Impacts of fire and fire surrogate treatments on ecosystem nitrogen storage patterns: similarities and differences between forests of eastern and western North America

2008 ◽  
Vol 38 (12) ◽  
pp. 3056-3070 ◽  
Author(s):  
R. E.J. Boerner ◽  
Jianjun Huang ◽  
Stephen C. Hart
Keyword(s):  
Management Strategies ◽  
N Deposition ◽  
Atmospheric N Deposition ◽  
N Losses ◽  
Total N ◽  
Wildfire Hazard ◽  
Forest Sites ◽  
C And N ◽  
C And N Cycling ◽  
The Impact

The Fire and Fire Surrogates (FFS) network is composed of 12 forest sites that span the continental United States, all of which historically had frequent low-severity fire. The goal of the FFS study was to assess the efficacy of three management treatments (prescribed fire, mechanical thinning, and their combination) in reducing wildfire hazard and increasing ecosystem sustainability. This paper describes the impact of the FFS treatments on nitrogen (N) storage and distribution. At the network scale, total ecosystem N averaged 4480 kg·ha–1, with ∼9% in vegetation, ∼9% in forest floor, ∼2% in deadwood, and ∼80% in soil. The loss of vegetation N to fire averaged (±SE) 25 ± 11 kg·ha–1, whereas the mechanical and combined mechanical and fire treatments resulted in N losses of 133 ± 21 and 145 ± 19 kg·ha–1, respectively. Western coniferous forests lost more N from each treatment than did eastern forests. None of the manipulative FFS treatments impacted >10%–15% of total N of these ecosystems. Management strategies that maximize ecosystem carbon (C) gain by minimizing loss of N should be a focus in western forests, where C and N cycling are tightly linked, but perhaps not in those eastern forests where atmospheric N deposition has decoupled C and N cycles.

scholarly journals Understanding the Impact of Different Landscape-Level Fuel Management Strategies on Wildfire Hazard in Central Portugal

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 522
Author(s):  
Akli Benali ◽  
Ana C. L. Sá ◽  
João Pinho ◽  
Paulo M. Fernandes ◽  
José M. C. Pereira
Keyword(s):  
Management Strategies ◽  
Treatment Strategies ◽  
Fire Season ◽  
Burned Area ◽  
Treatment Area ◽  
Fuel Treatment ◽  
The North ◽  
Wildfire Hazard ◽  
Central Portugal ◽  
The Impact

The extreme 2017 fire season in Portugal led to widespread recognition of the need for a paradigm shift in forest and wildfire management. We focused our study on Alvares, a parish in central Portugal located in a fire-prone area, which had 60% of its area burned in 2017. We evaluated how different fuel treatment strategies may reduce wildfire hazard in Alvares through (i) a fuel break network with different extents corresponding to different levels of priority and (ii) random fuel treatments resulting from a potential increase in stand-level management intensity. To assess this, we developed a stochastic wildfire simulation system (FUNC-SIM) that integrates uncertainties in fuel distribution over the landscape. If the landscape remains unchanged, Alvares will have large burn probabilities in the north, northeast and center-east areas of the parish that are very often associated with high fireline intensities. The different fuel treatment scenarios decreased burned area between 12.1–31.2%, resulting from 1–4.6% increases in the annual treatment area and reduced the likelihood of wildfires larger than 5000 ha by 10–40%. On average, simulated burned area decreased 0.22% per each ha treated, and cost-effectiveness decreased with increasing area treated. Overall, both fuel treatment strategies effectively reduced wildfire hazard and should be part of a larger, holistic and integrated plan to reduce the vulnerability of the Alvares parish to wildfires.

scholarly journals The interaction of seasonal rainfall and nitrogen fertiliser rate on soil N2O emission, total N loss and crop yield of dryland sorghum and sunflower grown on sub-tropical Vertosols

Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 604 ◽  
Author(s):  
G. D. Schwenke ◽  
B. M. Haigh
Keyword(s):  
Crop Yield ◽  
Crop Production ◽  
Field Experiments ◽  
N2o Emission ◽  
N2o Emissions ◽  
N Loss ◽  
N Losses ◽  
Total N ◽  
Tropical Regions ◽  
The Impact

Summer crop production on slow-draining Vertosols in a sub-tropical climate has the potential for large emissions of soil nitrous oxide (N2O) from denitrification of applied nitrogen (N) fertiliser. While it is well established that applying N fertiliser will increase N2O emissions above background levels, previous research in temperate climates has shown that increasing N fertiliser rates can increase N2O emissions linearly, exponentially or not at all. Little such data exists for summer cropping in sub-tropical regions. In four field experiments at two locations across two summers, we assessed the impact of increasing N fertiliser rate on both soil N2O emissions and crop yield of grain sorghum (Sorghum bicolor L.) or sunflower (Helianthus annuus L.) in Vertosols of sub-tropical Australia. Rates of N fertiliser, applied as urea at sowing, included a nil application, an optimum N rate and a double-optimum rate. Daily N2O fluxes ranged from –3.8 to 2734g N2O-Nha–1day–1 and cumulative N2O emissions ranged from 96 to 6659g N2O-Nha–1 during crop growth. Emissions of N2O increased with increased N fertiliser rates at all experimental sites, but the rate of N loss was five times greater in wetter-than-average seasons than in drier conditions. For two of the four experiments, periods of intense rainfall resulted in N2O emission factors (EF, percent of applied N emitted) in the range of 1.2–3.2%. In contrast, the EFs for the two drier experiments were 0.41–0.56% with no effect of N fertiliser rate. Additional 15N mini-plots aimed to determine whether N fertiliser rate affected total N lost from the soil–plant system between sowing and harvest. Total 15N unaccounted was in the range of 28–45% of applied N and was presumed to be emitted as N2O+N2. At the drier site, the ratio of N2 (estimated by difference)to N2O (measured) lost was a constant 43%, whereas the ratio declined from 29% to 12% with increased N fertiliser rate for the wetter experiment. Choosing an N fertiliser rate aimed at optimum crop production mitigates potentially high environmental (N2O) and agronomic (N2+N2O) gaseous N losses from over-application, particularly in seasons with high intensity rainfall occurring soon after fertiliser application.

Soil Type Modifies the Impacts of Warming and Snow Exclusion on Carbon and Nutrient Losses

2021 ◽  
Author(s):  
Stephanie M. Juice ◽  
Paul G. Schaberg ◽  
Alexandra M. Kosiba ◽  
Carl E. Waite ◽  
Gary J. Hawley ◽  
...  
Keyword(s):  
Climate Change ◽  
Nutrient Cycling ◽  
Soil Type ◽  
Soil Characteristics ◽  
Nutrient Loss ◽  
Climate Projections ◽  
Nutrient Losses ◽  
N Losses ◽  
Total N ◽  
The Impact

Abstract The varied and wide-reaching impacts of climate change are occurring across heterogeneous landscapes. Despite the known importance of soils in mediating biogeochemical nutrient cycling, there is little experimental evidence of how soil characteristics may shape ecosystem response to climate change. Our objective was to clarify how soil characteristics modify the impact of climate changes on carbon and nutrient leaching losses in temperate forests. We therefore conducted a field-based mesocosm experiment with replicated warming and snow exclusion treatments on two soils in large (2.4 m diameter), in-field forest sapling mesocosms. We found that nutrient loss responses to warming and snow exclusion treatments frequently varied substantially by soil type. Indeed, in some cases, soil type nullified the impact of a climate treatment. For example, warming and snow exclusion increased nitrogen (N) losses on fine soils by up to four times versus controls, but these treatments had no impact on coarse soils. Generally, the coarse textured soil, with its lower soil-water holding capacity, had higher nutrient losses (e.g., 12-17 times more total N loss from coarse than fine soils), except in the case of phosphate, which had consistently higher losses (23-58%) from the finer textured soil. Furthermore, the mitigation of nutrient loss by increasing tree biomass varied by soil type and nutrient. Our results suggest that potentially large biogeochemical responses to climate change are strongly mediated by soil characteristics, providing further evidence of the need to consider soil properties in Earth system models for improving nutrient cycling and climate projections.

