Fire regimes and forest resilience: alternative vegetation states in the West African tropics
Autor: | Francis K. Dwomoh, Michael C. Wimberly |
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Rok vydání: | 2017 |
Předmět: |
0106 biological sciences
010504 meteorology & atmospheric sciences Ecology Fire regime Agroforestry Geography Planning and Development Vegetation Land cover 010603 evolutionary biology 01 natural sciences Alternative stable state Forest ecology Environmental science Secondary forest Terrestrial ecosystem Regime shift 0105 earth and related environmental sciences Nature and Landscape Conservation |
Zdroj: | Landscape Ecology. 32:1849-1865 |
ISSN: | 1572-9761 0921-2973 |
Popis: | Terrestrial ecosystems, including tropical forests, are hypothesized to have tipping points beyond which environmental change triggers rapid and radical shifts to novel alternative states. We explored the overarching hypothesis that fire-mediated alternative stable states exist in the semi-deciduous tropical forest zone of Ghana, and that increased fire activity has pushed some forests to a new state in which a novel ecosystem with low tree density is maintained by fire. We combined a 30-year time series of remotely-sensed data with field measurements to assess land cover trends, the effects of fire on forest vegetation, and the reciprocal effects of vegetation change on fire regimes, in four forest reserves. We analyzed precipitation trends to determine if shifts in vegetation and fire regime reflected a shift to a drier climate. Two of the reserves experienced forest loss, were impacted by frequent fires, and transitioned to a vegetation community dominated by shrubs and grasses, which was maintained by fire–vegetation feedbacks. The other two reserves experienced less fire, retained higher levels of forest cover, and resisted fire encroachment from surrounding agricultural areas. Precipitation remained relatively stable, suggesting a hysteresis effect in which different vegetation states and fire regimes coexist within a similar climate. There is potential for human land use and fire to create novel and persistent non-forest vegetation communities in areas that are climatically suitable for tropical forests. These disturbance-mediated regime shifts should be taken into account when assessing future trajectories of forest landscape change in West Africa. |
Databáze: | OpenAIRE |
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