Resource requirements of Asterionella formosa and Fragilaria crotonensis in oligotrophic alpine lakes: implications for recent phytoplankton community reorganizations

2005 ◽  
Vol 62 (7) ◽  
pp. 1681-1689 ◽  
Author(s):  
Jasmine E Saros ◽  
Timothy J Michel ◽  
Sebastian J Interlandi ◽  
Alexander P Wolfe
Keyword(s):  
Phytoplankton Community ◽  
Alpine Lakes ◽  
N Deposition ◽  
Mountain Range ◽  
P Availability ◽  
Asterionella Formosa ◽  
Resource Requirements ◽  
Fragilaria Crotonensis ◽  
N Enrichment ◽  
Enrichment Experiments

A widespread increase in the relative abundances of Asterionella formosa and Fragilaria crotonensis has occurred in oligotrophic alpine lakes across the western United States. Previous investigations have suggested that enhanced atmospheric nitrogen (N) deposition is driving these shifts in diatom community structure; however, little information is available on N requirements of these taxa. We examined the distributions of these two taxa in relation to a variety of physicochemical parameters in a suite of lakes situated in the Beartooth Mountain Range (Montana–Wyoming, USA). We also conducted a series of nutrient enrichment experiments to assess the response of these taxa to changes in N, phosphorus (P), and silica (Si) supply. The distributions of both taxa were positively correlated with C:P, N:P, and Si:P seston ratios, revealing that these taxa are abundant when P availability is very low and the supply of N and Si are moderate to high. In the enrichment experiments, both taxa responded strongly to N additions, whereas P or Si enrichment alone had no effect. While these two taxa are indicative of P enrichment in temperate lakes, our results indicate that in these oligotrophic alpine lakes, N enrichment is driving their recent increase.

Assessing the effects of nitrogen deposition on mountain waters: A study of phytoplankton community dynamics

1998 ◽  
Vol 38 (10) ◽  
pp. 139-146 ◽  
Author(s):  
Sebastian J. Interlandi ◽  
Susan S. Kilham
Keyword(s):  
Community Dynamics ◽  
Phytoplankton Community ◽  
N Deposition ◽  
Atmospheric N Deposition ◽  
Large Lakes ◽  
Phytoplankton Communities ◽  
Fragilaria Crotonensis ◽  
Greater Yellowstone ◽  
N Loading ◽  
Laboratory Bioassays

We assessed the phytoplankton communities and the relevant aquatic chemistry in three large lakes in the Greater Yellowstone Ecosystem. While N limitation of phytoplankton is most common, it appears that a recent regional increase in atmospheric N deposition is causing both P and Si limitation to occur to some degree. N additions in semi-continuous laboratory bioassays of mixed diatom assemblages produced a dramatic increase in biomass in two of the three study lakes. Relative abundances of species were altered relative to control treatments with both added N and Si. Higher levels of N primarily favored the alga Fragilaria crotonensis. This result is consistent with previous laboratory and field observations which suggest that F. crotonensis is not a good competitor for N, and only thrives in N rich environments. We hypothesize that continued increases in N loading will alter natural species assemblages in all the study lakes.

scholarly journals Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes

Hydrobiologia ◽  
2021 ◽  
Author(s):  
A.-K. Bergström ◽  
A. Deininger ◽  
A. Jonsson ◽  
J. Karlsson ◽  
T. Vrede
Keyword(s):  
Community Composition ◽  
Resource Use ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
N Fertilization ◽  
Zooplankton Biomass ◽  
Nitrogen Enrichment ◽  
C:N:P Stoichiometry ◽  
Food Quantity ◽  
N Enrichment

AbstractWe used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.

scholarly journals 15N natural abundances in two podsol soils of two spruce forests differing in their atmospheric N deposition conditions

2011 ◽  
Vol 51 (No. 9) ◽  
pp. 416-422 ◽  
Author(s):  
S.P. Sah
Keyword(s):  
Mineral Soil ◽  
Vertical Gradient ◽  
N Deposition ◽  
Climatic Conditions ◽  
Organic Layer ◽  
Atmospheric N Deposition ◽  
Spruce Forests ◽  
Humus Layer ◽  
N Enrichment ◽  
Deposition Conditions

