Tree Invasion of Montane Meadows in Oregon

Vale, Thomas R.

doi:10.2307/2425010

Cited by 70 publications

(67 citation statements)

References 9 publications

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“…Selective logging prior to the 1960s may have played a role on the Waldron site as well. Similar pulses of tree establishment occurring in response to release from grazing pressure have been reported in other grassland systems (Dunwiddie 1977, Vale 1981, Bakker and Moore 2007, Beschta and Ripple 2009. But, livestock grazing was never a factor on Yellow Island, which also experienced a simultaneous episode of Douglas-fir recruitment.…”

Section: Changes In Stand Composition and Structure: Post Euro-americsupporting

confidence: 64%

“…Exactly which factors triggered this wave of oak establishment, and subsequent pulses of Douglas-fir establishment, are not entirely clear. 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.…”

Section: Changes In Stand Composition and Structure: Pre Euro-americamentioning

confidence: 99%

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Differential Tree Colonization of Old Fields in a Temperate Rain Forest

Riege

Moral

2004

The American Midland Naturalist

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Section: Changes In Stand Composition and Structure: Post Euro-americsupporting

confidence: 64%

Section: Changes In Stand Composition and Structure: Pre Euro-americamentioning

confidence: 99%

Differential Tree Colonization of Old Fields in a Temperate Rain Forest

Riege

Moral

2004

The American Midland Naturalist

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“…Heavy grazing followed by periods of moderate grazing is often associated with the onset of tree regeneration invasion of many sites [14,53,58]. In fact, moderate livestock grazing may facilitate tree establishment since few seedlings are trampled, bare mineral soil is exposed and competition from grasses is reduced [35].…”

Section: Discussionmentioning

confidence: 99%

Human land-use, forest dynamics and tree growth at the treeline in the Western Italian Alps

Motta

Morales²,

Nola

2006

Ann. For. Sci.

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-Three plots were sampled along an altitudinal gradient in the upper Susa Valley (Piedmont, Italy) on a northeastern slope from 1800 to 2300 m a.s.l. In order to reconstruct recent dynamics at this altitudinal range various techniques were used. Dendroecological methods were used to reconstruct the age structures of tree populations. Growth dynamics were investigated both by observing Basal Area Increment (BAI) in old and dominant trees and by comparing the BAIs within a given cambial age class in different time periods. Historical documents were analyzed as an independent data source to explain changes in establishment rate. As far as the tree establishment at the forestline and at the treeline is concerned we observed three distinct periods: during the first one (1850-1930) larch establishment was reduced or prevented because of heavy grazing and the stone pine establishment was almost null because of the grazing and of the human anthropogenic removal. During the second one ) the past heavy grazing followed by periods of moderate grazing favored the larch establishment; stone pine establishment was still prevented both by grazing and by anthropogenic removal. Finally the third period (1960-present) has been the period of massive stone pine regeneration. The growth rates of stone pine and larch have increased in the last decades: individuals in the 100-, 150-and 200-year age classes grow more rapidly in present times as compared to the previous two centuries. In the same time younger trees (1-50 years old) showed a decline in growth because the current stands are denser and the young and suppressed trees have worse growth conditions respect the previous open stands. An analysis of all the data taken together in the present study argues in favor of the fact that the tree establishment, and more in general the forest dynamic, has been mainly controlled by human land-use and that the tree growth has been mainly climatically controlled. dendroecology / Larix decidua / Pinus cembra / tree-rings / basal area increment (BAI) / herbivory Résumé -Histoire de l'occupation du sol, et dynamique forestière à la limite supérieure des arbres dans la vallée de Suse (Piémont, Italie). Afin de reconstruire la dynamique récente de l'étage subalpin, la présente étude a mis en oeuvre plusieurs techniques. Des méthodes dendrochronologiques ont permis de reconstruire la structure d'âges des populations d'arbres. La croissance a été étudiée à la fois par l'observation de l'accroissement en surface terrière des vieux arbres dominants et en comparant les accroissements en surface terrière des classes d'arbres avec la même classe d'âge cambial à différentes périodes de temps. De plus, des documents d'archives ont été étudiés. On a observé trois phases distinctes d'établissement des arbres : la première (1850-1930) durant laquelle il n'y a pas d'établissement d'arbre à cause de la forte pression du pâturage, la deuxième durant laquelle il y a établissement de mélèzes, car la pression du pâturage diminue et la troisième (1960-au...

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“…In particular, studies in the U.S.A. highlight substantial encroachment of trees into meadows (e.g., Miller and Halpern, 1998). Tree invasion in western North America began in the mid-1800s, with several discrete invasion peaks since, and has been attributed to regional climate warming (Kearney, 1982;Jakubos and Rornme, 1993;Taylor, 1995;Woodward et aI., 1995;Rochefort and Peterson, 1996), changes to site disturbance regimes (Dunwiddie, 1977;Vale, 1981;Mast et aI., 1998) and changes in local groundlayer competition (Magee and Antos, 1992).…”

Section: Introductionmentioning

confidence: 99%

Recent Forest Encroachment into Subalpine Grasslands near Mount Hotham, Victoria, Australia

Wearne

Morgan

2001

Arctic, Antarctic, and Alpine Research

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Establishment of forest trees into subalpine grasslands near Mt. Hotham, southeast Australia, was quantified in 1998 across long-established forestgrassland boundaries in belt transects at four sites. Although the grasslands varied in their dominant species and groundlayer biomass, tree encroachment (principally by Eucalyptus paucijlora) occurred at all sites. Tree encroachment is a recent and synchronous event; all invading saplings were :S31-yr-old and the majority (54%) established between 1991 and 1995. Most sapling establishment (66%) occurred within 5 m of the forest-grassland boundary where the number of plants present was positively associated with the amount of overhanging tree cover at three of the four sites. No correlation between encroachment and groundcover type or biomass, however, was found at any site. Some of the recently established plants are now small trees (1-8 m in height) and have become reproductive, indicating that establishment in grasslands is successful, making ecotone shifts possible. Any changes in boundary position, however, will be slow given the limited distance that trees established from the forest edge. Tree encroachment near Mt. Hotham is likely the outcome of small-scale (e.g., regeneration microsite) and landscape-scale (e.g., climate, grazing) processes that require further clarification.

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Tree Invasion of Montane Meadows in Oregon

Cited by 70 publications

References 9 publications

Differential Tree Colonization of Old Fields in a Temperate Rain Forest

Differential Tree Colonization of Old Fields in a Temperate Rain Forest

Human land-use, forest dynamics and tree growth at the treeline in the Western Italian Alps

Recent Forest Encroachment into Subalpine Grasslands near Mount Hotham, Victoria, Australia

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