مطالعۀ فلور منطقۀ حفاظت‌شده استند، نهبندان، استان خراسان جنوبی، ایران

منطقه حفاظت‌شدۀ اِستِند واقع در جنوب استان خراسان جنوبی، نقطۀ همپوشانی بخشی از فلور شرق ایران با غرب افغانستان است. اختصاصات عمدۀ منطقه شامل تنوع زیستی نسبتاً بالا، مجاورت با کویر لوت، استقرار در مرز گذر ایرانو-تورانی و صحارا-سندی، حداکثر ارتفاع 2111 متر و متوسط بارش سالانه 102 میلیمتر است. نمونه‌برداری‌ها در فواصل سال‌های 1398 تا 1401 در منطقه‌ای به مساحت 101051 هکتار انجام شدند. مطالعه فلور، شکل زیستی، پراکنش جغرافیایی انجام گرفت. در این مطالعه 106 آرایه متعلق به 96 گونه، 78 سرده و 30 تیره شناسایی شدند. از نهاندانگان، 28 تیره دولپه‌ای و یک تیرۀ تک لپه‌ای و از بازدانگان، یک تیره شناسایی شدند. تیره‌های کاسنیان (asteraceae) و تاج خروسیان (amaranthaceae) با 19 گونه بزرگ‌ترین تیره‌ها و سرده‌های cousinia، artemisia، haloxylon و suaeda هریک با 3 گونه بزرگ‌ترین سرده‌های گیاهی هستند. کامفیت ها و تروفیت ها به‌ترتیب با %28 و %26 شایع‌ترین اشکال زیستی، 21 آرایه شن رُست، 6 آرایه انحصاری ایران و 30 گونه با خواص دارویی هستند. ازنظر کورولوژی، بیشتر گونه‌ها متعلق به ناحیه ایرانو-تورانی (%52) هستند. تعیین جایگاه حفاظتی گونه‌های منطقه با نرم‌افزار آنلاین geocat انجام گرفت؛ 13 گونه (%13.54) در بحران انقراض (cr)، 2 گونه (%2.08) در شرف تهدید (nt) و 81 گونه (%84.4) در کمترین نگرانی انقراض (lc) هستند.

floristic study of estand protected region, nehbandan, south khorassan province, iran

