Historic nitrogen deposition determines future climate change effects on nitrogen retention in temperate forests

Abstract

Nitrogen (N) cycle processes in terrestrial ecosystems are highly sensitive to temperature and soil moisture variations. Thus, future climate change may affect the degree to which N deposited from the atmosphere will be retained in forest ecosystems. We evaluated the effect of future changes in climate and N deposition on ecosystem N cycling using the model LandscapeDNDC forced with historical data from eight long-term forest ecosystem monitoring stations in Austria and downscaled future N deposition and climate scenarios. With every 1°C of warming, annual N uptake in biomass increased by +0.03 to +0.54 kg N ha , and mean annual N leaching was between −0.09 and −2.03 kg N ha −1 lower. The magnitude of N deposition in the years from 1990 to 2010 was by far the most important determinant of the response of nitrogen cycling to future warming, including statistically significant relationships with humus N content and N leaching. We conclude that climate change will likely increase ecosystem N retention in temperate forest ecosystems, and even more so at forest sites with high past N deposition.

Light and warming drive forest understorey community development in different environments

“…This lack of interaction on the short term does not imply that such interactive effects are not important to understorey community development in response to global change. It rather shows the complementary of experimental research to long‐term vegetation resurveys (Perring, Bernhardt‐Römermann, et al, ; Perring, Diekmann, et al, ; Verstraeten et al, ) or mechanistic modelling approaches (Dirnböck et al, ; Landuyt et al, ). Long‐term experiments, vegetation resurveys and modelling are perhaps better suited to unravel such long‐term interactive effects between global change drivers on understorey communities (Luo et al, ; Verheyen et al, ).…”

Representing sub-grid scale variations in nitrogen deposition associated with land use in a global Earth system model: implications for present and future nitrogen deposition fluxes over North America

“…In the US, oxidized N deposition is projected to decrease as a result of effective controls on NO emissions, but deposition of reduced N (NH x ≡ NH 3 + NH + 4 ), primarily from agricultural emissions of NH 3 , is projected to remain elevated or even increase (Dentener et al, 2006;Ellis et al, 2013;Paulot et al, 2013;Lamarque et al, 2013;Li et al, 2016). This raises concerns of irreversible damage to sensitive biomes (Pardo et al, 2011;Meunier et al, 2016;Grizzetti, 2011;Dise, 2011), such as high-elevation lakes (Wolfe et al, 2003;Baron et al, 2012;Lepori and Keck, 2012) and organisms (e.g., lichen;Johansson et al, 2012).…”

“…Many approaches have been developed to provide high-resolution, ecosystem-relevant estimates of both wet and dry N deposition, including statistical models (Singles et al, 1998;Dore et al, 2007Dore et al, , 2012Weathers et al, 2006), a high-resolution nested chemical transport model ( 4 km × 4 km; Vieno et al, 2009;Simkin et al, 2016), and hybrid approaches that combine high-resolution regional chemical transport models with observed N fluxes and atmospheric concentrations (e.g., using the Community Multiscale Air Quality Modeling System; Schwede and Lear, 2014;Bytnerowicz et al, 2015;Williams et al, 2017). However, the elevated computational requirement associated with high-resolution atmospheric models makes such approaches impractical for assessing the long-term impact of N deposition on ecosystems, its sensitivity to climate change, and ultimately its coupling with the carbon cycle Zaehle et al, 2010;Fleischer et al, 2013;Dirnböck et al, 2017;Fleischer et al, 2015). For such questions, estimates of N deposition are generally derived from global models with coarse resolution ( 100 km; Dentener et al, 2006;Lamarque et al, 2013).…”

Reply to reviewers comments

“…In the US, oxidized N deposition is projected to decrease as a result of effective controls on NO emissions, but deposition of reduced N (NH x ≡ NH 3 + NH + 4 ), primarily from agricultural emissions of NH 3 , is projected to remain elevated or even increase (Dentener et al, 2006;Ellis et al, 2013;Paulot et al, 2013;Lamarque et al, 2013;Li et al, 2016). This raises concerns of irreversible damage to sensitive biomes (Pardo et al, 2011;Meunier et al, 2016;Grizzetti, 2011;Dise, 2011), such as high-elevation lakes (Wolfe et al, 2003;Baron et al, 2012;Lepori and Keck, 2012) and organisms (e.g., lichen;Johansson et al, 2012).…”

“…Many approaches have been developed to provide high-resolution, ecosystem-relevant estimates of both wet and dry N deposition, including statistical models (Singles et al, 1998;Dore et al, 2007Dore et al, , 2012Weathers et al, 2006), a high-resolution nested chemical transport model ( 4 km × 4 km; Vieno et al, 2009;Simkin et al, 2016), and hybrid approaches that combine high-resolution regional chemical transport models with observed N fluxes and atmospheric concentrations (e.g., using the Community Multiscale Air Quality Modeling System; Schwede and Lear, 2014;Bytnerowicz et al, 2015;Williams et al, 2017). However, the elevated computational requirement associated with high-resolution atmospheric models makes such approaches impractical for assessing the long-term impact of N deposition on ecosystems, its sensitivity to climate change, and ultimately its coupling with the carbon cycle (Smith et al, 2014;Zaehle et al, 2010;Fleischer et al, 2013;Dirnböck et al, 2017;Fleischer et al, 2015). For such questions, estimates of N deposition are generally derived from global models with coarse resolution ( 100 km; Dentener et al, 2006;Lamarque et al, 2013).…”