An unexpected finding

These three repeat photography sets are part of the Plant Conservation Unit's Repeat Photography Project based on historical photographs of southern African landscapes, 4 000 of which were digitised as part of the Humanitec project. View the Plant Conservation Unit's Repeat Photography Project on the Digital Collections website.

'The digitisation of these archival photographs enables researchers to use these historical images as a reference point in trying to gauge land change over time.'

One of the historic collections of landscape photographs that has been digitised comprises the photographs taken by devoted ecologist Ulrich Nänni.

The first photograph in each repeat photography set was taken by Nänni. The second is a contemporary replication taken by Sam Jack as part of a recent research project conducted by UCT Biological Science Department’s Plant Conservation Unit to try and assess the changes that have taken place in the landscape between then and now.

In 2014 Jack and Honours student, Daniel Poultney, undertook a three-week field trip to the Drakensberg to reshoot many of Nänni’s original photographs taken in the early 1960s. Poultney’s project investigates the abundance and distributional change of two prominent Drakensberg Protea species – P. caffra and P. roupelliae. Through an initial correlational study and subsequent model building exercise he also determined which environmental variables are most likely to be responsible for any observed changes in Protea abundance.

Nänni was based in the Cathedral Peak area of the Drakensberg, so most of his photographs were taken around the region of Cathedral Peak, Monks Cowl and Njasuti. Other photographs from the Northern Drakensberg were also included in the study, which is focused on the central and northern Drakensberg.

'Although in certain parts there has been a decrease, it appears that overall there has been in an increase of proteas growing in the area. It's an unexpected finding.’

'Although in certain parts there has been a decrease, it appears that overall there has been in an increase of proteas growing in the area,' says Poultney. 'It's an unexpected finding. It doesn't necessarily have ecological implications, but considering that it is such an iconic plant family, it is good to know that they are stable and, for some reason, increasing.

‘Now that we have established that there is change, we are trying to find out the driver of that change. It’s a complex system, which makes it difficult to disentangle a single environmental aspect that is the driver, but we are looking at fire, temperature, rainfall and CO2…

'What appealed to me about this project were the really beautiful landscapes,’ he says. ‘When I first saw some of the historical photographs, I thought: ‘Wow, I'd love to do my work there!’

‘It took a really long time, flying around in the virtual reality of Google Earth trying to find reference points that would enable us to find the exact sites. We'd often get very close using that method – sometimes we'd be a just few hundred metres off.’

The first task for the researchers was to find the site, which wasn't easy because there were no GPS co-ordinates when the original photographs were taken by Nänni. ‘It took a really long time, flying around in the virtual reality of Google Earth trying to find reference points that would enable us to find the exact sites,’ Poultney explains. ‘I had to get used to the land forms – the mountains and stuff – flying in on Google Earth and trying to find the exact sites. We'd often get very close using that method – sometimes we'd be a just few hundred metres off.

‘We had to be quite specific in terms of replicating the photograph as perfectly as possible. While Sam [Jack] was taking the photograph, I'd gather field data, counting the number of trees, their different sizes, and so on...’

The digitisation of the archival photographs enables researchers to use these historical images as a reference point in trying to gauge land change over time. ‘You can only do that if you have the same material to compare across time, so the format has to be pretty much identical,’ says Poultney. ‘It is massively useful to have the old photographs scanned as a template and reference point for assessing how the landscape has changed over time.’

‘After hiking through some tough terrain, enduring the winter cold, surviving fire scares and +100 kmph winds, Daniel and Sam returned home with 65 repeated photos and more detailed measurements from 15 selected populations,’ reads the Plant Conservation Unit’s project report. ‘With the generous help of James Puttick and Res Altwegg, Daniel was able to show that – contrary to predictions – the number of P. caffra had actually increased in the Drakensberg over time. The increase was greatest at lower elevations and this was thought to be due to higher temperatures and increased atmospheric CO2 concentrations allowing for faster growth and quicker post-burn recovery. Conversely, declines in Protea numbers at higher elevations were ascribed to more intense fires on the more exposed headslopes.’