Geocrinia vitellina extent of occurrence is calculated to be 6km2 with an area of occupancy based on suitable habitat estimated at 0.08km2 (Conroy 2001) (Figure 1). The entire range of G. vitellina lies within the Blackwood River National Park, an area managed by Department of Parks and Wildlife and relatively free from major modification. Figure 1: Extent of occurrence for Geocrinia alba (left) and Geocrinia vitellina (right). Status of populations All known populations of both species are considered important. The recognition of discrete populations is however difficult because the of isolation is small and there is an implied consecutiveness along drainage systems (Wardell-Johnson et al. 1995). For the purpose of this plan the following definitions apply: Discrete populations represent discrete management – defined cautiously given the high probability of limited dispersal and the low likelihood of natural dispersal. Discrete populations often occur on separate creek systems, but can also occur on the same creek line (or connecting tributaries) if any one of three factors exist: A physical barrier, such as a road. Given the low dispersal ability of both species, roads may be an effective barrier to population connection. A change in land use. If the land use adjacent to an area of occupancy changes along the creek line this may have a local impact on immediately adjacent frog populations (e.g. water use by adjacent blue gum plantations; spray drift from vineyards). A lack of survey in intervening If calling frogs have been recorded at two places but surveys have not been undertaken in the intervening area, then they are considered discrete populations (also refer to Appendix 1 in Wardell-Johnson et al. 1995 for more details). The uncertainty about presence/absence in the unsurveyed gap is a cautious approach to population definition. A subpopulation is delineated within a population by a distance of 50m along the same creek line but not separated by a physical barrier, change of land use or lack of survey. The known and predicted range of G. alba was surveyed in the early 1990s. This resulted in the number of known populations increasing from 26 recorded in 1991 to 54 in 1993. The definition of a population
Geocrinia vitellina extent of occurrence is calculated to be 6km2 with an area of occupancy based on suitable habitat estimated at 0.08km2 (Conroy 2001) (Figure 1). The entire range of G. vitellina lies within the Blackwood River National Park, an area managed by Department of Parks and Wildlife and relatively free from major modification. Figure 1: Extent of occurrence for Geocrinia alba (left) and Geocrinia vitellina (right). Status of populations All known populations of both species are considered important. The recognition of discrete populations is however difficult because the of isolation is small and there is an implied consecutiveness along drainage systems (Wardell-Johnson et al. 1995). For the purpose of this plan the following definitions apply: Discrete populations represent discrete management – defined cautiously given the high probability of limited dispersal and the low likelihood of natural dispersal. Discrete populations often occur on separate creek systems, but can also occur on the same creek line (or connecting tributaries) if any one of three factors exist: A physical barrier, such as a road. Given the low dispersal ability of both species, roads may be an effective barrier to population connection. A change in land use. If the land use adjacent to an area of occupancy changes along the creek line this may have a local impact on immediately adjacent frog populations (e.g. water use by adjacent blue gum plantations; spray drift from vineyards). A lack of survey in intervening If calling frogs have been recorded at two places but surveys have not been undertaken in the intervening area, then they are considered discrete populations (also refer to Appendix 1 in Wardell-Johnson et al. 1995 for more details). The uncertainty about presence/absence in the unsurveyed gap is a cautious approach to population definition. A subpopulation is delineated within a population by a distance of 50m along the same creek line but not separated by a physical barrier, change of land use or lack of survey. The known and predicted range of G. alba was surveyed in the early 1990s. This resulted in the number of known populations increasing from 26 recorded in 1991 to 54 in 1993. The definition of a population
draft-recovery-plan-geocrinia.docx