Nutrient concentrations in mire vegetation as a measure of nutrient limitation in mire ecosystems

1995 ◽  
Vol 6 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Martin J. Wassen ◽  
Harry G.M. Olde Venterink ◽  
Evalyne O.A.M. Swart
Keyword(s):  
Nutrient Limitation ◽  
Nutrient Concentrations ◽  
Mire Vegetation

scholarly journals Foliar Applications of Biostimulants Promote Growth, Yield and Fruit Quality of Strawberry Plants Grown under Nutrient Limitation

Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 483 ◽  
Author(s):  
Sebastian Soppelsa ◽  
Markus Kelderer ◽  
Claudio Casera ◽  
Michele Bassi ◽  
Peter Robatscher ◽  
...  
Keyword(s):  
Nutrient Limitation ◽  
Fruit Quality ◽  
Growth Yield ◽  
Biomass Accumulation ◽  
Nutrient Concentrations ◽  
Negative Effects ◽  
Nutritional Conditions ◽  
Entire Duration ◽  
Single Fertilization

Biostimulants have been found effective in enhancing plant resistance toward stressful conditions. The aim of the present study was to evaluate the efficacy of selected biostimulants to overcome the negative effects of nutrient limitation on the growth performances and on the fruit quality of soilless cultivated strawberry plants. The condition of nutrient limitation was imposed by supplying the plants with only a single fertilization at transplantation and by excluding any further nutrient supply for the entire duration of the experiment (three months, from May to July). Strawberry plants were treated seven times during the period from preflowering up to berry maturation with different classes of biostimulants (humic acids, alfalfa hydrolysate, macroseaweed extract and microalga hydrolysate, amino acids alone or in combination with zinc, B-group vitamins, chitosan, and a commercial product containing silicon) at commercial dosages. The use of alfalfa hydrolysate, vitamins, chitosan, and silicon was able to promote biomass accumulation in roots (four to seven folds) and fruits (+20%) of treated plants, whereas the total leaf area increased by 15%–30%. Nutrient concentrations in leaves and roots showed variations for microelements (e.g., Fe, B, Zn, and Si) in response to biostimulant applications, whereas no significant differences were observed for macronutrient contents among treatments. Final berry yield was found around 20% higher in chitosan- and silicon-treated plants. Chitosan treatment significantly increased pulp firmness (by 20%), while a high nutritional value (e.g., phenolic compounds concentration) was observed in alfalfa- and seaweed-treated fruits (+18%–20% as compared to control). The overall outcomes of the present experiment show that selected biostimulants can be considered as a valid agronomic tool able to contrast the negative consequence of growing crops under insufficient nutritional conditions.

scholarly journals Microbial nutrient limitation in arctic lakes in a permafrost landscape of southwest Greenland

2015 ◽  
Vol 12 (14) ◽  
pp. 11863-11890
Author(s):  
B. Burpee ◽  
J. E. Saros ◽  
R. M. Northington ◽  
K. S. Simon
Keyword(s):  
Nutrient Limitation ◽  
Enzyme Activities ◽  
Arctic Lakes ◽  
The Arctic ◽  
Nutrient Concentrations ◽  
Nutrient Inputs ◽  
P Limitation ◽  
Microbial P ◽  
Microbial Nutrient Limitation ◽  
Southwest Greenland

Abstract. Permafrost is degrading across regions of the Arctic, which can lead to increases in nutrient concentrations in surface freshwaters. The oligotrophic state of many arctic lakes suggests that enhanced nutrient inputs may have important effects on these systems, but little is known about microbial nutrient limitation patterns in these lakes. We investigated microbial extracellular enzyme activities (EEAs) to infer seasonal nutrient dynamics and limitation across 24 lakes in southwest Greenland during summer (June and July). From early to late summer, enzyme activities that indicate microbial carbon (C), nitrogen (N), and phosphorus (P) demand increased in both the epilimnia and hypolimnia by 74 % on average. Microbial investment in P acquisition was generally higher than that for N. Interactions among EEAs indicated that bacteria were primarily P limited. Dissolved organic matter (DOM, measured as dissolved organic carbon) was strongly and positively correlated with microbial P demand (R2 = 0.84 in July), while there were no relationships between DOM and microbial N demand. Microbial P limitation in June epilimnia (R2 = 0.67) and July hypolimnia (R2 = 0.57) increased with DOM concentration. The consistency of microbial P limitation from June to July was related to the amount of DOM present, with some low DOM lakes becoming N-limited in July. Our results suggest that future changes in P or DOM inputs to these lakes are likely to alter microbial nutrient limitation patterns.

