Nitrogen mineralization and nitrification in a mixed-conifer forest in southern California: controlling factors, fluxes, and nitrogen fertilization response at a high and low nitrogen deposition site

2005 ◽  
Vol 35 (6) ◽  
pp. 1464-1486 ◽  
Author(s):  
Mark E Fenn ◽  
Mark A Poth ◽  
Joseph D Terry ◽  
Timothy J Blubaugh
Keyword(s):  
Pinus Ponderosa ◽  
N Mineralization ◽  
Mineral Soil ◽  
N Deposition ◽  
Net N Mineralization ◽  
Conifer Forest ◽  
Monthly Basis ◽  
San Bernardino Mountains ◽  
Net Nitrification ◽  
Key Factor

Net fluxes of nitrogen (N) mineralization and nitrification were measured in situ on a monthly basis for 3 years at a high (HN) and low (LN) N deposition site in the San Bernardino Mountains, California. Mean N mineralization fluxes in the forest floor and top 10 cm of mineral soil were 19.0 and 59.8 kg N·ha–1·year–1 at LN and HN, respectively. Mean net nitrification fluxes were 11.2 and 55.9 kg N·ha–1·year–1 at LN and HN, respectively. Relative nitrification (the percent N mineralized that was nitrified) was generally lower under Pinus ponderosa Dougl. ex P. & C. Laws. (or Pinus jeffreyi Grev. & Balf.) canopies than under Quercus kelloggii Newb. or open canopies. The rate of net N mineralization was the key factor for predicting the rate of net nitrification. Fertilization with 50 and 150 kg N·ha–1 at LN significantly increased the rates of net mineralization and net nitrification. At HN fertilization had no significant effect on net nitrification. We conclude that at low-deposition sites increased nitrification occurs in the short term in response to added N, but that sustained elevated net nitrification is driven by the accumulation of N-enriched litter and soil organic matter in conjunction with chronic throughfall N deposition inputs.

Variation with slope aspect in effects of temperature on nitrogen mineralization and nitrification in mineral soil of mixed hardwood forests

2015 ◽  
Vol 45 (7) ◽  
pp. 958-962 ◽  
Author(s):  
Frank S. Gilliam ◽  
Julia E. Galloway ◽  
Jacob S. Sarmiento
Keyword(s):  
N Mineralization ◽  
Incubation Temperature ◽  
Global Climate ◽  
Mineral Soil ◽  
Slope Aspect ◽  
Net N Mineralization ◽  
Inorganic N ◽  
N Dynamics ◽  
Net Nitrification ◽  
Effects Of Temperature

This study examined the effects of temperature on soil nitrogen (N) dynamics and variation with slope aspect (northeast (NE) versus southwest (SW)) at two forested sites in West Virginia — Beech Fork Lake (BFL) and Fernow Experimental Forest (FEF) — with similar soil and overstory characteristics but with different latitudes and elevations. Previous work on mineral soil from both sites had shown sharp differences in microbial communities between SW slopes and NE slopes. Mineral soil was sampled from three and eight plots per aspect at FEF and BFL, respectively. Inorganic N was extracted from samples, which were then divided into polyethylene bags for 7-day incubations at 4 °C, 15 °C, 25 °C, and 35 °C. Following incubation, soils were extracted and analyzed for inorganic N. Net N mineralization varied significantly between aspects and temperatures but did not vary between sites; net nitrification varied significantly between aspects, temperatures, and sites. Net N mineralization increased with incubation temperature at all aspects and sites. Net nitrification rates increased with incubation temperature for BFL soils; however, maximum net nitrification rates occurred at 20–25 °C for FEF soils. Net nitrification was essentially undetectable for SW soils at either site. Results underline the complexities of the N cycle in temperate forest ecosystems, representing challenges in predicting alterations in soil N dynamics under conditions of global climate change.

scholarly journals Factors Influencing Spatial Variability in Nitrogen Processing in Nitrogen-Saturated Soils

