The nitrogen budget of a pine forest under free air CO2 enrichment

Finzi, Adrien C.; DeLucia, Evan H.; Hamilton, Jason G.; Richter, Daniel D.; Schlesinger, William H.

doi:10.1007/s00442-002-0996-3

Cited by 166 publications

(164 citation statements)

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“…Nevertheless, the estimated nitrogen productivities are in line with values reported previously (Å gren and Bosatta 1998) and the responses to CO 2 are in line with other studies (Table 1). The increase caused by increased CO 2 was higher than the 12% calculated in the DUKE FACE experiment (Finzi et al 2002). However, in the latter experiment there was a steady decline from 20 to 4% in the response over the four years of the experiment.…”

Section: Discussionmentioning

confidence: 60%

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

Ågren

Kattge

2016

Trees

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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.

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Section: Discussionmentioning

confidence: 60%

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

Ågren

Kattge

2016

Trees

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“…At the DukeFACE, a wide range of response to CO 2 enrichment across replicate plots correlated with differences in soil N availability. Under low N availability, CO 2 enrichment increased NPP by 19%, whereas under intermediate and high N availability the percent CO 2 stimulation was 27% (36). Where soils are poor or prolonged water limitation occurs, represented only through within-site variation in our dataset, forests may have limited capacity to support any response to CO 2 enrichment (37).…”

Section: Discussionmentioning

confidence: 96%

Forest response to elevated CO₂is conserved across a broad range of productivity

Norby

DeLucia

Gielen

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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921

746

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Climate change predictions derived from coupled carbon-climate models are highly dependent on assumptions about feedbacks between the biosphere and atmosphere. One critical feedback occurs if C uptake by the biosphere increases in response to the fossil-fuel driven increase in atmospheric [CO 2] (''CO2 fertilization''), thereby slowing the rate of increase in atmospheric [CO 2]. Carbon exchanges between the terrestrial biosphere and atmosphere are often first represented in models as net primary productivity (NPP). However, the contribution of CO 2 fertilization to the future global C cycle has been uncertain, especially in forest ecosystems that dominate global NPP, and models that include a feedback between terrestrial biosphere metabolism and atmospheric [CO 2] are poorly constrained by experimental evidence. We analyzed the response of NPP to elevated CO 2 (Ϸ550 ppm) in four free-air CO 2 enrichment experiments in forest stands. We show that the response of forest NPP to elevated [CO 2] is highly conserved across a broad range of productivity, with a stimulation at the median of 23 ؎ 2%. At low leaf area indices, a large portion of the response was attributable to increased light absorption, but as leaf area indices increased, the response to elevated [CO 2] was wholly caused by increased light-use efficiency. The surprising consistency of response across diverse sites provides a benchmark to evaluate predictions of ecosystem and global models and allows us now to focus on unresolved questions about carbon partitioning and retention, and spatial variation in NPP response caused by availability of other growth limiting resources.CO2 fertilization ͉ global change ͉ leaf area index ͉ net primary productivity A nalysis and prediction of the effects of human activities, particularly the combustion of fossil fuels, on climate and the biological, physical, and social responses to changing climate require an integrated view of the complex interactions between the biosphere and atmosphere. Carbon cycle models are now being coupled to atmosphere-ocean general circulation climate models to achieve a dynamic analysis of the relationships between C emissions, atmospheric chemistry, biosphere activity, and climatic change (1-3).Exchanges between the terrestrial biosphere and atmosphere are represented in models using empirical and theoretical expressions of net primary productivity (NPP), the net fixation of C by green plants into organic matter, or the difference between photosynthesis and plant respiration. Because the photosynthetic uptake of carbon that drives NPP is not saturated at current atmospheric concentrations (4), NPP should increase as fossilfuel combustion adds to the atmospheric [CO 2 ]. Increased C uptake into the biosphere in response to rising [CO 2 ] (''CO 2 fertilization'') can create a negative feedback that slows the rate of increase in atmospheric [CO 2 ] (3, 5). Hence, assumptions regarding CO 2 fertilization of the terrestrial biosphere greatly affect predictions of future atmospheric [CO 2 ] (3)...

