River and stream water quality and ecology - Greater Wellington ...

River and stream water quality and ecology in the Wellington region: State and trends
(Source: LUCAS – MfE 2010)
Figure 3.3: Landcover of the Wellington region, derived from aerial photographs
taken in 2008
Sorensen (2012) summarises recent land use change across the region, based
on aerial photographs taken in 2002 7 and 2010, interpreted from soil
intactness surveys reported by Crippen and Hicks (2004; 2011). According
to these surveys, the largest land use change between 2002 and 2010 was a
reduction in drystock farming (2.6% or over 21,000 ha of the region’s land
area), with over half of this reduction attributed to the conversion of pasture
land to exotic forest. The majority of land converted into exotic forest over
this time is located in the eastern hill country of the Wairarapa which is
highly susceptible to erosion (Sorensen 2012). Between 2002 and 2010 small
increases were also evident for dairying (0.7% of region’s land area or
approximately 5,600 ha 8 ) and the ‘other’ category (0.7%), which includes
urban areas. Some of the highest urban growth has occurred in the northern
suburbs of Wellington city where there has been significant re-zoning and
clearance of low producing pasture and bushland for residential subdivision
and development. According to the Wellington City Council (2003), average
growth in the number of new dwellings in the northern suburbs between 1996
and 2001 was 7.8% compared with 5.2% in Wellington city overall.
With approximately half of the region covered in pasture, agriculture is an
important industry for the region. Sorensen (2012) notes that while there are
still significantly more sheep than all other livestock in the region, sheep
numbers have reduced consistently since 1990 (from around 2,600,000 to just
over 1,600,000). In contrast, beef cattle and deer numbers remained reasonably
7 The aerial photographs which were interpreted were taken from 2001 to 2003 across the region. For the purposes of this report the
period is reported as 2002.
8 Sorensen (2012) notes that this is in contrast to data reported by Dairy NZ (2010), which indicates an 11% decrease in effective farming
area for dairying (See Table 3.2).
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