Tag Archives: Uganda

Why should anyone care about Ugandan lianas?

Liana_group

The liana team surveying in 2015 (Takuji Usui, Julian Baur and first author Telma Laurentino). Bridget Ogolowa (far left) did not participate in the study. Photo by Line Holm Andersen.

Habent sua fata libelli as the Latin epithet puts it, meaning ‘little books also have their destinies’. I’d like to think that the same is true of papers. Not every scientific publication appears in a major journal, or attracts media attention, or becomes a highly-cited classic. Some, perhaps, are never read again by anyone. This doesn’t mean that publishing them wasn’t valuable. A paper represents a new piece of knowledge or insight that adds to our total understanding of the world. And in some cases its small part in the greater whole is the main reason why it matters.

As an example, our latest paper just came out in African Journal of Ecology, a minor regional journal with an impact factor so small (0.797 in 2017) that in the metric-obsessed world of Higher Education it barely registers. Some would argue that the effort of publishing in such a low-status journal is a waste of time*. Why bother?

In this case, our study — small and limited in scope as it was — adds an important point on the map. Over recent years it has been noted that the abundance of lianas is increasing in South American forests. This process, sometimes known as ‘lianification’, is troubling because lianas can impede the growth of forest trees, or the recovery of forests following disturbance (including logging). At a time when we need forests to capture carbon from the atmosphere, an increase in the abundance of lianas could be exactly what we don’t want.

The causes of this increase in lianas are unknown, and it is also uncertain how widespread the effect might be. The best evidence that it’s happening comes from neotropical forests**, but we can’t be sure whether the same process is occurring in Southeast Asia, or Sri Lanka, or Africa. If the driver is global one, for example a change in the climate (warming, higher carbon dioxide concentrations, or longer dry seasons) then we would expect the same trend to be occurring everywhere. If it’s a purely local effect within South America then it might reflect historical factors, modern disturbance or the particular composition of plant communities.

It’s not just that we don’t know whether lianas are increasing in all parts of the world simultaneously; for most forests we don’t even know how many lianas were there in the first place. We could only find evidence of four published studies of liana abundance in the entirety of Africa, of which two were in secondary or transitional forests. That means only two previous studies on the continent had measured lianas in a primary forest. If we want to monitor change then we first need a starting point.

aje12584-fig-0001-m

Location of our study in in Kanyawara, Kibale National Park, Uganda. Figure 1 in Laurentino et al. (2018).

What did we find? Actually it turns out that liana densities in our forest were quite similar to those seen elsewhere in the world. An average liana basal area of 1.21 m2/ha is well within the range observed in other forests, as are the colonisation rates, with 24% of saplings and 57% of trees having at least one liana growing on them. These figures are unexceptional.

What does this tell us about lianification? To be completely honest, nothing. Or at least not yet. A single survey can’t say anything about whether the abundance of lianas in Africa is increasing, decreasing, or not changing at all. The point is that we now have baseline data from a part of the world where no-one had looked before. On their own these data aren’t particularly interesting. But considering the global context, and the potential for future studies to compare their work with ours, means that we have placed one more small piece in the jigsaw. And for the most part, that’s what science is about.

 

CODA: There’s another story behind this paper, because it came about through the awesome work of the Tropical Biology Association, an educational charity whose aims are capacity-building for ecologists in Africa and exposing ecologists from species-poor northern countries to the diversity and particular challenges of the tropics. Basically they’re fantastic, and I can’t recommend their courses highly enough. The work published here is based on a group project from the 2015 field course in Uganda and represents the first paper by three brilliant post-graduate students, Telma Laurentino, Julian Baur and Takuji Usui, who did all the real work***. That alone justifies publishing it, and I hope it’s only the first output of their scientific careers.


 

* A colleague at a former employer once memorably stated in a staff meeting that any journal with an IF of less than 8 was ‘detritus’. This excluded all but a handful of the most prestigious journals in ecology but was conveniently mid-ranking in his own field.

