Are We Destroying Our Insurance Policy? The Effects of Alien Invasion and Subsequent Restoration - Landscape Ecology for Sustainable Environment and Culture - page 333

Table 16.1 The key to the different land-uses mapped in the Kromme Catchment, using aerial
photograph based polygons captured using the ArcMAPsoftware

- - Land-use Description

- 1 Dams Including small farm dams and a large municipal dam

- 2 Mountain Seep Wetlands High altitude/gradient wetlands on the mountain slopes

- 3 Palmiet Wetlands Wetlands in the valley, dominated by Prionium serratum

- 4 Riparian Vegetation Woody vegetation in ravines, either thicket or Afromontane forest

- 5 Unproductive Fynbos 7 Different unproductive fynbos and renosterveld vegetation types

- 6 Productive Fynbos 3 Different productive fynbos and renosterveld vegetation types

- 7 Degraded Fynbos Degraded by heavy grazing or poor fire management

- 8 Irrigated Fields Any agriculture that is not irrigated

- 9 Dryland Farming Agriculture that has an irrigation system (sprinkler or central pivot)

- 10 Orchards Orchards with irrigation systems

- 1 Acacia mearnsii The dominant woody invasive alien plant in the catchment

- 12 Pinus Sp The 2nd most common woody invasive alien plant in the catchment

- 13 Alien Plants All other woody invasive plants, mainly Eucalyptus Sp

- 14 Infrastructure All unnatural structures: houses, roads, railway lines, quarries

- 15 Open Soil Open soil, sites of erosion or deposition in the river valley

mountain seep wetlands, as it is difficult to distinguish them from surrounding
dryland fynbos. Indeed the sizes of these seep wetlands are likely to fluctuate
seasonally and to be different each year. However this error was justified in that
mapping was done for hydrological modelling purposes and the hydrological
differences between fynbos and seep wetlands would be marginal when compared
to other land-use types such as floodplain wetlands.
Mapping done using the most recent photographs was ground-truthed by
mapping land-cover adjacent to the road that traverses the catchment. Some
additional areas were verified using photographs and observations made during a
helicopter trip over the catchment. The 2007 aerial photographs and map were
used to cross-check identifications made from historical aerial photographs where
the mapped classes could not be verified. Additional verification was done using
maps compiled by different organizations and individuals: National Land Cover
(NLC) (Van den Berg et al. 2008 ), maps showing extent, clearing and follow up
done by Working for Water, land-use maps for the Baviaansklo of Mega Reserve,
and land-use maps for the Garden Route Initiative (GRI) (Vlok et al. 2008 ).

16.2.3 Geomorphology Changes

The total active channel length was measured along the center line of the Kromme
River from the aerial photographs from each of the four time slices.