Divergent nitrogen and phosphorus allocation strategies in terrestrial plant leaves and fine roots: a global meta-analysis

The quantification of the allocation of nitrogen (N) and phosphorus (P)
among plant organs is essential to improve our understanding of plant
growth, life-history strategies, and ecosystem nutrient and energy cycles.
However, allocation strategies of N and P between terrestrial plant leaves
and fine roots are unclear. Here, we compiled a global dataset comprising
807 terrestrial plant species to analyze the stoichiometric scaling of N
and P between leaves and fine roots across species, families, plant
groups, biomes, and locations. We found that N and P, and N:P ratios
manifest different scaling exponents (α-values) between leaves and fine
roots. Specifically, overall αN and αP were >1 and <1,
respectively, and αN:P = 1, indicating a higher proportional increase of N
to fine roots and P to leaves. However, there were differences in αN, αP,
and αN:P among major species, families, plant groups, biomes, and
locations. In addition, αN and αN:P increased with latitude; there was no
clear trend for αP. Mean annual temperature accounted for the greatest
proportion of variation in αN, whereas soil total P accounted for the
greatest proportion of variation in αP and αN:P. Synthesis. Our results
demonstrate a divergent N and P allocation strategy between leaves and
fine roots in terrestrial plants. This study improves our understanding of
the effects of the environment (including changes in global climate, and
life history strategies) on nutrient allocation patterns between these two
important plant organs.