Ukulinga Grassland Project Marks 75 Years Of Pioneering Research Shaping Global Ecosystem Knowledge

Grasslands and savannas cover more than 60% of South Africa. They are vital not only for livestock and wildlife forage but also for providing key ecosystem services such as water regulation, carbon storage, biodiversity, cultural resources and recreation.

The Ukulinga Research Farm of the University of KwaZulu-Natal is a species-rich grassland with scattered trees. It hosts two long-term experiments that have provided crucial insights into how fire, grazing and soil nutrients shape ecosystems.

In 1950, Professor J.D. Scott, founder of the discipline of grassland science at the university, established two complex grassland experiments at Ukulinga: the Veld Burning and Mowing Trial and the Veld Fertilisation Trial. They are now internationally known as the Ukulinga Grassland Fire Experiment and the Ukulinga Grassland Nutrient Experiment. Initially designed to improve hay yield and forage quality, these experiments have run uninterrupted for 75 years. They have evolved into invaluable ecological laboratories.

They are respectively the longest-running fire experiment in the world and the longest-running nutrient addition experiment in Africa.

Scientific studies on these grassland experiments have spanned molecular, microbial, plant community, and ecosystem scales. They have covered fire effects, nutrient cycling, soil processes, biodiversity responses and remote sensing. Comparative and collaborative studies, often involving US and European teams, highlight the global relevance of these datasets. They connect local observations to international ones, revealing universal patterns while highlighting the unique characteristics of southern African grasslands.

I’m a grassland scientist who has been involved in this research. My colleagues and I looked back to assess the value of research done on the farm. We concluded that it has contributed to ecological theory, shaped local management practices, and supported a wide range of comparative studies, networking and education.

The core scientific value of these experiments lies in their duration and the consistent application of the same treatments over time. Decades of continuous treatments (like burning or fertiliser) have generated data that reveal slow ecological processes, long-term interactions, and effects that short-term studies cannot detect.

The outdoor laboratories allow researchers to pursue new multidisciplinary investigations and examine interactions with emerging environmental pressures, including climate change.

Early grazing experiments

Valuable livestock grazing experiments were conducted in the 1950s and 1960s. One trial (1958-1974) examined three sheep grazing systems – continuous, rotational, and seasonal rest – at different stocking rates. Another 24-year study (1967-1991) tested nine combinations of rotational grazing periods to evaluate multi-paddock systems.

These early trials and several focused short-term studies provided insights into how grass species respond to grazing or mowing. The findings, many of them published in the African Journal of Range and Forage Science, revealed complex relationships between grazing intensity, plant resilience and grassland productivity. They continue to inform rangeland management today.

Some key results of the long-term experiments

Over decades, excluding fire and mowing transformed some plots into dense, woody thickets, dramatically altering both plant composition and ecosystem function. Regularly burned or mown plots maintained productive, species-rich grasslands.

The nutrient experiment has shown that while nitrogen and phosphorus fertilisers can boost grassland productivity, they also alter the original grassland by promoting fast-growing grasses. Over time, added nutrients reduce plant diversity.

Together, the experiments demonstrate how natural disturbances versus artificial nutrient addition drive distinct ecological outcomes. They offer insights into the mechanisms that maintain grassland biodiversity and resilience.

Over the past 75 years, research output from the experiments has steadily grown, and has achieved a broad international reach. Fifty peer-reviewed papers have been produced, and the top 10 cited papers from each experiment have collectively been cited in 458 journals by 1,172 principal authors from 78 countries outside South Africa.

The impact

The Ukulinga long-term grassland experiments have shaped sustainable management practices by providing empirical evidence for optimal burning frequencies and seasons in mesic (moderately wet) grasslands. They have highlighted the ecological risks of nutrient enrichment from industrial pollutants, showing how added nutrients can alter grassland composition and reduce diversity.

Beyond research, the experiments have had a profound educational and outreach impact, training generations of students and engaging visitors who carry these insights into policy, conservation and grassland management across South Africa.

Ukulinga now also hosts global-network experiments such as the Nutrient Network (NutNet), Drought Network (DroughtNet), and Disturbance and Recovery Across Global Grasslands Network (DragNet), linking local observations to international studies. Through these collaborations, researchers can compare Ukulinga’s results with similar experiments worldwide.

What next

Preserving these long-term studies is critical for understanding slow ecological responses, succession, and tipping points that only emerge over decades.

Ukulinga (isiZulu for “to test”) provides a platform for addressing pressing questions in grassland science. To safeguard its unique scientific value, the long-term burning, mowing and nutrient addition experiments should be maintained without alteration. Continued support and broader collaboration are essential to fully realise their potential for monitoring long-term ecological responses, testing new hypotheses, and guiding sustainable grassland management.

This article is republished from The Conversation under a Creative Commons license. Read the original article.