** Although this might be confounded by other factors — look out for a paper on this hopefully some time in 2019.

*** I also blogged about the liana study at the time here.

Advertisements

Field notes from Uganda 8: Farewell, potatoes

It’s the end of the field course here in Kibale and I’m now looking forward to getting home. The day my plane lands there’s a wedding to attend, but even before that there are many things I’ve missed — my wife, hot running water, reliable electricity, my record collection, and the ability to walk in the forest without fear of being trampled by elephants.

On the very last night here I went out with a small group to look for bush babies. We were rapidly successful, scanning trees with our torches and looking for the orange reflections of their large eyes amongst the foliage. I was walking slightly ahead, looking for the next one, when from the vegetation at the side of the road, moving as silently as an iceberg, a large bull elephant emerged right in front of us. What are the chances. It made it clear that we were not welcome, but luckily wasn’t interested in causing us any further trouble.

The elephants will not be missed. There are, however, a number of things that I will remember fondly. In no particular order:

1. The potatoes. I’m not joking. The potatoes here in Uganda are the best I’ve tasted in my entire life, especially when roasted. I could eat them continuously. I’ve never had potatoes like them before and all others will pale in comparison. The only other foodstuff worthy of note are the doughnuts of death, which occasionally appear at afternoon tea — small blobs of hard, salty deep-fried dough. They’re basically vegetarian pork scratchings and they’re incredible, even though each one palpably reduces your life expectancy.

2. The students. Normally at the end of a field course I watch the tearful parting of the participants with absolute equanimity. It’s not that I’m glad to get rid of them so much as relieved at the lifting of responsibility and the peculiar social tension that results from the teacher-student relationship. On a TBA course, however, it’s completely different. All the students are mature post-graduates, all highly talented and motivated. It also helps that we’re not assessing them, which allows us to completely separate the important roles of teaching and support from any academic judgement. This dissolves one of the major social barriers, and not coincidentally, they learn a lot more as a result.

3. Primates. To quote Liza Comita, a fellow forest ecologist, if you’re going to do dull and repetitive fieldwork, do it somewhere with monkeys. I’ve never been anywhere with such a fantastic abundance and diversity.

4. This view in the morning:

frontview

One could easily get used to opening a front door to this view.

Some things, however, I won’t miss at all.

1. Ironing underpants and socks. This isn’t for aesthetic reasons, but to kill the eggs of the mango fly, which are often laid on wet clothes when they’re hung out to dry. On contact with skin the eggs hatch and the larvae burrow under the skin causing painful, infected swellings. One of the other teachers has pulled almost 40 larvae out following an unwise excursion to the swamp where they swarm in abundance. This has been enough of a warning to make everyone a little paranoid.

2. Finding an internet connection. In the Dark Ages, monks travelled the world looking for the exact location where the firmament was thinnest and their prayers would ascend most readily to heaven. High, desolate places were particularly favoured for establishment of holy sites. The same principle applies to obtaining a mobile signal in Uganda. I am sending this while sat on a pile of rocks on the hill above the field station. Returning to a place with reliable wireless will be a delight.

kate_internet

On this occasion, the internet beam fell around the septic tank

3. Elephant terror. Once you’ve had a bad experience with the elephants, every noise in the forest becomes a potential elephant. Branches swaying in the wind, an animal running away in the undergrowth, a hornbill squaking as it lands clumsily in the canopy. All these make me jump and scan for the nearest escape route. In most forests I’m confident that, as a human being, I’m pretty much the most dangerous animal around. Everything else tends to run away. Here I’m definitely not. It’s a new experience for me to be scared in the forest and it’s not one I’ve enjoyed.

4. This view in the morning:

baboons

The baboons hold their morning conference to plot the day’s mayhem.

Actually, the baboons aren’t too much of an issue, so long as you ensure that your doors and windows are locked whenever you’re not around. They’re certainly not aggressive, other than to each other. In a place with limited electricity and internet, an no TV, they provide a permanent soap opera on your doorstep. The researchers who study them have almost come to love them. I doubt I’ll ever get that far but they at least provide good entertainment. It still baffles me though that a standard greeting among male baboons is for one to grab the other’s testicles. It’s one way to get their attention I suppose.