2001 ◽  
Vol 1 ◽  
pp. 505-513 ◽  
Author(s):  
Frank S. Gilliam ◽  
Frank C.C. Somerville ◽  
Frank N.L. Lyttle ◽  
Frank M.B. Adams
Keyword(s):  
Spatial Variability ◽  
N Mineralization ◽  
Forest Floor ◽  
Mineral Soil ◽  
Nitrifying Bacteria ◽  
Saturated Soils ◽  
N Saturation ◽  
Net N Mineralization ◽  
Net Nitrification ◽  
Floor Material

Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4) and WS4 (untreated control). Samples of forest floor material (O1 horizon) and mineral soil (to a 5-cm depth) were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively) of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C), lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3-to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30°C), followed by 1 NKCl extraction and analysis for NH4+and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30°C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of N-treated/high N), whereas untreated/low N exhibited no net nitrification. However, soils exhibiting no net nitrification tested positive for presence of nitrifying bacteria, causing us to reject our initial hypothesis. We hypothesize that nitrifier populations in such soil are being inhibited by a combination of low Ca to Al ratios in mineral soil and allelopathic interactions with mycorrhizae of ericaceous species in the herbaceous layer.

scholarly journals Effects of experimental freezing on soil nitrogen dynamics in soils from a net nitrification gradient in a nitrogen-saturated hardwood forest ecosystem

2010 ◽  
Vol 40 (3) ◽  
pp. 436-444 ◽  
Author(s):  
Frank S. Gilliam ◽  
Adam Cook ◽  
Salina Lyter
Keyword(s):  
N Mineralization ◽  
Soil Freezing ◽  
N Saturation ◽  
Net N Mineralization ◽  
N Dynamics ◽  
Net Nitrification ◽  
Soil Nitrogen Dynamics ◽  
Soil N Cycle ◽  
N Mineralization Potential ◽  
Fernow Experimental Forest

This study examined effects of soil freezing on N dynamics in soil along an N processing gradient within a mixed hardwood dominated watershed at Fernow Experimental Forest, West Virginia. Sites were designated as LN (low rates of N processing), ML (moderately low), MH (moderately high), and HN (high). Soils underwent three 7-day freezing treatments (0, –20, or –80 °C) in the laboratory. Responses varied between temperature treatments and along the gradient. Initial effects differed among freezing treatments for net N mineralization, but not nitrification, in soils across the gradient, generally maintained at LN < ML ≤ MH < HN for all treatments. Net N mineralization potential was higher following freezing at –20 and –80 °C than control; all were higher than at 0 °C. Net nitrification potential exhibited similar patterns. LN was an exception, with net nitrification low regardless of treatment. Freezing response of N mineralization differed greatly from that of nitrification, suggesting that soil freezing may decouple two processes of the soil N cycle that are otherwise tightly linked at our site. Results also suggest that soil freezing at temperatures commonly experienced at this site can further increase net nitrification in soils already exhibiting high nitrification from N saturation.

Effect of landscape position on N mineralization and nitrification in a forested watershed in the Adirondack Mountains of New York

1999 ◽  
Vol 29 (4) ◽  
pp. 497-508 ◽  
Author(s):  
Kiyokazu Ohrui ◽  
Myron J Mitchell ◽  
Joseph M Bischoff
Keyword(s):  
New York ◽  
N Mineralization ◽  
Forest Floor ◽  
Landscape Position ◽  
Nitrification Rate ◽  
Forested Watershed ◽  
Net N Mineralization ◽  
Adirondack Mountains ◽  
Net Nitrification ◽  
Intermediate Rate

Within a forest ecosystem in the Adirondack Mountains of New York, net N mineralization and nitrification rates were measured at different landscape positions (zones). Net N mineralization rates (0-15 cm depth) were less (39 kg N·ha-1 per year) within a wetland without alder and with a coniferous overstory than an upland conifer zone (82 kg N·ha-1 per year) and an upland hardwood zone (107 kg N·ha-1 per year). Net N mineralization rates (39 to 82 kg N·ha-1 per year) and the forest floor N concentrations (2.3 to 2.5%) were higher than values reported (1.2-29 kg N·ha-1 and 1.1-2.12%, respectively) for other spruce forests. The net nitrification rates were higher at the upland hardwood zone (29 kg N·ha-1 per year) than the upland conifer zone (2 kg N·ha-1 per year). The wetland conifer zone without alders had an intermediate rate of net nitrification (13 kg N·ha-1 per year) compared with the upland zones. The presence of white alder (Alnus incana (L.) Moench) in the wetland increased the NO3- content and net nitrification rate of the soil.

