Mineral Soil and Solution Responses to Experimental N and S Enrichment at the Bear Brook Watershed in Maine (BBWM) (original) (raw)
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Soil response to s and n treatments in a Northern New England low elevation coniferous forest
Water Air and Soil Pollution, 1990
A field experiment was designed to evaluate the effects of differing forms of acidifying S and N compounds on the chemistry of soils and soil solutions in a low elevation coniferous forest in northern New England. Treatments consisted of O, 1500, 3000, and 6000 eq of SO42− or NO3− ha−1 for the 1987 growing season applied biweekly as H2SO4 or HNO3, or in a single application as dry] (NH4)2SO4. Acidifying treatments resulted in a significant increase in soil solution SO42− (1.2 to 2.6) or NO3− (12 to 80) in the upper B horizon. Excess strong acid anion leaching was associated with an accelerated loss of base cations, particularly MG2+ As solutions passed through the upper 25 cm of the soil profile, mean SO42− concentrations decreased by 5 to 50% of the initial values, indicating that much of the applied SO42− was immobilized in the upper portion of the pedon. Elevated concentrations of adsorbed and water-soluble SO42− indicate that abiotic adsorption of SO42− by soils is the dominant mechanism for the initial attenuation of SO42− concentrations in these solutions. Other soil properties showed only small or no change due to treatments over the single growing season of this study. These results indicate that H2SO4, HNO3, and (NH4)2SO4 can all effectively increase strong acid anion concentrations in the soil-soil solution system.
Soil chemical and physical properties at the Bear Brook Watershed in Maine, USA
Environmental Monitoring and Assessment, 2010
Acidic deposition leads to the acidification of waters and accelerated leaching and depletion of soil base cations. The Bear Brook Watershed in Maine has used whole-watershed chemical manipulations to study the effects of elevated N and S on forest ecosystem function on a decadal time scale. The objectives of this study were to define the chemical and physical characteristics of soils in both the reference and treated watersheds after 17 years of treatment and assess evidence of change in soil chemistry by comparing soil studies in 1998 and 2006. Results from 1998 confirmed depletion of soil base cation pools and decreased pH due to elevated N and S within the treated watershed. However, between 1998 and
Journal of Environment Quality, 1999
Effects of reduced deposition of N, S, and C B on nutrient pools, fluxes, soil, and soil solution chemistry were simulated for two Appalachian forest ecosystems using the nutrient cycling model. In the extremely acidic, N-and S-saturated red spruce [Picea rubens (Sarg.)] forest (Nolan Divide), reducing C B deposition by 50% reduced C B leaching by-40% during the 24-yr simulation period. This was due solely to the effects of C B deposition on the soil exchanger rather than effects on soil solution. Reducing S and N by 50% caused immediate reductions in total anion and cation leaching at Nolan Divide, but the effects on soil solution C B diminished and C B leaching was reduced by only 17% over the simulation period. Reducing S and N deposition had a greater effect on soil solution aluminum (Al) and molar Ca/Al ratio than reducing base cation deposition at Nolan Divide. In the moderately acidic, N-and S-accumulating mixed deciduous forest at Coweeta, reduced C B deposition by 50% caused a very slight (<4%) reduction in C E leaching as a result of slightly reduced base saturation and increased soil sulfate adsorption. The effects on reducing S and N deposition by 50% on C B leaching (16% over the simulation period) were greater than those of reduced C B deposition. The system continued to accumulate both S and N even at reduced deposition at Coweeta, although growth and vegetation uptake were slightly reduced (-5%) because of increased N deficiency. Base saturation remained well above the Al buffering range at all times at Coweeta and Al was an unimportant component of soil solutions in all scenarios.
