Ecosystem response to elevated CO2 levels limited by nitrogen-induced plant species shift (original) (raw)
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Plant diversity enhances ecosystem responses to elevated CO 2 and nitrogen deposition
Nature, 2001
Human actions are causing declines in plant biodiversity, increases in atmospheric CO2 concentrations and increases in nitrogen deposition; however, the interactive effects of these factors on ecosystem processes are unknown. Reduced biodiversity has raised numerous concerns, including the possibility that ecosystem functioning may be affected negatively, which might be particularly important in the face of other global changes. Here we present results of a grassland field experiment in Minnesota, USA, that tests the hypothesis that plant diversity and composition influence the enhancement of biomass and carbon acquisition in ecosystems subjected to elevated atmospheric CO2 concentrations and nitrogen deposition. The study experimentally controlled plant diversity (1, 4, 9 or 16 species), soil nitrogen (unamended versus deposition of 4 g of nitrogen per m2 per yr) and atmospheric CO2 concentrations using free-air CO2 enrichment (ambient, 368 micromol mol-1, versus elevated, 560 micromol mol-1). We found that the enhanced biomass accumulation in response to elevated levels of CO2 or nitrogen, or their combination, is less in species-poor than in species-rich assemblages.
2015
The Earth’s atmosphere will continue to be enriched with carbon dioxide (CO2) over the coming century. Carbon dioxide enrichment often reduces leaf transpiration, which in water-limited ecosystems may increase soil water content, change species abundances and increase the productivity of plant communities. The effect of increased soil water on community productivity and community change may be greater in ecosystems with lower precipitation, or on coarsertextured soils, but responses are likely absent in deserts. We tested correlations among yearly increases in soil water content, community change and community plant productivity responses to CO2 enrichment in experiments in a mesic grassland with fineto coarse-textured soils, a semi-arid grassland and a xeric shrubland. We found no correlation between CO2-caused changes in soil water content and changes in biomass of dominant plant taxa or total community aboveground biomass in either grassland type or on any soil in the mesic grass...
Nitrogen limitation constrains sustainability of ecosystem response to CO2
Nature, 2006
Enhanced plant biomass accumulation in response to elevated atmospheric CO 2 concentration could dampen the future rate of increase in CO 2 levels and associated climate warming. However, it is unknown whether CO 2 -induced stimulation of plant growth and biomass accumulation will be sustained or whether limited nitrogen (N) availability constrains greater plant growth in a CO 2 -enriched world 1-9 . Here we show, after a six-year field study of perennial grassland species grown under ambient and elevated levels of CO 2 and N, that low availability of N progressively suppresses the positive response of plant biomass to elevated CO 2 . Initially, the stimulation of total plant biomass by elevated CO 2 was no greater at enriched than at ambient N supply. After four to six years, however, elevated CO 2 stimulated plant biomass much less under ambient than enriched N supply. This response was consistent with the temporally divergent effects of elevated CO 2 on soil and plant N dynamics at differing levels of N supply.
Links across ecological scales: Plant biomass responses to elevated CO 2
Global Change Biology
The degree to which elevated CO 2 concentrations (e[CO 2 ]) increase the amount of carbon (C) assimilated by vegetation plays a key role in climate change. However, due to the short-term nature of CO 2 enrichment experiments and the lack of reconciliation between different ecological scales, the effect of e[CO 2 ] on plant biomass stocks remains a major uncertainty in future climate projections. Here, we review the effect of e[CO 2 ] on plant biomass across multiple levels of ecological organization, scaling from physiological responses to changes in population-, community-, ecosystem-, and global-scale dynamics. We find that evidence for a sustained biomass response to e[CO 2 ] varies across ecological scales, leading to diverging conclusions about the responses of individuals, populations, communities, and ecosystems. While the distinct focus of every scale reveals new mechanisms driving biomass accumulation under e[CO 2 ], none of them provides a full picture of all relevant processes. For example, This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Progressive Nitrogen Limitation of Ecosystem Responses to Rising Atmospheric Carbon Dioxide
BioScience, 2004
