|Fraleigh, H - COLORADO STATE UNIVERSITY|
|Beck, K - COLORADO STATE UNIVERSITY|
|Parton, W - COLORADO STATE UNIVERSITY|
Submitted to: Ecological Society of America Bulletin
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 1999
Publication Date: August 8, 1999
Citation: Fraleigh, H.D., Peters, D.C., Beck, K.G., Parton, W.J. 1999. Using Century to investigate ecosystem effects of a non-native species and implications for restoration [abstract]. Ecological Society of America Bulletin. 80:95. Technical 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.