This study aims to investigate the changes in isotope ratios in foliage and soils of the two spruce forests [Picea abies (L.) Karst.] differing greatly in their atmospheric N deposition and climatic conditions. As expected, both N concentrations and <sup>15</sup>N values in both needles and litter were found to be significantly higher in the Solling stand (N-saturated) compared to the Hyytial&auml; stand (N-poor). For the N-limited site (Hyytial&auml; plot), a typical vertical gradient of the soil <sup>15</sup>N-enrichment (both in organic and mineral soil) was observed. The N-saturated site (Solling) differs from the N-limited site (Hyytial&auml;) with respect to the <sup>15</sup>N abundance trend in organic layer. In the upper organic layer up to O-f horizon, i.e. mor layer (0&ndash;3.5 cm depth) of Solling plot, there is almost a trend of slight soil <sup>15</sup>N-depletion with increasing depth, and then there is a <sup>15</sup>N-enrichment from O-h horizon (humus layer) of organic layer to mineral soil horizons. This is explained by the presence of prominent NO<sub>3</sub><sup>&ndash;</sup> leaching at this plot

Nitrogen addition accelerates ecosystem phosphorus cycling at multiple scales in a temperate grassland of Northeast China

2020 ◽  
Author(s):  
Haiying Cui ◽  
Manuel Delgado-Baquerizo ◽  
Wei Sun ◽  
Jian-Ying Ma ◽  
Wenzheng Song ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Northeast China ◽  
Nitrogen Addition ◽  
N Deposition ◽  
Organic P ◽  
N Addition ◽  
Resorption Efficiency ◽  
P Deficiency ◽  
P Mineralization ◽  
N Enrichment

&lt;p&gt;Plant phosphorus (P) resorption, mutualistic symbiosis with mycorrhizas, such as arbuscular mycorrhizal fungi (AMF) and soil organic P mineralization are crucial strategies for acquiring sufficient P to meet plant nutrient demand. Which is the main strategy, however, responding to elevated nitrogen (N) addition to alleviate P deficiency caused by N enrichment remains unclear in terrestrial ecosystems. We explored the responses of foliar P resorption of dominate species (Leymus chinensis), soil microbial properties and organic P mineralization to multi-level N addition in a temperate meadow steppe, Northeast China. We found the enhancements in plant biomass, microbial biomass C and N (MBC, MBN), alkaline phosphatase activities (ALP), and phoD gene abundance (main gene coded soil ALP), while the reductions in soil pH, available P, microbial biomass P, and AMF abundance, and no significant responses of foliar P content under simulative N deposition. When the rates exceeded the threshold 10 g N m&lt;sup&gt;-2&lt;/sup&gt;yr&lt;sup&gt;-1&lt;/sup&gt;, plants and microbes had little additional responses to N enrichment. Notably, N addition had distinct effects on three plant P acquisition strategies, that no conspicuous increase in P resorption efficiency, reduced dependence on mutualistic with AMF symbiosis and accelerated organic P mineralization. A positive correlation between ALP activity, phoD gene abundance and P mineralization rate suggested increases in phosphatase activities and its functional gene copies play crucial roles in organic P mineralization. Nitrogen addition aggravated P deficiency to the production of plant and microbial biomass, which further accelerated soil organic P mineralization and foliar P resorption. Due to lack of plasticity in P resorption efficiency and reduced dependence on mutualistic with AMF symbiosis, however, the organic P mineralization dominated in P acquisition to meet increased P demand. Furthermore, the increase in ALP activities, activation of phoD genes and decrease in soil pH were the main pathways to accelerate organic P mineralization and consequently alleviated P deficiency caused by anthropogenic N deposition, especially at conditions of N saturation. Our results provide strong evidences that N addition can accelerate the rate of P cycling and mobilize plant P uptake strategies such as soil organic P mineralization and leaf P resorption, which are important to better maintain sustainable ecosystem development in the more fertilized word.&lt;/p&gt;&lt;p&gt;Acknowledgments: This work was supported by the National Key Research and Development Program of China (2016YFC0500602), National Natural Science Foundation of China (31570470, 31870456), the Fundamental Research Funds for the Central Universities (2412018ZD010), and the Program of Introducing Talents of Discipline to Universities (B16011). H.C. acknowledges support from Chinese Scholarship Council (CSC).&lt;/p&gt;

scholarly journals Testing mechanisms of N-enrichment-induced species loss in a semiarid Inner Mongolia grassland: critical thresholds and implications for long-term ecosystem responses

