Volume 8 Issue 2
Forest Floor and Mineral Soil Respiration Rates in a Northern Minnesota Red Pine Chronosequence
Matthew Powers, Randall Kolka, John Bradford, Brian Palik and Martin Jurgensen
1Department of Forest Engineering Resources and Management, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA
2USDA Forest Service Northern Research Station, 1831 Hwy 169 E, Grand Rapids, MN 55744, USA
3US Geological Survey Southwest Biological Science Center, 2255 N. Gemini Dr., Flagstaff, AZ 86001, USA
4School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA
*Author to whom correspondence should be addressed.
Abstract
We measured total soil CO2 efflux (RS) and efflux from the forest floor layers (RFF) in red pine (Pinus resinosa Ait.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and RS were often lower in a 31-year-old stand (Y31) than in 9-year-old (Y9), 61-year-old (Y61), or 123-year-old (Y123) stands. This pattern was most apparent during warm summer months, but there were no consistent differences in RFF among different-aged stands. RFF represented an average of 4–13% of total soil respiration, and forest floor removal increased moisture content in the mineral soil. We found no evidence of an age effect on the temperature sensitivity of RS, but respiration rates in Y61 and Y123 were less sensitive to low soil moisture than RS in Y9 and Y31. Our results suggest that soil respiration’s sensitivity to soil moisture may change more over the course of stand development than its sensitivity to soil temperature in red pine, and that management activities that alter landscape-scale age distributions in red pine forests could have significant impacts on rates of soil CO2 efflux from this forest type.
Keywords:carbon cycling; Pinus resinosa; soil respiration; stand age