We investigated the role of rock-derived mineral nutrient availability on the nutrient dynamics of overlying forest communities (Populus tremuloides and Picea engelmanni-Abies lasiocarpa v. arizonica) across three parent materials (andesite, limestone, and sandstone) in the southern Rocky Mountains of Colorado. Broad geochemical differences were observed between bedrock materials; however, bulk soil chemistries were remarkably similar between the three different sites. In contrast, soil nutrient pools were considerably different, particularly for P, Ca, and Mg concentrations. Despite variations in nutrient stocks and nutrient availability in soils, we observed relatively inflexible foliar concentrations and foliar stoichiometries for both deciduous and coniferous species. Foliar nutrient resorption (P and K) in the deciduous species followed patterns of nutrient content across substrate types, with higher resorption corresponding to lower bedrock concentrations. Work presented here indicates a complex plant response to available soil nutrients, wherein plant nutrient use compensates for variations in supply gradients and results in the maintenance of a narrow range in foliar stoichiometry.
Bibliographical noteFunding Information:
This work was supported by an Andrew Mellon Foundation grant. Sample collection was completed with assistance from Corey Lawrence, Dan Fernandez, Jon Carrasco, and Jessica Kelleher. Sample preparation and processing was done, in part, by Dan Fernandez and Cody Flagg. The Laboratory for Environmental Geochemistry at the University of Colorado provided ICP analyses. We thank Cindy Prescott, Bill Bowman, Nichole Barger, and two anonymous reviewers for their comments on an earlier version of this manuscript.
- Nutrient availability