2012 ◽  
Vol 367 (1606) ◽  
pp. 3125-3134 ◽  
Author(s):  
Zhichun Lan ◽  
Yongfei Bai
Keyword(s):  
Ecosystem Services ◽  
Rare Species ◽  
Inner Mongolia ◽  
Global Environmental Change ◽  
N Deposition ◽  
Critical Threshold ◽  
Species Loss ◽  
N Addition ◽  
Precipitation Regimes ◽  
N Enrichment

The increase in nutrient availability as a consequence of elevated nitrogen (N) deposition is an important component of global environmental change. This is likely to substantially affect the functioning and provisioning of ecosystem services by drylands, where water and N are often limited. We tested mechanisms of chronic N-enrichment-induced plant species loss in a 10-year field experiment with six levels of N addition rate. Our findings on a semi-arid grassland in Inner Mongolia demonstrated that: (i) species richness (SR) declined by 16 per cent even at low levels of additional N (1.75 g N m –2 yr −1 ), and 50–70% species were excluded from plots which received high N input (10.5–28 g N m −2 yr −1 ); (ii) the responses of SR and above-ground biomass (AGB) to N were greater in wet years than dry years; (iii) N addition increased the inter-annual variations in AGB, reduced the drought resistance of production and hence diminished ecosystem stability; (iv) the critical threshold for chronic N-enrichment-induced reduction in SR differed between common and rare species, and increased over the time of the experiment owing to the loss of the more sensitive species. These results clearly indicate that both abundance and functional trait-based mechanisms operate simultaneously on N-induced species loss. The low initial abundance and low above-ground competitive ability may be attributable to the loss of rare species. However, shift from below-ground competition to above-ground competition and recruitment limitation are likely to be the key mechanisms for the loss of abundant species, with soil acidification being less important. Our results have important implications for understanding the impacts of N deposition and global climatic change (e.g. change in precipitation regimes) on biodiversity and ecosystem services of the Inner Mongolian grassland and beyond.

scholarly journals Fungi exposed to chronic nitrogen enrichment are less able to decay leaf litter

2016 ◽  
Author(s):  
Linda T.A. van Diepen ◽  
Serita D. Frey ◽  
Elizabeth A. Landis ◽  
Eric W. Morrison ◽  
Anne Pringle
Keyword(s):  
Growth Rates ◽  
Common Garden ◽  
N Deposition ◽  
Plant Litter ◽  
Atmospheric N Deposition ◽  
Saprotrophic Fungi ◽  
Soil C ◽  
Litter Decay ◽  
N Enrichment

AbstractSaprotrophic fungi are the primary decomposers of plant litter in temperate forests, and their activity is critical for carbon (C) and nitrogen (N) cycling. Simulated atmospheric N deposition is associated with reduced fungal biomass, shifts in fungal community structure, slowed litter decay, and soil C accumulation. Although rarely studied, N deposition may also result in novel selective pressures on fungi, affecting evolutionary trajectories. To directly test if long-term N enrichment reshapes fungal behaviors, we isolated decomposer fungi from a longterm (28 year) N addition experiment and used a common garden approach to compare growth rates and decay abilities of isolates from control and N amended plots. Both growth and decay were significantly altered by long-term exposure to N enrichment. Changes in growth rates were idiosyncratic, but litter decay by N isolates was generally lower compared to control isolates of the same species, a response not readily reversed when N isolates were grown in control (low N) environments. Changes in fungal behaviors accompany and perhaps drive previously observed N-induced shifts in fungal diversity, community composition, and litter decay dynamics.

scholarly journals Consistent effects of vegetation loss on abundant and rare soil microbial phylotypes across nitrogen-enrichment levels

