Element Fluxes and Landscape Position in a Northern Hardwood Forest Watershed Ecosystem

Johnson, Chris; Driscoll, Charles T.; Siccama, Thomas G.; Likens, Gene E.

doi:10.1007/s100210000017

Cited by 172 publications

(196 citation statements)

References 72 publications

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“…The area is generally covered with glacial till derived from local bedrock with a depth ranging from zero along the ridge tops to several meters at the lower elevations (Palmer et al 2004). The soils are well-drained Spodosols, mostly Haplorthods (Johnson et al 2000), with a well-developed organic horizon (3-15 cm; Likens et al 1977) and underlain by impervious bedrock (Littleton Formation, schist). Higher elevation soils tend to be shallowest and soil depth increases with decreasing elevation (Lawrence et al 1986).…”

Section: Site Descriptionmentioning

confidence: 99%

“…In the spruce-fir-birch zone, DOC concentrations were highest in part because of the recalcitrant nature of coniferous litter, cooler temperatures and greater soil moisture, which lead to reduced decomposition rates at higher elevation (Driscoll et al 1988a). There is greater accumulation of organic matter with increasing elevation at Hubbard Brook, with the greatest amounts in the spruce-fir-birch zone (Gosz et al 1976;Johnson et al 2000). The depth of mineral soil is lowest in the spruce-fir-birch zone (Lawrence et al, 1986;Johnson et al, 2000) and consequently, there are a limited number of adsorption sites to facilitate the immobilization of DOC (and DOC-metal complexes) draining through the soil profile to stream waters (McDowell and Wood 1984;Fuller et al 1985).…”

Section: Chemistry Of Drainage Waters: Soil Solution and Stream Watermentioning

confidence: 99%

“…There is greater accumulation of organic matter with increasing elevation at Hubbard Brook, with the greatest amounts in the spruce-fir-birch zone (Gosz et al 1976;Johnson et al 2000). The depth of mineral soil is lowest in the spruce-fir-birch zone (Lawrence et al, 1986;Johnson et al, 2000) and consequently, there are a limited number of adsorption sites to facilitate the immobilization of DOC (and DOC-metal complexes) draining through the soil profile to stream waters (McDowell and Wood 1984;Fuller et al 1985). The solubility of Fe was also greater in drainage waters of the spruce-fir-birch zone, due to lower pH and higher concentrations of organic acids (Driscoll et al 1988b).…”

Section: Chemistry Of Drainage Waters: Soil Solution and Stream Watermentioning

confidence: 99%

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Dynamics of oxidized and reduced iron in a northern hardwood forest

et al. 2010

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Section: Site Descriptionmentioning

confidence: 99%

Section: Chemistry Of Drainage Waters: Soil Solution and Stream Watermentioning

confidence: 99%

Section: Chemistry Of Drainage Waters: Soil Solution and Stream Watermentioning

confidence: 99%

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Dynamics of oxidized and reduced iron in a northern hardwood forest

et al. 2010

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“…In the deciduous forest below two zones are distinguished (high and low elevation hardwoods). These zones exhibit contrasting biogeochemical behavior as summarized by Johnson et al (2000). Our calculations of C pools and fluxes in the mature forest ecosystem are based upon the biogeochemical reference watershed, W6, where most measurements have been made.…”

Section: Study Sitementioning

confidence: 99%

“…As infiltrating water percolates through the forest floor horizons both inorganic and organic C are dissolved, and net leaching from the forest floor amounts to about 25 g C/m 2 -yr (i.e., 22 g C/m 2 -yr DOC, 3 g C/m 2 -yr DIC; Table 2; Johnson et al 2000). This value represents the largest dissolved C flux in the system and, as discussed later, probably plays an important role in soil development.…”