In situ evidence for a nutrient limitation of phytoplankton growth in pelagic Antarctic waters

1994 ◽  
Vol 6 (3) ◽  
pp. 315-324 ◽  
Author(s):  
Osmund Holm-Hansen ◽  
Anthony F. Amos ◽  
Nelson Silva S. ◽  
Virginia Villafañe ◽  
E. Walter Helbling
Keyword(s):  
Nutrient Limitation ◽  
Surface Waters ◽  
Phytoplankton Biomass ◽  
Drake Passage ◽  
Nutrient Concentrations ◽  
Ancillary Data ◽  
Water Types ◽  
Antarctic Waters ◽  
Subsurface Maximum

Studies in a large (30000 km2) sampling grid around Elephant Island, Antarctica, during January–March of four successive years (1990–1993) have shown that one of the water types within the sampling area (Drake Passage water) shows low chlorophyll a in surface waters and a subsurface maximum between 50 and 80 m depth. Ancillary data (beam attenuation, in situ chl a fluorescence) support the view that the extracted chl a values actually do represent increased phytoplankton biomass at depth; other data (oxygen concentrations and upwelling radiance at 683 nm) suggest that the phytoplankton within this subsurface maximum layer are photosynthetically active and do not represent a senescent, sinking population of cells. Such deep chl a maxima were found only in Drake Passage waters; in the other four water types sampled, chl a concentrations were maximal in surface waters and decreased with depth. Phytoplankton biomass and activity in Drake Passage waters is suggestive of a nutrient limitation for phytolankton growth in surface waters. Nutrient concentrations of N, P, and Si were high throughout the euphotic zone at all stations, and hence it is unlikely that any macronutrient would be limiting. The data presented in this paper support the hypothesis of Martin and colleagues that availability of Fe may limit phytoplankton biomass in pelagic Antarctic waters, but not in coastal waters where Fe concentrations are relatively high. All other reports on the effects of Fe on Antarctic phytoplankton have utilized deck incubations from which it is difficult to extrapolate such evidence of nutrient limitation to in situ conditions. Our data represent the first in situ evidence linking Fe limitation to the paradox of high macronutrient concentrations and low phytoplankton biomass in Antarctic pelagic waters.

The Dynamic Vegetation Model HUMBOLDT (LSMbio) The role of biodiversity and nutrient limitation in driving ecosystem processes on a tropical altitudinal gradient

2020 ◽  
Author(s):  
Mateus Dantas de Paula ◽  
Thomas Hickler
Keyword(s):  
Nutrient Limitation ◽  
Altitudinal Gradient ◽  
Plant Traits ◽  
Full Range ◽  
Elevation Gradient ◽  
Nutrient Concentrations ◽  
Vegetation Model ◽  
Nitrogen And Phosphorus ◽  
Dynamic Vegetation Model ◽  
Trait Diversity

<p>The HUMBOLDT-LSM<sub>bio</sub> component is an expansion of the LPJ-GUESS dynamic vegetation model , including local diversity of plant traits and an organic matter module representing the Nitrogen and Phosphorus cycles. In the new trait variation module the initial full range of possible traits is filtered along the altitudinal gradient with the aim to predict the trait distribution of communities observed in the field. The model was parameterized using local trait data per species collected by field campaigns along the whole altitudinal gradient, considering the leaf and wood economics spectrum and tissue nutrient concentrations, and locally measured N and P flux data, in which we were able to use deposition and weathering rates, as well as soil organic and mineral layer nutrient concentrations. In order to evaluate the model with regards to nutrient limitation, the simulation experiment was designed with the NUMEX nutrient manipulation experiment in mind, meaning that the reference nutrient limited community was compared to simulations in which N or/and P limitations were deactivated (i.e. plants could grow independent of their N or P demands being met). Results in NUMEX suggested that the removal of nutrient limitation would produce more biotically homogenous communites, and taller trees with higher productivity and more allocation to belowground biomass.</p><p>Our results indicate that including trait diversity and nutrient limitation provide a significant improvement in relation to ecosystem representation especially at higher elevations. Deactivation of nutrient limitation suggests reduced community trait differentiation along the elevation gradient (e.g. specific leaf area), and increased productivity (i.e. Carbon and NPP values). Deactivation of trait diversity impels plant survival at higher altitudes. Significant model improvements are expected in the future with further field trait measurements from the RESPECT subprojects, and the inclusion of other significant processes such as leaf herbivory, seed dispersal and of course the coupled model runs with LSM<sub>atmo</sub> and LSM<sub>hydro</sub>.</p>

scholarly journals Contrasting glacial meltwater effects on post-bloom phytoplankton on temporal and spatial scales in Kongsfjorden, Spitsbergen

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Willem H. van de Poll ◽  
Gemma Kulk ◽  
Patrick D. Rozema ◽  
Corina P. D. Brussaard ◽  
Ronald J. W. Visser ◽  
...  
Keyword(s):  
Nutrient Limitation ◽  
Water Column ◽  
Chlorophyll A ◽  
Carbon Fixation ◽  
Spatial Scales ◽  
Nutrient Concentrations ◽  
Fixation Rate ◽  
Glacial Meltwater ◽  
Chl A ◽  
N Limitation

