Longterm Kruger Park Vegetation Monitoring Project

Holger Eckhardt drives his bakkie down a degenerating dirt road, tyres rattling over rocky patches, guided by a precise set of instructions to a specific place in Kruger. He reaches a lonely spot, distinguished from the rest of the bush around him solely by its GPS coordinates.

No one has stood on this precise spot for the last three years, when Holger was last here. Once in place, Holger climbs onto a platform on his bakkie, turns to face a specific compass bearing and starts snapping photos, turning through a complete circle.

Photos taken, he climbs back in the bakkie and continues on his journey to another lonely location in the park. The scene is repeated at more than 580 sites, some in the remote wilderness areas of the park, some on busy tourist roads. Some 3,000 photographs will have been taken before Holger is finished, about 4,000km travelled and 24 man-days spent criss-crossing the park.

All of this is part of a medium- to longterm vegetation monitoring project, started in 1977, that takes panoramic pictures at fixed points in the park for comparison purposes as time progresses.

Over the years, the fixed points decided on in 1977 have been maintained, and more spots added as time passed. Less than a hundred sites were initially chosen. The number rose to 500 in the early 1980s, with a few more being added after huge fires swept Kruger's landscapes in 1996, and finally in the new millennium sites were added to cover specific landscape types that had not previously been photographed. All 580 sites are photographed every three years. Sites along rivers, streams and pans are photographed every year.

The photos are taken at the same time every year, beginning in March and April, and ending several weeks later. Each spot has a reference sheet to tell Holger exactly where and how to stand to take the photos. A time-consuming task, the photography process has become more involved over the years. The Kruger Park's zoning policy, which dictates development in the park, allows for certain areas of the park to become wilderness areas, untouched by any form of modern technology - including maintenance of access roads.

Some roads in the park are now only travelled by Holger and his camera, becoming increasingly impassable as nature heals the scar of the road. The closing down of windmills has also meant that photographs previously taken from the windmill itself can no longer be precisely repeated. With some places in the park having been photographed over more than a 25-year period, changes in the number, size and density of trees becomes apparent.

Holger, programme manager for spatial ecology, has presented his analysis of some of the photographs at an international rangeland congress, and again at the elephant indaba held in Kruger earlier in the year. Holger says that when it comes to medium to large trees "The major architects are elephants and fire combined". Healthy trees over five metres are usually not affected by fire. However, elephants ring barking these large trees can allow fire, woodborers and fungi to take their toll.

Holger says that too frequent fires in the past have meant that not many new trees have entered the large tree class (over five metres). Along with elephant impacts, this means that in the analysed sites there has been a 45 percent decline in this height class. Other findings show that there has been an increase in the number of trees that are less than two metres high. Fires easily affect these small trees and so density can change dramatically in a few years unlike with larger trees.

Tree densities are also different depending on what rocks underlie the trees dictating the soil type. Overall there is more woody cover in granitic areas, which tend to have sandy soils. Large tree loss over the years has been higher in areas dominated by basalts, which form clay soils. The average number of large trees has declined in all the areas analysed. A concern with the loss of large trees is that if the growth of new seedlings does not occur, either because of fire or browsing pressure, some species of trees that are not common in the veld may not be replaced over the years, decreasing the biodiversity.

As more time passes, the photos will increase in value, and more insights into the changes taking place in Kruger's landscape will be revealed. This year just before the rainy season starts again, Holger will once again bring out his digital camera, load his platform onto his bakkie, and set out with a light heart to battle degenerating roads, enjoy the great outdoors and the task of snapping as many photographs as possible within the limited daylight hours.

By Melissa Wray

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