نوع مقاله : مقالات پژوهشی
1 واحد بین الملل دانشگاه فردوسی مشهد
2 دانشگاه فردوسی مشهد
3 دانشیار، بخش تحقیقات علفهای هرز، موسسه تحقیقات گیاهپزشکی کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
عنوان مقاله [English]
The everyday increasing of the population has resulted in the expansion of the cities and density of the population so the Pressure has intensified on the use of application services especially green space services. This is due to the fixed area of green space in comparison to increasing population density which has resulted in increasing usage of green space and decreasing efficiency of ecological and recreational functions of it. Tehran, in terms of extent, is the 26th megacity of the world. Tehran’s urban greenspace per capita is 15.5 square meters per person (Statistical yearbook of Tehran (2015). One of the affecting factors to maintain and increase the amount of greenspace and to reach up to international standards per capita is proper management of weeds in the greenspace. A research has been conducted in parks of 22 districts of Tehran in order to assess, specify diversity, density, dominance and distribution map of weeds in Tehran.
Material and methods
The above research has been conducted in years 2014-2015 in 48 parks of 22 districts of Tehran. Sampling has been conducted in summer using W systematic method. The parks in each area were chosen according to the extent of green space in the area, the location of the park in the area (whether the park was in the suburbs of Tehran or other parts of the area) and according to the three following scales. In the 5 acre parks, 10 samples, 6 to 15 acre parks, 15 samples and in 16 and more than 16 acre parks 25 samples were taken. In the 5 acre parks, 25 meters, 6 to 15 acre parks, 40 meters and in 60 and more than 60 acre parks 70 meters of margin was considered for each park. Weeds of each quadrat were identified and counted according to their species. Then according to W systemic method weeds were separated and counted according to their species. And finally, using Thomas equations (1985), their frequency, uniformity, average aggregation and dominance index were calculated. In order to create distribution map of weeds Arcgis and Arcmap soft-wares were used. Shannon-Wiener and uniformity indexes were calculated for all parks. For comparing and grouping 22 districts, cluster analysis was performed using Pc-ord software.
Results and discussion
A total of 52 weed species from 21 families were observed in parks of Tehran. Maximum weed densities were found in the Region 17 and Region 16 with 34.38 and 36.25 plant/m2, respectively and minimum in the region 5, 12, 20, 21 with 5.7,9.05, 9.31 and 9.55 plant/ m2, respectively. The 28 species of 51 species belonging to four major families, Asteraceae,Poaceae, Fabaceae, and Chenopodiaceae, with 10, 7, 6 and 4 species, respectively. Lion′s tooth (Taraxacum officinale), greaet plantain (Plantago major), knotweed (Polygonum patulum) and bermuda grass (Cynodon dactylon) were dominant species based on a abundance index (AI). Regions park of 2, 1, 19 with 3.52, 3.06 and 2.99 respectively, had maximum diversity in weed community and regions park of 15, 18, 21, 16, 12, 11 and 14 with 2.03, 2.22, 2.26, 2.30, 2.31, 2.34 and 2.36 respectively had minimum diversity. Also presence of Beggarticks (Bidens parviflora Willd), garden anchusa (Anchusa italica Retz), garden orache (Atriplex hortensis L.), common reed ((Phragmmites austrialis (Cav.) Trin exsteud), ribwort plantain (Plantago lanceoleta L.), nappola minor (Xanthium brasilicum), yellow sweet clover (Mellilotus officnalis L. Desr), common mallow (Malva sylvestris L.) weeds in some specific areas makes it necessary to observe and control these weeds to stop their reproduction in these specific area and expansion of infected seeds from these areas to other areas of Tehran. . Lion′s tooth distribution maps showed that the highest plant density above regions 21, 18, 16, 17, 19 and the lowest density in regions 4, 1, 5, 22 , 3 there.
The determination of number, type, species and life cycle of weeds in Tehran, allows detailed plan to manage and reduce weeds damages and using integrated pest management method it is possible to take the best actions in order to reduce weeds and stop them from spreading from one area to another. Also close monitoring and precise control of combined soil and manure used in lawns of Tehran is effective in reducing the density of weeds in different areas.
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