Enhancing resilient Agroecosystems : looking at two extremes of Pyric Herbivory in Mesic Grasslands
Robyn Nicolay *, Michelle Tedder , Ntuthuko Mkhize and Kevin Kirkman
FEATURE
Current Address : University of KwaZulu-Natal , Pietermaritzburg
Fires have been an inherent part of the Southern African landscape for centuries , co-evolving with and shaping the native flora and fauna . This co-evolution has had profound impacts on their structure , composition , and overall functioning resulting in remarkable adaptions of plants and animals to these fire regimes . Many grassland species have developed mechanisms such as greater lignification or underground root systems that allow them to survive and even thrive in fire-prone environments .
Ungulate and livestock grazing help control the dominance of certain plant species , allowing for the coexistence of a diverse range of plants with different growth strategies . Grazing and prescribed fires promote the removal of excess biomass , moribund material and reduce the risk of catastrophic fires as well as preventing the dominance of certain plant species .
The role of Pyro-herbivory in the grassland agro-ecosystem
Fire and grazing play vital roles in shaping grassland ecosystems and species adaptation by replicating historical ecological processes and aiding in the adjustment to changing environmental conditions . Considerable research has focused on treating fire and grazing as independent factors , rather than a combined and coordinated use of pyric herbivory as a single management approach . The synergistic effects of fire and grazing can induce shifts in vegetation composition and structure , influencing the quality of available forage in grassland biomes and altering the dynamics of nutrient and carbon cycling within both aboveground and belowground biomass . However , this is dependent on how the grasslands are managed .
Contrasting extremes in the grassland agro-ecosystem
Extremes can exist within a pyro-herbivorous agro-ecosystem , specifically in terms of fire frequency . Both too frequent fires and complete exclusion of fires can impact system on dynam-
Figure 1 . Wakefield Farm near Fort Nottingham demonstrates differing approaches , where most of the grasslands are left unburnt and relies on grazing cattle as the primary source of defoliation , against the contrast of mandatory boundary fire breaks burnt annually . ( Photo : Nicolay and Tedder )
The occurrence of fire in mesic grasslands promotes enhanced forage quality by stimulating the regrowth of nutrient-rich vegetation and reducing the dominance of course , fibrous plant material . Furthermore , controlled burns mimic natural fire regimes , rejuvenating the grassland and preventing the encroachment of woody vegetation . By effectively combining fire and grazing , pyric herbivory has emerged as a sustainable management method in helping to maintain a balance within the agroecosystem and strengthening the resilience of mesic grasslands through the restoration of natural disturbance regimes . We looked at two sides to this extreme and present a brief summary of findings .
Grassroots Vol 23 No 2 July 2023 12