Theme 1: Rangeland/Grassland Ecology--Oral Sessions

Description

Rangelands cover almost 50% of the earth’s land surface and are often found in marginal areas that often face climate extremes. The production of herbaceous biomass has strongly declined over the last decades due to overgrazing and adverse climatic conditions such as frequent droughts and flooding. While different rangeland restoration methods are being used, their effect on vegetation quality and quantity over time has rarely been experimentally tested and monitored. Our research comprises experiments of various rangeland restoration tools we have used across eastern and southern Africa. We conducted passive restoration through exclosure experiments and compared vegetation in and outside of exclosures to understand regrowth patterns as well as overall forage quality. The active restoration methods we tested comprised domestic livestock species diversification, i.e., inclusion of browsers in rangeland systems. Further, we investigated how reseeding of nutritious rangeland grass species and subsequent grazing regimes can improve the rangeland health. We found that exclosures strongly improved biomass and productivity but that regular moderate grazing can further enhance those compared to no grazing. Our results further suggest that including browsers might enhance nutrients of herbaceous vegetation and soils of rangeland systems. We also claim that young grass species such as Chloris gayana and Cenchrus ciliaris, which are commonly used for reseeding of rangelands, show higher nutrient contents and productivity under light or moderate grazing pressure while mature grasses did not show this effect. We conclude that a combination of active and passive restoration methods can greatly enhance quality and quantity of African rangelands and enhance their sustainable use and resilience towards climatic shocks such as increasing drought frequencies.

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Rangeland Management in a Changing World – Active and Passive Restoration Case Studies from Ethiopia, Tanzania, and South Africa

Rangelands cover almost 50% of the earth’s land surface and are often found in marginal areas that often face climate extremes. The production of herbaceous biomass has strongly declined over the last decades due to overgrazing and adverse climatic conditions such as frequent droughts and flooding. While different rangeland restoration methods are being used, their effect on vegetation quality and quantity over time has rarely been experimentally tested and monitored. Our research comprises experiments of various rangeland restoration tools we have used across eastern and southern Africa. We conducted passive restoration through exclosure experiments and compared vegetation in and outside of exclosures to understand regrowth patterns as well as overall forage quality. The active restoration methods we tested comprised domestic livestock species diversification, i.e., inclusion of browsers in rangeland systems. Further, we investigated how reseeding of nutritious rangeland grass species and subsequent grazing regimes can improve the rangeland health. We found that exclosures strongly improved biomass and productivity but that regular moderate grazing can further enhance those compared to no grazing. Our results further suggest that including browsers might enhance nutrients of herbaceous vegetation and soils of rangeland systems. We also claim that young grass species such as Chloris gayana and Cenchrus ciliaris, which are commonly used for reseeding of rangelands, show higher nutrient contents and productivity under light or moderate grazing pressure while mature grasses did not show this effect. We conclude that a combination of active and passive restoration methods can greatly enhance quality and quantity of African rangelands and enhance their sustainable use and resilience towards climatic shocks such as increasing drought frequencies.