Robert L. Edmonds

Mercury Distribution Across 14 U.S. Forests. Part I: Spatial Patterns of Concentrations in Biomass, Litter, and Soils

Results from a systematic investigation of mercury (Hg) concentrations across 14 forest sites in the United States show highest concentrations in litter layers, strongly enriched in Hg compared to aboveground tissues and indicative of substantial postdepositional sorption of Hg. Soil Hg concentrations were lower than in litter, with highest concentrations in surface soils. Aboveground tissues showed no detectable spatial patterns, likely due to 17 different tree species present across sites. Litter and soil Hg concentrations positively correlated with carbon (C), latitude, precipitation, and clay (in soil), which together explained up to 94% of concentration variability. We observed strong latitudinal increases in Hg in soils and litter, in contrast to inverse latitudinal gradients of atmospheric deposition measures. Soil and litter Hg concentrations were closely linked to C contents, consistent with well-known associations between organic matter and Hg, and we propose that C also shapes distribution of Hg in forests at continental scales. The consistent link between C and Hg distribution may reflect a long-term legacy whereby old, C-rich soil and litter layers sequester atmospheric Hg depositions over long time periods. Based on a multiregression model, we present a distribution map of Hg concentrations in surface soils of the United States.

Biomass and nutrient concentrations of sporocarps produced by mycorrhizal and decomposer fungi in Abies amabilis stands

SummarySporocarps and sclerotia were collected for a one-year period in 23- and 180-year-old Abies amabilis stands in western Washington. All sporocarps were classified and chemically analyzed for N, P, K, Ca, Mg, Na and Fe. Lactarius sp. and Cortinarius sp. contributed the largest proportion of the total annual epigeous sporocarp production in both stands. Annual epigeous production was 34 kg/ha in the young stand and 27 kg/ha in the mature stand. Hypogeous sporocarp production increased from 1 kg ha-1 yr-1 to 380 kg ha-1 yr-1 with increasing stand age. High sclerotia biomass occurred in the young (2,300 kg/ha) and mature (3,000 kg/ha) stands. Peak sclerotia and epigeous sporocarp biomass in the young stand and epigeous and hypogeous sporocarp biomass in the mature stand coincided with the fall peak of mycorrhizal root biomass.In the young stand, sporocarps produced by decomposer fungi concentrated higher levels of Ca and Mn than those produced by mycorrhizal fungi. In the mature stand, sporocarps of decomposer fungi concentrated higher levels of N, P, Mn, Ca and Fe than sporocarps of mycorrhizal fungi. Epigeous and hypogeous sporocarps concentrated higher levels of N, P, and K than sclerotia or mycelium. The highest concentration of N (4.36%), P (0.76%), K (3.22%) and Na (1,678 ppm) occurred in epigeous sporocarps. Highest Mn (740 ppm) and Ca (20,600 ppm) concentrations occurred in mycelium, while highest Mg (1,929 ppm) concentrations were in hypogeous sporocarps and highest Fe (4,153 ppm) concentrations were in sclerotia.

Relationships between CO2 evolution, ATP concentrations and decomposition in four forest ecosystems in western Washington.

tumn and spring peaks of CO2 evolution, while highest levels of CO2 evolution occurred during summer and autumn in the coniferous ecosystems. Higher levels of ATP were measured during the winter and spring months in all four ecosystems. The highest ATP levels were measured in the subalpine Pacific silver fir ecosystem. Carbon dioxide evolution and ATP levels were inversely related in the summer and autumn. Red alder leaves lost the greatest amount of weight (55.1%) after one year followed in decreasing order by Douglas-fir (41.9%), western hemlock (35.5%) and Pacific silver fir (15.4%) needles. No relationship was observed between the amount of weight loss and CO2 production. Highest levels of CO2 evolution occurred in the Pacific silver fir ecosystem during the summer when no weight loss of needles was measured.

