『Abstract
The input of phosphorus (P) through mineral aerosol dust deposition
may be an important component of nutrient dynamics in tropical
forest ecosystems. A new dust deposition calculation is used to
construct a broad analysis of the importance of dust-derived P
to the P budget of a montane wet tropical forest in the Luquillo
Mountains of Puerto Rico. The dust deposition calculation used
here takes advantage of an internal geochemical signal (Sr isotope
mass balance) to provide a spatially integrated longer-term average
dust deposition flux. Dust inputs of P (0.23±0.08 kg ha-1
year-1) are compared with watershed-average inputs
of P to the soil through the conversion of underlying saprolite
into soil (between 0.07 and 0.19 kg ha-1 year-1),
and with watershed-average losses of soil P through leaching (between
0.02 and 0.14 kg ha-1 year-1) and erosion
(between 0.04 and 1.38 kg ha-1 year-1).
The similar magnitude of dust-derived P inputs to that of other
fluxes indicates that dust is an important component of the soil
and biomass P budget in this ecosystem. Dust-derived inputs of
P alone are capable of completely replacing the total soil and
biomass P pool on a timescale of between 2.8 ka and 7.0 ka, less
than both the average soil residence time (〜15 ka) and the average
landslide recurrence interval (〜10 ka).
Keywords: Luquillo Mountains; Dust; Nutrient cycling; Phosphorus』
Introduction
Site description
Calculation of P mass balance for the Rio Icacos watershed in
the Luquillo Mountains
Dust-derived inputs of P
Denudation-driven inputs of P to soils (conversion of saprolite
to soil)
Losses of P from soils
Overall P budget and turnover time
Availability of P in soil and dust
Temporal and spatial variability of P fluxes
Comparison with P cycling in the Amazon and Hawaii
Conceptual models of P depletion
Conclusions
Acknowledgments
References