IDM Cape Peninsula - Needlebushes - Hakea
There are only three species of Needlebush that are serious problems in southem Africa. All three are present on the Cape Peninsula.
Surprisingly, although the Silky Needlebush is by far the most common and widespread Hakea off the Peninsula, it is usurped by the Sweet Needlebush which is almost one-and-a-half times more abundant on the Peninsula. Part of this pattern may be that fires occur at less-frequent intervals on the Cape Peninsula perhaps due to a better fire-fighting vigilance. The Silky Needlebush prefers frequent fires and occurs most densely at the various passes. 'Ihe Sweet Needlebush is more frequent adjacent to built-up areas, on peninsulas and steeper, more wooded slopes.
Although the pattern of distribution of the three Needlebushes is similar on the Peninsula, there are some interesting differences. The Silky Needlebush, is the only species north of 34°S. South of the Fish Hoek gap, the Sweet Needlebush dominates, with only the Rock Needlebush locally dominating at Dido Valley and the Sweet Needlebush at Klawer Valley. Apart from Dildo Valley, the dense Rock Needlebush infestations occur with the Silky Needlebush.
More interesting patterns will emerge with an analysis of relative densities of these aliens with one another and other alien species. What is certain is that these species could be relatively easily contained and eliminated, with the possible exception of the really dense stands on Skoorsteenkop and above the Swartkopsberg coastal road which will require major clearing effort.
Interesting, despite our relatively good cover of these aliens, we lack seasonal data. It is especially interesting, given that all three grow together on the Peninsula, to find out when the different species flower and grow. This phenology may in part explain why some of the above patterns of dispersal and abundance exist. Seasonal atlas data are thus especially important. Particularly poorly collected are the months of January, February, April and May, but the first six months are a lot more poorly collected than the second half of the year, for which only October is short of data.