Section: Hydrologic Fluxes Of Carbonmentioning

confidence: 99%

The Biogeochemistry of Carbon at Hubbard Brook

et al. 2005

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Abstract. The biogeochemical behavior of carbon in the forested watersheds of the Hubbard Brook Experimental Forest (HBEF) was analyzed in long-term studies. The largest pools of C in the reference watershed (W6) reside in mineral soil organic matter (43% of total ecosystem C) and living biomass (40.5%), with the remainder in surface detritus (14.5%). Repeated sampling indicated that none of these pools was changing significantly in the late-1990s, although high spatial variability precluded the detection of small changes in the soil organic matter pools, which are large; hence, net ecosystem productivity (NEP) in this 2nd growth forest was near zero (± about 20 g C/m 2 -yr) and probably similar in magnitude to fluvial export of organic C. Aboveground net primary productivity (ANPP) of the forest declined by 24% between the late-1950s (462 g C/m 2 -yr) and the late-1990s (354 g C/m 2 -yr), illustrating age-related decline in forest NPP, effects of multiple stresses and unusual tree mortality, or both. Application of the simulation model PnET-II predicted 14% higher ANPP than was observed for 1996-1997, probably reflecting some unknown stresses. Fine litterfall flux (171 g C/m 2 -yr) has not changed much since the late-1960s. Because of high annual variation, C flux in woody litterfall (including tree mortality) was not tightly constrained but averaged about 90 g C/m 2 -yr. Carbon flux to soil organic matter in root turnover (128 g C/m 2 -yr) was only about half as large as aboveground detritus. Balancing the soil C budget requires that large amounts of C (80 g C/m 2 -yr) were transported from roots to rhizosphere carbon flux. Total soil respiration (TSR) ranged from 540 to 800 g C/m 2 -yr across eight stands and decreased with increasing elevation within the northern hardwood forest near W6. The watershedwide TSR was estimated as 660 g C/m 2 -yr. Empirical measurements indicated that 58% of TSR occurred in the surface organic horizons and that root respiration comprised about 40% of TSR, most of the rest being microbial. Carbon flux directly associated with other heterotrophs in the HBEF was minor; for example, we estimated respiration of soil microarthropods, rodents, birds and moose at about 3, 5, 1 and 0.8 g C/m 2 -yr, respectively, or in total less than 2% of NPP. Hence, the effects of other heterotrophs on C flux were primarily indirect, with the exception of occasional 2 -yr) were small, larger quantities of C were transported within the ecosystem and a more substantial fraction of dissolved C was transported from the soil as inorganic C and evaded from the stream as CO 2 (4.0 g C/m 2 -yr). Carbon pools and fluxes change rapidly in response to catastrophic disturbances such as forest harvest or major windthrow events. These changes are dominated by living vegetation and dead wood pools, including roots. If biomass removal does not accompany large-scale disturbance, the ecosystem is a large net source of C to the atmosphere (500-1200 g C/m 2 -yr) for about a decade following disturbance and becomes a net si...

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Searching for biogeochemical hot spots in three dimensions: Soil C and N cycling in hydropedologic settings in a northern hardwood forest

Morse

Werner

Gillin

et al. 2014

J. Geophys. Res. Biogeosci.

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Understanding and predicting the extent, location, and function of biogeochemical hot spots at the watershed scale is a frontier in environmental science. We applied a hydropedologic approach to identify (1) biogeochemical differences among morphologically distinct hydropedologic settings and (2) hot spots of microbial carbon (C) and nitrogen (N) cycling activity in a northern hardwood forest in Hubbard Brook Experimental Forest, New Hampshire, USA. We assessed variables related to C and N cycling in spodic hydropedologic settings (typical podzols, bimodal podzols, and Bh podzols) and groundwater seeps during August 2010. We found that soil horizons (Oi/Oe, Oa/A, and B) differed significantly for most variables. B horizons (>10 cm) accounted for 71% (±11%) of C pools and 62% (±10%) of microbial biomass C in the sampled soil profile, whereas the surface horizons (Oi/Oe and Oa/A; 0-10 cm) were dominant zones for N-cycle-related variables. Watershed-wide estimates of C and N cycling were higher by 34 to 43% (±17-19%) when rates, horizon thickness, and areal extent of each hydropedologic setting were incorporated, versus conventionally calculated estimates for typical podzols that included only the top 10 cm of mineral soil. Despite the variation in profile development in typical, bimodal, and Bh podzols, we did not detect significant differences in C and N cycling among them. Across all soil horizons and hydropedologic settings, we found strong links between biogeochemical cycling and soil C, suggesting that the accumulation of C in soils may be a robust indicator of microbial C and N cycling capacity in the landscape.

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Element Fluxes and Landscape Position in a Northern Hardwood Forest Watershed Ecosystem

Cited by 172 publications

References 72 publications

Dynamics of oxidized and reduced iron in a northern hardwood forest

Dynamics of oxidized and reduced iron in a northern hardwood forest

The Biogeochemistry of Carbon at Hubbard Brook

Searching for biogeochemical hot spots in three dimensions: Soil C and N cycling in hydropedologic settings in a northern hardwood forest

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