Clutching our equipment and a few scribbled notes, we descended into the Bwindi Impenetrable Forest. We were not looking for Mountain gorillas. We were coming because we plan to watch the trees. In fact, working with instructions from Conservation International in the USA, we were going to check out proposed plot ” VGBIF4P”. Not as glamorous as gorilla tracking but important nonetheless.

We intend to add Bwindi to a select number of tropical forests around the world which will be closely monitored. The hope is that these observations will help provide a better idea of the World’s health. The site we were checking is one out of a longer list of places where we plan to set up a big square 100 meter by 100 meter plot (one hectare) in which we shall record and measure trees every year.

Initially we followed the steep trail down from just below the station. Elephants had just been here! There were broad elephant footprints in the soft mud, fresh mounds of dung, and several smaller snapped trees. I am surprised we hadn’t heard that as we live so close by. We followed the signs as we descended. In this forest even elephants prefer paths.

After about an hour we had to leave the path and cut across country moving through the dense undergrowth relying on compasses and global positioning units (these use satellites to provide a precise location; we are lucky to have had a good one donated recently by a visiting student from Edinburgh University). Moving through the forest is much slower and harder than following the trail – our lead field assistant had to cut and hack through the thick vegetation. Bwindi is a Mountain gorilla salad bar but the salad is tough.

If you know tropical rain forests, this thick herbaceous vegetation is not what you expect. In most tropical forests the vegetation near ground level is heavily shaded, plants are widely scattered and easy to walk between. But in this part of Bwindi the trees are often patchy and the canopy is open casting little shade. As in a normal rain forest many of the trees hold clumps of orchids and other plants high in their branches (plants growing on plants = epiphytes). Many trees are swathed in vines and other climbers. The difference is in the open nature of the forest which means that plenty of sunlight gets near to the ground. Plants grow thickly and the undergrowth is dense with a tangle of vegetation that catches around ankles as you try to take extra high steps to get over them. The main plants are called Mimulopsis – if you were a Mountain gorilla, these would be part of your daily diet.

I tried with mixed success to avoid the more localised long-spined nettles. These had little trouble penetrating the thin fabric of my trousers. The flora here is rich in stinging and spiny plants.

Forests are constantly changing. Trees germinate from seeds, grow and after years or centuries, they die. Because most of these changes are so slow they are hard to observe. So we need careful research.

Why do we need such research? Let me provide a couple of arguments (let me know if you get bored!).

If forests are always changing, the quality and value of the habitat is also changing. Conservation values are not guaranteed. For example, will the forest continue to provide the food that Bwindi’s Mountain gorillas depend upon? If we don’t make good observations it is hard to know (and there are reasons to worry – I’ll leave that discussion for another time).

Let’s zoom out and look at the bigger picture. A recent United Nations global summary of changes in our planet’s ecosystems summarised 30,000 sets of scientific observations. Sounds impressive right? But for those of us concerned about the wealth of species that live in the tropics there is an important clarification. Only 15 of these studies, (0.05% of the whole) are from the tropics. Scarcity of reliable data is one reason there are still so many arguments about climate change etc. and its implications. It bears repeating too that we know least about the places which have most of the species – the tropical forests!

A recent study I contributed to combined many small localised periods of observations of forest changes across tropical Africa and reached a surprising conclusion: the forests were increasing in the bulk-amount of trees they contained. While we argue about the causes of these trends they seem real and are big enough to influence the world’s atmosphere (reducing carbon dioxide – the main gas responsible for concerns about global warming). Similar forest changes have been observed in the Amazon rain forests and elsewhere suggesting a truly global phenomenon. This is important as it helps explain where some of the carbon dioxide that humans have been releasing into the atmosphere has been going.

Anyway, back to our plot. We eventually found our selected point after about 3 hours. Luckily we were all in rubber boots because this was a bog … the plot would have to be moved. We followed our guidelines carefully locating a series of sites in turn until we had a location which satisfied all the criteria. We took time setting up the square and marking the corners. The rain came pouring down. The bog’s frogs started singing. We were quickly soaked.

When the plot survey was finished we returned to the station as quickly as we could without slipping. My rubber boots making dramatic slurping noises on each step as my wet socks pumped the air in and out. Finally we were back: a hot drink, a wash and a chance to dry my by now horribly wrinkly water-logged feet. A successful day. One site checked … many more to go. Then there’ll be years of measurements to do (as long as Conservation International agrees to support it). Who knows what we’ll discover?

Tree watching is not as glamorous as tracking gorillas, but I think it’s important. Let me know what you think.