Effects of elevated CO2 and N on tree–grass interactions: an experimental test using Fraxinus excelsior and Dactylis glomerata

Bloor, Juliette; Barthes, Laure; Leadley, Paul

doi:10.1111/j.1365-2435.2008.01390.x

Cited by 22 publications

(23 citation statements)

References 72 publications

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“…Furthermore, the addition of nutrients increased the relative difference in mass and height between those seedlings exposed to grass competitor and those grown without a competitor. These results support the notion that competitive importance of the herbaceous layer increases along soil fertility gradients (Bloor, Barthes, & Leadley 2008). This may reflect the reported shift from root‐to‐shoot competition when light becomes a limiting factor under increased grass growth, due to the asymmetry of an established grass clump vs. that of a seedling.…”

Section: Discussionsupporting

confidence: 89%

“…Woody species are generally regarded as ineffective competitors for below‐ground resources when establishing. In particular, grass neighbours are known to induce large reductions in woody seedling growth (Aerts, Boot, & van der Aart 1991; Wilson 1998; Nano & Clarke 2009), and increasing soil fertility reinforces the competitive superiority of grass vegetation (Aerts, Boot, & van der Aart 1991; Bloor, Barthes, & Leadley 2008). In fire‐prone ecosystems, seedlings of both facultative resprouters and non‐resprouting species initially escape the competitive effect of neighbours by rapid germination and establishment.…”

Section: Introductionmentioning

confidence: 99%

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Trade‐offs in resource allocation that favour resprouting affect the competitive ability of woody seedlings in grassy communities

Clarke¹,

Knox

2009

Journal of Ecology

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Summary1. Differences in the competitive ability of plant functional groups at early life-history stages can have important consequences for community structure. In particular, trade-offs in allocation to roots by woody plant seedlings may influence competitive ability with grasses in fire-prone vegetation.2. We followed post-fire survival of seedlings of facultative resprouter and obligate seeder (firekilled) shrubs for 3 years in adjacent communities with a grassy ⁄ graminoid ground stratum (54 plots, 20 m 2 ) or a non-graminoid ground stratum (54 plots, 20 m 2 ). 3. The competitive effect of a grass (Poa) on seedlings of three congeneric pairs of resprouters and obligate seeder shrubs was tested in a factorial experiment where nutrients and the grass competitor were manipulated. The effects of grass ( +,)) and nutrients ( +,)) on the growth response, biomass allocation and root carbohydrate storage were measured after harvest at 26 weeks and the relative neighbour effect calculated. 4. Post-fire shrub seedling survival was high with about 50% (2163 seedlings) surviving over 3 years, but this varied between habitats and functional groups. In the grassy ⁄ graminoid ground layer communities 27% of shrub seedlings survived, whereas in the habitats with a more open ground stratum 55% of seedlings survived. In grassy habitats, obligate seeder survival was lower (23% survival) than that of resprouter seedlings (35% survival). Similarly, in open habitats, obligate seeder seedling survival was lower (51%) than that of resprouter seedlings (64% survival). 5. Growth of both resprouters and obligate seeders in our manipulative experiment was strongly reduced in the presence of a grass competitor. Moreover, the addition of nutrients increased the relative difference in mass and height between those seedlings exposed to a grass competitor and those grown without a competitor. Resprouter species allocated more to roots under competition and were less affected by grass competition than obligate seeders. 6. Synthesis. The results of seedling survival and of the experiment on the effects of grass competition on woody plant seedlings suggest that early life-history trade-offs in allocation influence seedling survival. Allocation to resprouting appears to enhance the ability of shrub seedlings to survive grass competition. We propose that grass competition across productivity gradients plays an important role in influencing landscape-level distribution patterns of woody resprouters.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Trade‐offs in resource allocation that favour resprouting affect the competitive ability of woody seedlings in grassy communities

Clarke¹,

Knox

2009

Journal of Ecology

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“…The elevated CO 2 concentration corresponds to the intermediary IPCC projections at the horizon 2050 (Stocker 2014), whereas the N addition (equivalent to 100 kg N ha −1 ) is in line with local fertiliser practices (Bloor, Barthes and Leadley 2008). Each mesocosm consisted of a PVC pot (15 × 20 × 50 cm) filled with soil from a nearby grassland (pH = 8.5, 2.46 g C kg −1 , organic matter content 4.26 g kg −1 , 0.23 g N kg −1 , cation exchange capacity 1.81 cmol kg −1 ).…”

