Differential Tree Colonization of Old Fields in a Temperate Rain Forest

Environmental History of a Garry Oak/Douglas-Fir Woodland on Waldron Island, Washington

“…Three principle mechanisms are frequently cited for stimulating tree establishment in grasslands and savannas: changes in climate (Rochefort andPeterson 1996, Woodward et al 1995), alterations in grazing regimes (Dunwiddie 1977, Vale 1981, and changes in fire intensity or frequency (Arno and Gruell 1986). These mechanisms may interact with one another and with factors such as seed availability, herbivory, and vegetation competition, resulting in complex patterns of tree establishment (Riege & Del Moral 2004, Dovciak et al 2008, MacDougall 2008. Furthermore, in much of North America, these changes occurred simultaneously with declines in Native American populations, and with Euro-American settlement and the associated suppression of native-set fires, introduction of livestock, and hunting of native herbivores (MacDougall 2008).…”

Microclimate and seeding predation as drivers of tree recruitment in human-disturbed oak forests

“…This behavior of herbivores can strongly reduce the establishment rates of tree species beneath the forest canopy (Nystrand and Granström, 2000;Gómez et al, 2003;Rizkalla and Swihart, 2007). Seedling predation by vertebrates is also likely to occur in human matrices, but its impact on tree recruitment is usually less severe than within the forest because most species inhabiting these areas are opportunistic-generalist species that consume a wide variety of resources (Gill and Marks, 1991;Tellería et al, 1991;Riege and Del Moral, 2004). Nevertheless, seedling predation may increase at edges between forests and human matrices because they are exposed to herbivores from both habitats and this may preclude the establishment of late successional tree species (Ostfeld et al, 1997;Cadenasso and Pickett, 2000;Manson et al, 2001).…”

Facilitation of afforestation byLupinus nootkatensisand by black plastic mulch in south-west Iceland

“…The inhibitor of tree seedling establishment appeared to be the increased density of grasses that were stimulated by the fertility provided by lupine. Dense grass cover has been reported to inhibit establishment and growth of Sitka spruce seedlings in North America (Coates et al, 1993;Riege & del Moral, 2004). In the absence of dense grass, dense lupine facilitated tree seedling establishment at site FB and at the site of Ó skarsson and Sigurgeirsson (2004).…”

“…In southern Iceland, Sitka spruce seedlings have performed well within lupine cover (Ó skarsson & Sigurgeirsson, 2004). In the USA, growth of Sitka spruce seedlings in old fields was better under bracken fern (Pteridium aquilinum) cover than in the open (Riege & del Moral, 2004). Both lupine and bracken die back over winter.…”