2019 ◽  
Author(s):  
Dima Chen ◽  
Ying Wu ◽  
Muhammad Saleem ◽  
Bing Wang ◽  
Shuijin Hu ◽  
...  
Keyword(s):  
Soil Bacteria ◽  
Alpha Diversity ◽  
N Deposition ◽  
Bacterial Phylotypes ◽  
Soil Microbial ◽  
N Enrichment ◽  
Soil Bacteria And Fungi ◽  
Bacteria And Fungi ◽  
Vegetation Loss ◽  
First Time

Abstract Soil harbors highly diverse abundant and rare microbial phylotypes that drive multiple soil functions. Given increasing intensity and frequency of vegetation loss and anthropogenic reactive nitrogen (N) inputs to the soil in the future, we lack a mechanistic understanding of how vegetation loss may influence abundant and rare microbial phylotypes at various N-enrichment levels. In the current study, we assessed the effects of vegetation loss on abundant and rare phylotypes of soil bacteria and fungi across three N-enrichment levels in a semi-arid grassland ecosystem. After six years of experimentation in with and without vegetation plots, the vegetation loss increased the total relative abundance of abundant soil bacterial phylotypes but not that of abundant fungal phylotypes at across N-enrichment levels. It is very likely because the number of abundant bacterial phylotypes with positive than negative responses to vegetation loss was higher; however, the number of abundant fungal phylotypes with positive than negative responses to vegetation loss was similar during this period. Moreover, the vegetation loss did not alter the alpha-diversity of abundant or rare bacterial phylotypes, or, of abundant fungal phylotypes; however, it reduced the alpha-diversity of rare fungal phylotypes at across N-enrichment levels. The vegetation loss, however, altered the beta-diversity of abundant and rare bacterial and fungal phylotypes across N-enrichment levels. We found that, against expectations, the effects of vegetation loss on the diversity of abundant and rare phylotypes of both bacteria and fungi were relatively consistent across N-enrichment levels. Our findings provide, for the first time, the phylotype-based data on how vegetation loss affects abundant and rare phylotypes of soil bacteria and fungi across N-enrichment levels. The results also indicate that the effects of vegetation loss on belowground functions may be relatively insensitive to the differences in the N-deposition rates.

scholarly journals Linking Soil Acidity to P Fractions and Exchangeable Base Cations under Increased N and P Fertilization of Mono and Mixed Plantations in Northeast China

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1274
Author(s):  
Nowsherwan Zarif ◽  
Attaullah Khan ◽  
Qingcheng Wang
Keyword(s):  
Soil Acidification ◽  
Northeast China ◽  
Soil Acidity ◽  
Organic Phosphorus ◽  
Base Cations ◽  
N Deposition ◽  
Limiting Factor ◽  
P Availability ◽  
P Fertilization ◽  
P Addition

Atmospheric N deposition is increasing worldwide, especially in China, significantly affecting soil health, i.e., increasing soil acidification. The northern region of China is considered to be one of the N deposition points in Asia, ranging from 28.5 to 100.4 N ha−1yr−1. Phosphorus (P) is the limiting factor in the temperate ecosystem and an important factor that makes the ecosystem more susceptible to N-derived acidification. However, it remained poorly understood how the soil acidification process affects soil P availability and base cations in the temperate region to increased N deposition. To address this question, in May 2019, a factorial experiment was conducted under N and P additions with different plantations in Maoershan Experimental Forest Farm, Northeast China, considering species and fertilization as variables. The effective acidity (EA) increased by N and NP fertilizations but was not significantly affected by P fertilization. Similarly, the pH, base saturation percentage (BS%), calcium (Ca2+), and magnesium (Mg2+) were decreased under N addition, while the Al:Ca ratio increased, whereas NaHCO3 inorganic phosphorus (Pi) and NaOH organic phosphorus (Po) significantly decreased under N enrichments. However, NaOH Pi increased in N-enriched plots, while H2O Pi and NaHCO3 Pi increased under the P addition. Thus, the results suggest that the availability of N triggers the P dynamics by increasing the P uptake by trees. The decrease in base cations, Ca2+, and Mg2+ and increase in exchangeable Fe3+ and Al3+ ions are mainly responsible for soil acidification and lead to the depletion of soil nutrients, which, ultimately, affects the vitality and health of forests, while the P addition showed a buffering effect but could not help to mitigate the soil acidity.

Sign in / Sign up

Export Citation Format

Share Document