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In South America, the intensity and frequency of forest disturbances are increasing. Windstorms, an important disturbance mechanism, have the potential to exacerbate the damage caused by drought, fire, and deforestation in tropical forests. In this study, we investigated the impact of windthrow events on the vertical structure of degraded forests in southern Amazonia and hypothesized the additional impact of concurrent wind and precipitation extremes from the local to the regional scale. The frequency of windthrows influenced the vegetation height of the Amazon forests (R2 = 0.20), and the concurrency with precipitation is more prevalent where extreme wind is the predominant effect. Compound extreme wind and precipitation events are most likely to occur within five days of each other (84%) and up to 1.75° apart in space, and regions at higher elevations experience more frequent extreme winds (R2 = 0.67), with potential to affect vegetation height. This understanding, supported by field data and remote sensing, enhances our knowledge of the meteorological conditions behind tropical storms with windthrows and their effects on the structural and diversity. Given the exacerbation of climate extremes due to climate change, integrating field and remote sensing data is vital for comprehending regional climate patterns and their implications for the resilience of Amazonian forests.
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Hillslope roughness reveals forest sensitivity to extreme winds
Windthrow, or the uprooting of trees by extreme wind gusts, is a natural forest disturbance that creates microhabitats, turns over soil, alters hydrology, and removes carbon from the above-ground carbon stock. Long recurrence intervals between extreme wind events, however, make direct observations of windthrow rare, challenging our understanding of this important disturbance process. To overcome this difficulty, we present an approach that uses the geomorphic record of hillslope topographic roughness as a proxy for the occurrence of windthrow. The approach produces a probability function of the number of annual windthrow events for a maximum wind speed, allowing us to explore how windthrow or tree strengths may change due to shifting wind climates. Slight changes to extreme wind speeds may drive comparatively large changes in windthrow production rates or force trees to respond and change the distribution. We also highlight that topographic roughness has the potential to serve as an important archive of extreme wind speeds.
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- Award ID(s):
- 2218293
- PAR ID:
- 10439721
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 120
- Issue:
- 3
- ISSN:
- 0027-8424
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1073/pnas.2212105120
