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Afrikaanse Inligting
Alien Proteas
One
of the biggest surprises yielded by the Protea Atlas Project is the extent of veld
manipulation practiced by conservation authorities. Of course, this should not have come
as a surprise. There is lots of evidence that the wrong mammals have been introduced into
our nature reserves (see African Wildlife 54: 9). Coupled with these unwise
policies has been the need to "improve the veld" – a process that saw
– for example - fields of Kikuyu grass planted in the Cape of Good Hope Nature
Reserve to feed the exotic Springbuck, Hartmann’s Zebras, and other inappropriate
game. Similar "improvement programmes", involving fire, bush cutting, and sowing
alien grasses, were practiced in most reserves containing game. That plants might also
have been translocated, like game, is also hinted at. For instance, illustrations and
photographs on pamphlets show sunbirds on Ls cordifolium in nature reserves
way outside of the distribution range of this species. And yet, it is easy to dismiss
these as simply poorly designed pamphlets – after all, how many people even notice
the plant species in the illustrations of birds and scenery found on these brochures?
We expect alien proteas to be planted in botanical gardens and wild flower gardens. But surely nature reserves are areas where plants and animals are protected from aliens, hybridization and genetic attrition? Not so! Let us take three nature reserves as a cross-section for appraisal: Silvermine Nature Reserve on the Cape Peninsula, Salmonsdam Nature Reserve in a secluded valley east of Hermanus, and Bontebok National Park near Swellendam.
Bontebok National Park
The National Parks Board had a reputation of being animal centric – in fact, their
first botanist was only employed a few years ago. It is not surprising then that the
Bontebok National Park is managed for the Bontebok, rather than the Fynbos. Still there
are 12 species of proteas in the park. (Fortunately 9 of these resprout, so frequent fires
ideal for grazers will keep them happy as well. It is a bit tough on Pr decurrens
though, which is almost extinct in the reserve.) More surprising, is that entrance area
and old lands to the east of the offices have been planted up with alien proteas: some
five species have survived and are quite happy in the area. Fortunately, they are not
related to any of the indigenous species and their numbers are low. No hybrids or problems
have been recorded. One can only hope that, under its new name - South African National
Parks - and with a fair number of National Parks that are based on plant biodiversity, the
department continues its trend of becoming more eco- and botano-centric.
Silvermine Nature Reserve
The Cape Peninsula is known as the jewel of the Cape Floral Kingdom. It is scarcely
surprising then that there are 25 protea species present (more than half of all species in
the Peninsula) in this nature reserve. However, this was obviously not beautiful or
diverse enough for the Peninsula conservation authorities. An additional 18 species have
been planted in this reserve, mostly around the picnic sites and on the road to the
Silvermine dam. Some five hybrids between these aliens and natural species have been
recorded in the reserve, suggesting that these introductions are not benign, but are
threatening the very species that the reserve is supposed to protect! Like the three Hakea
species in the reserve, they are now naturalized, regenerating from seeds and boles after
fires. The conservation authorities are careful not to allow Bontebok and Blesbok, or
Hartmanns and Mountain Zebra, to be placed within the same reserve because they hybridize,
but will this care ever be applied to plants? The question is, will these aliens ever be
removed? Are they now perceived as part of the landscape?
Salmonsdam Nature Reserve
As its name suggests, this reserve started off its life as an attempt to stock up the
local rivers with "suitable" fish. Indigenous fish were simply not good enough:
exotic species were required! It is not surprising then, that the same attitude has
prevailed with regard to the plants. The reserve has 29 protea species that appear to
occur naturally in it. However, some 24 additional species have been planted. These are
mainly in a formal garden near the offices, but also in restored areas between the offices
and the campsite, and along the road up to the top of the hill. With so many planted
species it is not surprising that problems have arisen. It has not helped that a fire has
been through parts of these areas. Some 11 hybrid taxa have been recorded, some comprising
just a few plants, but some quite abundant. The chief problem species are Pr aurea
and susannae - these seem to hybridize with a fair cross-section of species! Here
the problem is far more problematic than in the previous reserves. Here exotic protea
species have been used to try and restore old agricultural lands back to Fynbos. Clearing
and containing the "invasion" is going to be a far larger problem. And with the
hybrids it will not always be possible to tell just which plants are invaders.
These are not isolated instances. Anecdotal evidence relates how the Friends of the Cape of Good Hope Nature Reserve obtained Pr repens from near Atlantis for planting at the Information Centre at Smith’s Farm (together with Ld linifolium), because the local forms were not red enough! Following the last fire at the Helderberg Nature Reserve, it has become impossible to identify the White Water Sugarbushes – hybrids between Pr aurea, lacticolor, mundii, punctata (and between these and Pr coronata) have resulted in a riot of forms spreading up out of the formal garden into the indigenous veld above. This invasion is viewed with pride by locals, few of whom are aware of the genetic adulteration involved! Even atlassers appear intimidated by the identification problems they experience – novice atlassers and laymen do not even notice them or realize that they are as much a problem to conserving biodiversity as the alien Hakea, Acacia or Stinkbean.
Also documented by atlassers are the extensive commercial protea orchards planted all over the Biome. These vary from remote areas in private veld to right on the border of our Wilderness areas. Usually considered as environmentally friendly, many of these enterprises occur in sensitive habitats bearing extremely rare species. The relatively recent categorization of protea growing as a farming enterprise belies its direct impacts on veld. What is not known is the effect on the neighbouring veld as pollen and seeds disperse. The 15-year fire cycle makes observing differences in veld very difficult, with most conservation officials only experiencing two or three cycles during their busy careers. This applies especially to differences in abundance and distribution within a landscape. Until sterile (both pollen sterile and fruitless) protea cultivars are developed, protea orchards, like wild flower gardens and "veld improvement schemes", will contaminate neighbouring veld if careful consideration is not given to natural species occurring in the area.
Fortunately, we have the Protea Atlas Project as benchmark data. The current situation is documented, allowing any interested party to determine the extent of the problem, monitor future changes, lobby for action by the conservation authorities, and identify those species that are particularly undesirable. We have helped to identify a major problem. Now comes the task of solving it.
Tony Rebelo
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