Durban’s bush-covered green lungs coped fairly well with the floods, thanks to the capacity of roots to hold in certain areas, according to KZN Wildlife and Environment Society of SA (Wessa) chairperson Margaret Burger.
Speaking after having had a good look at Burman Bush, Virginia Bush and Pigeon Valley during last weekend’s iNature City Conservation Challenge, she said the natural bush was “all actually there to hold the water for these times like the floods that we’ve just had, which were unprecedented”.
However, where there was damage, it highlighted the importance of maintaining alien plant growth control, said Burger.
“Creepers cover the trees and that weighs them down and makes the branches heavy, just like the staghorn that we have seen increasingly invasive on any rough bark species.”
She also noted that Virginia Bush was “pretty flooded”.
Crispin Hemson, a guardian of Pigeon Valley, wrote in a column in the Berea Mail that, apart from around human-made infrastructure, there had been remarkably little erosion in much of Pigeon Valley, demonstrating the capacity of the soil to absorb water.
“There is inevitably heavy run-off when the soil is saturated; however, the root systems of trees and plants held the soil successfully. Looking at the videos taken from helicopters, I was struck by how irresponsible so much building on the coastal strip and other steep areas has been. People have pushed onto the edges of steep slopes. Trees and undergrowth have been replaced by lawn or concrete, so the overwhelming run-off has dug into the slopes.”
The iNature City Conservation Challenge, which has 400 cities taking part ‒ 20 in southern Africa ‒ aims to record biodiversity. About 120 Durbanites took part, photographing living things and loading them on to the iNaturalist app which, using artificial intelligence, immediately presents options of its identity, be it a plant, animal, insect or bird.
Also on board are the SA National Biodiversity Institute (Sanbi) and eThekwini Municipality.
This week, experts at computers around the world added a human intelligence contribution to the identification process. The winning city is expected to be announced over the weekend.
“I think there has definitely been an increase this year ‒ each year it’s incremental. We have more observers. We have had more champions for areas coming on board and we’ve really focused on hot spots for biodiversity, like the eThekwini nature reserves,” said Burger.
The final day of the count, on Monday, saw a team from Wessa Youth at the Japanese Gardens and Bridgevale Park in Durban North, exotic species being no less important to the database than their indigenous neighbours.
“It’s been quite interesting here in Japanese Garden. We’ve seen a lot of plant species,” said Azie Mpukwana. “In the nature reserves we saw many of the same plants. There’s more variety here.”
Ndumiso Manzini also noted the diversity, saying he had uploaded 200 images of different species.
Sibonelo Sikhakhane said: “I liked the ocean the most. At Treasure Beach, I was surprised to see sea animals like sea cucumber. I had only seen them once, in the aquarium. So, it was great to to see it in its natural place.”
Thembeka Mkhwanazi spoke of how the iNaturalist app was a great guide which offered a couple of suggestions as to what species had been photographed.
Burger said it would be ambitious for Durban to hope to beat Cape Town when the final results come out over the weekend.
“They have more observers.”
Another identification opportunity awaits in October, the Great Southern BioBlitz, which was started in Australia and involves only the southern hemisphere.
“It’s not as competitive, but it gets more citizen scientists on board,” said Burger.
The Independent on Saturday