Geochemical and tectonic uplift controls on rock nitrogen inputs across terrestrial ecosystems

Abstract

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 À3 (80 to 534 mg N kg À1 ) across the nine geomorphic provinces of California and estimates a rock N denudation flux of 20-92 Gg yr À1 across the entire study area (natural atmospheric inputs~140 Gg yr À1 ). 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.

Nutrient remobilization in tree foliage as affected by soil nutrients and leaf life span

“…Indeed, because sedimentary materials contain more N than magmatic rocks (Morford et al. ), it was expected that N remobilization might be lower in sedimentary contexts than in magmatic contexts. Our results, however, did not follow this pattern, suggesting that the direct supply of N from bedrock to plant (Morford et al.…”

Vectors with autonomy: what distinguishes animal‐mediated nutrient transport from abiotic vectors?

“…nitrogen, phosphorous, and carbon) that influence primary productivity and biomass (Cook & McElhinny, 1979;Vitousek, 2004;Elser et al, 2007;LeBauer & Treseder, 2008;Vitousek et al, 2013). This initial distribution is modified by environmental and physical factors ('passive subsidies'; Earl & Zollner, 2014), including wind, current, gravity and erosion (Zhao & Running, 2010;Cleveland et al, 2013;Houlton & Morford, 2015;Morford, Houlton & Dahlgren, 2016). In addition to these abiotic processes, biotic vectors further redistribute nutrients through various mechanisms, mostly via animal movement (Fig.…”

Bedrock Nitrogen Weathering Stimulates Biological Nitrogen Fixation

“…2; Appendix S1: Fig. This is likely a product of variations in climate, denudation, and underlying bedrock within each region, all of which affect the mobilization of N from bedrock into soil (Morford et al 2016). Similarly, across the paired lithology sites, we find that P concentrations in soil and litter are significantly influenced by the interaction between region and bedrock N content, in addition to bedrock N alone (Table 2), with the highest soil P concentrations at the two wettest sampling regions.…”

“…Similarly, across the paired lithology sites, we find that P concentrations in soil and litter are significantly influenced by the interaction between region and bedrock N content, in addition to bedrock N alone (Table 2), with the highest soil P concentrations at the two wettest sampling regions. This is likely a product of variations in climate, denudation, and underlying bedrock within each region, all of which affect the mobilization of N from bedrock into soil (Morford et al 2016).…”