Field notes from Uganda 7: Journey to the Mountains of the Moon

The three teachers on our Tropical Biology Association field course here in Kibale abandoned the station for a day trip to the Rwenzori mountains, around two hours drive away (if nothing goes wrong, which it did). These fabled peaks are known as the Mountains of the Moon and comprise the tallest mountain range in Africa*. The Rwenzori Mountains National Park runs along the border with DR Congo where it merges with Virunga NP on the other side. Both are UNESCO World Heritage Sites.

We began at the main park gate at around 1700 m and were led by our guide through several kilometres of valley floor which had been cultivated prior to the park’s gazetting. This remained in a rather sorry state, with little evidence of regeneration. I wondered why this might be the case, and whether this was a site where assisted regeneration through tree planting would be justified. Regardless of the stature of the vegetation, however, it makes good habitat for several of the endemic chameleon species, as well as an easier habitat for the bird watchers**.

kate_chameleon

One of the local endemic chameleon species — not easy to spot. Photo credit: Kate Lessells.

After a while the gradient steepened considerably as we ascended a knife-point ridge which afforded spectacular views on each side, as well as supporting a forest vegetation quite unlike the steep slopes. I say steep; if you fell then you wouldn’t bounce many times before reaching the white water at the bottom. It’s a wonder any vegetation clings to them at all, though in fact they’re covered by a mosaic of wooded patches and tangles of vines and shrubs.

After a 1000 m climb we reached the top of the ridge, panting and with burning muscles in our legs. We emerged into some delightful cloud forest. Trees were shrouded in the characteristic straggly Usnea lichens, and branches bore dense carpets of aerial-rooted epiphytes. Combined with the fresh breeze blowing across the mountains it was a narrow strip of paradise.

epiphytes

A carpet of epiphytes cover this branch hanging out over a steep ridge slope.

Above this, at around 3000 m, lay what I was really interested in — bamboo forest. I’ve heard about it but never had the opportunity to see it for myself. It was majestic; giant bamboos tower above you to a height of around six metres, and scattered amongst them are ancient Podocarpus trees which frequently exceed a metre in diameter.

Almost all the trees were large, with relatively few smaller stems. This made me wonder about the processes regulating these forests. I presume that episodic dieback of the bamboo (which happens after they flower en masse) opens up occasional opportunities for tree regeneration, perhaps only a few times a century. Those lucky recruits which manage to establish can then survive until the bamboo crowds around them again. This is my guess; once I get back to a reliable internet connection there will be plenty of reading to do.

bambooforest

Bamboo forest at around 3000 m asl.

We made it all the way to Lake Mahoma at 3000 m then returned after a thorough workout. Sadly there wasn’t time (or energy) to explore the heath forests that form the treeline, nor the endemic montane flora that lies above them. I’m intrigued enough by this landscape to already be planning a return.


I’ve completed the set! I have now seen in Kibale (drumroll please) black and white colobus, red colobus, red-tailed guenons, blue monkey, grey-cheeked mangabay, L’Hoest’s monkey, olive baboons and chimpanzees. Seven diurnal primates in one site and none of them hard to find (the nocturnal bush baby and potto are slightly trickier). It helps that so many of the groups are habituated thanks to generations of primatologists passing through.

Why are there so many primates here? I can’t give a definitive answer (though I’m sure that more informed people than me have speculated before), but suspect that part of the story lies in the age of these forests. Even those defined as primary show every sign of being in late stages of regeneration. Their canopies are short, dominated by long-lived pioneers which begin branching quite low, and with basal areas below 40 m2/ha. Whether they were cleared by humans or some catastrophic disturbance, the forests I’ve seen appear to be no more than a few hundred years old.

Why should this matter for primates? Long-lived pioneer trees have large leaves with high nutrient content, and often produce fruits which are animal-dispersed (and hence much favoured by frugivorous primates). Compare this to, for example, a much taller dipterocarp forest in Southeast Asia, where most of the leaves are practically inedible and most trees only fruit once every five or so years. Such forests are described as food deserts and primates exist at comparatively low densities.

