Roger W. Ruess

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Fine root processes play a prominent role in the carbon and nutrient cycling of boreal ecosystems due to the high proportion of biomass allocated belowground and the rapid decomposition of fine roots relative to aboveground tissues. To examine these issues in detail, major components of ecosystem carbon flux were studied in three mature black spruce forests(More)
Constraints on nitrogen fixation are the ultimate causes of N limitation of primary production, but hypotheses concerning limitations to N2 fixation remain largely untested in natural terrestrial ecosystems. We examined limitations to N2 fixation by thinleaf alder (Alnus tenuifolia) in two stages of primary forest succession on the Tanana River floodplain(More)
We examined the dynamics of organic nitrogen (N) turnover in situ across a primary successional sequence in interior Alaska, USA, in an attempt to understand the magnitude of these fluxes in cold, seasonally frozen soils. Through a combination of soil extraction procedures and measurements of 13C-enriched CO2 efflux from soils amended in the field with(More)
We studied the effects of grazing by Black Brant (Branta bernicla nigricans) geese (hereafter Brant) on plant community zonation and gosling growth between 1987 and 2000 at a nesting colony in southwestern Alaska. The preferred forage of Brant, Carex subspathacea, is only found as a grazing lawn. An alternate forage species, C. ramenskii, exists primarily(More)
The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often been studied according to arbitrary size classes, e.g., all roots less than 1(More)
CATHERINE E. LOVELOCK, SARA F. WRIGHT*, DEBORAH A. CLARK† and ROGER W. RUESS‡ Smithsonian Environmental Research Center, PO Box 28, Edgewater, MD 21037, USA, * USDA-ARS, Sustainable Agricultural Systems Laboratory, Beltsville, MD 20705, USA, † Department of Biology, University of Missouri-St Louis, 8001 Natural Bridge Road, St Louis, MO 63121–4499, USA, and(More)
Root respiration uses a significant proportion of photosynthetically fixed carbon (C) and is a globally important source of C liberated from soils. Mangroves, which are an important and productive forest resource in many tropical and subtropical countries, sustain a high ratio of root to shoot biomass which may indicate that root respiration is a(More)
Alders (Alnus spp.) are important components of northern ecosystems due to their ability to fix nitrogen (N) in symbiosis with Frankia bacteria. Availability of optimal Frankia may be a contributing factor in limiting the performance and ecological effects of Alnus, but the factors underlying distribution of Alnus-infective Frankia are not well understood.(More)
The effects of browsing by moose and snowshoe hares on fine root production, mortality, and decomposition in early successional forest ecosystems along the Tanana River floodplain in interior Alaska were studied over a 3-yr period using minirhizotrons placed inside and outside large permanent exclosures. Fine root production and mortality varied seasonally,(More)
We report the results of a pot experiment that examined the effects of three ecologically important factors controlling plant growth rates in savanna grasslands: defoliation, soil nitrogen and soil water availability. The experiment was conducted in the Amboseli region in east Africa, and was designed to simulate natural conditions as far as possible, using(More)