A major floristic boundary in Minnesota: an analysis of 280 taxa occurring in the western and southern portions of the state

Wheeler, Gerald A.; Cushing, Edward J.; Gorham, Eville; Morley, Thomas; Ownbey, Gerald B.

doi:10.1139/b92-043

Cited by 12 publications

(11 citation statements)

References 29 publications

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“…Interactions between environmental controls on vegetation are manifested as changing relationships along an ecological gradient or through space. The presence of such interactions in the PFB over gradients of both spatial scale (Grimm 1984, Wheeler et al 1992, Keitt et al 2002) and temporal scale (Umbanhowar et al 2006) can complicate conclusions about the relative importance of controls.…”

Section: Discussionmentioning

confidence: 99%

“…In Minnesota, USA, prior site‐specific and broader‐scale studies taken together suggest that the apparent controls on the PFB vary across space and spatial scale (McAndrews 1966, Grimm 1984, Almendinger 1992, Wheeler et al 1992). The challenge for ecologists working along grassland–forest transitions such as the PFB is to identify processes operating at different spatial scales and to differentiate the ultimate versus proximate modifiers of boundary structure (Mills et al 2006).…”

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confidence: 99%

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Vegetation controls vary across space and spatial scale in a historic grassland-forest biome boundary

Danz¹,

Frelich²,

Niemi³

2010

Ecography

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Ecological boundaries are critical landscape regions of transition between adjacent ecological systems. While environmental controls of boundaries may operate in a scale‐dependent manner, multiple‐scale comparisons of vegetation–environment relationships have been characterized for few boundary systems. We used approximately 250 000 point records on the occurrence of woody versus grassland vegetation in conjunction with climatic, topographical, and soils data to evaluate scale effects and spatial heterogeneity in a 650‐km section of the historic prairie–forest biome boundary of Minnesota, USA. We chose this as a model system because of the availability of historical vegetation data, a considerable spatial extent, a sharp ecological transition, and the ability to avoid confounding from more recent anthropogenic land use change. We developed modeling techniques using hierarchical variance partitioning in a spatially‐structured format that allowed us to simultaneously evaluate vegetation–environment relationships across two‐dimensional space (i.e. the prairie‐forest boundary) and across spatial scales (i.e. varying extents). Soils variables displayed the least spatial autocorrelation at shortest lag distances and tended to be the least important predictors of woody vegetation at all spatial extents. Topographical variables displayed greater spatial heterogeneity in regions dominated by forest compared with prairie and were more important at fine‐intermediate spatial scales, highlighting their likely control on fire regimes. An integrated climatic variable (precipitation minus potential evapotranspiration) displayed a trend of increasing spatial variance across the study region and was unambiguously the strongest biome boundary control, although its joint influence with fire was difficult to characterize. Spatially heterogeneous vegetation–environment relationships were observed at all scales, especially at finer scales. Our results suggest that the importance of environmental controls changes smoothly rather than discretely across scales and demonstrate the need to account for spatial non‐stationarity and scale to predict and understand vegetation distribution across ecological boundaries.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Vegetation controls vary across space and spatial scale in a historic grassland-forest biome boundary

Danz¹,

Frelich²,

Niemi³

2010

Ecography

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“…A "tension zone" [Curtis and McIntosh, 1951] that traverses our study area is defined by a combination of geographic transitions, from warm and dry continental interior to cool and wet lake-influenced landscapes. This tension zone marks the approximate southern extent of the Laurentian glaciation with resulting gradients in soil types [Schaetzl et al, 2005;Danz et al, 2013] and encompasses a gradient in natural vegetation types [Wheeler et al, 1992;Bockheim and Schliemann, 2014], from prairie and hardwood forests in the southwest (now mixed with agriculture) to subboreal evergreen and temperate mixed forests closer to Lake Superior. This transition is clearly visible in land cover maps of the region based on the U.S. Geological Survey National Land Cover Database products [Jin et al, 2013;Homer et al, 2015] ( Figure S1 in the supporting information) and can be identified by using the U.S. Environmental Protection Agency [2011] ecoregion maps of our study area [Omernik et al, 2000;Omernik, 2004] (Figure S2).…”

Section: Study Area and Backgroundmentioning

confidence: 99%

Recent climatological trends and potential influences on forest phenology around western Lake Superior, USA

