Theme 1: Rangeland/Grassland Ecology--Oral Sessions

Description

South African old-growth grasslands are hyper-diverse ecosystems which evolved under naturally occurring rainfall variability. It is predicted that future precipitation patterns will become more variable, which could lead to increased frequencies of extreme and prolonged drought events. This study aimed to investigate the effects of climate variability on plant diversity of the fragmented pristine, mistbelt grasslands of the Woodbush Granite Grasslands (WGG) at Haenertsburg, South Africa. It has been reported that species composition has changed substantially in this area, as disturbance-tolerant species enter these systems or existing competitor species become more dominant. A Temporal Beta-diversity Index (TBI) was used to determine the gains and losses in taxonomic and functional diversity, and of endemic and threatened species since 2009. Results show that there was a gain in species from before (2009) to onset of drought (2015) and a loss in species from the onset of the drought (2015) to after the drought (2019), while the overall effect of the drought on species occurrence from 2009 to 2019 was non-significant suggesting ecosystem resilience to drought.

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Climate Variability in the Woodbush Granite Grasslands of South Africa: Effects on Grassland Diversity

South African old-growth grasslands are hyper-diverse ecosystems which evolved under naturally occurring rainfall variability. It is predicted that future precipitation patterns will become more variable, which could lead to increased frequencies of extreme and prolonged drought events. This study aimed to investigate the effects of climate variability on plant diversity of the fragmented pristine, mistbelt grasslands of the Woodbush Granite Grasslands (WGG) at Haenertsburg, South Africa. It has been reported that species composition has changed substantially in this area, as disturbance-tolerant species enter these systems or existing competitor species become more dominant. A Temporal Beta-diversity Index (TBI) was used to determine the gains and losses in taxonomic and functional diversity, and of endemic and threatened species since 2009. Results show that there was a gain in species from before (2009) to onset of drought (2015) and a loss in species from the onset of the drought (2015) to after the drought (2019), while the overall effect of the drought on species occurrence from 2009 to 2019 was non-significant suggesting ecosystem resilience to drought.