Are vascular epiphytes nitrogen or phosphorus limited? A study of plant 15N fractionation and foliar N : P stoichiometry with the tank bromeliad Vriesea sanguinolenta

Wanek, Wolfgang; Zotz, Gerhard

doi:10.1111/j.1469-8137.2011.03812.x

Cited by 55 publications

(52 citation statements)

References 48 publications

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“…Nitrate and ammonium supply rates in soil did not correlate strongly with either standing biomass or growth rates of fine roots, signifying that inorganic N may only be secondarily limiting or that acquisition of N via mycorrhizal associations may be more important. Second, foliar d 15 N was negatively related to N:P ratio, consistent with other studies of P-limited systems (McKee et al 2002;Clarkson et al 2005;Wanek and Zotz 2011). Although trees may store excess P in leaves, foliar N:P ratios are considered an indicator of the relative limitation of plant growth by N versus P (Güsewell 2004).…”

Section: Discussionsupporting

confidence: 71%

Nitrogen uptake strategies of edaphically specialized Bornean tree species

et al. 2013

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The association of tree species with particular soil types contributes to high b diversity in forests, but the mechanisms producing such distributions are still debated. Soil nitrogen (N) often limits growth and occurs in differentially available chemical forms. In a Bornean forest where tree species composition changes dramatically along a soil gradient varying in supplies of different N-forms, we investigated whether tree species' N-uptake and soil specialization strategies covaried. We analyzed foliar 15 N natural abundance for a total of 216 tree species on clay or sandy loam (the soils at the gradient's extremes) and conducted a 15 N-tracer experiment with nine specialist and generalist species to test whether species displayed flexible or differential uptake of ammonium and nitrate. Despite variation in ammonium and nitrate supplies and nearly 4 % difference in foliar d 15 N between most soil specialists and populations of generalists on these soils, our 15

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Section: Discussionsupporting

confidence: 71%

Nitrogen uptake strategies of edaphically specialized Bornean tree species

et al. 2013

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“…Compared with the forest floor, suspended soils associated with epiphytes are nitrogen poor [53], and are likely to depend upon inorganic nitrogen from the atmosphere [54]. It is possible that the fern soil microorganisms at the Eden Project were not nitrogen limited, which would explain the lack of a response to the addition of nitrogen consistent with observations of other tropical soils [55].…”

Section: Discussionsupporting

confidence: 72%

Physical Conditions Regulate the Fungal to Bacterial Ratios of a Tropical Suspended Soil

Donald

Bonnett

Cutler

et al. 2017

Forests

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Abstract:As a source of 'suspended soils', epiphytes contribute large amounts of organic matter to the canopy of tropical rain forests. Microbes associated with epiphytes are responsible for much of the nutrient cycling taking place in rain forest canopies. However, soils suspended far above the ground in living organisms differ from soil on the forest floor, and traditional predictors of soil microbial community composition and functioning (nutrient availability and the activity of soil organisms) are likely to be less important. We conducted an experiment in the rain forest biome at the Eden Project in the U.K. to explore how biotic and abiotic conditions determine microbial community composition and functioning in a suspended soil. To simulate their natural epiphytic lifestyle, bird's nest ferns (Asplenium nidus) were placed on a custom-built canopy platform suspended 8 m above the ground. Ammonium nitrate and earthworm treatments were applied to ferns in a factorial design. Extracellular enzyme activity and Phospholipid Fatty Acid (PLFA) profiles were determined at zero, three and six months. We observed no significant differences in either enzyme activity or PLFA profiles between any of the treatments. Instead, we observed decreases in β-glucosidase and N-acetyl-glucosaminidase activity, and an increase in phenol oxidase activity across all treatments and controls over time. An increase in the relative abundance of fungi during the experiment meant that the microbial communities in the Eden Project ferns after six months were comparable with ferns sampled from primary tropical rain forest in Borneo.

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“…In response to the increase in foliar [P], foliar N/P ratios decreased in the three eudicot species. These declines in foliar N/P ratios caused the typical tropical tree N/P ratios (c. 30) to decline towards those found in high-latitude, putatively N- (Garrish et al 2010) or when a switch from P limitation to N limitation occurs (Wanek & Zotz 2011). The lack of foliar P accumulation by the O. mapora palm suggests that this species is (i) incapable of luxury consumption; (ii) is uniquely capable of down regulating P uptake; or (iii) that increased P uptake was allocated to greater production or stored elsewhere in the palm.…”

Section: F O L I a R N P A N D N / Pmentioning

confidence: 98%

Species‐specific responses of foliar nutrients to long‐term nitrogen and phosphorus additions in a lowland tropical forest

2013

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Summary1. The concentration, stoichiometry and resorption of nitrogen (N) and phosphorus (P) in plant leaves are often used as proxies of the availability of these growth-limiting nutrients, but the responses of these metrics to changes in nutrient availability remain largely untested for tropical forest trees. 2. We evaluated changes in N and P concentrations, N/P ratios and resorption for four common tree species after 13 years of factorial N and P additions in a lowland tropical forest in Panama. 3. Chronic P addition increased foliar P concentrations, decreased P resorption proficiency and decreased N/P ratios in three locally common eudicot tree species (Alseis blackiana, Heisteria concinna, Tetragastris panamensis). The increase in foliar P involved similar proportional increases in organic and inorganic P in two species and a disproportionately large increase in inorganic P in A. blackiana. 4. Nitrogen addition did not alter foliar N concentrations in any species, but did decrease N resorption proficiency in H. concinna. 5. A fourth species, the palm Oenocarpus mapora, demonstrated remarkably static foliar nutrient concentrations, responding only with a marginal decrease in P resorption proficiency under N plus P co-addition. 6. Synthesis. Collectively, these results suggest that adjustment of N/P ratios can be expected in eudicots exposed to elevated P, but foliar N appears to already be at optimal levels in these lowland rain forest tree species. The complexity of species-specific responses to altered nutrient availability highlights the difficulty in predicting future responses of tropical forest trees to a changing world.

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Are vascular epiphytes nitrogen or phosphorus limited? A study of plant 15N fractionation and foliar N : P stoichiometry with the tank bromeliad Vriesea sanguinolenta

Cited by 55 publications

References 48 publications

Nitrogen uptake strategies of edaphically specialized Bornean tree species

Nitrogen uptake strategies of edaphically specialized Bornean tree species

Physical Conditions Regulate the Fungal to Bacterial Ratios of a Tropical Suspended Soil

Species‐specific responses of foliar nutrients to long‐term nitrogen and phosphorus additions in a lowland tropical forest

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