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Determining the optimal plot size and sample size for vegetation monitoring and biodiversity assessment in Birjand flood spreading area
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Moslem Rostampour *   , Seyedeh Mahbubeh Mirmiran2 , Reza Yari |
| Department of Rangeland and Watershed Management and Research Group of Drought and Climate Change, Faculty of Natural Resources and Environment, University of Birjand, Birjand, Iran |
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Abstract: (26 Views) |
Management and monitoring of vegetation cover in flood spreading systems based on its quantitative characteristics are essential and vital. The foundation of plant research results is the sampling and determination of the plot size and sample size. This research was conducted to determine the optimal size and number of plots for monitoring vegetation cover and assessing biodiversity in a part of the rangelands of the flood spreading project in the Birjand plain in the spring of 2024. In this study, plots measuring 1, 2, 3, 4, 5 and 6 square meters with the same number (30 plots each) were established along 5 transects of 100 meters each to determine plot dimensions. The time required to measure the density for each plot size was recorded, and based on Wiegert's method, relative variance and relative cost were calculated to determine the optimal plot size for vegetation cover in the flood spreading area. After determining the appropriate plot size, 10, 20, 30, 40, 50, and 60 plots were established along 6 transects, and the density, vegetation cover, and numerical biodiversity indices were determined within them. In this study, in addition, the required number of plots was also calculated using Cochran's method. All statistical analyses were performed in R and PAST software. The results of the Wiegert's method and coefficient of variation (CV) showed that plot size of 4 square meters was the most accurate in measuring vegetation cover in the study area. Considering the dominant growth form of the region's plants and to avoid wasting time and reduce costs, a total of 35 plots of 4 square meters are sufficient to determine the percentage of vegetation cover in this area. Additionally, to investigate and calculate species diversity indices in the flood-spreading area, 90 plots of 6 square meters are required. Since the results of graphical methods (refraction curve and diversity ordering curve) and nonparametric permutation tests showed that density and species diversity and dominance are affected by sampling effort, it is recommended that before starting the monitoring designs, plot size and sample size should be determined by a combination of statistical and graphical methods so that the results can be evaluated and generalized.
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Article number: 2 |
| Keywords: Rangeland assessment Sampling intensity Species richness Water harvesting Wiegert's method |
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Type of Study: Research |
Subject:
Special
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