EFFECT OF SOIL SURFACE TOPOGRAPHY AND LITTER COVER ON THE GERMINATION, SURVIVAL, AND GROWTH OF MUSK THISTLE (CARDUUS NUTANS)

Abstract

In natural populations of musk thistle (Carduus nutans L.) germination occurs over several months in the fall and spring. To better understand the physical environmental mechanisms that influence this pattern of germination, a greenhouse experiment was established consisting of ten treatments in which soil surface topography and the amount and consistency of litter cover was varied. Significant differences occurred among the treatments for germination percentage, levels of mortality and individual growth rates. Optimum levels of germination, survival and growth occurred in treatments that provided microhabitats with reduced evaporation. Treatments with cracks or moderately irregular surface topographies provided the best conditions. A light covering of litter benefited establishment and growth but thick layers of litter prevented seeds from reaching the soil surface and reduced germination and establishment. These results were consistent with what is known about the germination ecology of musk thistle in natural populations.