estand protected region, situated in the south of south khorassan province, is the overlapping point of part of the flora of eastern iran with western afghanistan. the main characteristics of the region include high biodiversity, proximity to the lut desert, a maximum height of 2111 meters, average annual rainfall of 102 mm, and serving as a transitional zone between the irano-turanian (it) and saharo-sindian (ss) regions. sampling was conducted randomly between 2019 and 2022 in an area of 101,051 hectares. the flora, life form, and chorology of the species were investigated. in this study, 106 taxa belonging to 96 species, 78 genera, and 30 families of angiosperms, with 28 dicotyledonous families & one monocotyledon family, and gymnosperms, with one family, were identified. the most important plant families & genera in terms of species richness were asteraceae and amaranthaceae with 19 species, and artemisia, cousinia, haloxylon and suaeda genera, each with 3 species. chamaephytes and therophytes were dominant life forms in the region, with 28% and 26%, respectively. among them, 21 psammophytes, 6 endemic species, and 30 medicinal species were identified. chorologically, most of the species belong to the irano-turanian (it) region (52%), and the conservation status was determined by geocat online software. thirteen (13.54%) species are classified as critically endangered (cr), 2 (2.08%) as near threatened (nt), and 81 (84.4%) as least concern (lc).keywords: botany, east of iran, estand protected region, south korassan province, taxonomy.  introductionthe results of floristic research in conservation biology include the identification and evaluation of taxa that are vulnerable or at risk of extinction. such studies allow more evolutionary units to be defined under conservation laws. finding species with local medicinal properties can pave the way for future studies to discover medicines and beneficial properties for the health of human societies (malekpourzadeh et al. 2024). the study of the flora of different regions of iran is of great importance due to the very high diversity and richness of plants, from completely xerophytic plants to hydrophytic ones, along with their special geographical and biological features. the history of studies in this field dates back quite far. the presence of heights such as the alborz and zagros mountain ranges, vast pastures and plains between them, with a difference in elevation from 26 meters below sea level to 5774 meters, as well as climate and especially geological differences in different parts of the country, has caused a wide diversity in the fauna and flora of iran. south khorassan province, with an area of 88,404 km², is located in the east of iran and covers 5.4% of the total area of the country. the length of the common border with afghanistan is about 330 km. the main features of the studied region, the estand protected region, include its high geological diversity, proximity to the lut desert, numerous springs, and the distance from the village of estand to the afghanistan border in the east of the country, which is 77 km. the region is situated on the ecotone border of the irano-turanian (it) and saharo-sindian (ss) regions, with a maximum elevation of 2111 meters and an average annual rainfall of 102 mm.materials and methodsto conduct the floristic study of the estand protected area, the preliminary preparations involved obtaining maps of the area from the environmental protection organization of birjand, south khorassan province. these maps were used together with the existing geocat (geospatial conservation assessment tool) findings to analyze the conservation status of the species. subsequently, a comprehensive survey was conducted on the site. plant specimens were systematically collected during the periods from 2019 to 2022, during different growing seasons, and were identified using known plant classification methods and floristic scientific resources, especially the database of the ipni-powo websites. the sampling process was carried out in 15 stages in the study area, during which comprehensive photographic documentation of all samples in their natural habitat was made. then the collected samples were transferred to the herbarium botanical laboratory of kharazmi university (t) for identification. following preparation and cleaning, each sample was mounted on specialized cardboard sheets. the specimens collected in this study are currently kept in the herbarium of kharazmi university (t). research findingsthe field research findings of the estand protected region show that in the last few years (2019-2022), the floristic composition and the protective status of flora in the region have decreased significantly under the influence of mining activities, livestock grazing, and the spread of pests and diseases, which has resulted in the critically endangered (cr) status of 13% of the species in the region, as indicated by the geocat findings, and the low number of identified taxa (106). this situation requires stronger management by the relevant organizations to restore the natural resources of the region. among the 250 plant samples collected, 96 plant species belonging to 30 families and 78 genera were documented. the most abundant families, including asteraceae and amaranthaceae, each with 19 species, and the most abundant genera, including cousinia, artemisia, haloxylon, and suaeda, each with 3 species, indicated not only high speciation but also high diversity of distribution. on the other hand, the chorology of the species shows that the percentage of irano-turanian (it) species has reached 52%, which itself is evidence of the influence of saharo-sindian (ss) elements from the south on the irano-turanian (it) region in the north, or the expansion of its ecotone border from south to north. discussion of results & conclusionthe analysis of life forms of plants in the region revealed the prevalence of chamaephytes (28%), indicating that in the flora of the region, the forms of shrubs and semi-shrubs are more common. this situation, which can be seen in most areas of south khorassan, is a sign of the desert and semi-desert environment prevailing in the region, which occurs under the influence of low rainfall and atmospheric precipitation, livestock grazing, and seasonal river floods. the percentage of annual species or therophytes (26%) indicates that, from the point of view of edaphics, annual species can spread significantly in the shallow soil bed provided. the closeness of chamaephytes percentages with therophytes is another sign of unfavorable weather conditions in the region. the low percentage of hemicryptophytes (19%) and geophytes (4%) supports the claim that the region did not have the necessary power and opportunity to expand rhizome and tuberous species. this issue can be related to the presence of dominant animal species in the region, such as hystrix indica kerr, or other root-eating rodents, which have practically caused the destruction of tuberous species due to the droughts of the last several years. this has introduced damage to plant communities, especially the pistacia atlantica desf. trees, or it could be a sign of the presence of livestock, camels, goats, and sheep that eat roots, preventing the regeneration of pastures, which needs to be solved by serious management and control of overgrazing. in terms of chorology, plant species from the irano-turanian (it) region (52%) demonstrated extensive distribution within the studied region, while only 13% exhibited a wide distribution (pl). specifically, 35 species, constituting 35% of the total, belonged to other regions such as it-ss, it-sa, it-os, it-m, ss-sa, and os only. in other words, the ecotone of the saharo-sindian (ss) region is expanding into the it region.