Building on the Tierberg legacy

Helga van der Merwe (right) gets a top-notch induction to the Karoo from Sue Milton (Picture: Joh Henschel)

By Helga van der Merwe, RCA Fellow, SAEON Arid Lands Node

There is a global need for long-term environmental observation as well as research to detect, understand, and predict environmental change as a basis for decision making at local, national and global levels (Milton et al. 2007).

One of the means to address this need is the establishment of long-term ecological research (LTER) sites focusing on environmental change. The Tierberg Karoo Research Centre is such a site. With good foresight, Tierberg was established in 1987 for precisely this reason, and is now a plum in SAEON’s palette of research platforms.

SAEON’s acquisition of the Tierberg LTER did not only include the transfer of a piece of land in the Karoo; it also included a host of well-established research experiments. These were developed during many dedicated years of field surveys in the blazing sun and under bitterly cold conditions, as well as hours of data input and analysis by mainly Sue Milton and Richard Dean and a host of students and other researchers.

The positive relationship forged between these researchers and adjacent land owners has ensured that SAEON can continue its scientific endeavours on a sound footing at Tierberg and on adjacent farm land. Additionally, Tierberg has served as a training facility for numerous school groups as well as students from various universities in South Africa and abroad.

Rich heritage of data sets

A lengthy list of publications has been generated for Tierberg, spanning topics that include flora, vegetation, rehabilitation, fire, birds, mammals, insects and important ecosystem characteristics such as heuweltjies¹. The publications are accompanied by numerous data sets, many of which are already included in the SAEON data system. Data from a weather station have also been collected regularly since 1987.

In the span of Tierberg’s existence, data have been collected from various projects, either regularly or intermittently. Some of these projects lend themselves to repeat surveying and thus the generation of data sets that capture environmental change over time. The unique situation of the (enclosed) Tierberg (i.e. stock exclusion) adjacent to a farm currently grazed by merino sheep, and another farm that had been historically overgrazed, enables the comparison of these three land uses and management strategies:

• Tierberg Karoo Research Centre with stock excluded but open to most wildlife;
• Tierberg farm (Portion 2 of Sand River), with stocking density at economically viable levels and open to game; and
• Argentina farm, a historically overgrazed area, now farmed at economically viable levels and open to game.

Tierberg is brimming with new opportunities for research given the combination of classic Karoo landscape, shrubs, steenbok and many other animals, instruments and loads of data and knowledge (Picture: Joh Henschel)

Surveys

Various surveys conducted over the years can be repeated by SAEON and other researchers. These surveys include projects such as the monitoring of projected plant canopy cover and densities following (i) exclusion of all mammals; (ii) clearing of indigenous vegetation; (iii) fire induced by burning invasive alien grass on a normally fire-free arid environment; and (iv) fertilisation experiments.

By conducting subsequent field surveys, renewing data sets, and broadening the monitoring to include organisms other than plants, SAEON’s Arid Lands Node aims to build on the existing Tierberg legacy. Some of the projects are now being monitored by SAEON itself and others by researchers at various other institutions such as the South African Biodiversity Institute (SANBI) and the Centre for Invasion Biology (CIB).

Field surveys will be repeated and new projects launched in an attempt to further bridge some of the research gaps identified on the Tierberg site. Data will be archived in the SAEON database and scientific publications will be generated in order to disseminate information and promote interest and the initiation of other scientific studies on the Tierberg site.

Further reading

MILTON, S.J. & DEAN, W.R.J. 1990. Mima-like mounds in the southern and western Cape: are the origins so mysterious? Suid-Afrikaanse tydskrif vir Wetenskap 86: 207-208.

MILTON, S.J., DEAN, W.R.J., O’CONNOR, T.G. & MILLS, A.J. 2007. Scaling up from site-based research to a national research and monitoring network: lessons from Tierberg Karoo Research Centre and other design considerations. South African Journal of Science 103: 311 – 317.

¹ The formation of heuweltjies is a slow process where mounds form above termite nests, grow larger and then contract when they have passed a certain stage, probably when they are no longer occupied by the small harvester termite Microhodotermes viator. When the termite colony dies, the heuweltjies gradually fade and disappear. (Milton & Dean 1990)