Are We Destroying Our Insurance Policy? The Effects of Alien Invasion and Subsequent Restoration - Landscape Ecology for Sustainable Environment and Culture - page 348

Fig. 16.21 Snapshots capturing the rate of the invasion of Black Wattle from 1954 to 2007 along
the Kromme River. Important land-use changes include: palmiet wetlands, Black Wattle,

dryland agriculture, irrigated agriculture, orchards, exposed soil, seep wetlands and

fynbos

Table 16.2 The expansion and rate of invasion by Black Wattle from 1954 to 2007 along the
Kromme River

Reference 1954 1969 1986 2007 Mean

Acacia mearnsii (ha) 0.00 1,440 2,886 3,097 4,134 -

Rate of change (ha/decade) - 1,440 1,447 211 1,037 -

Number of years - 54 15 17 21 -

Rate of change (ha/a) - 27 96 12 49 46.0

absorb. However, with most of the wetlands in the Kromme transformed, the
catchment may have lost its buffering ability and may no longer be able to absorb
these extreme events. The wetlands that do remain are located upstream, near the
headwaters, and as a result have no ability to filter and purify water downstream