After the Fire
Wild fires are a natural part of every forest ecosystem, renewing, reshaping, and restoring them and ultimately keeping them healthier. It’s the start of the relentless summer here in the Okavango Delta, which means that these fires will be on the rise. With the summer comes dramatic storms, and, if a lucky lightning strike finds just the right target, ta-da! A fire is born. The word ‘wildfire’ has an intrinsic fear-inducing quality in us humans, probably as we’re so used to hearing about devastating fires spreading across the globe on our news platforms. But if you have the good fortune of seeing a fire in person here in the Delta, you’ll be shocked at just how calm everything is. Carmine bee-eaters dive into the flames to catch escaping insects, herbivores graze in its periphery completely unfazed by the carnage surrounding them, and little mice emerge from their burrows in the burnt areas to feast on the bounty of roasted seeds left in its wake.
A lioness walks calmly in front of the flames.
In excess, it's true that fires are a bad thing. Frequent fires are devastating for tree recruitment and the animals that rely on them. In fact, research shows that 55% of first-year shoots are killed by fires in the dry-land forests of Botswana (Ben-Shahar, 1996, 1998; Rietbergen-McCracken and Abaza, 2000). Sadly, these fires are becoming increasingly frequent thanks to our obsession with starting them, in combination with climate change wreaking havoc with the environment. As warming temperatures dry out the forests, these fires grow larger, spread faster, and reach higher. As a consequence, pollution chokes the surrounding water, animals cannot outrun the flames, and soils are scorched black beyond repair. But, speak to anyone who knows what they’re talking about, and they’ll tell you that natural fires, in moderation, are an incredibly important part of any forest’s life cycle.
Many species of trees actually require fire to grow. The classic example of this are California’s iconic giant sequoia trees that rely on fire to complete their lifecycle. Fires dry and crack open their green cones, spreading their seeds that have laid dormant in there for up to 20-years, waiting for the perfect conditions. These conditions being a start to life with no competition, as well as a perfect, nutrient-rich, ashy medium for the new saplings to grow in. Others species, such as gum trees, are known as active pyrothins, and have even have evolved flammable resins in their leaves to encourage fires (and fire-resistant bark to cope with them). Several plants here in the Okavango system are also known to rely on fire, including a pyrophytic (fire-loving!) grassland at the head of the Rio Cuanavale valley.
The fact that these characteristics have evolved in so many plants is testament to the beneficial qualities of natural fire. Wildfires clear out the underbrush and destroy any weakened and pest-riddled trees, letting more light through the canopy, and stamping out pest populations. This opens up the forest floor and without such intense competition, the trees that do survive can grow taller and stronger, and new plant species can move in to diversify the forest. With more plants comes more animals, and with different plants comes different animals. A diverse forest is a healthy forest, and the ash-rich nutrient smoothie fires leave in their wake gives new plants the perfect head-start at life. With this natural clean-up service of underbrush and excess timber, fires are ultimately their own worst enemy. When one passes through an area, there will inevitably be less fuel for the next one. It is for this reason that our obsession with halting every fire, even the natural ones, can have devastating consequences when less frequent, but much larger, fires rip through an area.
Other than the leadwood branches that remain smouldering for months after, soon after a fire, it is hard to believe that there was one at all. Vibrant green carpets of grass coat the once barren, blackened ground, where it seemed life could never return to again. This short, sweet snack is favoured preferentially by the herbivores, who inevitably attract the predators. The newly opened up landscapes are an ideal hunting ground for a cheetah that needs wide open spaces to clock their unfathomable speeds of over 70 miles per hour. Other predators who rely on ambush, however, must change tactic if they hope to get close to their targets. Leopards dive onto unsuspecting impalas from the canopies of trees, and lions work in large prides to corner and chase their prey.
All the benefits described above, however, disappear if a fire gets too strong. Poor fire control practice, climate change, and man-made fires all threaten to do this. Once a fire reaches a certain size, they can leap across wet areas and engulf tree canopies, killing entire stands of forest. The plants that usually give us the free oxygen we live and depend on instead become carbon sources once burnt, further compounding the problem. The Okavango without its trees would be an unrecognisable habitat, without many of its most iconic residents. Indeed, the constant evapotranspiration through its tree's leaves is the only reason that this bizarre inland oasis in the middle of a desert remains the fresh-water system that is able to support the abundance of life that it does.
Wildfires are a natural part of any forest’s life cycle, but they must be left to do that without interference from man. Be fire-conscious next time you go camping, educate others on the importance of fire safety and protocol, and do your bit to combat climate change. It might sound scary and overwhelming to fight climate change from home, but it doesn’t have to be – have a vegetarian meal or ride public transport to work just one extra time this week. Switch to a renewable energy supplier or take a local holiday instead of travelling abroad. If we all started making these small and tangible changes in our lives, then the outcome won’t be so bad. If not for you, then do it for the Okavango Delta, which needs your help now more than ever.