Influence of sampling date and substrate on nitrogen mineralization: comparison of laboratory-incubation and buried-bag methods for two Massachusetts forest soils

1992 ◽  
Vol 22 (12) ◽  
pp. 1895-1900 ◽  
Author(s):  
Richard D. Boone
Keyword(s):  
Organic Matter ◽  
N Mineralization ◽  
Unit Area ◽  
Seasonal Pattern ◽  
Mineral Soil ◽  
Net N Mineralization ◽  
Laboratory Incubation ◽  
Mineralization Potential ◽  
Organic Horizons ◽  
N Mineralization Potential

Nitrogen (N) mineralization potential and net N mineralization insitu were measured monthly over 7 months for the forest floor horizons (Oi, Oe, Oa) and mineral soil (0–15 cm) of a pine stand and the mineral soil (0–15 cm) of a maple stand in Massachusetts, United States. In all cases, N mineralization potential per unit organic matter (anaerobic laboratory incubation) varied significantly by sampling month but was unrelated to the seasonal pattern for net N mineralization (buried-bag method). The organic horizons in the pine stand exhibited the most variable N mineralization potential, with the Oe horizon having more than a fourfold seasonal range. For the pine stand the Oe horizon also had the highest N mineralization potential (per unit organic matter) and the highest net N mineralization insitu (per unit area). In general, temporal and depth-wise variability should be considered when sites are assessed with respect to the pool of mineralizable N.

Empirical relationships between temperature and nitrogen availability across North American forests

1992 ◽  
Vol 22 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Xiwei Yin
Keyword(s):  
N Mineralization ◽  
Regional Scale ◽  
Mineral Soil ◽  
Published Data ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Litter Fall ◽  
Available N ◽  
N Pool

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.

scholarly journals Reviews and syntheses: measuring ecosystem nitrogen status – a comparison of proxies

2016 ◽  
Vol 13 (18) ◽  
pp. 5395-5403 ◽  
Author(s):  
Maya Almaraz ◽  
Stephen Porder
Keyword(s):  
N Mineralization ◽  
Nitrogen Availability ◽  
N Availability ◽  
Net N Mineralization ◽  
Tropical Regions ◽  
Net Nitrification ◽  
Kendall’S Τ ◽  
Soil Δ15n ◽  
N Status

Abstract. There are many proxies used to measure nitrogen (N) availability in watersheds, but the degree to which they do (or do not) correlate within a watershed has not been systematically addressed. We surveyed the literature for intact forest or grassland watersheds globally, in which several metrics of nitrogen availability have been measured. Our metrics included the following: foliar δ15N, soil δ15N, net nitrification, net N mineralization, and the ratio of dissolved inorganic to organic nitrogen (DIN : DON) in soil solution and streams. We were particularly interested in whether terrestrial and stream based proxies for N availability were correlated where they were measured in the same place. Not surprisingly, the strongest correlation (Kendall's τ) was between net nitrification and N mineralization (τ  =  0.71, p < 0.0001). Net nitrification and N mineralization were each correlated with foliar and soil δ15N (p < 0.05). Foliar and soil δ15N were more tightly correlated in tropical sites (τ  =  0.68, p < 0.0001), than in temperate sites (τ  =  0.23, p  =  0.02). The only significant correlations between terrestrial- and water-based metrics were those of net nitrification (τ  =  0.48, p  =  0.01) and N mineralization (τ  =  0.69, p  =  0.0001) with stream DIN : DON. The relationship between stream DIN : DON with both net nitrification and N mineralization was significant only in temperate, but not tropical regions. To our surprise, we did not find a significant correlation between soil δ15N and stream DIN : DON, despite the fact that both have been used to infer spatially or temporally integrated N status. Given that both soil δ15N and stream DIN : DON are used to infer long-term N status, their lack of correlation in watersheds merits further investigation.