It’s only a guess, but I can’t help feeling that the extraordinarily high diversity and abundance of primates here owes much to the relative youth of the forests.


Finally, some sad news. We heard this week that Dr Jerry Lwanga, the director of the Makere University Biological Field Station (MUBFS) at Kanyawara, and an instrumental force in the gazetting of Kibale Forest National Park, has died. I never met Dr Lwanga, but the sombre mood among the staff here is a reflection of the high regard in which he was held by all and their fondness for him. Everyone has spoken of him as a good man of impeccable probity and decency. Writing now from the field station which he founded, in the park to which he dedicated his career, it was certainly a life with many accomplishments.


* As individual mountains, Mt Kilimanjaro and Mt Kenya are taller than anything in the Rwenzori range, but they are both stand-alone peaks of volcanic origin. The Rwenzori peak of Mt Margherita is the third-tallest in Africa at 5109 m and is surrounded by a cluster of others which come pretty close.

** Apparently we saw the Rwenzori endemic purple-breasted sunbird. Or something. I include this information purely to irritate twitchers.

Field notes from Uganda 6: I am an elephant magnet

It’s official. I am an elephant magnet. Among over 30 people here on this Tropical Biology Association field course, I’m still the only one to have seen elephants in the forest. Three times. This last encounter was by far the most unsettling.

Most of the forest close to the research station here in Kibale is logged, and of the primary forest that remains, the majority is on steep rocky slopes where extraction of timber would have been impossible. I was getting a little frustrated at not seeing any tall-stature primary forest, but that may be because the forests here seem to be relatively young.

Yesterday afternoon I decided it was time to extend the range of my excursions and, following a tip-off from one of the local PhD students, I copied his GPS base maps and headed to the southeast, descending in altitude most of the way.

At one point I almost walked into a large male chimpanzee. Crossing a boggy patch at the bottom of a gorge and watching where I was putting my feet, I was already quite close before noticing him. Startled, I scampered back a few paces then looked to see how he would respond. Not a twitch. He cast me a laconic, disinterested glance, then continued grazing on a bush. I managed to take a couple of pictures before he moved on and allowed me to pass. I’m used to meeting orang utan in the forest, when that kind of proximity to an adult male would be a dangerous situation. It’s taking a little time to adjust to how habituated these chimpanzees are.

A large male chimp finally decides to vacate the path in front of me, in no particular hurry.

Eventually the trail ended, running into a larger orthogonal path that looked like it would connect with one of the main tracks through the reserve and give me an easy trip home. This led me for a mile through some beautiful dry forest which looked to be infilled savannah dominated by Olea trees. It had a nice, open understorey and some lovely views to forested ridges beyond. Having taken two hours to get out there I was tired but it was worth the effort.

Hill forest dominated by Olea trees with some spectacular lianas. Definitely worth a two-hour hike.

Sadly my chosen trial petered out, or rather it turned into a delta of narrow interweaving and overgrown paths through tall spiny Acanthus thickets. I knew the main trail was only a few hundred metres away, but it became increasingly obvious that the paths I was using had not been made by humans. This was exactly the kind of vegetation in which I met the elephants the first time, and visibility was only a few metres. Keen not to take many risks so far from base I turned back and retraced my steps for a few miles.

The outbound trip had been over some demanding topography, but there was a ridge trail to the north that was wide and easy-going, so I took a side trail up to meet it. On the way I passed an elephant wallow and a salt lick, which meant my senses were already tingling, but it didn’t look like there had been any activity there for some time. Nevertheless I was proceeding with extreme caution.

Meeting the ridge trail was a relief, though this was soon dispelled when I found a fresh pile of elephant dung. The ground was dry so there was no definitive way of knowing whether they were ahead or behind me, and this trail was the most efficient and direct route home. I proceeded with extreme caution, practically on tiptoes, listening constantly for any sign that there might be elephants nearby. There were broken branches and a characteristic stench that I’m belatedly coming to recognise. The problem was the trail, which had high banked walls with thick scrubby vegetation on each side. It didn’t offer many means of escape.

