Nitrogen Deposition Maintains a Positive Effect on Terrestrial Carbon Sequestration in the 21st Century Despite Growing Phosphorus Limitation at Regional Scales

Abstract

Nitrogen (N) and phosphorus (P) are two dominant nutrients regulating the productivity of most terrestrial ecosystems. The growing imbalance of anthropogenic N and P inputs into the future is estimated to exacerbate P limitation on land and limit the land carbon (C) sink, so that we hypothesized that P limitation will increasingly reduce C sequestered per unit N deposited into the future. Using a global land surface model (CABLE), we simulated the effects of increased N deposition with and without P limitation on land C uptake and the fate of deposited N on land from 1901 to 2100. Contrary to our hypothesis, we found that N deposition continued to induce land C sequestration into the future, contributing to 15% of future C sequestration as opposed to 6% over the historical period. P limitation reduced the future land C uptake per unit N deposited only moderately at the global scale but P limitation increasingly caused N deposition to have net negative effects on the land C balance in the temperate zone. P limitation further increased the fraction of deposited N that is lost via leaching to aquatic ecosystems, globally from 38.5% over the historical period to 53% into the future, and up to 75% in tropical ecosystems. Our results suggest continued N demand for plant productivity but also indicate growing adverse N deposition effects in the future biosphere, not fully accounted for in global models, emphasizing the urgent need to elaborate on model representations of N and P dynamics.

China's Interannual Variability of Net Primary Production Is Dominated by the Central China Region

“…Time-varying of forcing indicated as "1901-2100"; constant forcing expressed as "1990s." For spin up, the model is run by recycling the meteorological forcing and nitrogen deposition of 1901-1910 until the modeled pools reach an equilibrium state (<0.01% difference in any pool size between the two consecutive cycles) using an atmospheric CO 2 concentration at 296.6 ppm and nitrogen deposition for the year 1901 (see Fleischer et al, 2019). The pool sizes at equilibrium are used as the initial values for CABLE2.1 simulations from 1901 to 2100.…”

“…All the meteorological variables are interpolated from 6-hourly to hourly with a resolution of 0.5° × 0.5°, as described in Qian et al (2006), and then "coarsed up" to a spatial resolution of 1.9° × 2.5° for all simulations in this study. From 2006 to 2100, hourly meteorological variables are generated from the daily corresponding meteorological variables with the same spatial resolution as CESM 1.0 (1.9° × 2.5°) (Hurrell et al, 2013 (Fleischer et al, 2019). Annual nitrogen deposition data sets are available from the atmospheric chemistry model CAM-Chem (Lamarque et al, 2012) for the period 1900-1999 and the RCP8.5 scenario for 2000-2100, with a spatial resolution of 1.9° × 2.5° (Fleischer et al, 2019).…”

“…From 2006 to 2100, hourly meteorological variables are generated from the daily corresponding meteorological variables with the same spatial resolution as CESM 1.0 (1.9° × 2.5°) (Hurrell et al, 2013 (Fleischer et al, 2019). Annual nitrogen deposition data sets are available from the atmospheric chemistry model CAM-Chem (Lamarque et al, 2012) for the period 1900-1999 and the RCP8.5 scenario for 2000-2100, with a spatial resolution of 1.9° × 2.5° (Fleischer et al, 2019).…”

Nitrogen enrichment buffers phosphorus limitation by mobilizing mineral‐bound soil phosphorus in grasslands

“…Worldwide phosphorus (P) limitations on terrestrial primary productivity can strongly constrain the ecosystem carbon sink under scenarios of human‐enhanced nitrogen (N) enrichment (Elser et al, 2007; Fleischer et al, 2019; Wieder et al, 2015). Soil mineral‐bound phosphate (P i ) accounts for up to 82% of the soil total P (TP) (Crews et al, 1995).…”

Soil prokaryotic community shows no response to 2 years of simulated nitrogen deposition in an arid ecosystem in northwestern China

“…Anthropogenic activities, such as fossil fuel combustion and agricultural practices, have considerably increased the rate of atmospheric nitrogen (N) deposition worldwide since the early 1900s (Galloway, 1995). Except for the positive effects on terrestrial carbon sequestration (Fleischer et al ., 2019), the biodiversity loss and biogeochemical cycling alteration caused by increased N deposition are threats to global ecosystem stability, functioning, and sustainability (Stevens et al ., 2004; Clark and Tilman, 2008; Zhang et al ., 2014) and projected to have a negative effect on future global climate (Etzold et al ., 2020). Although N deposition rate and frequency have started to decline in some areas in Europe (Wright et al ., 2001; Erisman et al ., 2003), the increase in N deposition has been observed in many developing countries, even in arid and semi‐arid regions (IPCC, 2014).…”