Premium
Geochemical and tectonic uplift controls on rock nitrogen inputs across terrestrial ecosystems
Author(s) -
Morford Scott L.,
Houlton Benjamin Z.,
Dahlgren Randy A.
Publication year - 2016
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2015gb005283
Subject(s) - weathering , geology , denudation , lithology , bedrock , biogeochemical cycle , ecosystem , terrestrial ecosystem , biogeochemistry , earth science , geochemistry , tectonics , physical geography , geomorphology , ecology , paleontology , oceanography , biology , geography
Rock contains > 99% of Earth's reactive nitrogen (N), but questions remain over the direct importance of rock N weathering inputs to terrestrial biogeochemical cycling. Here we investigate the factors that regulate rock N abundance and develop a new model for quantifying rock N mobilization fluxes across desert to temperate rainforest ecosystems in California, USA. We analyzed the N content of 968 rock samples from 531 locations and compiled 178 cosmogenically derived denudation estimates from across the region to identify landscapes and ecosystems where rocks account for a significant fraction of terrestrial N inputs. Strong coherence between rock N content and geophysical factors, such as protolith, (i.e. parent rock), grain size, and thermal history, are observed. A spatial model that combines rock geochemistry with lithology and topography demonstrates that average rock N reservoirs range from 0.18 to 1.2 kg N m −3 (80 to 534 mg N kg −1 ) across the nine geomorphic provinces of California and estimates a rock N denudation flux of 20–92 Gg yr −1 across the entire study area (natural atmospheric inputs ~ 140 Gg yr −1 ). The model highlights regional differences in rock N mobilization and points to the Coast Ranges, Transverse Ranges, and the Klamath Mountains as regions where rock N could contribute meaningfully to ecosystem N cycling. Contrasting these data to global compilations suggests that our findings are broadly applicable beyond California and that the N abundance and variability in rock are well constrained across most of the Earth system.