Rounding a corner I suddenly found myself metres away from the backside of a large male elephant. My heart was already pounding, but fortunately I had seen them before they saw me, and I was still walking as silently as possible. I crept back a short way then walked briskly back down the trail, putting some fast yards between myself and the herd. It was only when I heard movement — and they were out of sight — that I broke off the trail and sped into the forest.

This stuff is no fun to run through, especially with elephants on your tail.

This stuff is no fun to run through, especially with elephants on your tail.

The forest was filled with thick undergrowth on a steep slope, but I knew that my best course of action was to head west and get to the other side of the valley, so I aimed for the sun and pulled out my machete. I dropped right back down to the valley floor, waded through the swampy vegetation (if I’ve picked up mango flies I’ll be very displeased), then hacked up the other side. Here the GPS came into its own as I was able to eventually pick up another main trail on the next ridge which led safely back to base from the other direction, completely circumnavigating the elephants. Overall the diversion added several hard miles to the return journey. I made it back at dusk, shaken, soaked in sweat and exhausted. I then bought a beer.

Surely this can’t keep happening to me?


One of our students had a memorable though less pleasant encounter with the chimps. While measuring one of the liana plots, the chimp troop came past and the group of students decided, quite reasonably, to down tools and watch. One of the girls stood on the trail directly beneath a pair of chimps engaged in enthusiastic congress when a small deposit of something warm and slimy landed on her cheek. By all accounts this was not well-received.

In all the millions of years for which our two species have shared this planet, how many times do you think that has happened?

Field notes from Uganda 5: lianas — not just for chimps to swing on

I’ve been looking at tropical forests with fresh eyes on this trip, largely due to two books which I’ve been reading out here. The first, Second Growth by Robin Chazdon, is a compelling argument for the conservation of logged, degraded and secondary forests around the world. Far from being wastelands whose only worthwhile use is development or conversion to agriculture (hence the spread of oil palm), they should be viewed as valuable repositories of future diversity. Left to their own devices, or assisted when necessary, these forests can and will recover. It’s an important positive message regarding modern tropical landscapes. This isn’t to say that primary forests can be ignored — what remains still needs to be protected — but that regenerating forests have a crucial role to play in the future of conservation in the tropics.

The second book is Ecology of Lianas which I’m reviewing for Frontiers of Biogeography (spoiler alert: it’s brilliant). Lianas have been neglected for a long time partly due to the difficulties of measuring them, and partly due to a belief on the part of foresters that they impede tree growth, and should therefore be stripped from forests. The former problem has been removed by the publication in 2006 of a standard protocol for the measurement of lianas, encouraging many new studies and allowing researchers across the world to properly compare their results. The latter belief is being dispelled by evidence that lianas are not merely structural parasites but important engines of forest dynamics and vital for the redistribution of nutrients. Far from being deleterious, current evidence suggests that forests regenerate at at least the same rate in the presence of lianas*.

lianas

A cluster of lianas ascend into the canopy. These large lianas are a characteristic feature of old-growth forests in this area.

Inspired by the liana book, and having noticed how little work has been done in East African forests, I now have two of my student groups doing projects on them. Their broad aims are to discern how the abundance, biomass, diversity and composition of lianas change between primary, logged and secondary forests. With just over a week to collect data we’re not going to add much to the sum total of human knowledge, but we will at least be providing some baseline data, and it’s a line of enquiry which I might follow up in the future. Maybe it will be my excuse to return to Kibale one day.


While walking through the primary forest taking pictures of lianas, I happened to hear some rustling in the canopy far above me, and looked up to spot two female chimps with young! This is the first time I’ve seen chimps in the wild, and given that there were also plenty of interesting lianas in the vicinity, it seemed reasonable to stop and see what happened.

After examining me carefully, and deciding that I wasn’t a threat, the chimps began gradually descending from their lofty perch, where two nests suggested that they had spent the night. For some time they paused in the sub-canopy, then eventually worked their way down to the ground and came towards me. One crossed the path carrying her baby, which dropped off her onto the trail and sat, contentedly watching me, while she rummaged through the vegetation just out of sight. The other female stopped less than ten metres away and sat playing with her baby, entirely ignoring me.

