تحقيقات جغرافيايی (Mar 2018)
Pasture Covering Status in Growth Period, Case Study: Shirvan Darasi Aquiferous Zone
Abstract
The aim of current research is to access pasture covering status in drought and rainy conditions during pasture germination beginning and climax periods in different altitudes of Shirvan darasi aquiferous zone at Meshkinshahr city. So, by using precipitation data, total daily, participation, minimum, maximum and mean temperature of Meshkinshahr were measured during 1996-2016 statistical period and were used for determining pasture growth in different periods and calculating standard precipitation index (SPI) in 3 time intervals with 1, 3 and 6 months and also TM Landset satellite images were applied for plant covering difference index (NDVI) and leaf area index (LAI) during pasture germination beginning and climax periods in different altitudes of studied zone. In order to investigation the relationship between studied indices, (R2) correlation, (R) Pearson correlation and RMSE (root mean of square error) coefficients were used. Based on SPI index results, precipitation position was normal in most of years in the region, but the most drying conditions have happened during April, May, June months for pasture growth period. Obtained results from implementation and evaluation of indices showed that the most correlation between leaf area index at standard participation and pasture germination climax periods at pasture germination beginning period was equal to 0/874, with the least error rate which it is equal to 1/32. According to Pearson correlation coefficient there is significant relationship between participation amount during pasture germination beginning period with pasture covering area at germination climax period. Generally, results showed that precipitation decline during early stages of pasture growth period has a more significant impact in determining growth conditions and pasture congestion compared to dry conditions in other pasture growth stages.
