Tree Age and Phosphorus Limitation: A Mechanistic Exploration

Multiple mechanisms may contribute to the observed increase in phosphorus (P) limitation with tree age. Firstly, the increase in photosynthetic rate with tree age can promote plant P demand, thereby exacerbating P limitation. Phosphate plays a crucial role as a reactant in the light reaction of photosynthesis for adenosine triphosphate (ATP) synthesis (Li et al., 2016). Numerous studies have reported an age-related increase in photosynthesis rate as more leaves are exposed to light (Yokota & Hagihara, 1996; Bond, 2000). The chloroplast, a cellular organelle predominantly found in green leaves, serves as a primary site for photosynthesis (Kubinova et al., 2014; Li et al., 2019). With increasing tree age, there is a significant augmentation in the number of green leaves (Stephenson et al., 2014; Forrester et al., 2017), resulting in enhanced exposure of leaves to sunlight. Consequently, the intensity of photosynthesis in trees also escalates with advancing age, potentially intensifying plant P limitation.