Short-Term N-Fertilization Differently Affects the Leaf and Leaf Litter Chemistry of the Dominant Species in a Mediterranean Forest under Drought Conditions

Nitrogen (N) deposition is a key driver of global change with significant effects on carbon (C) cycling, species fitness, and diversity; however, its effects on Mediterranean ecosystems are unclear. Here, we simulated N deposition in an N-fertilization experiment with 15N-labeled fertilizer in a montane evergreen Mediterranean holm oak forest, in central Catalonia, to quantify short-term impacts on leaf, leaf litter elemental composition, and resorption efficiency in three dominant species (Quercus ilex, Phillyrea latifolia, and Arbutus unedo). We found that even under drought conditions, 15N isotope analysis of leaf and leaf litter showed a rapid uptake of the added N, suggesting an N deficient ecosystem. Species responses to N fertilization varied, where A. unedo was unaffected and the responses in P. latifolia and Q. ilex were similar, albeit with contrasting magnitude. P. latifolia benefited the most from N fertilization under drought conditions of the experimental year. These differences in species response could indicate impacts on species fitness, competition, and abundance under increased N loads in Mediterranean forest ecosystems. Further research is needed to disentangle interactions between long-term N deposition and the drought predicted under future climate scenarios in Mediterranean ecosystems.

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Drivers of soil respiration in response to nitrogen addition in a Mediterranean mountain forest

Biogeochemistry ◽

10.1007/s10533-021-00827-2 ◽

2021 ◽

Author(s):

María José Fernández-Alonso ◽

Eugenio Díaz-Pinés ◽

Agustín Rubio

Keyword(s):

Soil Respiration ◽

Tree Species ◽

N Fertilization ◽

N Deposition ◽

Short Term ◽

Deposition Rates ◽

Tree Species Composition ◽

Soil Stoichiometry ◽

N Enrichment ◽

Soil Responses

AbstractAtmospheric nitrogen (N) deposition rates affect soil N dynamics, influencing soil respiration (RS) rates. However, for the Mediterranean region, the effect of changes in atmospheric N deposition on RS are not well constrained yet. We investigated the interplay between increased N deposition and tree species composition on RS at a Scots pine—Pyrenean oak ecotone in Central Spain, and whether the observed responses were mediated by changes on selected soil properties. Throughout 3 years, we simulated two N deposition rates—10 (medium) and 40 kg N ha−1 a−1 (high)—over the background deposition (control) in neighbouring stands in which tree species composition (pine or oak) shapes soil stoichiometry and microbial communities. We monitored RS on a monthly basis during 3 years; in addition, we performed targeted measurements 24 h after the N fertilization events to assess short-term soil responses. During winter and summer, RS did not respond to enhanced N deposition rates. In spring and autumn, higher RS rates were observed in the medium-fertilization, but the size and duration of this effect was tree species dependent. We suggest that climate seasonality modulates the response of RS to N availability, with tree species effects becoming relevant only when environmental conditions are adequate. RS in fertilized plots was larger from February to May and in September under pine, while under oak a response was observed only in April, probably due to differences in native soil stoichiometry under each tree species. Overall, RS showed high stability during 3 years of N enrichment in this Mediterranean ecotone area. However, we observed short-term soil responses after N fertilization events—loss of base cations, soil acidification and reduced microbial biomass—which emphasize the need to investigate consequences for the belowground C and N cycles if chronic N enrichment persists in the long run.

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Effects of experimental nitrogen deposition on peatland carbon pools and fluxes: a modelling analysis

Biogeosciences ◽

10.5194/bg-12-79-2015 ◽

2015 ◽

Vol 12 (1) ◽

pp. 79-101 ◽

Cited By ~ 7

Author(s):

Y. Wu ◽

C. Blodau ◽

T. R. Moore ◽

J. Bubier ◽

S. Juutinen ◽

...

