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Tehrān, Iran

Van Vliet N.,Copenhagen University | Van Vliet N.,for Center for International Forestry Research | Nebesse C.,University of Kisangani | Nasi R.,Forest
ORYX | Year: 2015

Understanding the importance of bushmeat consumption for household nutrition, both in rural and urban settings, is critical to developing politically acceptable ways to reduce unsustainable exploitation. This study provides insights into bushmeat consumption patterns relative to the consumption of other meat (from the wild, such as fish and caterpillars, or from domestic sources, such as beef, chicken, pork, goat and mutton) among children from Province Orientale, Democratic Republic of Congo. Our results show that urban and rural households consume more meat from the wild than from domestic sources. Of the various types of wild meat, bushmeat and fish are the most frequently consumed by children from Kisangani and fish is the most frequently consumed in villages. Poorer urban households eat meat less frequently but consume bushmeat more frequently than wealthier households. In urban areas poorer households consume common bushmeat species more frequently and wealthier households eat meat from larger, threatened species more frequently. Urban children eat more bushmeat from larger species (duiker Cephalophus spp. and red river hog Potamochoerus porcus) than rural children (rodents, small monkeys), probably because rural households tend to consume the less marketable species or the smaller animals. We show that despite the tendency towards more urbanized population profiles and increased livelihood opportunities away from forest and farms, wildlife harvest remains a critical component of nutritional security and diversity in both rural and urban areas of the Democratic Republic of Congo. © 2014 Fauna & Flora International. Source

Mirzaee S.,University of Tehran | Motagh M.,University of Tehran | Motagh M.,German Research Center for Geosciences | Arefi H.,University of Tehran | Nooryazdan M.,Forest
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014

Due to its special imaging characteristics, Synthetic Aperture Radar (SAR) has become an important source of information for a variety of remote sensing applications dealing with environmental changes. SAR images contain information about both phase and intensity in different polarization modes, making them sensitive to geometrical structure and physical properties of the targets such as dielectric and plant water content. In this study we investigate multi temporal changes occurring to different crop types due to phenological changes using high-resolution TerraSAR-X imagers. The dataset includes 17 dual-polarimetry TSX data acquired from June 2012 to August 2013 in Lorestan province, Iran. Several features are extracted from polarized data and classified using support vector machine (SVM) classifier. Training samples and different features employed in classification are also assessed in the study. Results show a satisfactory accuracy for classification which is about 0.91 in kappa coefficient. Source

Atlas W.I.,Simon Fraser University | Buehrens T.W.,108 Grand Boulevard | McCubbing D.J.F.,BC Research Inc. | Bison R.,Forest | Moore J.W.,Simon Fraser University
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2015

Changes in density-independent mortality can alter the spatial extent of populations through patch extinction and colonization, and spatial contraction may alter population productivity and compensatory capacity. Here, we analyze a time series of steelhead (Oncorhynchus mykiss) abundance and examine the hypothesis that spatial contraction can decrease compen- satory capacity. Over the last 20 years, steelhead in the Keogh River have declined by an order of magnitude because of a period of poor smolt-to-adult survival. Low abundance has been associated with more depressed production of out-migrating smolts than would be expected based on traditional models of compensatory dynamics. Patterns of juvenile density over time show changes in the spatial distribution of the population. We developed a spatially explicit population model to explore spatial structure and juvenile recruitment under varying marine survival. Results suggest that spatial contraction during a period of poor marine survival can strengthen density-dependent population regulation, reducing smolt production at the watershed scale. Our results highlight that spatial contraction can alter the fundamental density-dependent relationships that define population dynamics, recovery trajectories, and sustainable harvest levels of spatially structured populations. © 2015, National Research Council of Canada. All rights reserved. Source

Saadat H.,McGill University | Adamowski J.,McGill University | Tayefi V.,University of Tehran | Namdar M.,Forest | And 2 more authors.
Catena | Year: 2014

Having accurate soil erosion intensity/type maps using satellite imagery is not generally a difficult task. However, there are still difficulties for the generation of small scale erosion features at regional and national levels. It is even more problematic when high-resolution satellite images cannot be used due to their high cost at a regional level. The principal objective of this study is to investigate the applicability of brightness value to generate accurate interrill and rill erosion intensity maps using medium resolution satellite images at a regional level. In this study, Landsat ETM+ images are used and the Golestan dam watershed with an area of 4511.8km2 located at northeast of Iran is selected as the study area. In order to generate a Homogeneous Land Unit (HLU) map, three ancillary layers including slope, landform, land use and land cover, are overlayed on each other. The HLUs are used in a supportive role for identifying appropriate sampling points across the entire study area, at which the degrees of interrill and rill erosions are measured. The ground-truth erosion information collected at the 1328 locations is divided into training and reference data sets. Using the Tasseled Cap transformation technique, the brightness value of each pixel at the beginning (May), middle (July) and end (September) of growing season is obtained. By subtracting the May brightness value (BM) from the July one (BJ), and the July brightness value from the September one (BS), two new brightness images representing the brightness variations over May-July (BMJ) and July-September (BJS) are created. The two new brightness images are combined to generate a map where its pixels indicate the state (i.e. increase, I, decrease, D, and constant, C) of brightness variation over the two growing seasons. Using the measured interrill and rill erosion information at the training sampling locations, a unique relationship is found between the trend of brightness variation and the erosion intensity. This relationship is validated using the reference data sets. The results show that the proposed method is able to produce an interrill-rill erosion intensity map with an overall field-checked accuracy of 96% at this study location. The main advantages of this method are its high accuracy, its lower demands on time and funds for field work, and the ready availability of required data. © 2013 Elsevier B.V. Source

Mirzaee S.,University of Tehran | Motagh M.,German Research Center for Geosciences | Arefi H.,University of Tehran | Nooryazdan A.,Forest
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2015

Remote sensing plays a key role in monitoring and assessing environmental changes. Because of its special imaging characteristics such as high-resolution, capabilities to obtain data in all weather conditions and sensitivity to geometrical and dielectric properties of the features, Synthetic Aperture Radar (SAR) technology has become a powerful technique to detect small scale changes related to earth surface. SAR images contain the information of both phase and intensity in different modes like single, dual and full polarimetric states which are important in order to extract information about various targets. In this study we investigate phenological changes in an agricultural region using high-resolution X-band SAR data. The case study is located in Doroud region of Lorestan province, west of Iran. The purpose is to investigate the ability of copolar and interferometric coherence extracted from TanDEM-X dual polarimetry (HH/VV) in bistatic StripMap mode for tracking the phenological changes of crops during growing season. The data include 11 images acquired between 12.06.2012 and 02.11.2012 and 6 images acquired between 30.05.2013 and 04.08.2013 in the CoSSC format. Results show that copolar coherence is almost able to follow phenological changes but interferometric coherence has a near constant behaviour with fluctuations mainly related to baseline variations. Source

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