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Impact of exceptional drought on transformation of a savanna grassland

Drought Savanna


Titre : Impact of exceptional drought on transformation of a savanna grassland

Organismes NSF : DEB Division Of Environmental Biology

Durée : February 1, 2017 // January 31, 2019

Kruger National Park (KNP), a biodiversity hotspot, is experiencing one of its worst droughts on record. This drought has resulted in large declines in forage for many grazing species, which have experienced significant population declines as a result. The remaining animals have been left to consume low quality, mostly unpalatable, forage. How these changes may alter future plant communities is not known. For almost a decade, scientists have been studying the impact of fire frequency and large grazers on ecosystem processes in savanna grassland in KNP under what used to be considered normal climatic conditions. With the onset of extreme drought, they now have an opportunity to study how the effects of fire and grazing may change as climatic conditions change, and what this might mean for plant productivity and populations of large grazer species. Climate models predict an intensification of climate extremes globally, a phenomenon that is already evident in weather patterns today, so there is a great need to develop a better understanding of how these rare climatic events may be reshaping ecosystems. In addition to enhancing understanding of savanna grasslands and testing fundamental ecological theory, this research will provide crucial information on the impact of climate extremes on plants and their grazers, which will be of great value to decision makers that manage national parks.

The proposed research will document the effects of a historically exceptional drought on a savanna grassland (characterized by a mixture of both woody and herbaceous plants) in KNP in the context of an existing long-term grazing and fire experiment. Documenting the potentially transformational nature of rare climatic events is in itself an opportunity seldom afforded ecologists, but to have pre-treatment data and a long-term, well-replicated experiment in place that manipulates the key disturbances most likely to interact with extreme drought is unprecedented. Because forecasts are for this exceptional drought to conclude in early 2017, this RAPID project focuses on gathering data at the end of this exceptional climate event to assess the potential for drought, fire and grazing to trigger a shift in the plant community that will result in an increase in the relative abundance of palatable grasses. This research has implications for not only understanding the determinants of grassland biodiversity, but also for increasing our knowledge of how rare climate extremes may transform ecosystems. Currently, KNP managers are grappling with a long-term trend of grassland degradation which has led to the loss of palatable forage for wildlife. The current exceptional drought, while exacerbating this problem in the short-term, may increase forage quality across much of KNPs grasslands. In addition, this project will establish close collaborative ties between US researchers and scientists in South Africa. The lead scientists on this project will continue to work closely with KNP scientists to ensure that all results are communicated in a way to inform management decisions in KNP. Dissemination of all datasets and results will be achieved via a dedicated webpage, housed at Colorado State University.

Partenaire (s) : Melinda Smith melinda.smith (Principal Investigator) Deron Burkepile (Co-Principal Investigator) Sally Koerner (Co-Principal Investigator) Alan Knapp (Co-Principal Investigator) Scott Collins (Co-Principal Investigator)

Sponsor  : Colorado State University

Financement : $70,439.00

National Science Foundation

Page publiée le 24 juin 2018