Assigned Session: FS 3.166: Alpine microclimates, biodiversity, and climate change
Under fire and heat: experimental warming increases plant biomass, but not species turn-over in Drakensberg grasslands of South Africa.
Abstract ID: 3.5556 | Accepted as Talk | Talk | TBA | TBA
Conor Eastment (1)
Mariska te Beest (2, 3), Paul Gordijn (3), Michelle Tedder (4), Max Rietkerk (2)
(1) South African Environmental Observation Network, 01 Peter Brown Drive, Montrose, 3201 Pietermartizburg, ZA
(2) Utrecht University, Science Park Utrecht, Utrecht
(3) South African Observation Network, Pietermaritzburg
(4) University of KwaZulu Natal, Pietermaritzburg
(2) Utrecht University, Science Park Utrecht, Utrecht
(3) South African Observation Network, Pietermaritzburg
(4) University of KwaZulu Natal, Pietermaritzburg
Climate change is influencing ecosystems worldwide. At high elevation, biodiversity and associated ecosystem functioning of mountainous ecosystems is are at a larger risk due to elevated temperatures. The nature and extent to which this will interact with fire, a primary driver of biodiversity and ecosystem functioning in many southern hemisphere of the Drakensberg grasslands is unknown. Few studies have investigated the interactive effect of fire and warming on plant diversity and productivity. We address this gap by using an in-situ full-factorial warming experiment with open-top chambers (OTCs). The OTCs were placed within the long-term Brotherton fire-manipulation experiment situated in the Maloti-Drakensberg mountains in South Africa. To observe variations in microclimate across all treatment conditions, we utilised high resolution loggers over the course of a year. Phytomass was measured across several seasons by a combination of the disc-pasture meter and comparative yield method. Species composition was determined using a descending point levy-bridge. In concurrence with the enhanced plant growth expected as a result of elevated temperature, we found higher plant biomass in the warming treatments. In total we recorded 35 grass and forb species in the experiment. Dissimilarity in composition was better explained by fire frequency than warming. W e found diverse microclimatic responses to the interaction of fire and warming, showing how vegetation can act as a mediator between macro and microclimatic conditions. With this information we provide guidelines for supporting future fire management policy in a warmer climate. While plant communities seem resistant to change from warming, there is an associated increase in phytomass with implications on fire severity. In concurrence with other studies in the area, we suggest a preference for intermediate fire frequencies as they can mitigate both soil moisture loss and extreme temperatures, associated with climate change.
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