Historical reconstruction unveils the risk of mass mortality and ecosystem collapse during pancontinental megadrought
| Autor: | John Busby, Francisco Encinas-Viso, Nunzio Knerr, Denise Godfree, Bruce A. Robertson, Robert C. Godfree |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Climate change
Extinction Biological Models Biological ecosystem collapse megadrought Animals Humans Ecosystem Trophic level Multidisciplinary Ecology Federation Drought Australia Biota History 19th Century Biological Sciences History 20th Century trophic impact Droughts Geography PNAS Plus Spatial ecology mass mortality Landscape ecology Megadrought Global biodiversity |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | Significance It is thought that extreme, decade-scale megadroughts pose a major future threat to global biodiversity under climate change. However, such events occur rarely and so their capacity to drive ecosystem change remains largely unknown. Here we address this question by reconstructing the impacts of an extreme, historical megadrought period (1891 to 1903) on plant and animal assemblages across the Australian continent. The geographic extent (≥2.8 million km2) and taxonomic depth (>45 families) of impacts observed during this event were remarkable and include mass population mortality and broad, bottom-up trophic collapse in multiple subcontinental hotspots. Our work provides insights into the potential pattern and magnitude of ecological change that can occur during continental-scale megadrought. An important new hypothesis in landscape ecology is that extreme, decade-scale megadroughts can be potent drivers of rapid, macroscale ecosystem degradation and collapse. If true, an increase in such events under climate change could have devastating consequences for global biodiversity. However, because few megadroughts have occurred in the modern ecological era, the taxonomic breadth, trophic depth, and geographic pattern of these impacts remain unknown. Here we use ecohistorical techniques to quantify the impact of a record, pancontinental megadrought period (1891 to 1903 CE) on the Australian biota. We show that during this event mortality and severe stress was recorded in >45 bird, mammal, fish, reptile, and plant families in arid, semiarid, dry temperate, and Mediterranean ecosystems over at least 2.8 million km2 (36%) of the Australian continent. Trophic analysis reveals a bottom-up pattern of mortality concentrated in primary producer, herbivore, and omnivore guilds. Spatial and temporal reconstruction of premortality rainfall shows that mass mortality and synchronous ecosystem-wide collapse emerged in multiple geographic hotspots after 2 to 4 y of severe (>40%) and intensifying rainfall deficits. However, the presence of hyperabundant herbivores significantly increased the sensitivity of ecosystems to overgrazing-induced meltdown and permanent ecosystem change. The unprecedented taxonomic breadth and spatial scale of these impacts demonstrate that continental-scale megadroughts pose a major future threat to global biodiversity, especially in ecosystems affected by intensive agricultural use, trophic simplification, and invasive species. |
| Databáze: | OpenAIRE |
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