Growth Responses of C4Grasses of Contrasting Origin to Elevated CO2

Kellogg, Elizabeth A.; Farnsworth, Elizabeth J.; Russo, Elizabeth T.; Bazzaz, F. A.

doi:10.1006/anbo.1999.0899

Cited by 16 publications

(9 citation statements)

References 43 publications

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“…Integrating functional traits into SEFs and SRFs is valuable because analogous – as opposed to truly homologous – traits may function in subtly different ways (Pausas et al 2004), producing different SEF or SRF values. For example, although C4 grasses are commonly treated as a single functional type, members of separately evolved lineages of C4 grasses have different SRFs in the face of elevated CO 2 (Kellogg et al 1999). Similarly, levels of carbonic anhydrase vary considerably among C4 plants, which therefore have different potential to contribute to global carbon flux, an SEF (Gillon and Yakir 2001; Edwards et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Functional traits, the phylogeny of function, and ecosystem service vulnerability

Dı́az

Purvis

Cornelissen³

et al. 2013

Ecology and Evolution

476

419

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People depend on benefits provided by ecological systems. Understanding how these ecosystem services – and the ecosystem properties underpinning them – respond to drivers of change is therefore an urgent priority. We address this challenge through developing a novel risk-assessment framework that integrates ecological and evolutionary perspectives on functional traits to determine species’ effects on ecosystems and their tolerance of environmental changes. We define Specific Effect Function (SEF) as the per-gram or per capita capacity of a species to affect an ecosystem property, and Specific Response Function (SRF) as the ability of a species to maintain or enhance its population as the environment changes. Our risk assessment is based on the idea that the security of ecosystem services depends on how effects (SEFs) and tolerances (SRFs) of organisms – which both depend on combinations of functional traits – correlate across species and how they are arranged on the species’ phylogeny. Four extreme situations are theoretically possible, from minimum concern when SEF and SRF are neither correlated nor show a phylogenetic signal, to maximum concern when they are negatively correlated (i.e., the most important species are the least tolerant) and phylogenetically patterned (lacking independent backup). We illustrate the assessment with five case studies, involving both plant and animal examples. However, the extent to which the frequency of the four plausible outcomes, or their intermediates, apply more widely in real-world ecological systems is an open question that needs empirical evidence, and suggests a research agenda at the interface of evolutionary biology and ecosystem ecology.

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Section: Discussionmentioning

confidence: 99%

Functional traits, the phylogeny of function, and ecosystem service vulnerability

Dı́az

Purvis

Cornelissen³

et al. 2013

Ecology and Evolution

476

419

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“…Previous studies have suggested that annual plants may be more responsive to elevated CO 2 levels than perennial plants (Zangerl & Bazzaz, 1984;Smith et al, 1987). NADP-ME C 4 grasses, which include D. sanguinalis, can have stronger responses to elevated CO 2 than other subtypes, but results have been mixed in the small number of species that have been examined (LeCain & Morgan, 1998;Kellog et al, 1999). A larger comparison of the effects of elevated CO 2 on the carbohydrate composition of C 4 annual and perennial NADP-ME and NAD-ME species is needed to examine these patterns further.…”

Section: Discussionmentioning

confidence: 99%

C₃ grasses have higher nutritional quality than C₄ grasses under ambient and elevated atmospheric CO₂

