Comparing the impact of water vapor pressure deficit and soil moisture on the performance of forest plants photosynthesis using remote sensing data

Earth's climate is the result of complex interactions between its effective components and a function of solar radiation, which has a significant role on the afore said components. Among the most important climatic factors that are effective in the vegetation of humid, dry and semi-arid regions, we can mention the variables of vapor pressure and soil moisture, which play an important role in the process of plant photosynthesis. Chlorophyll plays a significant role in photosynthesis of plants, including coniferous. According to the research conducted in Chitgar and Nowshahr, the effect of two different components has been evaluated. The effects of the season on the fluorescence value of two components can’t be denied. The highest value of correlation in soil moisture and its effect on the amount of fluorescence in Chitgar forest park in autumn and winter seasons is estimated with R²=0.44 and 0.56, respectively. The RMSE were calculated 7.4 and 6.7(mg/m2), respectively. In Nowshahr, the highest correlation value with total depth moisture was obtained in summer season. The numerical value of R² is calculated as 0.21. Also, P-Value is estimated at 0.498. The effects of environmental stresses on the amount of soil moisture in different depths are undeniable, especially in the seasons when the plant activity is high and the amount of photosynthesis will be more exposed to drought and salinity stresses. Regarding the effect of vapor pressure in Nowshahr, the highest degree of correlation has been calculated with the fluorescence value in the autumn season. The peak of the rainy season in the north of the country can be estimated in the autumn season, and with the increase in relative humidity, the water vapor pressure will increase.