scholarly journals Inorganic and Organic Losses of Nitrogen from Upland Regions of Britain: Concentrations and Fluxes

2001 ◽  
Vol 1 ◽  
pp. 589-596 ◽  
Author(s):  
P.J. Chapman ◽  
A.C. Edwards
Keyword(s):  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
N Deposition ◽  
Atmospheric N Deposition ◽  
Total N ◽  
Inorganic And Organic

The nitrogen (N) composition of streams draining eight upland regions of Britain was compared using monthly samples collected between April 1997 and April 1998. Stream samples were analysed for total N (TN), particulate N (PN), nitrate (NO3), ammonium (NH4), and dissolved organic nitrogen (DON). Concentrations of TN were small, generally less than 1.5 mg N l�1, were dominated by dissolved forms of N, and varied significantly between regions. NO3 accounted for the majority of variability. Concentrations of DON also varied between regions but to a smaller extent than those of NO3. There were considerable variations in TN fluxes between upland regions, which ranged between 3.8 and 16.1 kg N ha�1 year�1. The majority of the variation was due to NO3 fluxes, which were largest in regions receiving largest inputs of atmospheric N deposition and ranged between 1.4 and 13.5 kg N ha�1 year�1. Fluxes of DON ranged between 1 and 3.5 kg N ha�1 year�1, while fluxes of PN were generally less than 0.5 kg N ha�1 year�11, and NH4 fluxes ranged between 0.1 and 0.4 kg N ha�1 year�11. NO3 was the dominant fraction (47�84%) of N exported from all upland regions except the Highlands, where DON accounted for 52% of the TN flux. This study has shown that the DON fraction is an important component of the total N transported by upland streams in Britain.

scholarly journals Too Much of a Good Thing? Inorganic Nitrogen (N) Inhibits Moss-Associated N2 Fixation But Organic N Can Promote It

2021 ◽  
Author(s):  
Yinliu Wang ◽  
Signe Lett ◽  
Kathrin Rousk
Keyword(s):  
Boreal Forests ◽  
Inorganic Nitrogen ◽  
N Deposition ◽  
Ecosystem Functions ◽  
Organic N ◽  
Inorganic N ◽  
Atmospheric N Deposition ◽  
Moss Species ◽  
The Impact ◽  
N Additions

Abstract Moss-associated nitrogen (N2) fixation is one of the main inputs of new N in pristine ecosystems that receive low amounts of atmospheric N deposition. Previous studies have shown that N2 fixation is inhibited by inorganic N (IN) inputs, but if N2 fixation in mosses is similarly affected by organic N (ON) remains unknown. Here, we assessed N2 fixation in two dominant mosses in boreal forests (Pleurozium schreberi and Sphagnum capillifolium) in response to different levels of N, simulating realistic (up to 4 kg N ha−1 yr−1) and extreme N deposition rates in pristine ecosystems (up to 20 kg N ha−1 yr−1) of IN (NH4NO3) and ON (alanine and urea). We also assessed if N2 fixation can recover from the N additions. In the realistic scenario, N2 fixation was inhibited by increasing NH4NO3 additions in P. schreberi but not in S. capillifolium, and alanine and urea stimulated N2 fixation in both moss species. In contrast, in the extreme N additions, increasing N inputs inhibited N2 fixation in both moss species and all N forms. Nitrogen fixation was more sensitive to N inputs in P. schreberi than in S. capillifolium and was higher in the recovery phase after the realistic compared to the extreme N additions. These results demonstrate that N2 fixation in mosses is less sensitive to organic than inorganic N inputs and highlight the importance of considering different N forms and species-specific responses when estimating the impact of N inputs on ecosystem functions such as moss-associated N2 fixation.