Glacial meltwater discharge in fjords on the west coast of Spitsbergen is increasing due to climate change. The influence of this discharge on phytoplankton nutrient limitation, composition, productivity and photophysiology was investigated in central (M) and inner (G) Kongsfjorden (79°N, 11°40’E). Freshwater influx intensified stratification during June 2015, coinciding with surface nutrient depletion. Surface nutrient concentrations were negatively correlated with stratification strength at station M. Here, nitrate addition assays revealed increasing N limitation of surface phytoplankton during the second half of June, which was followed by a pronounced compositional change within the flagellate-dominated phytoplankton community as dictyochophytes (85% of chl a) were replaced with smaller haptophytes (up to 60% of chlorophyll a) and prasinophytes (20% of chlorophyll a). These changes were less pronounced at station G, where surface phosphate, ammonium and nitrate concentrations were occasionally higher, and correlated with wind direction, suggesting wind-mediated transport of nutrient-enriched waters to this inner location. Therefore, glacial meltwater discharge mediated nutrient enrichment in the inner fjord, and enhanced stratification in inner and central Kongsfjorden. Surface chlorophyll a and water column productivity showed 3–4-fold variability, and did not correlate with nutrient limitation, euphotic zone depth, or changed taxonomic composition. However, the maximum carbon fixation rate and photosynthetic efficiency showed weak positive correlations to prasinophyte, cryptophyte, and haptophyte chlorophyll a. The present study documented relationships between stratification, N limitation, and changed phytoplankton composition, but surface chlorophyll a concentration, phytoplankton photosynthetic characteristics, and water column productivity in Kongsfjorden appeared to be driven by mechanisms other than N limitation.

Understanding effects of small dams on benthic metabolism and primary production in temperate forested streams

2020 ◽  
Vol 193 (3) ◽  
pp. 227-237
Author(s):  
John P. Ludlam ◽  
Allison H. Roy
Keyword(s):  
Nutrient Limitation ◽  
Ecosystem Processes ◽  
Nutrient Concentrations ◽  
Ecosystem Responses ◽  
Stream Ecosystem ◽  
Benthic Metabolism ◽  
Factors Associated ◽  
Physical Conditions ◽  
And Control ◽  
Func Tion

Dams can alter the chemical and physical conditions of downstream environments by increasing stream temperatures, altering nutrient limitation, reducing flow variability, and reducing fine sediment deposition. However, little is known about how fundamental stream ecosystem processes like productivity and respiration respond to dams. Nutrient diffusing substrates were installed in three dam streams and three control streams to evaluate the effect of dams on benthic gross primary productivity (GPP), respiration (R), and chlorophyll α production. Dam streams were an average of 5.6 °C warmer than control streams but GPP, R and chlorophyll α were not different between control and dam streams. Phosphorus enrichment increased heterotrophic R relative to controls (~1.8×) but not autotrophic GPP, R or chlorophyll α. Stream nutrient concentrations and nutrient limitation of heterotrophic R were similar in dam and control streams, suggesting that the dams had limited effects on nutrient transport downstream. Autotrophic GPP, R and chlorophyll α were limited by light and varied within and across streams, potentially masking our ability to detect differences caused solely by dams. Dams may alter stream ecosystem func- tion but consideration of other factors associated with and independent of dams is critical for predicting ecosystem responses to dams.

scholarly journals Patterns in nutrient limitation and chlorophyll a along an anthropogenic eutrophication gradient in French Mediterranean coastal lagoons

2010 ◽  
Vol 67 (4) ◽  
pp. 743-753 ◽  
Author(s):  
Philippe Souchu ◽  
Béatrice Bec ◽  
Val H. Smith ◽  
Thierry Laugier ◽  
Annie Fiandrino ◽  
...  
Keyword(s):  
Nutrient Limitation ◽  
Chlorophyll A ◽  
Nutrient Enrichment ◽  
Coastal Waters ◽  
Coastal Lagoons ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Chl A ◽  
Mediterranean Lagoons ◽  
Ecosystem Comparison

A cross-ecosystem comparison of data obtained from 20 French Mediterranean lagoons with contrasting eutrophication status provided the basis for investigating the variables that best predict chlorophyll a (Chl a) concentrations and nutrient limitation of phytoplankton biomass along a strong nutrient enrichment gradient. Summer concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) comprised only a small fraction of total nitrogen (TN) and total phosphorus (TP). On the basis of inorganic nutrient concentrations, the most oligotrophic lagoons appeared to be phosphorus-limited, with a tendency towards the development of nitrogen limitation as eutrophication increased, as evidenced by decreasing DIN:DIP ratios. A weak but significantly positive relationship was found between dissolved silicate (DSi) and Chl a, reflecting DSi accumulation in the water column along the trophic state gradient and implying a progressive shift away from potential Si limitation of phytoplankton growth. Observed concentrations of Chl a were far better explained by TN and TP than by DIN and DIP concentrations, suggesting that a total nutrient based approach is likely to be the most appropriate for managing eutrophication in Mediterranean lagoons and other coastal waters. These results give credence to the idea that marine and freshwater environments respond in a similar fashion to nutrient enrichment.

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