Shifts in seed size across experimental nitrogen enrichment and plant density gradients

Manning, Peter; Houston, Kelly; Evans, Tess

doi:10.1016/j.baae.2008.08.004

Cited by 35 publications

(32 citation statements)

References 31 publications

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“…Changes in the quantity and quality of seeds produced per individual are therefore plausible mechanisms that may further generate changes in community structure (Breen and Richards 2008;Manning et al 2009). We see the potential for this in Asterolinon; this species did not alter its germination with the fertilization but its fruit yield was increased in the 20 kg N ha -1 year -1 treatment.…”

Section: Discussionmentioning

confidence: 99%

Nitrogen fertilization and water supply affect germination and plant establishment of the soil seed bank present in a semi-arid Mediterranean scrubland

Ochoa‐Hueso

Manrique

2010

Plant Ecol

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Anthropogenic nitrogen (N) inputs in terrestrial ecosystems are higher than those that occur naturally and have been related to global biodiversity loss and altered ecosystem functioning. However, its effects on Mediterranean-type ecosystems, where production is water-limited and N regulated, remain unclear. We conducted a green-house experiment where we evaluated the effects of four simulated scenarios of N pollution (0, 10, 20 and 50 kg N ha -1 year -1 ) and two differential water supply regimes on the germination (experiment 1) and early plant establishment (experiment 2) of a seed bank from a semi-arid Mediterranean ecosystem of central Spain. Seed bank density was estimated as 62,374 ± 3,279 seeds m -2 . Approximately 99.5% of emerged seeds corresponded to only 14 species of a total of 52, the majority of which were the annual forb Sagina apetala. The responses for N treatments were speciesspecific, mainly positive or unimodal, with watering treatments having some interactive effects. N and water supply also affected total and specific productivity; the responses found for N treatments were mainly humpback-shaped and an increased water supply had additive effects on community establishment in terms of total plant biomass. This response was linked to forb responsiveness. Contrary to predictions, grass biomass did not change with N supply; however, grass to forb ratio was affected because of changes in the latter. Overall, these experiments suggest a critical load for plant biomass production and conclude that N and water availability and supply can modify germination and plant establishment. This should be taken into account when analysing the effects of global change on the dynamics of plant communities where annuals are dominant or vegetation must establish from seed following a natural or anthropogenic disturbance regime.

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Section: Discussionmentioning

confidence: 99%

Nitrogen fertilization and water supply affect germination and plant establishment of the soil seed bank present in a semi-arid Mediterranean scrubland

Ochoa‐Hueso

Manrique

2010

Plant Ecol

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“…Despite the importance of these plant structures, there are no studies of the effects of N availability on their growth and development and ultimately, their ability to provide shelter to natural enemies. However, at the plant community scale, increased nitrogen availability substantially increases the density and changes the composition of plant communities (e.g., Manning et al 2009). This is likely to extend over the longterm as atmospheric N levels continue to rise in response to increased N from fertilization and combustion of fossil fuels (Vitousek et al 1997).…”

Section: Plants As Food and Shelter Of Natural Enemiesmentioning

confidence: 99%

Effects of nitrogen fertilization on tritrophic interactions

Chen

Olson²,

Ruberson

2010

Arthropod-Plant Interactions

141

101

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Tritrophic interactions (plant-herbivorenatural enemy) are basic components of nearly all ecosystems, and are often heavily shaped by bottom-up forces. Numerous factors influence plants' growth, defense, reproduction, and survival. One critical factor in plant life histories and subsequent trophic levels is nitrogen (N). Because of its importance to plant productivity, N is one of the most frequently used anthropogenic fertilizers in agricultural production and can exert a variety of bottom-up effects and potentially significantly alter tritrophic interactions through various mechanisms. In this paper, the potential effects of N on tritrophic interactions are reviewed. First, in plant-herbivore interactions, N availability can alter quality of the plant (from the herbivore's nutritional perspective) as food by various means. Second, nitrogen effects can extend directly to natural enemies through herbivores by changes in herbivore quality vis-à-vis the natural enemy, and may even provide herbivores with a defense against natural enemies. Nitrogen also may affect the plant's indirect defenses, namely the efficacy of natural enemies that kill herbivores attacking the plant. The effects may be expressed via (1) quantitatively and/or qualitatively changing herbivore-induced plant volatiles or other plant features that are crucial for foraging and attack success of natural enemies, (2) modifying plant architecture that might affect natural enemy function, and (3) altering the quality of plant-associated food and shelter for natural enemies. These effects, and their interactive topdown and bottom-up influences, have received limited attention to date, but are of growing significance with the need for expanding global food production (with accompanying use of fertilizer amendments), the widening risks of fertilizer pollution, and the continued increase in atmospheric CO 2 .

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“…Numerous studies have focused on plant competition (e.g. Fetene 2003;Hunt et al 2006;Berger et al 2008;Manning et al 2009), because it is a key process affecting plant populations and communities (Berger et al 2008). Competition-density (C-D) is an effect explaining the common finding that average plant size decreases when stand density increases.…”

Section: Introductionmentioning

confidence: 99%

Density effects on the growth of self-thinning Eucalyptus urophylla stands

Xue

Pan

Zhang

et al. 2011

Trees

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Density effects on the growth of self-thinning Eucalyptus urophylla stands were examined for 7 years. Tree height and stem diameter at breast height were measured during the experimental period. Stems, branches, leaves, bark and roots of 45 E. urophylla trees were sampled in three different density stands in order to establish their biomass equations. Change trends of the biological time s and density q were described used corresponding equations. The stem weight ratio increased and leaf weight ratio decreased, whereas those of branch, bark and root were relatively steady from 2 years after the planting. The competition-density (C-D) effect equation of mean organ weight w o was derived by combining the allometric power relationship between mean tree weight w and w o with the C-D effect equation of self-thinning stands. The equations of the C-D effect for w and q and for w o and q were used to describe the C-D effects in tree and organs during course of self-thinning, respectively, and showed a good fit to the data. Leaf biomass of different density stands reached a more or less constant level with time elapse. High density produced the greatest biomass and stem biomass, so that it is the best choice in silvicultural practice.

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Shifts in seed size across experimental nitrogen enrichment and plant density gradients

Cited by 35 publications

References 31 publications

Nitrogen fertilization and water supply affect germination and plant establishment of the soil seed bank present in a semi-arid Mediterranean scrubland

Nitrogen fertilization and water supply affect germination and plant establishment of the soil seed bank present in a semi-arid Mediterranean scrubland

Effects of nitrogen fertilization on tritrophic interactions

Density effects on the growth of self-thinning Eucalyptus urophylla stands

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