As global temperatures continue to rise millions of life-forms around the globe are under threat. Plants and animals differ in their ability to cope with variable climate conditions with many being sensitive to the slightest change and thus may be the first to die. In contrast, baobabs are well adapted to changes in temperature and rainfall as can be seen by their wide geographic distribution and extreme longevity.
In an article published in Nature Plants in April 2024 and a summary published in The Conversation in August 2024, I reviewed the health of adult baobab population to assess if, as being claimed by social-media, baobabs were dying of climate change. My observations showed us that, far from dying, adult baobab populations were generally in good health and very few trees had died in the last two decades.
It is well-known that baobabs reach extraordinary old ages. Radio-carbon dating has repeatedly found baobabs well over 1000 years with the oldest among them reaching 2500 years in age. Over their life spans baobabs have survived erratic climate conditions including decadal and centennial droughts and floods. For example, carbon isotopes recovered from the pith of nine baobabs to recreate rainfall patterns for the last 1000 years. These records show that the region experienced numerous successive droughts, one of which was even severe enough to cause the abandonment of the Mapungubwe capital, a significant archeological settlement, in the early 14th century.
Of the 13 other trees I assessed, all were in good health without any signs of decay, such as crown loss or stem decay. Not only is the cohort of Africa’s oldest and largest baobabs enduring, but most baobab populations in the region are healthy and stable, with very low mortality rates. Indeed, nothing I saw supported the notion that Africa’s largest and oldest baobabs are dying of climate change.
I studied 106 baobabs in a semi-arid communal area of South Africa and found that in 17 years (2006 – 2023) not a single tree died. In another study in Musina Nature Reserve I tracked the growth and survival of 116 adult trees and found that in 25 years (1998 – 2023) no adult trees had died despite recurring droughts in the area. Several surveys across Africa have also reported stable adult populations.
My observations on the general good health of baobabs does not stand alone. Several surveys across many parts of Africa also show stable baobab populations. It is estimated that there are up to four million baobab trees in Zimbabwe alone, and this only represents a fraction of Africa’s population.
My review did however highlight two main threats. The first is the inability of seedlings to survive high domestic animal browsing leading to very poor recruitment. The second are elephants, which were responsible for huge losses of baobabs in Gonarezhou National Park and in Mapungubwe National Park adult baobabs are currently in crisis with dozens having died in the last ten years.
In conclusion, like any life-form on earth, baobabs are not immortal, but they may well be the “last tree standing”. Far from victims of climate change, as punted by social media, let’s rather celebrate them as symbols of resilience.
The review of the health of large baobabs and the current effects of climate change on adult trees was supported by Milbon.
