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ARU pioneering mountain range-expanding project

26 July 2021 | Story Nonsindiso Qwabe | Photo Nonsindiso Qwabe

ARU Read more web — On top of the Drakensberg. The ARU and Witsieshoek Mountain Lodge research team are, from the left: Grant Martin, Dr Ralph Clark, Jan van Niekerk, Prof Aliza le Roux, Prof Peter Taylor, and Dr Sandy Steenhuisen.

All mountains around the world have native and non-native species that are expanding their ranges quite dramatically; however, little research has been conducted towards understanding the long-term redistribution of species and the effects of global change on biodiversity.

The Afromontane Research Unit (ARU) on the University of the Free State Qwaqwa Campus – as part of the Mountain Invasion Research Network – has secured a two-year EU Horizon 2020 project under the Department of Science and Innovation, which will be looking at the mechanisms underlying the success and impact of range-expanding species on biodiversity and ecosystem functioning.

On Monday 19 July 2021, the ARU took a few of its researchers on a scenic helicopter ride to the summit of the Drakensberg for an alpine field-experiment site inspection of the Mont-aux-Sources peak, one of the highest sections of the Drakensberg range. This site has been identified for the project which the research unit will be leading on mountain research.

ARU Director, Dr Ralph Clark, said the project would explore the effects of global change, biological invasions (when species invade new geographic regions), as well as climate and land-use change. He said experiments were needed to explore the various possibilities and to test the extent to which species respond to experimental treatments. The project would therefore be conducting experiments for two years using open-top chambers – causing an increase in temperature of 3 or 4 degrees to what you find naturally – on plant species from lower down to the top of the mountain, to see how they function. “This will give us an idea of whether they will be able to survive in global warming scenarios. If temperatures get warmer, we might start seeing a lot of plants up here that we wouldn’t otherwise find here.”

Dr Clark said little is known about the long-term monitoring of species distribution and the effects of global change. Implementing the project in the Maloti-Drakensberg alpine area will therefore put the area in the global mountain research arena. The elevational gradient in the Maloti-Drakensberg Mountains provides space to explore the key processes underlying the variation in species elevation with climate change. “One of the things we don’t know much about are alpine systems. We are hoping to establish a long-term alpine research site and try to add as many studies as we can. The more science we can bring up here, the more we can know about mountain life. What happens on mountains has a lot of impact on social dynamics.

“This project is looking to see what is driving range expansion. Every mountain has its own context. In the Swiss alpine, fires are not a big factor, but fires are one of the biggest factors on our mountains. Some of our native and non-native species are therefore fire-driven, so as fire increases, you might have them spreading faster.”

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Well-established root system important for sustainable production in semi-arid grasslands

2015-02-24

Plot layout where production and root studies were done
Photo: Supplied

The importance of a well-established root system for sustainable production in the semi-arid grasslands cannot be over-emphasised.

A study of Prof Hennie Snyman from the Department of Animal and Wildlife and Grassland Sciences at the University of the Free State is of the few studies in which soil-water instead of rainfall has been used to estimate above- and below-ground production of semi-arid grasslands. “In the past, plant ecological studies have concentrated largely on above-ground parts of the grassland ecosystem with less emphasis on root growth. This study is, therefore, one of the few done on root dynamics in drier areas,” said Prof Snyman.

The longevity of grass seeds in the soil seed bank is another aspect that is being investigated at present. This information could provide guidelines in grassland restoration.

“Understanding changes in the hydrological characteristics of grassland ecosystems with degradation is essential when making grassland management decisions in arid and semi-arid areas to ensure sustainable animal production. The impact of grassland degradation on productivity, root production, root/shoot ratios, and water-use efficiency has been quantified for the semi-arid grasslands over the last 35 years. Because of the great impact of sustainable management guidelines on land users, this study will be continuing for many years,” said Prof Snyman.

Water-use efficiency (WUE) is defined as the quantity of above- and/or below-ground plant produced over a given period of time per unit of water evapotranspired. Sampling is done from grassland artificially maintained in three different grassland conditions: good, moderate, and poor.

As much as 86, 89 and 94% of the roots for grasslands in good, moderate and poor conditions respectively occur at a depth of less than 300 mm. Root mass is strongly seasonal with the most active growth taking place during March and April. Root mass appears to be greater than above-ground production for these semi-arid areas, with an increase in roots in relation to above-ground production with grassland degradation. The mean monthly root/shoot ratios for grasslands in good, moderate, and poor conditions are 1.16, 1.11, and 1.37 respectively. Grassland degradation lowered above- and below-ground plant production significantly as well as water-use efficiency. The mean WUE (root production included) was 4.79, 3.54 and 2.47 kg ha -1 mm -1 for grasslands in good, moderate, and poor conditions respectively.

These water-use efficiency observations are among the few that also include root production in their calculations.

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