Ecological Aspects of Nitrogen Nutrition

Popp, Marianne

doi:10.1007/978-3-642-78020-2_25

Cited by 4 publications

(4 citation statements)

References 63 publications

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“…The δ 15 N values of bromeliads, particularly those of atmospheric habit, were much lower than most of those previously reported for plants ( Virginia et al 1989 ; Popp 1993), including epiphytes. Although the lowest values found by Stewart et al (1995) were above –7‰, most atmospheric bromeliads in our study showed δ 15 N signals below –10‰.…”

Section: Discussioncontrasting

confidence: 76%

Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*

Hietz

Wanek

Popp

1999

Plant Cell & Environment

108

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The foliar content of nitrogen and the relative abundances of 13C and 15N were analysed in vascular epiphytes collected from six sites along an altitudinal gradient from tropical dry forests to humid montane forests in eastern Mexico. The proportion of epiphyte species showing crassulacean acid metabolism (CAM) (atmospheric bromeliads, thick‐leaved orchids, Cactaceae, and Crassulaceae) decreased with increasing elevation and precipitation from 58 to 6%. Atmospheric bromeliads, almost all of which had δ13C values indicating CAM, were more depleted in 15N (x=−10·9‰± 2·11) than the C3 bromeliads which form water‐storing tanks (−6·05‰± 2·26). As there was no difference in δ15N values between C3 and CAM orchids, the difference in bromeliads was not related to photosynthetic pathways but to different nitrogen sources. While epiphytes with strong 15N depletion appear to obtain their nitrogen mainly from direct atmospheric deposition, others have access to nitrogen in intercepted water and from organic matter decomposing on branches and in their phytotelmata. Bromeliads and succulent orchids had a lower foliar nitrogen content than thin‐leaved orchids, ferns and Piperaceae. Ground‐rooted hemi‐epiphytes exhibited the highest nitrogen contents and δ15N values.

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Section: Discussioncontrasting

confidence: 76%

Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*

Hietz

Wanek

Popp

1999

Plant Cell & Environment

108

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“…The 5'^N values of plants ate a function of both preferential use of isotopically distinct nitrogen sources and assimilatory ftactionation. S'^'N values recorded for terrestrial plants from various ecosystems range from -6 to + 15%c (Virginia et al 1989;Popp 1993) with low values of -17oo reported for plants growing in very young volcanic soils greatly depleted in ''^N (Vitousek, Shearer & Kohl 1989). There appear to be no ' "^N data for epiphytes, although epiphytes are extremely diverse and can represent a large proportion of the total biomass of some ecosystems.…”

Section: Introductionmentioning

confidence: 94%

¹⁵N natural abundance of vascular rainforest epiphytes: implications for nitrogen source and acquisition

Stewart

Schmidt

Handley³

et al. 1995

Plant Cell & Environment

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The foliar natural abundance of 15N was analysed to compare the potential nitrogen sources of vascular rainforest epiphytes and associated soil‐rooted trees. Leaves of epiphytes collected from six rainforest communities in Brazil, Australia and the Solomon Islands were depleted in 15N relative to the trees at each site. Epiphyte δ15N was as low as ‐6.4%o, while trees were generally enriched in 15N (0.7 to 3.5%o). These results indicate either that epiphytes use nitrogen sources depleted in 15N or that discrimination against 15N is an intrinsic function of epiphyte physiology. At three sites, epiphytes could be grouped into those having both low δ15N and low leaf‐nitrogen content and those possessing both high δ15N and high leaf‐nitrogen content. The second group had δ15N values in the range sometimes attributable to N2 fixation (‐2 to 0%o). There was no correlation between growth form and δ15N. It is concluded that epiphytes may utilize 15N‐depleted nitrogen from atmospheric deposition and N2 fixation.

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“…Soil, environment and management practices often result in plants being subject to constantly changing proportions of nitrate and ammonium in their rooting medium (Runge, 1983;Popp, 1993). The amounts of each can change rapidly from excessive to minimal as a result of nitrification, differential leaching and plant removal, llius plants that have attained an elevated nitrogen status resulting from exposure to high concentrations but different pro-* To vvliotn corre.spondeiice should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Attributes of the nitrogen uptake systems of maize (Zea mays L.): maximal suppression by exposure to both nitrate and ammonium

Jackson

Volk

1995

New Phytologist

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SUMMARYHigher plants are commonly exposed to rapid changes in the amounts and proportions of ammonium ancTnTtrate in their root environment. Some of the potential consequences of such changes have been determined by examining the suppressive effects of growing maize {Zea mays L.) seedlings with a high concentration (3 mM) of nitrogen on the subsequent uptake of nitrogen from a more dilute (0-2 mM) solution. To document the interactive role of nitrate and ammonium supply in suppression, ratios of these ions in the growth solution were maintained at 3:0, 2:1, 1:2 and 0:3. Rates of nitrate and ammonium uptake were then measured during initial (O-I h) exposure to 0 2 mM KNO., or NH^NO,, and hourly during a subsequent 7 h period of adaptation to the dilute solutions.Maximal suppression of nitrate uptake occurred only when both nitrate and ammonium were present (2:1 and 1:2) during prior growth. Nitrate uptake rates increased two-to three-fold as the seedlings adapted to the dilute KNC).| solution, but the presence of ammonium with nitrate in the prior growth solution restricted the rate and extent of recovery from suppression. Recovery was further restricted when ambient ammonium was present during the adaptation period. Neither the magnitude of suppression nor the rate and extent of recovery was readily explained by (a) the proportion of nitrate and ammonium present during prior growth, (6) carbohydrate concentrations in root and shoot tissues, (c) concentrations of nitrate and ammonium in the root tissue, or [d) indirect effects of ammonium on potassium uptake.Total nitrate reduction by the entire plant in the 8 h adaptation period decreased as tbe proportion of ammonium in the prior growth solution increased. Ambient ammonium restricted nitrate reduction only in seedlings previously grown entirely with ammonium. Thus the effect of ambient ammonium on nitrate reduction by the whole plant differed substantially from that on nitrate uptake. Since nearly all the ammonium taken up by the roots was assimilated, as well as that generated by nitrate reduction, it appears that carbohydrate supply did not limit the observed uptake of ammonium and nitrate. The accumulation in roots of both nitrate and specific metabolites of ammonium serving as negative effectors could account for most of the observations.

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Ecological Aspects of Nitrogen Nutrition

Cited by 4 publications

References 63 publications

Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*

Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*

¹⁵N natural abundance of vascular rainforest epiphytes: implications for nitrogen source and acquisition

Attributes of the nitrogen uptake systems of maize (Zea mays L.): maximal suppression by exposure to both nitrate and ammonium

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Ecological Aspects of Nitrogen Nutrition

Cited by 4 publications

References 63 publications

Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*

Stable isotopic composition of carbon and nitrogen and nitrogen content in vascular epiphytes along an altitudinal transect*

15N natural abundance of vascular rainforest epiphytes: implications for nitrogen source and acquisition

Attributes of the nitrogen uptake systems of maize (Zea mays L.): maximal suppression by exposure to both nitrate and ammonium

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¹⁵N natural abundance of vascular rainforest epiphytes: implications for nitrogen source and acquisition