Being human is not easy, but the aphorism "primum non nocere" is a good place to start
and one we try to apply at Skilderkrantz.
Invasive Alien Vegetation Control
Alien vegetation remains one of the biggest threats to biodiversity and ecological integrity in South Africa. Its control is a labour of
love and confirmation of the old adage that if one finds a job one loves, one will never work a day. This, I believe, gets to the heart of why
Working for Water, the national alien eradication and poverty relief program has had only limited success. Give individuals or groups responsibility
for looking after the ecology of an area on an ongoing basis, rather than just coming in like mercenaries, allow them to develop pride in
their patch , pay them retrospectively for an area kept clear, and they may just feel more motivated. This is a job needing passion and dedication,
as initial clearing, certainly in the case of Acacia mearnsii, (Black wattle), is only the start. Even after clearing of all adult seed producing
trees in a catchment, the seed bank can survive more than 50 years. Thankfully most of them come up at once like hairs on a dog�s back, and
as the system recovers it becomes more resistant to invasion. You will seldom find invasion of a pristine system, it is only after disturbance,
usually by humans, that aliens get a hold.
At Skilderkrantz the enthusiasm is so infectious that no-one passes by a cheeky alien in an otherwise clean area without pulling it up and
putting it out on the path as a trophy for all to see! This may seem harsh, but these plants really do devastate our natural systems. It has
been a joy to see how careful clearing has breathed new life into the landscape. Native vegetation is slowly retuning and with it bird and
Organic, manual methods are the default position at Skilderkrantz. For a few species such as Black wattle, the least- harmful herbicide
option is used for the initial clearing , and then only by careful stump application. We NEVER spray, and all follow-up of seedlings is done
by hand pulling. This means that chemical control will be phased out once clearing of adult plants is complete. Biological control (release of
predatory insects) has been used on Sesbania punicea, success depends on a number of factors and we are waiting to see the outcome. We think
that the wholesale dousing of the alien problem in herbicide is not the answer and probaby does as much harm as good. Giving people a livelihood
doing it manually is money well spent. Filling the pockets of the agro-chemical companies is not, so we use as little poison as we can without
being so purist we render the task impossible.
Acacia mearnsii (Black wattle) was originally introduced to South Africa for the production of tannin used in hide tanning. Unfortunately,
this tree produces tons of seeds. In the absence of natural enemies this species goes rampant, displacing all other vegetation, sucking up
mega litres of water and causing devastating erosion of stream banks. Now varieties with sterile seeds are now used commercially, but the
historic escapees remain a huge problem in many parts of the country. Over the past few years great progress has been made at Skilderkrantz
and most of the Bosrivier and Braamrivier catchments on Skilderkrantz land are now cleared. Clearing of new areas as well as follow up is ongoing.
Arundo donax (Spanish reed) is another useful specie which has escaped, blocking up and diverting entire waterways. We have found that the only way
to success here is patient and labour intensive grubbing out of the extensive rhizomes. Done properly, only one follow-up is needed. As with
all alien clearing, but especially in this case, a further challenge is the vulnerable period before native vegetation establishes when bare
stream banks are temporarily more prone to erosion during floods.
Another specie receiving attention at the moment is Hakea. This thorny shrub forms dense fire-prone thickets and once established is a
nightmare to chop out. There is possibly also a biological control agent on the horizon for this. Another thorny problem has been a particularly
rampant Opuntia sp on the Uitvlught section of the reserve. This garden ornamental started off as a handful of plants around one of the houses
and we were warned about it by our ecologist friend Japie Buckle. Not believing it to be a priority, we thought we would get around to it
eventually. Suddenly a year or so down the line we found the baboons had spread the seeds, and it was popping up everywhere! Finally after
three years of dogged work it is eradicated (we hope!) So therein lays a warning for all gardeners.
Most of the lowland sections of streams in the area have been denatured if not by wattles then mechanically by farmers and need extensive
rehabilitation. Not understanding how catchments, rivers and wetlands work, they take the view that canalising and straightening them will
prevent flooding, and allow cultivation of the floodplains. Notwithstanding the fact that it is illegal to cultivate or disturb the riparian
zone, this is what was and is still being done to devastating effect. Finally the authorities have realised the implications, not least for
urban water supply, and are clamping down. Why do stable doors and long-gone horses come to mind? And catchments are still being burned
annually, increasing runoff. When will we wake up and give our rivers and wetlands the awe and reverence they deserve? Even from a purely
anthropocentric viewpoint, water is life and they are our lifeblood.
A natural river will overflow its banks during flood times, reducing the force of the water as it spreads out, replenishing ground water.
Wetlands are the sponges which hold water, paying it out slowly in dry times. Canalisation of rivers on the other hand causes the water to
gather momentum with devastating results. The Tafelbergkloof stream is dry for much of the year, but has a large catchment, and handles a
huge amount of water when it rains. Canalisation to allow the planting of oranges has resulted in tons of topsoil and vegetation being ripped
out here, especially in the past decade with the advent of climate change and the extreme flood events this has brought. Another effect
apparently not understood by the perpetrators is that because water goes to the lowest level, causing a watercourse to cut down dries out the
surrounding lands too! How counter-productive for farming too!
Something needed to be done, and after much discussion with our ecologist and engineer, we
decided that a concrete weir structure would best achieve our aims at the lowest cost,
more longlasting and most likely to be effective. Gabions (rocks in wire baskets) is more expensive and a vast number of rocks would need
to be removed elsewhere. But there are no easy answers, and despite sourcing stone from an existing quarry on the property, the trucked-in
cement has a great jackboot of an ecological footprint. The structure is nearing completion after which we will wait with bated breath for
the first big rains The idea is that silt will build up behind the weir, raising the water table. Lowering the banks will allow natural
overflow and a low spreader wall will spread the water gently over the flood plain. But nature has other ideas and only time will tell whether
some good has been achieved, whether the benefits outweigh the costs and whether this exercise is to be repeated. Hopefully if the force of
the water can indeed be broken, smaller rock /basket structures can be used downstream. But we are aware that nothing approximates the
perfection of an undisturbed river and sincerely hope that they start to receive the awe and reverence they deserve.
Native Fish: of goldie barbs and redfins
We feel very lucky to share Skilderkrantz with not one, but at least 3 fish genera: Cape Minnows, also known as Redfins (pseudobarbus
afer), Sandelias (Sandelia capensis) and Goldie Barbs) Barbus pallidus. These delightful little spirits of the streams give us endless
enjoyment and on occasion will approach and dole out shoals of gentle fish kisses to any submerged body part. What magic!
These fish are endemic to our Cape streams and are highly threatened by introduced predatory
angling species such as Black bass and by habitat loss. We know
that they have been wiped out in our larger rivers such as the Kouga , but we are keen to preserve the populations in the smaller streams.
Earlier this year we welcomed two friends from the SA National Aquatic Biodiversity Institute who did an initial investigation and found our
populations to be in rude health. The two �fish doctors� as we soon dubbed them have a deep love and knowledge of these creatures, so
exploring the remote wild upper reaches of the streams with them has been a highlight of the year.
However there is no room for complacency, and they will be returning armed with their snorkels when the weather warms up to do a full
study on Skilderkrantz and our and neighbouring properties to better enable us to look after and expand the populations. Meanwhile we have
set about emptying those farm dams that harbour bass and bluegills which could otherwise potentially invade the streams.