Garcia

Townsend

2016

JGR Atmospheres

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We assess long‐term climatological means, trends, and interannual variability around the western end of Lake Superior during 1984–2013 by using available weather station data. Our results focus on changes in basic and derived climate indicators from seasonal and annual temperature and precipitation, to the traditionally defined frost‐free season, to a novel definition of the climatological growing season. We describe seasonal and year‐to‐year climate variability that influences forest phenology, using an alternative growing season metric that is based on the warm‐season plateau in accumulated chilling days as an indicator of environmental triggers for vegetation growth and senescence. Our results indicate +0.56°C regional warming during our 30 year study period, with cooler springs (−1.26°C) and significant autumn warming (+1.54°C). The duration of the climatological growing season has increased +0.27 d/yr, extending primarily into autumn. Summer precipitation in our study area has declined by an average −0.34 cm/yr, potentially leading to moisture stress that impairs vegetation carbon uptake rates and can render the forest more vulnerable to disturbance. Many changes in temperature, precipitation, and climatological growing season are most prominent in locations where Lake Superior exerts a strong hydroclimatological influence, especially the Minnesota shoreline and in forest areas downwind (southeast) of the lake. Observed trends in lake temperature and ice phenology have also changed, coincident with a large‐scale climatological regime shift around 1998. A number of factors are likely altering forest phenology and the role of the forest in the climate system of this ecologically important and highly varied forest‐and‐lake region.

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“…In some locations topography was apparently a strong modifier of boundary width through its influence on fire regimes (Grimm ; Wheeler et al. ). For example, the central boundary (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Within the limits imposed by climatic water availability, interactions of other environmental controls such as topography, soils and fire undoubtedly operated in conjunction with climate to determine the ultimate withinboundary structure, likely increasing the non-linearity of the relation with climate (Grimm 1984;Peterson & Reich Danz et al 2011). In some locations topography was apparently a strong modifier of boundary width through its influence on fire regimes (Grimm 1984;Wheeler et al 1992). For example, the central boundary (i.e.…”

Section: Discussionmentioning

confidence: 99%

Do vegetation boundaries display smooth or abrupt spatial transitions along environmental gradients? Evidence from the prairie–forest biome boundary of historic Minnesota, USA

Danz

Frelich

Niemi

2012

J Vegetation Science

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Questions: Two alternative mechanisms of abrupt vegetation change across ecological boundaries have been proposed: (1) concomitantly abrupt gradients in physical environmental variables and vegetation across the boundary, and (2) gradual environmental gradients that vegetation responds to in a non-linear or threshold manner. Here, we evaluate spatial patterns of climate and vegetation across a grassland-forest biome boundary to examine evidence in favour of either of these alternatives.Location: Minnesota, USA.Methods: Vegetation data represented the presence of prairie vs. forest vegetation in Minnesota from 1847 to 1908, generally prior to European settlement of the region, while the climatic variables represented an index of long-term average moisture availability (precipitation minus potential evapotranspiration (P -PET). Using linear and sigmoidal regression models, we evaluated spatial patterns of change in vegetation, climate and vegetation-climate relationships across 22 transects (170-400 km) oriented perpendicular to the biome boundary. We also evaluated boundary characteristics in light of dominant topographical controls and position along the boundary.Results: Vegetation followed a sigmoidal pattern of change across the boundary, with mean boundary width of ca. 100 km. The P -PET increased by ca. 100 mm across the boundary following a comparatively smooth pattern of change. Climate-vegetation relationships were clearly non-linear across the boundary, indicating these variables did not change in a common spatial pattern. Regional topographical controls modified relationships between vegetation and climate along the length of the boundary. Conclusions:Our results document strong non-linear relationships between the presence of forest vegetation and its dominant climate control across a grassland-forest biome boundary. An average change of ca. 100 mm in P -PET moving across the boundary is about 40% of the long-term mean annual range of this variable, suggesting that modest changes to P -PET may potentially cause substantial shifts in the location of the prairie-forest boundary.

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A major floristic boundary in Minnesota: an analysis of 280 taxa occurring in the western and southern portions of the state

Cited by 12 publications

References 29 publications

Vegetation controls vary across space and spatial scale in a historic grassland-forest biome boundary

Vegetation controls vary across space and spatial scale in a historic grassland-forest biome boundary

Recent climatological trends and potential influences on forest phenology around western Lake Superior, USA

Do vegetation boundaries display smooth or abrupt spatial transitions along environmental gradients? Evidence from the prairie–forest biome boundary of historic Minnesota, USA

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