مقايسه تاثير تفکيکي کمبود فشار بخارآب و رطوبت خاک بر عملکرد فتوسنتز پوشش گياهي جنگلي با استفاده از دادههاي سنجش از دور.

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 semiarid 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.Introduction In recent years, new methods for application in various fields of science, including meteorologyagriculture, have gained special importance. Remote sensing is applied to estimate the sun's chlorophyll fluorescence. As matter of fact the climate of the earth is the sum of the interactions between its effective components and vegetation is considered one of its important and inseparable components, in the meantime, the process of photosynthesis is particular of importance. Materials and Methods The data required for the research, including the vapor pressure and soil moisture in the two considered stations, have been received from the National Meteorological Organization. Also, the amount of chlorophyll data of the vegetation cover of the two regions in question has been obtained through programming in Google Earth Engine and from the Sentinel 2 satellite. Considering that chlorophyll data related to vegetation is needed, the best index to obtain its data is MTCI (Meris Terrestrial Chlorophyll Index), which is used to estimate vegetation content from 2017. It has been used on the said satellite. But its data has gradually been made available to the public for use in research work since 2019. Results and Discussion The main process of material production in plants is carried out by photosynthesis, in which SIF plays a very important role. Choosing a strong representative in this direction to correctly calculate the amount of fluorescence has been a challenging issue. Chlorophyll fluorescence is estimated by the three principles of light distribution in leaves, light conversion by fluorescence emission and fluorescence diffusion through the plant canopy. The seasonal changes of SIF should be independent of the surface pressure or temperature because biotic and abiotic stresses are dependent on this issue according to the canopy structure and it is also different on a seasonal and daily scale and the results of seasonal changes originate from physiological changes. Remote sensing data is a good indication of photosynthetic activity. And in this research, the SIF satellite data shows a strong relationship between the photosynthetic capacity component using the above two areas and the coniferous cover of the two areas. It is worth noting that on a short scale, the variation in photosynthetic capacity is low and on a monthly and seasonal scale, it will be more in a time series that is determined by the enzyme RUBISCO in the photosynthetic scale. Conclusion Although it is not easy to fully distinguish the effect of vapor pressure and soil moisture from each other and their effect on the SIF value and finally the plant cover performance, but the effect of these two components on the coniferous plant cover in the two different climates mentioned above is quite evident. According to the analyzes carried out in the climate of Chitgar region, two factors, vapor pressure and soil moisture, are considered as limiting factors in plant photosynthesis, and the lack of any of these factors can seriously damage the photosynthetic performance of coniferous. Leave this area, which will then overshadow the biomass above the surface and the amount of chlorophyll fluorescence. The effect of each season, due to the presence of biotic and abiotic stresses, affects the amount of chlorophyll or vegetation, and will ultimately overshadow the photosynthetic performance of coniferous vegetation. For example, in arid and semi-arid regions, salinity stress is one of the most important stresses, the accumulation of salt caused by irrigation in the surrounding environment of the roots and the increase in water-soil potential are among the damages that are caused to the roots of these plants. . In addition, the most damage in salinity stress will be done to the aerial organs of the plant, including leaves, which play a significant role in photosynthesis. [ABSTRACT FROM AUTHOR]