Tolerance of perennating Stylosanthes plants to fire

Abstract

The resistance of sixteen Stylosanthes spp. accessions to fire was studied in the dry tropics of north Queensland. Perennating plants were subjected to one of five burns of varying temperature. Fire temperatures at the soil surface were measured with heat-sensitive crayons. Fires with intermediate temperatures provided the best discrimination within and between species. Only one line,S. guianensis cv. Schofield, failed to survive the coolest fire. Only S. scabra cv. Seca and S. viscosa CPI 38611 survived the hottest burn. Generally, lines of S. scabra and S. viscosa were fireresistant and S. guianensis more susceptible. However, within a species there were large and consistent differences in reaction: e.g. one S. viscosa line, CPI 34904, proved highly susceptible to fire. All new shoots on the six lines surviving a hot fire grew from 14-38 mm below ground level. In some, the shoots had clearly grown from root tissue. After burning twice, both perennial plants and seedlings were absent in five lines although some seed remained in the soil. The implications of these findings in the potential use of Stylosanthes spp, are discussed.