Soil solution response to acidic deposition in a northern hardwood forest
Agriculture, Ecosystems & Environment, 1993
An intensive plot-scale acidification experiment evaluated the effects of H2SO4, HNO3, and combined H2SO4 and HNO3 treatments on the chemistry of soils and soil solutions in a northern hardwood forest. Treatments were delivered to 18 plots (each of 15 m× 15 m, three plots per treatment) during 20-week field seasons by a hill-slope irrigation system and consisted of two levels of H2SO4 ( ~ 2000 and 4000 eq ha-1 year-1 ), two levels of HNO3 ( ~ 2000 and 4000 eq ha-~ year-~ ), one level of combined H2SO4/HNO3 ( ~ 2000 eq ha-t year-~ each of SO 2-and NO3-), and a control (water only).
Experimental Acidification Causes Soil Base-Cation Depletion at the Bear Brook Watershed in Maine
Soil Science Society of America Journal, 2003
There h concern that changes i n atmospheric deposition, climate, or land use have altered the biogeochemistry o f forests causing soil base-cation depletion, particularly C e The Bear Brook Watershed i n Maine (BBWM) is a paired watershed experiment with one watershed subjected to elevated N and S deposition through bimonthly additions of (NH,)aO,.
Soil-solution chemistry in a low-elevation spruce-fir ecosystem, Howland, Maine
Water, Air, & Soil Pollution, 1995
Soil solutions were collected monthly by tension and zero-tension lysimeters in a lowelevation red spruce stand in east-central Maine from May 1987 through December 1992. Soil solutions collected by Oa tension lysimeters had higher concentrations of most constituents than the Oa zero-tension lysimeters. In Oa horizon soil solutions growing season concentrations for SO4, Ca, and Mg averaged 57, 43, and 30 #mol L -l in tension lysimeters, and 43, 28, and 19 #mol L -1 in zero-tension lysimeters, respectively. Because tension lysimeters remove water held by the soil at tensions up to 10 kPa, solutions are assumed to have more time to react with the soil compared to freely draining solutions collected by zero-tension lysimeters. Solutions collected in the Bs horizon by both types of collectors were similar which was attributed to the frequency of time periods when the water table was above the Bs lysimeters. Concentrations of SO4 and NO3 at this site were lower than concentrations reported for most other eastern U.S. spruce-fir sites, but base cation concentrations fell in the same range. Aluminum concentrations in this study were also lower than reported for other sites in the eastern U.S. and Ca/A1 ratios did not suggest inhibition of Ca uptake by roots. Concentrations of SO4, Ca, K, and C1 decreased significantly in both the Oa and Bs horizons over the 56-month sampling period, which could reflect decreasing deposition rates for sulfur and base cations, climatic influences, or natural variation. A longer record of measured fluxes will be needed to adequately define temporal trends in solution chemistry and their causes.
Canadian Journal of Forest Research, 1999
Nitrogen saturation results in greater mobility of nitrate, which in turn is often correlated with concentrations of nutrient cations in soil solution and streamwater. At the Harvard Forest, U.S.A., under long-term NH 4 NO 3 inputs, a Pinus resinosa Ait. forest has exhibited signs of N saturation more rapidly than a mixed-Quercus forest. We test the hypothesis that increased nitrate leaching causes increased concentrations of nutrient cations in soil solution. Over 2 years (years 6 and 7 of treatment) we measured SO 4 2-, NO 3-, Cl-, Ca 2+ , K + , Mg 2+ , Na + , H + , and NH 4 + in throughfall solution and in forest-floor (Oa) leachate. Concentrations of NO 3 in forest-floor leachate increased with rates of N amendment and correlated positively with cation concentrations, with stronger overall correlations in the pine forest: r 2 values were 0.51 (pine forest) and 0.39 (oak forest) for Ca 2+ , 0.45 (pine) and 0.16 (oak) for K + , and 0.62 (pine) and 0.50 (oak) for Mg 2+. In summer and fall, the oak forest showed some negative relationships between nutrient cation leaching and rate of N amendment. These contrasts showed retention of cations and N to occur together in an Nlimited system, whereas increased nitrate mobility occurred with increased cation losses in an N-saturated system.
