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| Without exogenous rock-derived nutrient sources, terrestrial ecosystems may eventually regress
or reach a terminal steady state, but the degree to which exogenous nutrient sources buffer or slow to a
theoretical terminal steady state remains unclear. We used strontium isotope ratios (
87
Sr/
86
Sr) as a tracer and
measured
87
Sr/
86
Sr values in aeolian dust, soils, and vegetation across a well- constrained 3 Myr semiarid
substrate age gradient to determine (1) whether the contribution of atmospheric sources of rock-derived
nutrients to soil and vegetation pools varied with substrate age and (2) to determine if the depth of
uptake varied with substrate age. We found that aeolian-derived nutrients became increasingly important,
contributing as much as 71% to plant-available soil pools and tree (Pinus edulis) growth during the latter
stages of ecosystem development in a semiarid climate. The depth of nutrient uptake increased on older
substrates, demonstrating that trees in arid regions can acquire nutrients from greater depths as ecosystem
development progresses presumably in response to nutrient depletion in the more weathered surface soils.
Our results demonstrate that global and regional aeolian transport of nutrients to local ecosystems is a vital
process for ecosystem development in arid regions. Furthermore, these aeolian nutrient inputs contribute to
deep soil nutrient pools, which become increasingly important for maintaining plant productivity over long
time scales. | |
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