TY - JOUR A1 - Hemmerling, Reinhard A1 - Kniemeyer, Ole A1 - Lanwert, Dirk A1 - Kurth, Winfried A1 - Buck-Sorlin, Gerhard H. T1 - The rule-based language XL and the modelling environment GroIMP illustrated with simulated tree competition Y1 - 2008 ER -