Tree oxygen release dynamics in Uzbekistan: GIS and remote-sensing evidence from phenology, biomass development, spectral response, and climate scenarios

Abstract

Tree oxygen release is not a fixed ecological value, because it changes with phenological phase, biomass development, canopy condition, and long-term climate stress. This study assesses the dynamic controls on tree oxygen release in Uzbekistan using GIS and remotesensing-supported evidence derived from phenological, biomass, spectral, correlation, and climate-scenario materials. The analysis used species-level values for oak, pine, birch, and plane tree across four phenological phases and four biomass-development stages, together with landscape-specific graphical evidence for saxaul, tamarix, juniper, birch, maple, oak, pine, and almond. The phenological results showed that oxygen release increased sharply from early development to middle development, with the mean value rising from 135 to 287.5 kg ha⁻¹ yr⁻¹, before declining to 270 kg ha⁻¹ yr⁻¹ during reproduction and 48.75 kg ha⁻¹ yr⁻¹ during dormancy. The biomass results showed an even stronger pattern: mean oxygen release increased from 98.75 kg ha⁻¹ yr⁻¹ at the initial biomass stage to 337.5 kg ha⁻¹ yr⁻¹ at mature biomass, then declined to 175 kg ha⁻¹ yr⁻¹ during aging. Spectral-signature and correlation materials confirmed that oxygen release is linked to vegetation vigor indicators such as NDVI and LAI, although the available correlation values remain exploratory. Scenario projections suggested increasing oxygen-release potential under RCP 4.5 and declining performance under RCP 8.5. The study shows that oxygen-release assessment can support restoration monitoring in Uzbekistan when it is interpreted as an ecological productivity indicator and integrated with GIS, remote sensing, and long-term climate adaptation planning