Photosynthetically Active Radiation Dynamics: Implications for Grassland Productivity, Phenology, Carbon Cycling and Ecosystem Management

Albert Thembinkosi Modi
Department of Biological and Environmental Sciences, Walter Sisulu University, Mthatha 5099, South Africa; amodi@wsu.ac.za
Received: 4 June 2026 Revised: 13 August 2026 Accepted: 1 September 2026 Published: 16 September 2026

ABSTRACT

Ecosystem functioning depends on an integrated system of environmental factors that are directly or indirectly influenced by photosynthetically active radiation (PAR). The objective of this review is to synthesize and analyze grassland productivity dynamics as influenced by PAR as the primary factor influencing grassland productivity. The methodology followed a conceptual gap analysis of related literature. A PAR-Water-Structure framework was developed to propose how the grassland ecosystem drivers interact cohesively to explain the hierarchy of efficiency for Gross Primary Production (GPP). The key findings include confirmation that PAR seasonal variations are influenced by vegetation structure, water availability and PAR utilization efficiency. The narrative approach used in the study allowed conceptualization to provide a holistic understanding that can be used to relate PAR- ecosystem interactions in grassland ecosystems to other biomes. Significantly, the study also highlights the importance of alignment of management practices such as grazing and restoration with PAR ecophysiology regimes. It is recommended that the PAR-Water-Structure framework is essential for understanding existing models and contributes new perspectives to the understanding PAR dynamics in the context of sustainable grassland ecosystem management. The new perspective is important to inform strategies for changing climatic conditions affecting grassland ecosystems and other biomes.
Keywords: photosynthetically active radiation; grasslands, productivity; ecosystem dynamics; climate variability