Chimps also like lianas, which provide food and a means of movement around the canopy.

Chimps also like lianas, which provide food and a means of movement around the canopy.

The chimps here are thoroughly habituated to humans thanks to decades of study. Research assistants are constantly in the forest tracking them and observing their behaviour. It’s therefore one of the few places where one can get so close to chimps without any sign that they are troubled by human presence.

Eventually I moved off, partly because I had other lianas to look at, but also because it was beginning to feel voyeuristic. It’s a cliché to remark on the similarity of chimps to humans, but in such close proximity it’s too striking to miss, and brings home that the savannah apes and the forest apes are not so different from one another.


* I should stress that liana tangles in seriously degraded forests are a different matter. In such cases they can arrest succession and form alternative stable states that make it difficult for the forest to recover.

Field notes from Uganda 4: Are the elephants following me?

It seems that I’m an elephant magnet. Yesterday I encountered a herd while walking alone in the forest. As one of the local researchers put it, everyone wants to see the elephants, until they do. Actually I would have been quite happy not to see them at all. Instead I’ve now run into them twice in two days.

Following a morning spent accompanying my student research groups in the field, I decided to take off on my own for the afternoon and explore the infilled savannah on the far side of the swamp. The Land Rover dropped me at the swamp and left, but I didn’t get far. About a kilometre further on I came across a large, very fresh pile of elephant dung in the middle of the trail. A few beetles had found it and were enthusiastically burrowing but there was still plenty to go round. The only question was whether the elephants were ahead of me or — worse — behind.

That was soon answered by a loud bellow from around 30 m ahead, accompanied by the sound of several large animals turning round and the crashing of bushes. I didn’t stop to take a closer look; I was off. Meeting elephants at close quarters is not an opportunity for a selfie.

Everyone has their own recommendation as to what to do if you meet an elephant (as, in boreal fieldwork, I’ve heard a thousand ways to escape a grizzly bear). Most of these are likely untested by experience. Mine is to head into thick woody vegetation, preferably downhill, on the basis that a medium-bodied primate is faster than a bulky elephant under such conditions. Machete in hand I put a rapid hundred metres between myself and the herd, checked that I wasn’t being followed, then tracked back to the trail lower down. There were many nervous glances over my shoulder all the way home.


This morning I headed out again, accompanying one of the local PhD students, who is studying parasitoid wasps. He has a set of Malaise traps collecting ichneumonids and braconids, and having already collected many hundreds of species, he’s estimating a total species richness in the thousands. A high proportion will be undescribed; these are not groups about which much is known and even the basic taxonomy is lacking.

We joked about my elephant escape, especially in light of his own experience a week ago. He accidentally stumbled into the herd while they were asleep and ended up climbing a tree to escape. He was stuck there for three hours. Luckily mobile phone coverage in the forest is pretty reliable, especially if you can get high up, so he was able to text friends back at camp and summon help.

As we were wandering along one of the main trails — what are the chances — the elephants appeared just in front of us. This time it was a relatively open area, and his field assistant counted seven adults with five juveniles. One mock charged so we didn’t wait around but luckily they didn’t seem in the mood to follow us.

Tomorrow I’m planning to go for a walk in the complete opposite direction. What can go wrong?


In a previous post I was concerned that the baboons were up to something. They finally struck. They’ve eaten my soap and run away with my toilet paper. This means war.

Field notes from Uganda 3: How do you solve a problem like savannah?

RIMG0786

Savannah in Queen Elizabeth National Park

We’ve just returned from a four-day trip to Queen Elizabeth National Park, one of Uganda’s flagship tourist destinations. It’s an extensive tract of savannah where one can readily see buffalo, elephants, hippos, and, if you’re lucky, lions or leopards.