Cation distribution, cycling, and removal from mineral soil in Douglas-fir and red alder forests
Biogeochemistry, 1992
Overstory species influence the distribution and dynamics of nutrients in forest ecosystems. Ecosystem-level estimates of Ca, Mg, and K pools and cycles in 50-year old Douglas-fir and red alder stands were used to determine the effect of overstory composition on net cation removal from the mineral soil, i.e. cation export from the soil in excess of additions. Net cation removal from Douglas-fir soil was 8 kg Ca ha-' yr-~, 1 kg Mg ha-' yr-~, and 0.3 kg K ha-l yr-1. Annual cation export from soil by uptake and accumulation in live woody tissue and O horizon was of similar magnitude to leaching in soil solution. Atmospheric deposition partially offset export by adding cations equivalent to 28-88% of cation export. Net cation removal from red alder soil was 58 kg Ca ha-' yr-~, 9 kg Mg hayr-1, and 11 kg K ha-' yr-~. Annual cation accumulation in live woody tissue and O horizon was three times greater than in Douglas-fir, while cation leaching in soil solution was five to eight times greater. The lack of excessive depletion of exchangeable cations in the red alder soil suggests that mineral weathering, rather than exchangeable cations, was the source of most of the removed cations. Nitric acid generated during nitrification in red alder soil led to high rates of weathering and NO3-driven cation leaching. Woody tissue growth was determined for each live tree as the change in woody tissue biomass that occurred between successive measurements. Woody tissue mortality was defined as the transfer at tree death of live woody tissue to a detrital pool of coarse woody debris; this latter pool was not quantified but was considered to include dead standing trees, fallen logs, and large woody pieces (> 6 cm in diameter) lying on the surface of the O horizon. Net woody tissue increment was the difference between woody tissue growth and woody tissue mortality. Average rates of woody tissue growth, woody tissue mortality, and net woody tissue increment were determined for the 1979 to 1988 period. Total foliar mass in red alder was determined as 1.12 times foliar litter, based on the data of Turner et al. (1976). Current foliagethat produced during the most recent yearwas equivalent to total foliage for this deciduous species. Total foliar mass in Douglas-fir was determined as 5.88 times foliar litter, based on the studies of Marshall & Waring (1986) and Heilman & Gessel (1963a, b). Current foliage mass was assumed equivalent to annual foliar litter. Non-woody ('fine') root mass and production were not quantified. Foliage, branch, bole wood, and bole bark samples were taken from ten trees in each stand in late May 1985. Woody root samples were taken from five trees in each stand in September 1988. Samples were analyzed for Ca, Mg, and K by lithium sulfate/sulfuric acid digestion (Parkinson & Allen 1975) followed by atomic absorption of the digest. Cation pools were estimated by multiplying average concentrations by estimated treecomponent masses for each entire plot. Understory was collected in July 1986 from four 1 x 1 m subplots per plot. In the Douglas-fir stand, understory consisted mainly of salal (Gaultheria shallon Pursh.), Oregon grape (Berberis nervosa (Pursh.) Nutt.), and bracken fern (Pteridium aquilinum Kuhn var. pubescens Underw.). In the red alder stand, understory was predominantly sword fern (Polystichum munitum (Kaulf.) Presl.) and bracken fern intermixed with some Oregon grape. Organic (O) horizon was collected from a 0.5 X 0.5 m area within each understory subplot and separated into (i) wood and (ii) litter plus humus. Wood included all woody material within the O horizon plus woody material < 6 cm in diameter on the surface. Wood > 6 cm in diameter on the surface was not quantified. Samples were dried (70 ?C), weighed, and analyzed for Ca, Mg, and K by the method of Parkinson & Allen (1975). Cation pools were calculated separately for each subplot. Mineral soil was sampled by depth (0-7, 7-15, 15-30, 30-45 cm) in June 1985 (four soil pits in red alder plot, five in Douglas-fir). Soil was air dried and sieved. The < 2 mm fraction was analyzed for exchangeable