Regional variability in nitrogen mineralization, nitrification, and overstory biomass in northern Lower Michigan

1989 ◽  
Vol 19 (12) ◽  
pp. 1521-1526 ◽  
Author(s):  
Donald R. Zak ◽  
George E. Host ◽  
Kurt S. Pregitzer
Keyword(s):  
N Mineralization ◽  
Hardwood Forests ◽  
Net N Mineralization ◽  
Northern Hardwood Forests ◽  
Northern Hardwood ◽  
Net Nitrification ◽  
Biomass Increment ◽  
Annual Biomass ◽  
Oak Ecosystem ◽  
Northern Hardwood Ecosystem

Potential net nitrogen (N) mineralization, potential net nitrification, and overstory (boles and branches) biomass were measured in nine forest ecosystems commonly found within the well-drained uplands of northern Lower Michigan. The ecosystem types ranged from oak-dominated forests on coarse-textured outwash sands to mesic northern hardwood forests on sandy glacial till. Overstory biomass was calculated using species-specific allometric equations developed for Lake States hardwood species. Potential net N mineralization and potential net nitrification were measured by a 30-day aerobic laboratory soil incubation. Analyses of (co)variance were used to determine differences in potential N mineralization, net nitrification, overstory biomass, and biomass increment among the nine ecosystem types. Linear and nonlinear regression analyses were used to predict overstory biomass and biomass increment using potential net N mineralization as the independent variable. Overstory biomass ranged from 92 t•ha−1 in a xeric oak ecosystem to 243 t•ha−1 in a northern hardwood ecosystem; annual biomass production ranged from 1.3 to 3.5 t•ha−1 year−1, respectively. Potential net N mineralization was lowest in the xeric oak ecosystem (52.0 μg N•g−1) and greatest in the mesic northern hardwood ecosystem (127.8 μg N•g−1). Potential net nitrification was 45.5 μg NO3−-N•g−1 in the northern hardwood ecosystem; 10 to 230 times greater than in other ecosystems. A saturating exponential model (y = a(1–e−kx) + c) produced the smallest residual mean squares in predicting overstory biomass (R2 = 0.822) and annual biomass increment (R2 = 0.847) from potential net N mineralization. Maximum overstory biomass and biomass increment predicted from this equation were 247 t•ha−1 and 3.7 t•ha−1, respectively. In addition, laboratory net N mineralization potentials were highly correlated with annual rates of N mineralization determined by insitu incubation (r2 = 0.849). Overstory biomass and woody biomass increment were poorly correlated with potential net nitrification. The exponential function used to predict biomass increment from N mineralization suggests that the productivity of some northern hardwood forests in northern Lower Michigan is not limited by N availability.

Net nitrogen mineralization and nitrification in trembling aspen forest soils on the Boreal Plain

2003 ◽  
Vol 33 (11) ◽  
pp. 2262-2268 ◽  
Author(s):  
N Carmosini ◽  
K J Devito ◽  
E E Prepas
Keyword(s):  
Populus Tremuloides ◽  
N Mineralization ◽  
Growing Season ◽  
Large Contribution ◽  
Net N Mineralization ◽  
Trembling Aspen ◽  
Mineral Horizon ◽  
Net Nitrification ◽  
Winter Activity ◽  
Aspen Forest

In situ net N mineralization and net nitrification rates were measured in organic forest floor (LFH) and mineral horizons of mature and logged trembling aspen (Populus tremuloides Michx.) stands on the Boreal Plain in western Canada. Cumulative May to September mineralization for mature and logged plots was 1354 ± 534 and 1631 ± 1584 mg N·m–2, respectively, in the LFH horizon and 810 ± 394 and –305 ± 3957 mg N·m–2, respectively, in the mineral horizon. Net nitrification in mature and logged plots was 86 ± 142 and 658 ± 435 mg NO3-N·m–2, respectively, in the LFH horizon and 67 ± 50 and 409 ± 325 mg NO3-N·m–2, respectively, in the mineral horizon. Monthly mean NH4-N concentrations in the LFH tended to be higher in logged plots than in mature plots. Winter net N mineralization and nitrification rates in the LFH of mature plots were up to 7% and 11% of growing season net rates, respectively. In comparison, these rates in logged plots were up to 127% and 59% of the growing season net rates, respectively, indicating that winter activity may make a large contribution to annual net mineralization and nitrification after logging.

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