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بررسی میزان و جهت تغییرات پوشش گیاهی متراکم منطقۀ حفاظت‌شدۀ گشت رودخان با استفاده از رویکرد اکولوژی سیمای سرزمین | ||
| محیط شناسی | ||
| مقاله 4، دوره 41، شماره 4، اسفند 1394، صفحه 771-781 اصل مقاله (686.42 K) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22059/jes.2016.57131 | ||
| نویسندگان | ||
| محمد پناهنده* 1؛ حبیب فتحی دخت2 | ||
| 1استادیار گروه پژوهشی محیطزیست، پژوهشکدۀ محیطزیست، جهاد دانشگاهی | ||
| 2کارشناس ارشد علوم محیطزیست و کارشناس ارشد پژوهشی پژوهشکدۀ محیطزیست، جهاد دانشگاهی | ||
| چکیده | ||
| متریک‌های سیمای سرزمین می‌توانند به منظور تشریح ترکیب و ترتیب فضایی سرزمین استفاده شوند. هدف از این بررسی، تعیین میزان و جهت تغییرات در کلاس پوشش گیاهی متراکم منطقۀ حفاظت‌شدۀ گشت رودخان است. نخست محدودۀ تالاب انزلی از تصاویر ماهواره‌ای لندست مربوط به دو مقطع زمانی استخراج و در مرحلۀ بعد محدودۀ تقریبی پوشش گیاهی متراکم از طریق تفسیر بصری تصاویر در محیط نرم‌افزار Ermapper7.1 تهیه شد. سپس این ناحیه در قالب دو کلاس پوشش گیاهی متراکم و بدون پوشش گروه‌بندی شد. در گام دیگر، پس از جداکردن محدودۀ منطقۀ حفاظت‌شدۀ گشت رودخان، کلاس پوشش گیاهی متراکم آن نیز تهیه شد. بعد از آن لایه‌های وکتوری پوشش گیاهی ساخته و به‌منزلۀ ورودی اکستنشن Patch Analyst به منظور محاسبۀ متریک‌ها استفاده شدند. نتایج بیانگر تغییرات قابل ملاحظه در متریک‌های مجموع مساحت‌های تمام لکه‌های همسان (CA)، تعداد کل لکه‌ها (Numps)، متوسط اندازۀ لکه‌ها (Mps)، متوسط لبۀ لکه‌ها (MPE)، تراکم لبه (ED) و کل لبه (TE) در دو سطح لکۀ اصلی پوشش گیاهی متراکم حوزۀ تالاب انزلی و سطح کلاس پوشش گیاهی متراکم منطقۀ حفاظت‌شده است که با توجه به جهت تغییرات بیانگر افزایش فرایند تکه‌تکه شدن پوشش گیاهی متراکم است. | ||
| کلیدواژه‌ها | ||
| تالاب انزلی؛ تکه‌تکه شدن؛ سیمای سرزمین؛ سنجه | ||
| عنوان مقاله [English] | ||
| Investigation of extent and direction of dense vegetation cover changes of Gastroudkhan protected area with landscape ecology approach | ||
| نویسندگان [English] | ||
| Mohammad Panahandeh1؛ Habib Fathidokht2 | ||
| 1Assisstant Prof. Environmental Research, Academic Center for Education, Culture and Research(ACECR) | ||
| 22Research expert. Environmental Research, Academic Center for Education, Culture and Research(ACECR) | ||
| چکیده [English] | ||
| Introduction: Landscape structure means the pattern of a landscape, which is determined by its type of use, but also by its structure, i.e. the size, shape, arrangement and distribution of individual landscape elements. For the delineation of these landscape elements, or so-called patches, often land use or land cover units are used. In this context, “‘land cover’ refers to the physical surface characteristics of land (for example, the vegetation found there or the presence of built structures), while land use describes the economic and social functions of that land. The heterogeneity of landscapes – as a parameter of landscape structure – is connoted as the quality or state of consisting of dissimilar elements, as with mixed habitats or cover types occurring on a landscape. It is the “opposite of homogeneity, in which elements are the same. As indices of landscape structure, landscape metrics can be used to describe the composition and spatial arrangement of a landscape. They can be applied at different levels to describe single landscape elements by such features as size, shape, number or for whole landscapes by describing the arrangement of landscape elements and the diversity of landscape. The reason for using these metrics in spatial analysis may be to record the structure of a landscape quantitatively on the basis of area, shape, edge lines, diversity and topology-descriptive mathematical ratios; to document for purposes of monitoring; or to make the relevant information available as input parameters for landscape ecological simulation models. Biological diversity in all its dimensions and facets is always tied to habitats, which need a concrete areal section of the earth’s surface for their existence. Biological diversity is therefore always defined for a certain reference area, and landscape structure is a key element for the understanding of species diversity. Spatial heterogeneity, as an expression of landscape structure, indicates the variability of the system’s properties in spatial terms. Since the complexity of biological diversity is difficult to describe, most ecologists have taken the practical way to research and to identify the biological diversity at the species level Therefore, the selection of structural indicators was undertaken specific to the habitat type or tested species studied. Local data on species diversity can provide information as a proxy for regional biodiversity. An investigation of flora and fauna is, however, typically not comprehensive, but rather generally covers only a small proportion of all species. The clear determination of the diversity of various taxonomic groups requires very high efforts, knowledge and money. Hence a good substitute is needed. By combination of indicator species and groups with spatial environmental data and landscape structure, the power and deputy information can be increased and expanded geographically. Which parameters are suitable for the characterization and description of landscape diversity, and can therefore be used