PHOTOSYNTHETICALLY ACTIVE RADIATION AND TRANSPIRATION INDICES OF TREES AND SHRUBS IN THE WALNUT FORESTS OF THE WESTERN TIEN SHAN

Аннотация

This article studies the photosynthetically active radiation (PAR) and transpiration processes of various tree and shrub species in nut-bearing forests of the Western Tien Shan mountain range. The study analyzed the influence of climate, soil and microclimate factors on plant water exchange and photosynthesis processes. The results showed that light intensity and leaf temperature activate the transpiration process, while relative humidity of the air slows it down. It was noted that high temperature and low soil moisture negatively affected the development of seedlings. The results of the study are important as a scientific basis for ensuring the stability of forest ecosystems in mountainous areas and managing natural regeneration processes. INTRODUCTION. The processes of photosynthesis and transpiration of plants are of great importance for their growth, development, and adaptation to the environment . Forest ecosystems, especially in mountainous regions, are exposed to complex climatic conditions, which affect the ecological stability of plants. The nut-bearing forests of the Western Tien Shan are characterized by their biodiversity and sensitivity to climate change. Therefore, studying the photosynthesis and water exchange parameters of plants in this region is necessary to ensure ecosystem stability and scientifically manage natural regeneration processes. In this study, the photosynthetically active radiation (PAR) and transpiration indices of tree and shrub species were studied, and therelationship between them and climaticand soil parameters was analyzed. MATERIALSAND METHODS The process of photosynthesis and transpiration are the main mechanisms that ensure water and energy exchange in plants, and they depend on climatic conditions, soil properties, and biological characteristics of plant species [11]. Previous studies have shown that changes in elevation and relief can significantly affect photosynthesis and transpiration rates in mountainous regions [9]. Under conditions of high temperature and low humidity, stomatal control of plants can change, reducing photosynthetic efficiency [6]. However, there are limited studies on the adaptation of tree species to climate change in Uzbekistan, especially in the Western Tien Shan [3]. The research area was the walnut forests of the Qorankul forest department of the State Forest Service of the Republic of Uzbekistan, located at an altitude of 1030 m above sea level in the 180 INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE ISSN:2692-5206,ImpactFactor:12,23 AmericanAcademicpublishers,volume05,issue08,2025 Journal: https://www.academicpublishers.org/journals/index.php/ijai Western Tien Shan mountain range. 135 tree and shrub seedlings were identified in the selected 150 m² area, and their biometric and phenological indicators were regularly monitored on the 20thof each monthstarting from March 2024. Photosynthetically active radiation (PAR), transpiration rate and transpiration flux were recorded using a LI-COR 6400XT spectrophotometer and other special instruments. Microclimate parameters, including air and leaf temperature, relative air and leaf humidity, were measured using YSI and HOBO measuring devices. Soil samples were analyzed for pH, moisture and organic matter content using standard laboratory methods. The obtained data were entered into SPSS and Excel was studied using correlation analysis and statistical methods usingsoftware.