Nitrogen productivity and allocation responses of 12 important tree species to increased CO2

Abstract

Key message This paper provides responses in nitrogen productivities for 12 important tree species to elevated CO 2. Abstract The increasing atmospheric carbon dioxide concentration is expected to increase plant productivity. However, the strength of the response depends on the interaction with other limiting factors, of which nitrogen has been identified as one of the most important. This study analyzed the effects of increasing the CO 2 concentration from 380 ppm (ambient) to 1000 ppm (elevated) on nitrogen productivity (incl. biomass allocation and nutrient concentration of plant organs) in nine deciduous and three conifer tree species. No clear effects on biomass allocation were observed, but leaf nitrogen concentration decreased. Nitrogen productivity increased by 28% over all species, with the strongest response in deciduous trees (34%) and the weakest in conifers (8%). Although these changes are statistically not significant, we conclude that nitrogen productivity provides an integrative and robust concept to assess the effect CO 2 fertilization effects on tree growth under varying nitrogen availability, while more studies are required to firmly establish the magnitude of the response.

Patterns of plant carbon, nitrogen, and phosphorus concentration in relation to productivity in China’s terrestrial ecosystems

“…Annual GPP (i.e., stand-level photosynthesis) increased with both leaf N (R 2 = 0.20, P < 0.001 for a power relationship) and P (R 2 = 0.11, P < 0.001) content, consistent with previous studies at the leaf or stand level (35,36). However, the relationship was not consistent for the different biomes.…”

“…5). These results show that climate regulates plant productivity in terms of LNP and LPP and that, with unbalanced N and P deposition (7) or even without additional N or P, global warming may enhance GPP in China's terrestrial ecosystems via increasing LNP or LPP (36). Potential Applications.…”

Nitrogen Availability Dampens the Positive Impacts of CO2 Fertilization on Terrestrial Ecosystem Carbon and Water Cycles

“…Nutrient limitation, particularly plant available nitrogen (N), has been hypothesized to limit the projected C sink enhancing mechanisms under climate change and CO 2 fertilization. While there is less debate on the increased plant productivity under elevated CO 2 (Ainsworth & Long, 2005;Leakey et al, 2009;Norby et al, 2005Norby et al, , 2010Nowak et al, 2004), many studies found that leaf N, and therefore leaf chlorophyll content, are reduced with increasing CO 2 concentration accompanying the increased sequestration of N in long-lived biomass (Ågren & Kattge, 2017;Campo, 2016;Cotrufo et al, 1998;Fisher et al, 2013;Pellegrini, 2016;Reich et al, 2006), especially for young stands (LeBauer & Treseder, 2008), and tropical secondary forests (Davidson et al, 2007(Davidson et al, , 2004. As a result, potential increases in grass (Obermeier et al, 2016;Reich et al, 2014) and forest (Norby et al, 2010) productivity due to CO 2 fertilization are hampered by N limitation (Franklin et al, 2014).…”

Increased atmospheric CO2 changes the photosynthetic responses of Acrocomia aculeata (Arecaceae) to drought

“…The higher photosynthetic responses linked to stomatal control in macauba palm leaves under water stress and [CO 2 ]700 indicate no down-regulation of photosynthesis as commonly reported (Ainsworth & Long 2005;Leakey et al 2009;Córdoba et al 2017). In general, the stimulation of photosynthesis may cease partially or totally due to negative feedback effects, but the implications of exposure to high [CO 2 ] on trees are less clear compared to the responses of herbaceous species (Poorter & Navas 2003;Way et al 2015;Ågren & Kattge 2017). In most plant species, stomatal apertures shorten after exposure to high [CO 2 ], which, together with TPU limitation, might contribute to downward acclimation of photosynthesis after plants are exposed to high [CO 2 ] (Ainsworth & Rogers 2007).…”