What you won’t see are giraffes or zebra. Put aside for now that these glaring omissions are the result of staggering levels of poaching during the civil war. Their continued absence is a deliberate policy on the part of Uganda Wildlife Authority, who maintain the parks such that no single site contains the full complement of large animals. The rationale is that tourists will then travel around more and spread their largesse across the country. The obvious question is why would a wildlife tourist choose to come to Uganda when they could go on safari in Kenya or Tanzania and see all the big game in the same place?

RIMG0751

My curtains in QENP, which are the only place in the park to find giraffes and zebra.

Whatever one makes of this policy, it strikes at the heart of one of the most contentious debates in African conservation — how should savannahs be managed? Should it be to maximise the revenue from tourists, the enjoyment of local visitors, to minimise conflict with communities in and around the park, or to create systems as close to ‘natural’ as possible, whatever that is assumed to mean?

The problem is threefold. Firstly, there are a complex set of processes which act to create and maintain savannahs. While landscapes composed of scattered trees surrounded by grass form spontaneously in semi-arid areas with a pronounced dry season, there are large parts of the world where several types of vegetation are possible. They could turn into grasslands, savannahs, scrub or even closed-canopy dry forest. Multiple outcomes are possible.

Which one is found at any given site depends not solely on the climate but on the densities of large herbivores and the fire regime. Herds of species such as buffalo favour grasses, which are tolerant of grazing, and prevent woody seedlings from establishing. Larger animals like elephants feed on and break up woody vegetation. Grasses are also highly tolerant of fire, whereas tree seedlings are vulnerable, which means that regular fires hold back the trees and maintain open areas.

RIMG0810

Fires keep trees in check and promote grasses.

The twofold problem in the modern era is a dramatic reduction of the densities of large herbivores, and increased control of burning. This has led to shrub encroachment, widely believed to be a management problem. But this points towards the second issue, which is that there is no clear baseline to work towards.

Photographic records from a century ago show clearly that woody vegetation has expanded at the expense of open grasslands. Yet even when these photos were taken, they represented the state of savannah systems following several centuries of colonial game hunting and land management. This built on thousands of years of occupation by hunter-gatherers and native herdsmen, who were at the time being driven from the land. A general shortage of reliable palynological evidence (long-term pollen records) only further confounds the issue. We have no accurate means of determining what savannahs ‘should’ look like, or what that even means. Change is constant, from the scale of seasons to alterations in the balance between woody plants and grasses throughout the ice ages.

Savannahs are really a dynamic mosaic in which the shifting fortunes of trees and grasses are determined by changes in the climate, the populations of large animals, and the frequency of fire. The concept of ‘climax’ vegetation is of no use here. In a wet tropical rain forest it’s clear what state the system will default to once left alone. In a savannah we can only wait and see, or manage for what we prefer.

The final problem is that two other notable and crucial species are missing from these savannahs. The first is a tragic indictment of the greed and stupidity of humans — rhinos. The landscape in QENP is dominated by large Euphorbia candelabrum, which are practically inedible to all the local species, but are greatly favoured by rhinos. How different would this park look if the rhinos returned? Right now it’s a rhino buffet. If only we could guarantee their safety, and an end to their pointless exploitation for the sake of a medical myth, the landscape would appear very different.

RIMG0764

These large Euphorbia are delicious for rhinos, but ignored by everything else (elephant for scale). Would they be so abundant if rhinos were still here to eat them?

The last species that’s missing is easily forgotten because no-one realises that they’re threatened. It’s a keystone species, crucial as an ecosystem engineer, seed disperser and top predator. It’s also a charismatic primate averaging 60 kg in size, with fascinating behaviour and cascading impacts across savannah ecosystems. Does this ring any bells?

Modern humans evolved in Africa around 150 000 years ago from an ancestor which was also a savannah ape. For thousands of years they have managed these landscapes, particularly through fire. Burning was a tool not only to drive out game but to maintain open areas where hunting was easier and grassy plains where prey were abundant. More recently domesticated cattle spread across Africa, and all this long before the depredations of the modern era. These days we tend to assert that the only way to protect natural systems is to exclude people. But what if people are part of the system? Would it be reasonable to reintroduce the rhino but not the hunter-gatherer?