Keyword(s):

Ecosystem Respiration ◽

Model Performance ◽

Net Ecosystem Exchange ◽

N Fertilization ◽

N Deposition ◽

Competitive Advantages ◽

Long Term Effects ◽

N Content ◽

Modelling Analysis

Abstract. Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet long-term effects and controls are poorly understood. We applied the model PEATBOG to explore impacts of long-term nitrogen (N) fertilization on C cycling in an ombrotrophic bog. Simulations of summer gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosystem exchange (NEE) were evaluated against 8 years of observations and extrapolated for 80 years to identify potential effects of N fertilization and factors influencing model behaviour. The model successfully simulated moss decline and raised GEP, ER and NEE on fertilized plots. GEP was systematically overestimated in the model compared to the field data due to factors that can be related to differences in vegetation distribution (e.g. shrubs vs. graminoid vegetation) and to high tolerance of vascular plants to N deposition in the model. Model performance regarding the 8-year response of GEP and NEE to N input was improved by introducing an N content threshold shifting the response of photosynthetic capacity (GEPmax) to N content in shrubs and graminoids from positive to negative at high N contents. Such changes also eliminated the competitive advantages of vascular species and led to resilience of mosses in the long-term. Regardless of the large changes of C fluxes over the short-term, the simulated GEP, ER and NEE after 80 years depended on whether a graminoid- or shrub-dominated system evolved. When the peatland remained shrub–Sphagnum-dominated, it shifted to a C source after only 10 years of fertilization at 6.4 g N m−2 yr−1, whereas this was not the case when it became graminoid-dominated. The modelling results thus highlight the importance of ecosystem adaptation and reaction of plant functional types to N deposition, when predicting the future C balance of N-polluted cool temperate bogs.

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Insights into mechanisms governing forest carbon response to nitrogen deposition: a model–data comparison using observed responses to nitrogen addition

Biogeosciences ◽

10.5194/bg-10-3869-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 3869-3887 ◽

Cited By ~ 46

Author(s):

R. Q. Thomas ◽

G. B. Bonan ◽

C. L. Goodale

Keyword(s):

Plant Uptake ◽

Temperate Forest ◽

Growth Response ◽

N Fertilization ◽

N Deposition ◽

Forest Carbon ◽

Biogeochemical Model ◽

N Fixation ◽

N Availability ◽

Fertilization Experiments

Abstract. In many forest ecosystems, nitrogen (N) deposition enhances plant uptake of carbon dioxide, thus reducing climate warming from fossil fuel emissions. Therefore, accurately modeling how forest carbon (C) sequestration responds to N deposition is critical for understanding how future changes in N availability will influence climate. Here, we use observations of forest C response to N inputs along N deposition gradients and at five temperate forest sites with fertilization experiments to test and improve a global biogeochemical model (CLM-CN 4.0). We show that the CLM-CN plant C growth response to N deposition was smaller than observed and the modeled response to N fertilization was larger than observed. A set of modifications to the CLM-CN improved the correspondence between model predictions and observational data (1) by increasing the aboveground C storage in response to historical N deposition (1850–2004) from 14 to 34 kg C per additional kg N added through deposition and (2) by decreasing the aboveground net primary productivity response to N fertilization experiments from 91 to 57 g C m−2 yr−1. Modeled growth response to N deposition was most sensitive to altering the processes that control plant N uptake and the pathways of N loss. The response to N deposition also increased with a more closed N cycle (reduced N fixation and N gas loss) and decreased when prioritizing microbial over plant uptake of soil inorganic N. The net effect of all the modifications to the CLM-CN resulted in greater retention of N deposition and a greater role of synergy between N deposition and rising atmospheric CO2 as a mechanism governing increases in temperate forest primary production over the 20th century. Overall, testing models with both the response to gradual increases in N inputs over decades (N deposition) and N pulse additions of N over multiple years (N fertilization) allows for greater understanding of the mechanisms governing C–N coupling.

