Growth and survival relationships of 71 tree species with nitrogen and sulfur deposition across the conterminous U.S.

Abstract

Atmospheric deposition of nitrogen (N) influences forest demographics and carbon (C) uptake through multiple mechanisms that vary among tree species. Prior studies have estimated the effects of atmospheric N deposition on temperate forests by leveraging forest inventory measurements across regional gradients in deposition. However, in the United States (U.S.), these previous studies were limited in the number of species and the spatial scale of analysis, and did not include sulfur (S) deposition as a potential covariate. Here, we present a comprehensive analysis of how tree growth and survival for 71 species vary with N and S deposition across the conterminous U.S. Our analysis of 1,423,455 trees from forest plots inventoried between 2000 and 2016 reveals that the growth and/or survival of the vast majority of species in the analysis (n = 66, or 93%) were significantly affected by atmospheric deposition. Species co-occurred across the conterminous U.S. that had decreasing and increasing relationships between growth (or survival) and N deposition, with just over half of species responding negatively in either growth or survival to increased N deposition somewhere in their range (42 out of 71). Averaged across species and conterminous U.S., however, we found that an increase in deposition above current rates of N deposition would coincide with a small net increase in tree growth (1.7% per Δ kg N ha-1 yr-1), and a small net decrease in tree survival (-0.22% per Δ kg N ha-1 yr-1), with substantial regional and among-species variation. Adding S as a predictor improved the overall model performance for 70% of the species in the analysis. Our findings have potential to help inform ecosystem management and air pollution policy across the conterminous U.S., and suggest that N and S deposition have likely altered forest demographics in the U.S.

Higher CO2 Concentrations and Lower Acidic Deposition Have Not Changed Drought Response in Tree Growth But Do Influence iWUE in Hardwood Trees in the Midwestern United States

“…Acidic deposition has decreased in recent decades in the Midwest and this could have resulted in an increase in tree growth (Engel et al, ; Kosiba et al, ; Mathias & Thomas, ; Thomas et al, ), although other studies have shown little to no impact on growth (Bishop et al, ; Schaberg et al, ). Further, nitrogen deposition can act as a fertilizer to increase carbon storage of trees (Horn et al, ; Thomas et al, ) . However, the ability of nitrogen deposition to increase growth appears modest (Caspersen et al, ; Hyvönen et al, ; Ollinger et al, ; Walker et al, ).…”

A Spatially Explicit, Empirical Estimate of Tree‐Based Biological Nitrogen Fixation in Forests of the United States

“…Though there is no clear evidence that human activities disfavor BNF, changes in N deposition, atmospheric CO 2 concentration, and land use could enhance or limit BNF. Recent work (Horn et al, ) did not find evidence that the growth or mortality of N‐fixers is more sensitive to N deposition than nonfixers so it is unlikely that N deposition drove down abundance of N‐fixing trees. N‐fixing trees perform well in elevated CO 2 environments (Terrer et al, ).…”

“…To get the average BNF rate on a per ground area basis (kg N ha·ground −1 ·yr −1 ) we took the average N fixed across all plots in the grid cell and multiplied by the fraction of ground covered by forest (equation (1d)). The area of forest within the grid cell was obtained from U.S. FIA land cover maps (USGS, 2000) processed in R using the raster (Hijmans, 2017) and sp (Pebesma & Bivand, 2005) packages.…”

Long- and Short-Term Inorganic Nitrogen Runoff from a Karst Catchment in Austria

“…N retention in trees only decreases beyond a certain level of N deposition while it increases at lower levels [21][22][23]. Since the deposition of N is in the range of expected growth reduction in European beech and Norway spruce [22], the dominating tree species at Zöbelboden, we expected such an effect.…”