Invasive alien plants played a major role in fuelling Southern Cape fires

THE recent destruction caused by fires in Plettenberg Bay, Knysna and surrounds is a wake-up call of note.

Focusing on the risks posed by invasive alien plants to fire, water security and the destruction of biodiversity, the Southern Cape Landowners Initiative seeks to promote to address the problem with urgency, following the (regional) fire disaster.

Most certainly, the fires were the most severe in almost one-and-ahalf centuries, and caused the most havoc and devastation in the region in modern times.

The recent fires are nothing new, though, and the well documented Great Fire of 1869, after which historical buildings such as Portland had to be rebuilt, burned all the way to Riversdale in the West, and Uitenhage in the East.

What made the recent fires perhaps worse, was the dense stands of invasive alien plants that contributed exponentially to our fire risk exposure in the region.

For a fire to occur, people refer to what is known as the fire triangle.

The triangle illustrates the three elements a fire needs to ignite: heat, fuel and an oxidising agent (usually oxygen).

Towns such as George, Plettenberg Bay, Sedgefield and Knysna are subject to an interface with wild surroundings.

What made the Southern Cape fires (and potential exposure to fire risk) so severe and intense, is the fact that there were very strong and consistent (hot) berg wind conditions, enough fuel/biomass (eg tall pine/wattle/bluegum trees, litter, dead branches, fine plant material) to sustain an extremely hot wild fire.

Residents were exposed to risks posed by vegetation and biomass present in areas that include nature reserves, vacant land (often invaded by woody and invasive alien plants), timber plantations, orchards, and agricultural land.

To quote Theobald and Romme (2007): “It can also include ‘fingers’ of vegetation that protrude into built-up areas, ‘islands’ of development that are detached from, but in the proximity of, built-up areas and what are referred to as occluded areas of isolated wild land within an urban area.

Fingers often occur where land is too steep to build on.

“The management of these areas is therefore often neglected, allowing it to become overgrown by invasive alien plants and thus increasing the fuel load. Fingers are particularly important because they can serve as conduits, allowing wild land fires to enter and cause damage.”

Wildfires are increasingly affecting humans and their assets worldwide. Climate change and developments in fire-prone landscapes compound this problem (Moritz et al. 2014).

This is most pronounced along the wildland-urban interface (WUI) where urban development borders on and intermingles with flammable wild lands.

So what can we do to reduce falling victim to the same situation in a year or two from now?

Without sufficient heat, a fire cannot begin, and it cannot continue. Indigenous fauna will and can burn in the urban interface, but without the boost received from invasive alien plants, it can never be as hot and destructive.

What we need to understand, and what we pro-actively must address, is the re-growth of invasive alien plants in the burnt areas.

With the advent of spring, and following favourable winter rainfall, all burnt land runs the risk of being overrun by dense stands of invasive alien plants, which will allow the destructive cycle to repeat itself, only worse than before.

Without fuel, a fire will stop, or the intensity thereof will be significantly reduced.

Landowners and land managers will have to join forces and pro-actively prevent the ever-resilient invasive alien plants from growing back with a vengeance.

If we are to avert a repetition of the recent disaster, with no amount of higher intervention but ourselves, we will have to do the work ourselves.

Meiring is the manager of the Southern Cape Landowners Initiative, a public platform for landowners and land managers with an interest in the control and eradication of invasive alien plants.