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Effect of Short-Term Low-Nitrogen Addition on Carbon, Nitrogen and Phosphorus of Vegetation-Soil in Alpine Meadow

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph182010998 ◽

2021 ◽

Vol 18 (20) ◽

pp. 10998

Author(s):

Zhen’an Yang ◽

Wei Zhan ◽

Lin Jiang ◽

Huai Chen

Keyword(s):

Alpine Meadow ◽

Nitrogen Addition ◽

Ammonium Nitrogen ◽

N Deposition ◽

Total Carbon ◽

N Addition ◽

Short Term ◽

Nitrogen And Phosphorus ◽

Soil Rhizosphere ◽

And Function

As one of the nitrogen (N) limitation ecosystems, alpine meadows have significant effects on their structure and function. However, research on the response and linkage of vegetation-soil to short-term low-level N deposition with rhizosphere processes is scant. We conducted a four level N addition (0, 20, 40, and 80 kg N ha−1 y−1) field experiment in an alpine meadow on the Qinghai-Tibetan Plateau (QTP) from July 2014 to August 2016. We analyzed the community characteristics, vegetation (shoots and roots), total carbon (TC), nutrients, soil (rhizosphere and bulk) properties, and the linkage between vegetation and soil under different N addition rates. Our results showed that (i) N addition significantly increased and decreased the concentration of soil nitrate nitrogen (NO3−-N) and ammonium nitrogen, and the soil pH, respectively; (ii) there were significant correlations between soil (rhizosphere and bulk) NO3−-N and total nitrogen (TN), and root TN, and there was no strong correlation between plant and soil TC, TN and total phosphorus, and their stoichiometry under different N addition rates. The results suggest that short-term low-N addition affected the plant community, vegetation, and soil TC, TN, TP, and their stoichiometry insignificantly, and that the correlation between plant and soil TC, TN, and TP, and their stoichiometry were insignificant.

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Snail and millipede complementarity in decomposing Mediterranean forest leaf litter mixtures

Functional Ecology ◽

10.1111/j.1365-2435.2010.01694.x ◽

2010 ◽

Vol 24 (4) ◽

pp. 937-946 ◽

Cited By ~ 33

Author(s):

Tatiana De Oliveira ◽

Stephan Hättenschwiler ◽

Ira Tanya Handa

Keyword(s):

Leaf Litter ◽

Mediterranean Forest ◽

Litter Mixtures ◽

Forest Leaf Litter

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Impact of a Long-Term Fire Retardant (Fire Trol 931) on the Physico-chemical Properties of Leachates from a Mediterranean Forest Soil: a Short-Term, Lab-Scale Study

Water Air & Soil Pollution ◽

10.1007/s11270-015-2425-3 ◽

2015 ◽

Vol 226 (5) ◽

Cited By ~ 1

Author(s):

Sofia Koufopoulou ◽

Charalampos Michalopoulos ◽

Athina Pappa ◽

Nikolaos Tzamtzis

Keyword(s):

Forest Soil ◽

Chemical Properties ◽

Fire Retardant ◽

Mediterranean Forest ◽

Short Term ◽

Physico Chemical

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Foliar sulfur and nitrogen along an 800-km pollution gradient

Canadian Journal of Forest Research ◽

10.1139/x92-230 ◽

1992 ◽

Vol 22 (11) ◽

pp. 1761-1769 ◽

Cited By ~ 15

Author(s):

Kurt S. Pregitzer ◽

Andrew J. Burton ◽

Glenn D. Mroz ◽

Hal O. Liechty ◽

Neil W. MacDonald

Keyword(s):

