SMALL-MAMMAL RECOLONIZATION OF A FIRE-EXCLUSION CATCHMENT AFTER UNSCHEDULED BURNING

Small-mammal recolonization of a fire-exclusion catchment in the Natal Drakensberg Park was investigated by live-trapping at six-monthly int ervals for four years after unscheduled burning. During the first two years the pattern of recolonization was similar to that found in bienn ially burnt grassland during previous studies in the Drakensberg; alth ough numbers were initially lower. Low numbers during the first year m ay have been due to the extent of the burn (all surrounding grassland was also burnt), with limited nuclei from which recolonization could t ake place. During the second year, both the extent of the burn and low spring and early summer rainfall are believed to have affected the ra te of population increase of small mammals. At the end of the third ye ar, after average rainfall, total numbers reached a peak, slightly hig her than numbers recorded in the catchment before it was burnt, and mu ch higher than those recorded in pure grassland, where numbers general ly start to decline markedly three or four years after burning. In the fire-exclusion area the vegetation contained a high woody plant compo nent, which developed in the absence of fire, with an understorey of g rass and forbs. Recovery of this vegetation had taken place by three y ears, and it is hypothesized that small-mammal recolonization did not follow the pattern previously recorded at three to four years post fir e in grassland, but advanced beyond the decline and consequent low obs erved in pure grassland to the situation that exists in long-term fire -exclusion areas where woody vegetation has developed.