Abstract
Temperate montane grasslands and their unique biotas are declining worldwide as they are increasingly being invaded by forests. The origin and persistence of these landscapes have been the focus of such controversy that in many areas their conservation is in doubt. In the USA some biologists have largely dismissed the grass balds of the Southern Appalachians as human artifacts or anomalous and transitory elements of regional geography, worthy of only limited preservation efforts. On the basis of information from biogeography, community ecology, regional history and palaeontology and from consideration of two other montane grassland ecosystems—East Carpathian poloninas and Oregon Coast Range grass balds—we hypothesize that these landscapes are more widespread than was formerly recognized; they are, in many cases, natural and ancient and largely owe their origin and persistence to past climatic extremes and the activities of large mammalian herbivores.
Highlights
Often known as grass balds, with long histories of open expanses are being invaded and replaced by forests. These communities have been the focus of much research and debate regarding their origins, longevity, and landscape dynamics (Miller & Halpern, 1998; Weigl & Knowles, 1999; Wiser & White, 1999; Zald, 2009)
During the past 70 years some biologists and government agencies have tended to dismiss the balds as human artifacts—the result of relatively recent Native American activities, perhaps—or, more likely, the agricultural practices of European settlers (Gersmehl, 1970, 1973). Implicit in this view is the assumption that the eastern USA was once largely continuous forest with few grasslands until the advent of agriculture and that grass balds should be considered anomalous, isolated and transitory artifacts of Appalachian landscape history
On the basis of information from many sources, we advance the idea that grassy areas have persisted on the upper elevations of some of the Appalachians from at least the late Pleistocene
Summary
Temperate montane grasslands and their associated rare, endemic and relict biota are declining worldwide (Zald, 2009). We compare and synthesize information from three such mountain ecosystems—Southern Appalachian grass balds, East Carpathian poloninas, and Oregon Coast Range grass balds—and propose a new unified hypothesis for their origins and persistence involving climate and herbivory Such an hypothesis emphasizes an historical context for these landscapes and their biotas, incorporates insights from other grassland systems and provides an argument for future research and conservation. During the past 70 years some biologists and government agencies have tended to dismiss the balds as human artifacts—the result of relatively recent Native American activities, perhaps—or, more likely, the agricultural practices of European settlers (Gersmehl, 1970, 1973) Implicit in this view is the assumption that the eastern USA was once largely continuous forest with few grasslands until the advent of agriculture and that grass balds should be considered anomalous, isolated and transitory artifacts of Appalachian landscape history. It will take a major change in attitude towards, and understanding of, bald ecosystems to provide the impetus and rationale for bald protection
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