LISS-III image along with...

In this survey flora of Ghorkhood area has been studied. Ghorkhood area locate in North Khorasan province. Its geographical position is 56 o 08'E to 56 o 39'and 37 o 20'N to 37 o 31'. Plant species sampling was carried out in according to the beginning of growth season. Then collected plants were identified by using of indispensable references....

The aim of this study was to enhance the germination rate of Astragalus cyclophyllon seeds which have a very low germination rate under normal conditions. The seeds were soaked for 72 h in 100, 200, 300, 400 and 500 ppm gibberellic acid (GA3) solution, H2SO4 concentrations (50 and 98%) at two treatment times (5 and 10 min) and 60, 80 and 100ºC hot...

Ferula gummosa and Ferula assafoetida are belongs to Umbeliferae family. These plants are important for industrial, medical and grazing. There were many difficult Problems on seeds germination and growing of these plants. Different methods used for breaking seeds dormancy. In this study used four methods with different treatment levels. Treatments...

Dormancy breaking and germination requirements were investigated in seeds of Ferula assa-foetida L. and Prangos ferulacea (L) Lindl. Seeds of both species were collected from south and central rangelands of Iran and were subjected to different treatments. The evaluated treatments included various levels of gibberellic acid (GA3), prechilling and a...

Astragalus cyclophyllon is a perennial herb, a member of the family Papilionaceae, with vegetative form that is palatable for light animals. This experiment was done to investigate the best planting method for establishment of Astragalus cyclophyllon in Shahid Hamzavi station in Semirom. The study was carried out at two experiments. In first ex...

Land degradation is a major danger which restricting different areas of Iran. Systematic description of the environment for detection of environmental changes and the human-related causes and responses is essential in land cover change study. Use of land cover data allow detection of where certain changes occur, what type of change, as well as h...

Dormancy breaking and germination requirements were investigated in seeds of Ferula ovina and Ferula gummosa. Seeds of rather species were collected from north and eastern-north rangelands of Iran. Seeds of each of the species were subjected to different treatments including various levels of GA3, chilling and combination of GA3 and chilling (GA-ch...