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“…Nitrogen availability determines plant responses to elevated CO 2 concentrations more than any other environmental factor (52,53), but ecosystems show a broad range of responses to elevated CO 2 concentrations, possibly as a result of the seasonal and spatial fluctuations in the relative availabilities of NH 4 ϩ and NO 3 Ϫ . For instance, ecosystems in which NH 4 ϩ is the dominant nitrogen form, such as pine forests (54) or wetlands (55), show a relatively large increase (Ϸ25%) in net primary productivity under CO 2 enrichment, whereas ecosystems in which NO 3 Ϫ is dominant, such as grasslands (56) or wheat fields, at standard fertilizer levels (low fertilizer treatment at Maricopa, AZ; ref. 57) show declines in net primary productivity under CO 2 enrichment.…”

Section: Discussionmentioning

confidence: 99%

Nitrate assimilation in plant shoots depends on photorespiration

Rachmilevitch

Cousins

Bloom

2004

Proc. Natl. Acad. Sci. U.S.A.

285

210

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Photorespiration, a process that diminishes net photosynthesis by Ϸ25% in most plants, has been viewed as the unfavorable consequence of plants having evolved when the atmosphere contained much higher levels of carbon dioxide than it does today. Here we used two independent methods to show that exposure of Arabidopsis and wheat shoots to conditions that inhibited photorespiration also strongly inhibited nitrate assimilation. Thus, nitrate assimilation in both dicotyledonous and monocotyledonous species depends on photorespiration. This previously undescribed role for photorespiration (i) explains several responses of plants to rising carbon dioxide concentrations, including the inability of many plants to sustain rapid growth under elevated levels of carbon dioxide; and (ii) raises concerns about genetic manipulations to diminish photorespiration in crops.global climate change ͉ CO2 acclimation ͉ Arabidopsis ͉ wheat R ubisco, the most prevalent protein in plants, indeed in the biosphere, catalyzes the reaction of ribulose-1,5-bisphosphate with either CO 2 or O 2 and thereby initiates, respectively, the CO 2 assimilatory (C 3 reductive) or photorespiratory (C 2 oxidative) pathways. The balance between the two reactions depends on the relative concentrations of CO 2 and O 2 at the site of catalysis. At current atmospheric levels of CO 2 (Ϸ360 mol⅐mol Ϫ1 ) and O 2 (Ϸ209,700 mol⅐mol Ϫ1 ), photorespiration in C 3 plants dissipates Ͼ25% of the carbon fixed during CO 2 assimilation (1). Thus, photorespiration has been viewed as a wasteful process, a vestige of the high CO 2 atmospheres under which plants evolved (2). At best, according to current thought, photorespiration may mitigate photoinhibition under high light and drought stress (2, 3) or may generate amino acids such as glycine for other metabolic pathways (4). Genetic modification of Rubisco to minimize photorespiration in crop plants has been the goal of many investigations (5).Atmospheric CO 2 concentrations will rise to somewhere between 600 and 1,000 mol⅐mol Ϫ1 by the end of the 21st century (6). Transferring C 3 plants from ambient (Ϸ360 mol⅐mol Ϫ1 ) to elevated (Ϸ720 mol⅐mol Ϫ1 ) CO 2 concentrations decreases photorespiration and initially stimulates net CO 2 assimilation and growth by Ϸ30% (7). With longer exposures to elevated CO 2 concentrations (days to weeks), however, net CO 2 assimilation and plant growth slow down until they stabilize at rates that average 12% (8) and 8% (9), respectively, above those of plants kept at ambient CO 2 concentrations. This phenomenon, known as CO 2 acclimation, is often associated with diminished activities of Rubisco and other enzymes in the C 3 reductive photosynthetic carbon cycle (10, 11), but the influence of elevated CO 2 may not be specific to these enzymes (12). Rather, CO 2 acclimation follows a 14% decline in overall shoot nitrogen concentrations (13), a change nearly double what would be expected if a given amount of nitrogen were diluted by the additional biomass that accumulates under elevated CO 2 conce...

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The nitrogen budget of a pine forest under free air CO2 enrichment

Cited by 166 publications

References 64 publications

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

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

Forest response to elevated CO₂is conserved across a broad range of productivity

Nitrate assimilation in plant shoots depends on photorespiration

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The nitrogen budget of a pine forest under free air CO2 enrichment

Cited by 166 publications

References 64 publications

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

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

Forest response to elevated CO2is conserved across a broad range of productivity

Nitrate assimilation in plant shoots depends on photorespiration

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Forest response to elevated CO₂is conserved across a broad range of productivity