Spatial changes in nitrogen inputs drive short- and long-term variability in global nitrous oxide emissions

2021 ◽  
Author(s):  
Eliza Harris ◽  
Longfei Yu ◽  
Ying Ping Wang ◽  
Joachim Mohn ◽  
Edith Bai ◽  
...  
Keyword(s):  
Climate Warming ◽  
Anthropogenic Activities ◽  
Emission Factors ◽  
N Deposition ◽  
Mitigation Measures ◽  
N Losses ◽  
Total N ◽  
Mixing Ratios ◽  
Nitrogen Inputs ◽  
Negative Impacts

<p>Anthropogenic activities, particularly fertilisation, have resulted in significant increases in reactive nitrogen (<em>r</em>N) in soils globally, leading to eutrophication, acidification, poor air quality, and emissions of the important greenhouse gas N<sub>2</sub>O. Understanding the partitioning of <em>r</em>N losses into different environmental compartments is critical to mitigate negative impacts, however, loss pathways are poorly quantified, and potential changes driven by climate warming and societal shifts are highly uncertain. We present a coupled soil-atmosphere isotope model (IsoTONE; <strong>ISO</strong>topic <strong>T</strong>racing <strong>O</strong>f <strong>N</strong>itrogen in the <strong>E</strong>nvironment) to partition <em>r</em>N losses into leaching, harvest, NH<sub>3</sub> volatilization, and production of NO, N<sub>2</sub> and N<sub>2</sub>O based on a global dataset of soil δ<sup>15</sup>N, as well as numerous other geoclimatic and experimental datasets. The model was optimized in a Bayesian framework using a time series of N<sub>2</sub>O mixing ratios and isotopic compositions since the preindustrial era, as well as a global dataset of N<sub>2</sub>O emission factors (EF). The posterior model results showed that the total anthropogenic flux in 2020 (7.8 Tg N<sub>2</sub>O-N a<sup>-1</sup>) was dominated by indirect emissions resulting from N deposition, while the growth rate and trend in anthropogenic N<sub>2</sub>O was driven by both direct N fertilisation and deposition inputs. In contrast, inputs from fixation N drive natural N<sub>2</sub>O emissions, and were responsible for subdecadal interannual variability in total emissions.</p><p>Total N gas (N<sub>2</sub>O + NO + N<sub>2</sub>) production and N<sub>2</sub>O losses were strongly dependent on geoclimate and thus spatially variable, therefore the spatial pattern of N inputs strongly impacted resulting EFs and total N<sub>2</sub>O emissions. The area-weighted global EF for N<sub>2</sub>O was 1%  of anthropogenic N inputs in 2020, similar to the current IPCC default of 1.4%, however the N input-weighted global EF was 4.3%. Shifts in fertilisation inputs from the temperate Northern hemisphere towards warmer regions with higher EFs such as India and China have led to accelerating N<sub>2</sub>O emissions (1.02±0.7 Tg N<sub>2</sub>O-N a<sup>-1</sup>). In addition, N<sub>2</sub>O emissions have increased over the past decades due to climate warming (0.76±0.4 Tg N<sub>2</sub>O-N a<sup>-1</sup>). Predicted increases in fertilisation in India and Africa in the coming decades could further accelerate N<sub>2</sub>O-driven climate warming, unless mitigation measures are implemented to increase fertiliser N use efficiency and reduce N<sub>2</sub>O emission factors.</p>

scholarly journals Subalpine grassland carbon balance during 7 years of increased atmospheric N deposition