Leaf Litter ◽

Acidic Deposition ◽

N Deposition ◽

Hardwood Forests ◽

Litter Fall ◽

Pollution Gradient ◽

Northern Hardwood Forests ◽

Northern Hardwood ◽

Molar Ratios ◽

Foliar S

Emissions of sulfur (S) and nitrogen (N) oxides in the midwestern and northeastern United States result in pronounced regional gradients of acidic deposition. The objective of this study was to determine the extent to which atmospheric deposition alters the uptake and cycling of S and N in five analogous northern hardwood forests located along one of the most pronounced regional gradients of SO42−-S and NO3−-N deposition in the United States. We tested the hypothesis that acidic deposition would alter foliar S and N ratios and nutrient cycling in aboveground litter fall. Sulfate in both wet deposition and throughfall increased by a factor of two across the 800-km deposition gradient. The July concentration of S in sugar maple (Acersaccharum Marsh.) leaves increased from about 1600 μg•g−1 at the northern research sites to 1800–1900 μg•g−1 at the southern sites. Differences in leaf litter S concentration were even more pronounced (872–1356 μg•g−1), and a clear geographic trend was always apparent in litter S concentration. The 3-year average S content of leaf litter was 63% greater at the southern end of the pollution gradient. Nitrate and total N deposition were also significantly greater at the southern end of the gradient. The concentration of N in both summer foliage and leaf litter was not correlated with N deposition, but the content of N in leaf litter was significantly correlated with N deposition. The molar ratios of S:N in mid-July foliage and leaf litter increased as atmospheric deposition of SO42−-S increased. Ratios of S:N were always much greater in leaf litter than in mid-July foliage. The molar ratios of S:N retranslocated from the canopies of these northern hardwood forests were less than those in mid-July foliage or litter fall and showed no geographic trend related to deposition, suggesting that S and N are retranslocated in a relatively fixed proportion. Significant correlations between SO42−-S deposition and foliar S concentration, S cycling, and the molar ratio of S:N in foliage suggest that sulfate deposition has altered the uptake and cycling of S in northern hardwood forests of the Great Lakes region.

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Effects of Short-term Tillage of a Long-term No-Till Land on Crop Yield and Nutrient Uptake in Two Contrasting Soil Types

Sustainable Agriculture Research ◽

10.5539/sar.v5n3p32 ◽

2016 ◽

Vol 5 (3) ◽

pp. 32 ◽

Cited By ~ 3

Author(s):

Miles Dyck ◽

Sukhdev S. Malhi ◽

Marvin Nyborg ◽

Dyck Puurveen

Keyword(s):

Nutrient Uptake ◽

Crop Yield ◽

Crop Production ◽

N Uptake ◽

P Uptake ◽

N Fertilization ◽

Short Term ◽

Plant Yield ◽

No Till

Pre-seeding tillage of long-term no-till (NT) land may alter crop production by changing the availability of some nutrients in soil. Effects of short-term (4 years) tillage (hereafter called reverse tillage [RT]) of land previously under long-term (29 or 30 years) NT, with straw management (straw removed [SRem] and straw retained [SRet]) and N fertilizer rate (0, 50 and 100 kg N ha-1 in SRet, and 0 kg N ha-1 in SRem plots), were determined on plant yield (seed + straw, or harvested as forage/silage at soft dough stage), and N and P uptake in growing seasons from 2010 to 2013 at Breton (Gray Luvisol [Typic Cryoboralf] loam) and from 2009 to 2012 at Ellerslie (Black Chernozem [Albic Argicryoll] loam), Alberta, Canada. Plant yield, N uptake and P uptake tended to be greater with RT compared to NT in most cases at both sites, although significant in a few cases only at Ellerslie. On average over both sites, RT produced greater plant yield by 560 kg ha-1 yr-1, N uptake by 5.8 kg N ha-1 yr-1, and P uptake by 1.8 kg P ha-1 yr-1 than NT. There was no consistent beneficial effect of straw retention on plant yield, N uptake and P uptake in different years. Plant yield, N uptake and P uptake increased with N fertilization at both sites, with up to the maximum rate of applied N at 100 kg N ha-1 in 3 of 4 years at Breton and in 2 of 4 years at Ellerslie. In conclusion, our findings suggested some beneficial impact of occasional tillage of long-term NT soil on crop yield and nutrient uptake.

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