Section: Experimental Designmentioning

confidence: 89%

Short-term responses and resistance of soil microbial community structure to elevated CO2 and N addition in grassland mesocosms

Simonin

Nunan

Bloor

et al. 2017

FEMS Microbiology Letters

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One sentence summary: Elevated CO2 alone or in combination with N addition does not affect soil microbial community structure in grassland mesocosms. Editor: Juan Imperial ABSTRACT Nitrogen (N) addition is known to affect soil microbial communities, but the interactive effects of N addition with other drivers of global change remain unclear. The impacts of multiple global changes on the structure of microbial communities may be mediated by specific microbial groups with different life-history strategies. Here, we investigated the combined effects of elevated CO 2 and N addition on soil microbial communities using PLFA profiling in a short-term grassland mesocosm experiment. We also examined the linkages between the relative abundance of r-and K-strategist microorganisms and resistance of the microbial community structure to experimental treatments. N addition had a significant effect on microbial community structure, likely driven by concurrent increases in plant biomass and in soil labile C and N. In contrast, microbial community structure did not change under elevated CO 2 or show significant CO 2 × N interactions. Resistance of soil microbial community structure decreased with increasing fungal/bacterial ratio, but showed a positive relationship with the Gram-positive/Gram-negative bacterial ratio. Our findings suggest that the Grampositive/Gram-negative bacteria ratio may be a useful indicator of microbial community resistance and that K-strategist abundance may play a role in the short-term stability of microbial communities under global change.

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“…While shoot competition alone did not affect seedling growth, root competition reduced the mass of seedlings by 58% and height of ash by c . 35% in the first 19 weeks after germination (Bloor, Barthes & Leadley ). Added N (100 kg N ha −1 year −1 ) increased the effectiveness of Dactylis competition on ash, reducing the biomass of ash seedlings by 80% compared to the control (Bloor, Barthes & Leadley ).…”

Section: Response To Biotic Factorsmentioning

confidence: 99%

Biological Flora of the British Isles:Fraxinus excelsior

Thomas

2016

Journal of Ecology

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Summary1. This account presents information on all aspects of the biology of Fraxinus excelsior L. (Ash) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation. 2. Fraxinus excelsior is a large forest tree, native throughout the main islands of Britain and much of mainland Europe. Seedlings are shade tolerant, but adults are not so it tends to be an intermediate successional species, invading gaps in mixed stands rather than forming extensive pure stands. Ash grows on a wide range of soils but is commonest on nutrient-rich soils with a high base status and pH > 4.2, and is at its best on dry calcareous screes and fertile alluvial soils. 3. Fraxinus excelsior is trioecious or subdioecious with male, hermaphrodite and female flowers and trees. Seed production is prolific with periodic higher producing mast years. Seeds are primarily wind-dispersed, but they can float and be moved considerable distances along waterways. Germination is delayed by dormancy until usually the second spring after being shed. 4. Ash is tolerant of drought, but intolerant of spring frosts and so is predicted to fare well under current climate change scenarios, and indeed has recently been expanding in range in Europe. However, ash health and survival is currently seriously compromised by ash dieback caused by the fungus Hymenoscyphus fraxineus (Chalara fraxinea) that has the potential to kill all but a very few resistant trees. Moreover, the emerald ash borer beetle Agrilus planipennis, a serious pest of ash species in N. America, has reached Europe (though not yet the British Isles) and poses an equally if not more serious long-term threat to ash.

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Effects of elevated CO₂ and N on tree–grass interactions: an experimental test using Fraxinus excelsior and Dactylis glomerata

Cited by 22 publications

References 72 publications

Trade‐offs in resource allocation that favour resprouting affect the competitive ability of woody seedlings in grassy communities

Trade‐offs in resource allocation that favour resprouting affect the competitive ability of woody seedlings in grassy communities

Short-term responses and resistance of soil microbial community structure to elevated CO2 and N addition in grassland mesocosms

Biological Flora of the British Isles:Fraxinus excelsior

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