Tag Archives: forests

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.

Nottingham Forest go global

China recently released their global land cover map online, for anyone to view and download. It presents land cover at 30 m resolution, far superior to any previous map. It’s a brilliant achievement and provides data that up until now has only been available at great expense and could only be viewed with specialist tools. I’ve been having fun browsing it to find study sites and favourite places.

There’s something a little strange about it though. Look closely at the logo representing forests, then imagine the scene in the National Geomatics Center of China.

A: Let’s release our global land cover map to the world to display the glory of Chinese science!
B: We should add nice cartoons to illustrate each cover type.
A: Who will design those?
B: Don’t worry, we’ll just do a Google search and take the first thing that comes up.

And so it was that they came to represent forests using the logo of Nottingham Forest Football Club. Either that or someone at CAS is a secret fan of English lower-league football. Truly bizarre.