Influence of Tree Age and Functional Type on Phosphorus Limitation in Tropical Forests

Influence of Tree Age and Functional Type on Phosphorus Limitation in Tropical Forests

This study aimed to investigate the impact of tree age on plant phosphorus (P) limitation in tropical forests. By examining the relationship between tree age and P limitation, we sought to address critical knowledge gaps in tropical forest ecology.

We employed two key indicators as primary measures of plant P limitation: leaf N:P ratio and leaf PRE:NRE ratio (representing leaf N and P resorption efficiency, respectively). These indicators offer a more efficient and straightforward approach compared to traditional, and often logistically challenging, fertilization experiments (Koerselman & Meuleman, 1996; Du et al., 2020).

To explore the potential influence of plant functional type on P limitation, we selected 12 tree species representing three distinct functional groups: fast-growing, slow-growing, and N-fixing trees.

This study tested two primary hypotheses:

(1) Plant P limitation increases with tree age across all functional types. We posit that as trees age, their demand for P may outpace the supply available in the soil, leading to increased P limitation.

(2) The extent to which P limitation increases with tree age is greater in fast-growing and N-fixing trees compared to slow-growing trees. Fast-growing and N-fixing trees typically have higher nutrient demands, which may make them more susceptible to P limitation as they age.

By addressing these hypotheses, this study provides valuable insights into the factors that regulate nutrient cycling and plant growth in tropical forests, contributing to our understanding of these ecologically critical ecosystems.