Carryover Effects on Interclonal Competition in the Grass Holcus lanatus: A Response Surface Analysis

Abstract

estimates. In most clipping treatments the planting densities of the competitors affected the outcome of competition. Both carryover treatment and direct treatment significantly affected the model parameter estimates of both clones and changed the equivalence coefficients of the competitive interaction. The responses to the carryover treatment were affected by the direct treatment and vice versa. Therefore, the shortterm outcome of competition and the effects of the competitor densities on the outcome were different in each of the four treatment combinations. These results may explain the high genotypic diversity previously observed in the study population of H. lanatus. Spatial and temporal environmental heterogeneity, e.g. in grazing levels, may cause intra-population variation in the outcome of interclonal competition and thus promote genotypic coexistence. Carryover effects from past environmental conditions will magnify this process, effectively increasing the envi