Study of weeds biodiversity on wheat fields of Gorgan using geographic information system (GIS)

This research was carried out to investigate weeds biodiversity in wheat fields of Gorgan (Gharasoo basin) and measure the most important effecttive environmental factors on weed biodiversity. For this, four villeges located at four directions around Gorgan city were surveyed. Then sampeling was performed by W-shape method using 0.5×1 square meters quadrate. Weed in each segment were identified and counted according to their genus and species. Geographical coordinates (features) of each point was also recorded by GPS. Thereafter, biodiversity indices were calculated using Shanon & Winer diversity and Simpsonʼs uniformity indices. Collected and calculated data were used to provide related maps using Arc Gis (9. 3. 1 v.) by related Data processing. Provided Maps revealed that Simpson uniformity index was from 0.65 to 0.86 and around 60% of fields in studied area were placed in higher category which included Toshan and Heidar Abad villages. Related values for Shanon & Winer index were between 1.5 to 3.01. Around 61% of studied area in west side were placed in higher values class, including the same villages as measured for Simpson index. Environmental factors, specially maximum and minimum temperature had the positive effect on Shanon & Winer indices.