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Effects Of Experimental Freezing On Soil Nitrogen Dynamics In Soils From A Net Nitrification Gradient In A Nitrogen-Saturated Hardwood Forest Ecosystem, Frank S. Gilliam, Adam Cook, Salina Lyter
Effects Of Experimental Freezing On Soil Nitrogen Dynamics In Soils From A Net Nitrification Gradient In A Nitrogen-Saturated Hardwood Forest Ecosystem, Frank S. Gilliam, Adam Cook, Salina Lyter
Biological Sciences Faculty Research
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.
Effects Of Silvicultural Practices On Soil Carbon And Nitrogen In A Nitrogen Saturated Central Appalachian (Usa) Hardwood Forest Ecosystem, Frank S. Gilliam, David A. Dick, Michelle L. Kerr, Mary Beth Adams
Effects Of Silvicultural Practices On Soil Carbon And Nitrogen In A Nitrogen Saturated Central Appalachian (Usa) Hardwood Forest Ecosystem, Frank S. Gilliam, David A. Dick, Michelle L. Kerr, Mary Beth Adams
Biological Sciences Faculty Research
Silvicultural treatments represent disturbances to forest ecosystems often resulting in transient increases in net nitrification and leaching of nitrate and base cations from the soil. Response of soil carbon (C) is more complex, decreasing from enhanced soil respiration and increasing from enhanced postharvest inputs of detritus. Because nitrogen (N) saturation can have similar effects on cation mobility, timber harvesting in N-saturated forests may contribute to a decline in both soil C and base cation fertility, decreasing tree growth. Although studies have addressed effects of either forest harvesting or N saturation separately, few data exist on their combined effects. Our study …