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Mount Nelson
Since 2001 my staff and I spend most of our time clearing the property of the alien vegetation. It costs me a fortune – I once received two bottles of Garlon from the Eden District Municipality and that was all the help I ever got – but it is very rewarding. After the initial clearing of the alien invaders and the follow up work in the areas where the fire had raged in 1998 we now have beautiful fynbos. But where we removed the smaller alien trees and other alien vegetation under the bigger karri, pine, black wattle and blackwood trees, we saw and see many indigenous trees starting to grow; at first mainly pioneer species such as keurboom, notsung, taaibos, gonna etc., but in the meantime we count already more than 50 young indigenous tree species where there once was a jungle of aliens and of parts of our land we can say that the natural forest is coming back. I guess we are lucky that the Harkerville indigenous forest is on our northern and the Garden of Eden indigenous forest on our southern boundaries, so that the wind, birds, bush pigs, baboons, bushbuck etc. brought and are bringing the seeds of the indigenous trees.
The alien vegetation on Mount Nelson consists resp. consisted of black wattle, blackwood, rooikrans and other wattles, Eucalyptus species (mainly E. diversicolor), pine species, hakea, Opuntia, spanish reed, inkbessies, Ageratum, thistles, Cortaderia, Lantana camara, Passiflora, bramble,gifappel and so on and so forth. In the meantime we have removed all of them with the exception of the wattle, pine and Eucalyptus trees which we remove or ringbark gradually. We also had Kariba weed in our big dam but fortunately this free-floating monster has virtually disappeared thanks to biological control.
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Our methods
- Fynbos:
We started with removing all alien vegetation growing in the fynbos, felling or ringbarking the bigger trees and slashing the smaller ones. Stumps of black wattle, blackwood and other wattles and Eucalyptus stumps have to be treated with herbicide which we apply with a brush. Herbicides are not necessary for pine species or hakea but there should be no green needles or branches on the stumps. It would carry me too far to describe how we removed and control the other alien invaders.
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The follow-up treatment consists of hand pulling the numerous seedlings of the aliens. We hand pull them before they are 200mm tall as their roots have not spread very far when they are small. In areas where the soil is hard we do it after the rain has made the soil softer. When you let the seedlings grow bigger and their roots have spread, you disturb the soil considerably when you hand pull and the more you disturb the soil, the more alien seeds will germinate. Disturb the soil as little as possible! Why? Where bushpigs plough the land with their snouts in cleared areas, hundreds of black wattle and other alien invader seedlings appear within a couple of weeks. When we had to use a skidder which disturbed the soil very badly to fell giant karri trees next to an Eskom power line, there were millions of alien invader seedlings within weeks and although we do not like to use herbicide as foliar spray, then there was no alternative. |
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Above: One year ago. Masixole Vusani
and a young milkwood tree in an area
where we had ringbarked the last karri trees a year before.
- The jungle of aliens:
Although our jungle of aliens seemed to consist of just alien trees and other invaders, we soon noticed that there were small indigenous trees growing among them as well. The reason is that most indigenous forest species need shade to germinate and to grow well during their juvenile phase and the alien trees provide that shade. Typical pioneer species like keurboom, notsung and taaibos can grow in sunny positions and when big enough they also provide the shade for many indigenous forest species to grow.
We started by carefully thinning the jungle of aliens and scattered the debris over the site or piled it in small clumps where it decomposes relatively quickly. But we left enough big trees to provide shade for the forest species to grow; the shade also suppresses the germanition of alien invader seeds.
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There other advantages of hand pulling alien seedlings when small:
Indigenous seedlings will have a better chance to grow. When the indigenous plants grow taller and provide shade, less and less seeds of alien invaders will germinate as they need sun. That is one reason why we hardly ever spray herbicide; the chance that we will kill indigenous seedlings is simply too great.
If you let the alien trees grow until you cannot hand pull them anymore you will have to slash them or cut them with scissors and in many cases you will have to apply herbicide to the stumps. This is more time consuming, more costly and bad for the environment.
Above: Today. Masixole and the same milkwood tree.
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When there are enough young indigenous tree species and they have grown tall enough we progressively ringbark the alien trees. The advantage of ringbarking are many:
* Felling would damage or destroy the young indigenous trees.
* Ringbarking is a low-cost, quick and easy method to kill the alien trees. We find that the fastest way to do this is by making two parallel cuts just past the bark all around the stem of the tree with a chainsaw, approximately 100mm apart. After that we remove the bark between the cuts with an axe and paint herbicide between the cuts (this is not necessary for pine trees).
* On average it takes about a year before the leaves or needles of the ringbarked trees have fallen off. During this period the ringbarked trees still provide shade but more water becomes available; this an ideal situation for even more seeds of indigenous forest species to germinate.
* Dead trees standing are ecologically very valuable. They provide food for insects and the insects provide food for birds. Also fruit eating birds like to sit on the dead branches and in this way bring more seeds of forest species; we often find many seedlings of indigenous trees around the base of large ringbarked trees.
* In time the ringbarked trees decompose and provide nutriens to the soil.
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In areas where the indigenous species are big enough to provide shade we now have ringbarked all of the alien trees.
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Over the last years we have seen an enormous increase of wildlife activity on our land. Bushbuck, bushpigs, porcupines, baboons, vervet monkeys, caracal, honey badgers, snakes etc. The number of birds and butterflies has also increased dramatically and lots of insects are feasting on our ringbarked trees and on the dead wood lying. As I mentioned before, my property is in Fisanthoek and the name fits; we now see fisante everyday. After ten years Mount Nelson is already a corridor for indigenous plants and wildlife as it is connecting the two SANParks forests between a dairy farm on our eastern and an MTO pine plantation on our western boundary.
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 Above: Drieka Seekoei who discovered our one and only sewejaartjie |
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Some general observations:
We can confirm the heavy water consumption levels of alien trees. After we harvested twenty five big karri trees next to a road on our property, the road nearly washed away during the first heavy rains and there never was a problem before. We had to dig trenches and lay pipes. A year ago we ringbarked the last alien trees in an area where there were a number of old bosvlier which were as good as dead. They now have rounded, leafy crowns and sprouts on branches which looked totally dead. Today our dams are nearly always full.
There was a fire on the top of our hill in January 2010. Within weeks many fynbos and keurboom seeds germinated and there are now a couple of hundred young Leucospermum glabrum /common name Outeniqua pincushion (conservation status Endangered) growing with tremendous speed.
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Above: Nothing will grow where Eucalyptus have been growing? |
A number of experts warned me that Eucalyptus trees are allelopathic and that nothing will grow where they have been growing, but we find it seems to be a myth. Our young indigenous trees there are thriving; quite a few grow more than 1 meter per year, and also the other indigenous plants are doing very well there.
What gives me great joy is working with my staff. They have become experts in identifying and eradicating the alien invaders and are highly motivated because they see the wonderful results of their work. They know the names of many indigenous plants and trees and inform their colleagues and me when they find unusual ones. Not long ago my domestic discovered the only sewejaartjie growing on Mount Nelson and probably in our area.
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Is alien clearing difficult? NO! It is not, everybody can do it. Start clearing in the areas with the llightest infestation and only once these are under control should you progress to more densely infested areas. Start clearing from the top of slopes and stack debris horizontally to avoid soil erosion. Do not disturb the soil and pull invader seedlings when small. But don't bite off more than you can chew. Always remember that follow up clearing will often take more time than the initial clearing.
Above: Ringbarked pine, karri and black wattle and what came after.....
Is alien clearing worth the effort? YES! You will be richly rewarded.
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