2016 ◽  
Vol 13 (12) ◽  
pp. 3807-3817 ◽  
Author(s):  
Matthias Volk ◽  
Jan Enderle ◽  
Seraina Bassin
Keyword(s):  
Carbon Balance ◽  
N Deposition ◽  
Control Treatment ◽  
Atmospheric N Deposition ◽  
Total N ◽  
Plant Yield ◽  
Soil C ◽  
Grassland Ecosystems ◽  
Unimodal Response ◽  
Microbial N

Abstract. Air pollution agents interact when affecting biological sinks for atmospheric CO2, e.g., the soil organic carbon (SOC) content of grassland ecosystems. Factors favoring plant productivity, like atmospheric N deposition, are usually considered to favor SOC storage. In a 7-year experiment in subalpine grassland under N- and O3-deposition treatment, we examined C fluxes and pools. Total N deposition was 4, 9, 14, 29 and 54 kg N ha−1 yr−1 (N4, N9, etc.); annual mean phytotoxic O3 dose was 49, 65 and 89 mmol m−2 projected leaf area. We hypothesized that between years SOC of this mature ecosystem would not change in control treatments and that effects of air pollutants are similar for plant yield, net ecosystem productivity (NEP) and SOC content, leading to SOC content increasing with N deposition. Cumulative plant yield showed a significant N and N  ×  N effect (+38 % in N54) but no O3 effect. In the control treatment SOC increased significantly by 9 % in 7 years. Cumulative NEP did show a strong, hump-shaped response pattern to N deposition with a +62 % increase in N14 and only +39 % increase in N54 (N effect statistically not significant, N  ×  N interaction not testable). SOC had a similar but not significant response to N, with highest C gains at intermediate N deposition rates, suggesting a unimodal response with a marginal (P = 0.09) N  ×  N interaction. We assume the strong, pollutant-independent soil C sink developed as a consequence of the management change from grazing to cutting. The non-parallel response of SOC and NEP compared to plant yield under N deposition is likely the result of increased respiratory SOC losses, following mitigated microbial N-limitation or priming effects, and a shift in plant C allocation leading to smaller C input from roots.

scholarly journals Variation of runoff and nitrogen leaching in a small agricultural catchment in southern Finland

2004 ◽  
Vol 35 (4-5) ◽  
pp. 335-345 ◽  
Author(s):  
Kirsti Granlund
Keyword(s):  
Relative Proportion ◽  
Agricultural Practices ◽  
Weather Conditions ◽  
N Deposition ◽  
Annual Runoff ◽  
N Losses ◽  
Total N ◽  
Relative Contribution ◽  
Environmental Programme

Long term monitoring data from 1981–2000 was used to study nitrogen (N) losses from a small (15.4 km2) agricultural catchment in southern Finland. The annual loads of total N, NO3-N and NH4-N varied considerably during the study period. The mean total N load was 820 kg km−2 yr−1. More than half of the annual N load was in the form of NO3-N, while the relative contribution of NH4-N was low, which is common in Finnish agricultural fine-textured soils. The measured annual N loads were highly dependent on runoff. The highest annual N load (1310 kg km−2) was observed in 1984, in accordance with the highest annual runoff (616 mm). Due to mild weather conditions during the winters since 1989, the relative proportion of winter runoff was higher than earlier. So far, no decrease could be seen in annual N loads, even though most of the farmers are participating in the Finnish Agri-Environmental Programme established in 1995. However, the amount of NH4-N load seems to have remained very low (less than 50 kg km−2 yr−1) in Savijoki since 1995, which may reflect changes in agricultural practices and a decrease in N deposition.

scholarly journals Nitrogen in Water-Portugal and Denmark: Two Contrasting Realities

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1114 ◽  
Author(s):  
Soraia Cruz ◽  
Cláudia M.d.S. Cordovil ◽  
Renata Pinto ◽  
António G. Brito ◽  
Maria R. Cameira ◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Waters ◽  
Mineral Fertilizer ◽  
N Losses ◽  
Total N ◽  
Policy Responses ◽  
Mainland Portugal ◽  
Water Quality Status ◽  
Use Efficiency ◽  
The Impact