A t the onset of the industrial revolution in the 18th century, global pCO 2 , or partial pressure of atmospheric carbon dioxide (CO 2), began rising from approximately 27 pascals (Pa) to its current value of 37 Pa. The current pCO 2 is higher than at any time during the last 400,000 years. With the accelerating rate of increase of atmospheric CO 2 , we expect the global pCO 2 to reach 70 Pa by the end of the 21st century. According to predictions presented in the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2001), this CO 2 increase alone could enhance the net primary production (NPP) of Earth's ecosystems enough to increase carbon (C) sequestration by 350 to 890 petagrams (Pg) C in the 21st century (1 Pg = 10 15 grams [g]). To what extent soil nitrogen (N) availability will constrain the predicted C sequestration, however, is still an open question. This question has ramifications for the future of terrestrial ecosystem productivity, atmospheric CO 2 concentration, and resulting feedbacks on climate (Hungate et al. 2003). Experimental studies have examined N constraints on ecosystem C uptake in response to global change, primarily focusing on soil N availability and its regulation of photosynthesis and plant growth. Soil N availability has been found to decrease as a result of reduced decomposability of litter and to increase as a result of increased soil C substrate (Zak et al. 1993) and soil moisture (Hungate 1999) under elevated CO 2. Measures that are often used to assess whether plants or whole ecosystems are limited by soil N availability include
Species-specific responses of plant communities to altered carbon and nutrient availability
Global Change Biology, 2001
In a ®eld microcosm experiment, species-speci®c responses of aboveground biomass of two California annual grassland communities to elevated CO 2 and nutrient availability were investigated. One community grows on shallow, nutrient-poor serpentinederived soil whereas the other occurs on deeper, modestly fertile sandstone/greenstone-derived substrate. In most species, CO 2 effects did not appear until late in the growing season, probably because the elevated CO 2 increased water-use-ef®ciency easing, the onset of the summer drought. Responses of aboveground biomass to elevated CO 2 differed depending on nutrient availability. Similarly, biomass responses to nutrient treatments differed depending on the CO 2 status. For the majority of the species, production increased most under elevated CO 2 with added nutrients (N,P,K, and micro nutrients). Some species were losers under conditions that increased overall community production, including Bromus hordeaceus in the serpentine community (negative biomass response under elevated CO 2 ) and Lotus wrangelianus in both communities (negative biomass response with added nitrogen). Treatment and competitive effects on species-speci®c biomass varied in both magnitude and direction, especially in the serpentine community, signi®cantly affecting community structure. Individual resource environments are likely to be affected by neighbouring plants, and these competitive interactions complicate predictions of species' responses to elevated CO 2 .
Annual Review of Ecology, Evolution, and Systematics, 2006
Interactions involving carbon (C) and nitrogen (N) likely modulate terrestrial ecosystem responses to elevated atmospheric carbon dioxide (CO 2 ) levels at scales from the leaf to the globe and from the second to the century. In particular, response to elevated CO 2 may generally be smaller at low relative to high soil N supply and, in turn, elevated CO 2 may influence soil N processes that regulate N availability to plants. Such responses could constrain the capacity of terrestrial ecosystems to acquire and store C under rising elevated CO 2 levels. This review highlights the theory and empirical evidence behind these potential interactions. We address effects on photosynthesis, primary production, biogeochemistry, trophic interactions, and interactions with other resources and environmental factors, focusing as much as possible on evidence from long-term field experiments.
Plant community feedbacks and long-term ecosystem responses to multi-factored global change
AoB plants, 2014
While short-term plant responses to global change are driven by physiological mechanisms, which are represented relatively well by models, long-term ecosystem responses to global change may be determined by shifts in plant community structure resulting from other ecological phenomena such as interspecific interactions, which are represented poorly by models. In single-factor scenarios, plant communities often adjust to increase ecosystem response to that factor. For instance, some early global change experiments showed that elevated CO2 favours plants that respond strongly to elevated CO2, generally amplifying the response of ecosystem productivity to elevated CO2, a positive community feedback. However, most ecosystems are subject to multiple drivers of change, which can complicate the community feedback effect in ways that are more difficult to generalize. Recent studies have shown that (i) shifts in plant community structure cannot be reliably predicted from short-term plant phys...
Plant Biodiversity and Responses to Elevated Carbon Dioxide
Global Change — The IGBP Series
The general assumption, in the first phase of elevated carbon dioxide (CO 2) research, was that increasing atmospheric CO 2 concentration would act as a fertilizer for plant systems. Under this "large-plant-scenario" (Fig. 9.1), increased photosynthesis at elevated CO 2 would lead to higher plant biomass which would induce a negative atmospheric feedback loop that would offset anthropogenic carbon (C) emissions. A second general assumption in early research was that the effects of elevated CO 2 on plant community structure could be predicated using a C-based perspective with clear "winners" and "losers" based on species' ability to take advantage of the increased atmospheric CO 2 concentration (e.g., plant with C 3 vs. C 4 photosynthetic pathways). The reality unveiled by a decade of research proved more complex and the "large plant scenario" largely untenable. 9.1.1 Effects of CO 2 on Plant Diversity Through Alterations of the Physical Environment