Influence of excess nitrogen deposition on a white spruce (Picea glauca) stand in southern Alaska

Excess N delivered to forest ecosystems has been shown to alterinternal ecosystem biogeochemical cycles, contribute to forestdecline, and negatively affect the health of receiving waters.In the vicinity of the Nikiski Industrial Complex, Kenai Peninsula,Alaska, there has been recent concern about the influence ofNH3 emissions that have occurred for over twodecades on local soils and vegetation. The study site representedan opportunity to examine the influence of elevated N depositionon a northern coniferous ecosystem in an area with a low backgroundof N deposition. Overstory vegetation in the area is dominated bywhite spruce (Picea glauca Moench. Voss) and paper birch (Betulapapyrifera Marsh.). Mortality of both species has occurred adjacent(<2 km) to the industrial complex. Average annual Ndeposition rates ranged from 0.7 to 21.0 kg ha-1 y-1in the area, with the highest rates closest to the complex. Sulfatedeposition at the site was low. Due to the high NH3deposition, precipitation near the complex was less acidic thanprecipitation in general; bulk precipitation pH ranged from 5.51to 7.06. Within 1.80 km of the facility there was an increase inKCl- and resin- extractable soil NH4+ andNO3- in the O horizon, and a decrease in soil pHcompared to soils further from the facility. Spruce near thefacility had chlorotic foliage and thinning crowns, higherconcentrations of N, but lower foliar Ca and Mg. Foliar Mglevels approached deficiency levels, but foliar Ca was wellabove reported deficiency levels at all sites. Both Mg:N andCa:N ratios, however, suggest nutrient imbalances in the highN deposition zone. Canopy death and fertilization by N appearto have encouraged growth of the native bluejoint grass. Thepresence of elevated NO3- in O horizon soilextracts, elevated NO3- in resin bags placed betweenthe O and E horizons, and nutritional imbalances in the foliagesuggest that N saturation may be occurring in soils adjacent to thefacility.

Effects of forest management on soil nitrogen in Pinus radiata stands in the Australian Capital Territory

Abstract Field ammonium and nitrate levels, and nitrogen mineralization and nitrification rates, were determined in the 0–20-cm soil layer in Pinus radiata (D. Don) stands (recently clearcut, young (5 years old) and mature (45 years old) near Canberra (A.C.T.) from 17 November 1981 to 3 May, 1982. Total nitrogen contents in the yellow podzolic soils were low ( 4 -N were

Ozone concentrations above a Douglas-fir forest canopy in western Washington U.S.A.

Abstract Ozone concentrations were monitored above a 30 m Douglas-fir canopy at Cedar River, Washington from 1 April to 30 September in 1986 and 1987. Maximum average hourly ozone concentrations were similar in both years. Ozone concentrations exceeded 0.12 ppm on 2 days in 1986 and 1 day in 1987. Fifteen and 14 days had ozone concentrations greater than or equal to 0.08 ppm in 1986 and 1987, respectively. Ozone concentrations were positively related to daily radiation and maximum daily air temperature. However, only 46 per cent of the variance in ozone concentration in 1986 could be explained by solar radiation and even less was explained by maximum temperature (26%). In 1987, 51 and 54 per cent of the variation in ozone concentration was explained by solar radiation and temperature, respectively. Maximum average hourly ozone concentrations peaked near 1500 h (Pacific Standard Time) for days > 0.06 ppm with minimum values near 0600 h. Highest concentrations were observed when the wind was blowing from the northwest from the Seattle area indicating that photochemical oxidation of NO x was a major source of elevated ozone. If the data represent current levels of ozone some potential for forest damage exists in Puget Sound forests.

Municipal sewage sludge use in forests of the pacific northwest, U.S.A.: Environmental concerns

Abstract Forest applications of dewatered municipal sludge in Washington State, U.S.A. were monitored for heavy metals, pathogens, and nitrates. Heavy metals did not leach from the sludge in significant quantities and remained associated with the sludge for at least four years. Tree seedlings grown in sludge-amended soil and compost accumulated moderate metal levels, but growth was not adversely affected. Populus seedlings took up more metal than coniferous seedlings. Some coniferous seedlings grown directly in unamended sludge had reduced growth and developed symptoms of nutrient imbalances. Fecal coliform and total coliform levels in sludge were initially high, but decreased to background levels in 1.0–1.5 years, suggesting that site access should be limited for a time after application. Bacterial movement in the soil was limited and very few viable bacteria reached the groundwater. Aerosols may be generated during sludge applications. Nitrogen leaching is a major environmental concern or sludge application. Heavy applications resulted in high NO 3 − levels in soils and groundwater. A significant fraction of the nitrogen loss was in gaseous form. Sludge applications in forests can be environmentally sound if application rates are matched to site characteristics.

