Grass--A Story of Frankenwald.

South African grasslands and ploughing: Outlook for agricultural expansion in Africa

“…After a disturbance like fire, drought or herbivory, herbaceous plants 10 can resprout from various underground storage systems such as woody or tuberous root systems, which store carbon and other resources. 11 However, when a grassland is ploughed -an exogenous disturbance -these hardy herbaceous plants with their high underground storage system diversity and large carbon storage capacity are permanently removed from the soil. 4 Ploughing severely damages the feedback loop where plant species are dependent on the soil carbon stock for growth.…”

“…Unfortunately, studies that investigated this assumption show that even when restorative measures are implemented, species recovery takes much longer than anticipated, with no guarantee of full recovery. 11 Current studies show that disturbed grasslands will take at least a century to recover to former species richness, which means that the carbon pool that is irreversibly linked to aboveground vegetation will take just as long to recover to its original storage capabilities. 4 In South Africa, we have good knowledge of the carbon stored in our natural grasslands.…”

“…We also know, from groundbreaking work in the 20th century, that there is no evidence that grass composition in the Highveld ever recovers from ploughing. Evidence gathered by Eddie Roux 11 at the Frankenwald research station was the first evidence that the ideas of succession, first put forward by Clements in 1916 and adopted by ecologists globally, were not sufficient to explain dynamics of disturbance-driven temperate and tropical ecosystems. This is supported by the identified 'purple veld' or 'climax grasslands' that never returned in the ploughed plots, even after decades…”

“…However, these early researchers considered the recovery ofgrass species only, and did not document the loss or recovery of other herbaceous plants. 11 Recent demonstrations 11,12 showed that certain herbaceous functional groups were permanently lost from grasslands exposed to exogenous disturbance like silviculture, and that this impacted their belowground carbon reserves and functioning. This work raises questions about the degree to which our current legislation protects grasslands, and whether sufficient systems and efforts are in place to protect what remains, putting more effort into restoration, and planning our land use and biodiversity offsets accordingly.…”

Topo-edaphic environment and forest plantation disturbance explain patterns of grassland species richness, composition and structure in an agro-ecological landscape, Maputaland, South Africa

“…The composition and structure of secondary grassland after annual crop abandonment differs considerably from its undisturbed 'old-growth' counterpart (Roux 1969) but this tends to reflect the type of disturbance (O'Connor 2005;Buisson et al 2018). Factor affecting the composition of regenerating grassland include competition from pioneer grasses in fertile postagricultural soils (Tilman 1987;Lindsay and Cunningham 2011), propagule constraints that are influenced by the proximity to patches of untransformed grassland (Mentis 2006), and that the majority of grassland forb species (especially re-sprouting bulbs) resemble K-rather than r-selected species, as plants are usually long-lived post-establishment and their reproductive output is low (Bond and Midgley 2003;Zaloumis and Bond 2016).…”