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.

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3 thoughts on “Why should anyone care about Ugandan lianas?

  1. jeffollerton

    “A colleague at a former employer once memorably stated in a staff meeting: “I am clueless about how science works”……”

    Seriously though, nice post and I 100% agree – small-scale studies like this are the building blocks of ecological understanding and just as important as the blockbusters. In fact they are often the blocks that form the blockbusters.

    Is there a global database or summary paper showing where liana studies have been conducted?

    Great shout-out for the TBA too – I agree, it’s an important organisation.

    Like

    Reply

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