TRAMPLING RESISTANCE, STEM FLEXIBILITY AND LEAF STRENGTH IN 9 AUSTRALIAN GRASSES AND HERBS

The shoot, tiller or stem (collectively called stem in this paper) flexibility and leaf tensile strength of nine selected species of grasses and herbs were examined in a glass-house experiment; their relationship with resistance to trampling is discussed The stem flexibility was expressed as the stem breaking angle and leaf tensile strength as the ratio of the leaf breaking load to the dry weight of 5 cm length of leaf. The stems of Eragrostis tenuifolia, Lolium perenne, Sida rhombifolia and Sporobolus elongatus did not break or collapse at any degree of bending up to 180-degrees, over the period of the experiment. The stems of Cynodon dactylon, Panicum maximum and Chloris gayana had low flexibility and the stems of Axonopus compressus also had low flexibility when young. The leaf strength of all the species increased with the age. Eragrostis tenuifolia and Sporobolus elongatus had the greatest leaf tensile strengths. Axonopus compressus, Chloris gayana, Cynodon dactylon, Lolium perenne and Panicum maximum leaves had moderate tensile strengths while Hypochoeris radicata and Sida rhombifolia leaves had the lowest tensile strengths. In conclusion stem flexibility appears to be more important than leaf strength in respect to the resistance and survival of plants subject to trampling, and highly trampling-resistant species are likely to have flexible stems.