科研之友
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摘要
Open pine and oak forest ecosystems and floodplain forests have declined because of fire and flooding suppression. I determined tree species that have contracted in area occupied (where area occupied was a parts per thousand yen0.5 % of total species composition) or decreased in percent composition (i.e., percentage of all stems) during recent surveys (2000-2013) to a parts per thousand currency sign85 % of area occupied or composition during older surveys (1968-1999). I then identified whether species were associated with frequent fire, flooding, wetlands, postfire conditions, or other disturbances. Of 35 species that decreased in area occupied or composition, 16 species were associated with fire or postfire disturbance and fire-dependent species decreased in composition from 20 to 14 % during tree surveys. Even though species of floodplain forests and wetlands comprise a small percent of overall tree composition, 12 decreasing species were associated with floodplain forests or wetlands. Fire maintains open oak and pine ecosystems and flooding maintains floodplain forests, generally suspending succession. Suppression of fire in upland forests and flooding in floodplain forests has allowed disturbance-sensitive species to remain established and advance successional forests throughout the USA.
- 出版日期2014-11