Barbehenn

Chen

Karowe

et al. 2004

Global Change Biology

164

128

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Grasses with the C 3 photosynthetic pathway are commonly considered to be more nutritious host plants than C 4 grasses, but the nutritional quality of C 3 grasses is also more greatly impacted by elevated atmospheric CO 2 than is that of C 4 grasses; C 3 grasses produce greater amounts of nonstructural carbohydrates and have greater declines in their nitrogen content than do C 4 grasses under elevated CO 2 . Will C 3 grasses remain nutritionally superior to C 4 grasses under elevated CO 2 levels? We addressed this question by determining whether levels of protein in C 3 grasses decline to similar levels as in C 4 grasses, and whether total carbohydrate : protein ratios become similar in C 3 and C 4 grasses under elevated CO 2 . In addition, we tested the hypothesis that, among the nonstructural carbohydrates in C 3 grasses, levels of fructan respond most strongly to elevated CO 2 . Five C 3 and five C 4 grass species were grown from seed in outdoor opentop chambers at ambient (370 ppm) or elevated (740 ppm) CO 2 for 2 months. As expected, a significant increase in sugars, starch and fructan in the C 3 grasses under elevated CO 2 was associated with a significant reduction in their protein levels, while protein levels in most C 4 grasses were little affected by elevated CO 2 . However, this differential response of the two types of grasses was insufficient to reduce protein in C 3 grasses to the levels in C 4 grasses. Although levels of fructan in the C 3 grasses tripled under elevated CO 2 , the amounts produced remained relatively low, both in absolute terms and as a fraction of the total nonstructural carbohydrates in the C 3 grasses. We conclude that C 3 grasses will generally remain more nutritious than C 4 grasses at elevated CO 2 concentrations, having higher levels of protein, nonstructural carbohydrates, and water, but lower levels of fiber and toughness, and lower total carbohydrate : protein ratios than C 4 grasses.

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“…The lack of and even the negative response to high CO 2 is still poorly understood. Several explanations have been proposed for this growth depression: (1) either photosynthetic acclimation or downregulation (Lecain and Morgan 1998; Ziska et al 1999;Poorter and Navas 2003) or (2) internal regulatory changes related to accumulation of end products which inhibit carbon fixation due to reduced sink strength in the slow growing grasses (Roumet and Roy 1996;Kellogg et al 1999;Wand et al 1999;Poorter and Navas 2003). Also, it has been attempted to attribute differences in CO 2 response among grasses to phylogeny and climate (Taub 2000) but this seems not appropriate here.…”

Section: Gas Exchangementioning

confidence: 93%

Responses of tropical native and invader C4 grasses to water stress, clipping and increased atmospheric CO2 concentration

Baruch

Jackson

2005

Oecologia

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The invasion of African grasses into Neotropical savannas has altered savanna composition, structure and function. The projected increase in atmospheric CO(2) concentration has the potential to further alter the competitive relationship between native and invader grasses. The objective of this study was to quantify the responses of two populations of a widespread native C(4) grass (Trachypogon plumosus) and two African C(4) grass invaders (Hyparrhenia rufa and Melinis minutiflora) to high CO(2) concentration interacting with two primary savanna stressors: drought and herbivory. Elevated CO(2) increased the competitive potential of invader grasses in several ways. Germination and seedling size was promoted in introduced grasses. Under high CO(2), the relative growth rate of young introduced grasses was twice that of native grass (0.58 g g(-1) week(-1) vs 0.25 g g(-1) week(-1)). This initial growth advantage was maintained throughout the course of the study. Well-watered and unstressed African grasses also responded more to high CO(2) than did the native grass (biomass increases of 21-47% compared with decreases of 13-51%). Observed higher water and nitrogen use efficiency of invader grasses may aid their establishment and competitive strength in unfertile sites, specially if the climate becomes drier. In addition, high CO(2) promoted lower leaf N content more in the invader grasses. The more intensive land use, predicted to occur in this region, may interact with high CO(2) to favor the African grasses, as they generally recovered faster after simulated herbivory. The superiority of invader grasses under high CO(2) suggests further increases in their competitive strength and a potential increased rate of displacement of the native savannas in the future by grasslands dominated by introduced African species.

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Growth Responses of C4Grasses of Contrasting Origin to Elevated CO2

Cited by 16 publications

References 43 publications

Functional traits, the phylogeny of function, and ecosystem service vulnerability

Functional traits, the phylogeny of function, and ecosystem service vulnerability

C₃ grasses have higher nutritional quality than C₄ grasses under ambient and elevated atmospheric CO₂

Responses of tropical native and invader C4 grasses to water stress, clipping and increased atmospheric CO2 concentration

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Growth Responses of C4Grasses of Contrasting Origin to Elevated CO2

Cited by 16 publications

References 43 publications

Functional traits, the phylogeny of function, and ecosystem service vulnerability

Functional traits, the phylogeny of function, and ecosystem service vulnerability

C3 grasses have higher nutritional quality than C4 grasses under ambient and elevated atmospheric CO2

Responses of tropical native and invader C4 grasses to water stress, clipping and increased atmospheric CO2 concentration

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C₃ grasses have higher nutritional quality than C₄ grasses under ambient and elevated atmospheric CO₂