A High-severity Disturbance Event Alters Community and Ecosystem Properties in West Twin Creek, Olympic National Park, Washington, USA

Abstract Debris flows are mass movements of sediment, wood and water down stream channels that profoundly impact streams and adjacent riparian areas and are a major erosion process in many steep mountainous terrains. Their impact on aquatic ecosystems, however, is poorly understood. In this report, we describe the ecological effects of a debris flow on a headwater stream in old-growth temperate forest that occurred in December 1999. This geomorphic disturbance scoured our study reach to bedrock and removed live trees 5 to 15 m into the adjacent riparian forest. Summer water temperature was higher in the affected reach after the debris flow than before; these changes have persisted through 2002. Algal biomass after the debris flow was similar to before; however, we speculate that algal growth was constrained by herbivory, as the abundance of two insect herbivores Chironomidae and Baetis spp. increased 380 and 9300%, respectively, within the first year after the debris flow. Overall, these data show that a rare disturbance event can mediate the population dynamics of stream herbivores in small, headwater streams such as those found in Olympic National Park likely via increased primary production and water temperature.

Nutrient Limitation in Red Alder (Alnus Rubra) and Conifer Forested Streams of Western Washington State, U.S.A

ABSTRACT The extent and type of vegetation within watersheds are critical factors influencing stream water chemistry, specifically nitrogen and phosphorus concentrations. As stream productivity can be limited by nutrient supply, nutrient subsidies from red alder, a nitrogen fixing species prevalent in the Pacific Northwest of North America and other temperate climates, may influence the degree of nutrient limitation in streams. Our study was designed to determine the extent that algae are nutrient limited in three red alder and three coniferous forested second and third-order streams on the Olympic Peninsula, Washington, U.S.A. Nutrient diffusing substrates were used in each stream to test whether nitrogen and phosphorus additions at three concentrations (0.05 M, 0.1 M and 0.5 M) increased chlorophyll a concentrations compared to non-nutrient infused substrates. With the addition of nitrogen or phosphorus, three of six streams (two conifer and one alder stream) had significantly higher chlorophyll a concentrations relative to controls. Within each stream, we saw no difference in chlorophyll a concentrations between nutrient type (nitrogen or phosphorus) or concentration (0.05 M, 0.10 M or 0.50 M). Treatments increased chlorophyll a concentrations in alder streams to twice that of conifer streams. We speculate that other factors, such as algae community composition, contributed to differing algae production in alder and conifer streams in response to nutrient supplements.

Influence of Salmon Carcass Placement in Red Alder Riparian Areas on Stream Chemistry in Lowland Western Washington

Abstract Populations of Pacific salmon Oncorhynchus spp., which historically returned large quantities of marine-derived nutrients (MDN) to Pacific Northwest streams and riparian areas, are now much lower. In response, salmon carcasses are now being placed in streams and riparian areas to compensate for the loss of MDN, particularly organic N and P. Our objectives were to determine (1) whether placement of chum salmon O. keta carcasses in riparian areas dominated by red alder Alnus rubra, an N-fixing tree, changed stream chemistry and (2) whether carcass placement affected water quality. Study sites were Brown and Le Bar creeks, two small streams in the Skokomish River valley in western Washington. The amount of N in carcasses placed in riparian areas in Brown and Le Bar creeks in November 1999 was estimated to be 22.4 and 59.8 kg/ha, respectively, while the amount of P was 2.7 and 7.2 kg/ha. Monthly stream grab samples were taken between September 1999 and October 2000 upstream and downstream of salmon c...