as an indicator for biodiversity? In principle, a few indicators are sufficient to ascertain landscape patterns. However, biodiversity cannot be described only by a simple number, as there are various qualities of spatial patterns . A selection of indices representing various aspects of biodiversity is much more informative and capable of interpretation . However, the use of many highly correlated indices provides no new information, and leads to problems in interpreting the results. For this reason, mutually independent indices should be selected .By means of indicators in monitoring, dramatic changes in values can be detected and serve as an early warning, and as an indication of the necessity for deeper investigation, even if no specific limit values can be defined . Landscape metrics may also be used to identify hot spots of biodiversity. Although they do not replace direct measurement of species biodiversity, these surveys can help make them more effective and less. Habitat fragmentation also reduces the productivity of ecosystems because smaller areas of habitat are often less resilient to severe weather or disease shocks. Habitat fragmentation is often a cause of species becoming threatened or endangered. The existence of viable habitat is critical to the survival of any species, and in many cases the fragmentation of any remaining habitat can lead to difficult decisions for conservation biologists. Given a limited amount of resources available for conservation it is preferable to protect the existing isolated patches of habitat . The design of efficient and effective land conservation policies must therefore consider both the total amounts of habitat conserved and the spatial configuration of that habitat. Forest fragmentation has become a global concern for conservation of important habitats as well as biodiversity. Protected areas that have been a cornerstone for safeguarding biological diversity are also facing enormous stress due to the increasing anthropogenic activities. The impacts that fragmentation has on both wildlife and vegetation within a fragment and perhaps more importantly, the impact of loss of intact habitat and wildlife on the people relying on the remaining fragments, are important to understanding and slowing or preventing future decline. As fragments decrease and become more degraded, encroachment into the park and the number and severity of human-wildlife incidences may increas. Establishing protectd ara is the primary mechanism used to protect forest biodiversity, particularly in regions with high human densities. protected areas protect and maintain endemic, threatened or endangered, flora and fauna, geological features, and cultural heritage sites. In addition, they can generate income for the local and national economies, and provide important benefits associated with enhanced tourism sectors. However, many protected are also associated with negative social and ecological impacts. The processes that drive land cover change are complex and cannot be understood without addressing underlying cause and effect relationships. Changes in climate, population, and land use occur and interact simultaneously at different temporal and spatial scales, having major implications for both livelihoods and biodiversity. Forest loss and fragmentation are regarded as the greatest threat to global biological diversity. This study estimates the degree of spatial fragmentation in the protected area. Landsat TM 30 m satellite images of 1988 and 2014 were used as base maps in this study. The purpose of this study was to determine the extent and direction of changes in dense vegetation cover of Anzali watershed with using landscape ecology approach during period of1989-2014. Material and methods: As indices of landscape structure, landscape metrics can be used to describe the composition and spatial arrangement of a landscape. They can be applied at different levels to describe single landscape elements by such features as size, shape, number or for whole landscapes by describing the arrangement of landscape elements and the diversity of landscape. The purpose of this study was to determine the extent and direction of changes in dense vegetation cover of Anzali watershed with using landscape ecology approach during period of1989-2014.This area has been selected for its habitat values and its role in sustainability of international watershed of Anzali. First Anzali watershed area extracted then dense vegetative cover area extracted from it. This area was classified in two classes of vegetation cover and bare. In following after separating Gashtrodkhan protected area ,its dense vegetation cover was interpreted. After that vector layers of vegetation cover were built that it was used as input of patch analyst extension to calculate metrics. Discussion of results and conclusions : The results present considerable changes in CA,Numps,Mps,ED and TE metrics both in all patches and main patch that with respecting the direction of change it can be concluded fragmentation process is rising. | ||
| کلیدواژه‌ها [English] | ||
| landscape, metrics, Anzali Wetland, Fragmentation | ||
| مراجع | ||
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