Agricultural activities are responsible for most of the nitrogen (N) inputs that degrade water quality. To elucidate the drivers leading to N pressures on water, we examined the resulting state of surface waters in terms of N concentrations, the impact of this on water quality status and policy responses to these constraints across different climatic and management conditions. Portugal and Denmark were chosen as contrasting case studies for the Driver-Pressure-State-Impact-Response (DPSIR) analysis. Our results showed reductions of 39% and 25% in the use of mineral fertilizer in Portugal and Denmark, respectively, between 2000 and 2010. The N surplus in Portugal varied between 15 and 30 kg N ha−1 between 1995 and 2015. In Denmark, in 2015, this amount was 70 kg N ha−1, representing a 53% decrease from the 1990 value. The average amount of total N discharged to surface waters was 7 kg ha−1 for mainland Portugal in 2015 and 14.6 kg ha−1 for Denmark in 2014. These reductions in the N surplus were attributed to historical policies aimed at N pressure abatement. In Denmark, N losses are expected to decline further through the continuation or improvement of existing national action plans. In Portugal, they are expected to decline further due to the expansion of Nitrate Vulnerable Zones and the introduction of targeted policies aimed at improving N use efficiency and reducing losses to water.

scholarly journals N fluxes in two nitrogen saturated forested catchments in Germany: dynamics and modelling with INCA

2002 ◽  
Vol 6 (3) ◽  
pp. 383-394 ◽  
Author(s):  
J.-J. Langusch ◽  
E. Matzner
Keyword(s):  
Soil Depth ◽  
N Deposition ◽  
Model Complexity ◽  
N Saturation ◽  
Atmospheric N Deposition ◽  
Catchment Scale ◽  
Forested Catchments ◽  
Mineral N ◽  
N Fluxes ◽  
The Impact

Abstract. The N cycle in forests of the temperate zone in Europe has been changed substantially by the impact of atmospheric N deposition. Here, the fluxes and concentrations of mineral N in throughfall, soil solution and runoff in two German catchments, receiving high N inputs are investigated to test the applicability of an Integrated Nitrogen Model for European Catchments (INCA) to small forested catchments. The Lehstenbach catchment (419 ha) is located in the German Fichtelgebirge (NO Bavaria, 690-871 m asl.) and is stocked with Norway spruce (Picea abies (L.) Karst.) of different ages. The Steinkreuz catchment (55 ha) with European beech (Fagus sylvatica L.) as the dominant tree species is located in the Steigerwald (NW Bavaria, 400-460 m asl.). The mean annual N fluxes with throughfall were slightly higher at the Lehstenbach (24.6 kg N ha-1) than at the Steinkreuz (20.4 kg N ha-1). In both catchments the N fluxes in the soil are dominated by NO3. At Lehstenbach, the N output with seepage at 90 cm soil depth was similar to the N flux with throughfall. At Steinkreuz more than 50 % of the N deposited was retained in the upper soil horizons. In both catchments, the NO3 fluxes with runoff were lower than those with seepage. The average annual NO3 concentrations in runoff in both catchments were between 0.7 to 1.4 mg NO3-N L-1 and no temporal trend was observed. The N budgets at the catchment scale indicated similar amounts of N retention (Lehstenbach: 19 kg N ha-1yr-1 ; Steinkreuz: 17 kg N ha-1yr-1). The parameter settings of the INCA model were simplified to reduce the model complexity. In both catchments, the NO3 concentrations and fluxes in runoff were matched well by the model. The seasonal patterns with lower NO3 runoff concentrations in summer at the Lehstenbach catchment were replicated. INCA underestimated the increased N3 concentrations during short periods of rewetting in late autumn at the Steinkreuz catchment. The model will be a helpful tool for the calculation of "critical loads" for the N deposition in Central European forests including different hydrological regimes. Keywords: forest ecosystem, modelling, N budgets, N saturation, NO3 leaching, water quality, INCA

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