Effects of drainage, fire exclusion, and time-since-fire on endemic cutthroat grass communities in central Florida

In sites historically dominated by the central Florida endemic cutthroat gr ass (Panicum abscissum Swallen), we compared the effects of two management regimes in place for 55 years: natural (undrained, with periodic fire) vers us altered (drained and fire excluded). In 1995 we sampled a total of 55 si tes dominated by cutthroat grass in 1940 at Archbold Biological Station in south-central Florida. We assessed cutthroat grass abundance, flowering, an d associated community composition and structure. Cutthroat grass vigor was markedly reduced where management combined fire exclusion and altered drai nage. Nearly 75% of sites managed to mimic natural conditions remained in c utthroat grass, while nearly 66% of sites with altered management shifted t o other vegetation types. The most common results of fire exclusion and dra inage were the invasion of former cutthroat grass sites by bayhead species, xeric oaks, or pines. Cutthroat grass flowers only within a few months aft er fire, but no other effects of time-since-fire were found in a chronosequ ence of 0-28 years. Without hydrological alteration, cutthroat grass may pe rsist under a fairly wide range of fire-return intervals. Restoration of dr ained areas may be hampered by poor recolonization by cutthroat sass. Histo rically, highly flammable cutthroat grass communities may have been importa nt in increasing fin frequency in local landscapes.