PS 20-66 - Response of foliar traits and phosphorus fractions to fertilization in a tropical forest: understanding plant adaptation to P deficiency

Wednesday, August 10, 2016
ESA Exhibit Hall, Ft Lauderdale Convention Center
Faming Wang Sr.1, Qifeng Mo Sr.1 and Emma Sayer2, (1)South China Botanical Garden, CAS, Guangzhou, China, (2)Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
Background/Question/Methods

Phosphorus (P) is an essential nutrient in plant metabolism and frequently limits plant growth and productivity in tropical forests. However, the adaptive plant strategies to efficiently use P on infertile soils remain unclear.

We examined photosynthesis, leaf traits and P fractions in five plant species (Clerodendrum cyrtophyllum, Syzygium bullockii, Psychotria rubra, Schefflera octophylla and Uvaria microcarpa) after six years of nitrogen (N) and P fertilization in a tropical forest in southern China. 

Results/Conclusions

Our results show that fertilization did not significantly affect the area-based photosynthetic carbon assimilation. Nitrogen addition had no effect on photosynthetic N-use efficiency (PNUE), photosynthetic P-use efficiency (PPUE), or foliar P fractions, while P addition significantly decreased the PPUE and enhanced the concentrations and relative proportion of metabolic P over other P fractions across the five species.

In these tropical plant species, the higher PPUE in leaves of plants grown in unfertilized soils may be determined by the relatively self-balanced and consistent allocation of P to P-containing metabolic processes. These results suggest that these plant species have evolved adaptive strategies to efficiently use P in P-limited tropical forests; thus additional P availability did not improve leaf photosynthetic rates. We suggest a species-specific mechanism that optimizes the allocation of P among foliar P fractions maintains higher productivity and reduces demand for P at the leaf-level, and this adaptation allows for higher PPUE in P-poor tropical soils.