Abstract

Phosphorus (P) availability in terrestrial ecosystems
depends on soil age, climate, parent material,
topographic position, and biota, but the relative
importance of these drivers has not been assessed.
To ask which factor has the strongest influence on
long- and short-timescale metrics of P availability,
we sampled soils across a full-factorial combination
of two parent materials [quartz diorite (QD) and
volcaniclastic (VC)], three topographic positions
(ridge, slope, and valley), and across 550 m in
elevation in 17 sub-watersheds of the Luquillo
Mountains, Puerto Rico. VC rocks had double the P
content of QD (600 vs. 300 ppm; P < 0.0001), and
soil P was similarly approximately 29 higher in
VC-derived soils (P < 0.0001). Parent material also
explained the most variance in our two other longtimescale
metrics of P status: the fraction of
recalcitrant P (56% variance explained) and the
loss of P relative to parent material (35% variance
explained), both of which were higher on VC-derived
soils (P < 0.0001 for both). Topographic position
explained an additional 10–15% of the
variance in these metrics. In contrast, there was no
parent material effect on the more labile NaHCO3-
and NaOH-extractable P soil pools, which were
approximately 2.59 greater in valleys than on
ridges (P < 0.0001). Taken together, these data
suggest that the relative importance of different
state factors varies depending on the ecosystem
property of interest and that parent material and
topography can play sub-equal roles in driving
differences in ecosystem P status across landscapes.

Citation

Mage S.M., Porder S. (2013): Parent material and topography determine soil phosphorus status in the Luquillo Mountains of Puerto Rico. Ecosystems. DOI: 10.1007/s10021-012-9612-5

This Paper/Book acknowledges NSF CZO grant support.