Using CENTURY to investigate ecosystem effects of a non-native species and implications for restoration

Title	Using CENTURY to investigate ecosystem effects of a non-native species and implications for restoration
Publication Type	Conference Paper
Year of Publication	1999
Authors	Fraleigh H.D., Peters DC, Beck K.G., Parton W
Conference Name	84th Annual Meeting, Ecological Society of America
Date Published	August 8-12, 199
Conference Location	Spokane, WA
ARIS Log Number	100396
Abstract	Acroptilon repens (Russian knapweed), a non-native perennial composite, can form monospecific stands lasting decades on western rangeland. Biological control has limited success on A. repens expansion. Currently successful restoration efforts involve three key steps: herbicide application, soil cultivation, and seeding to grass. Cultivation is thought to release volatile allelochemicals trapped in the soil; however, cultivation can change many soil characteristics, including organic matter decomposition rates and nutrient availability. In order to simulate nitrogen cycles on paired rangeland plots dominated by either grass or A. repens, we used the CENTURY model with appropriately adjusted lignin:N and growth parameter values. CENTURY results suggest that net nitrogen mineralization is significantly reduced in soils under A. repens relative to soils under grass. After conversion from grass to A. repens domination, labile soil nitrogen pools decrease rapidly within the first couple of years, while slow soil nitrogen pools gradually increase for decades. Following chemical control and cultivation, the model predicts net nitrogen mineralization rates and labile soil nitrogen pools increase, in a pulse lasting a few years, to levels greater than that occurring in the paired grass-dominated rangeland. An empirical study is warranted to investigate whether the expected increase in nitrogen availability following cultivation is responsible for improved restoration success associated with cultivation, and if no-till restoration could be successful with nitrogen applications.