Randy Calcote
Datos Biográficos
| ID | 5002147 |
|---|---|
| NOMBRE | Randy Calcote |
| NOMBRES | Randy |
| APELLIDO | Calcote |
| FIRMA | CALCOTE R |
| AFILIACIONES | University of Minnesota |
| ORCID | 0000-0002-3096-6186 |
| VERIFICADO | Sí |
| TOTAL DE OBRAS | 12 |
| TOTAL DE CITAS | 32 |
| TOTAL COMO AUTOR | 12 |
| TOTAL COMO EDITOR | 0 |
| PRIMER AÑO DE PUBLICACIÓN | 1995 |
| AÑO MÁS RECIENTE DE PUBLICACIÓN | 2020 |
| ÍNDICE H | 3 |
Late-Holocene climate changes linked to ecosystem shifts in the Northwest Wisconsin Sand Plain, USA
Records of century-scale climate variability in the Upper Midwest generally agree that moisture availability increased between 4000 and 3000 cal. yr BP (calendar years before present = 1950 CE), and that there were large, frequent droughts 1000–700 cal. yr BP followed by wetter/cooler conditions. Variability among regional sites, however, remains problematic. In this study we reconstruct climate on the Northwest Wisconsin Sand Plain (NWSP), USA, …
The effects of anthropogenic land cover change on pollen-vegetation relationships in the American Midwest
Charcoal signatures defined by multivariate analysis of charcoal records from 10 lakes in northwest Wisconsin (USA)
We show how sedimentary charcoal records from multiple sites within a single landscape can be used to compare fire histories and reveal small scale patterns in fire regimes. Our objective is to develop strategies for classifying and comparing late-Holocene charcoal records in Midwestern oak- and pine-dominated sand plain ecosystems where fire regimes include a mix of surface and crown fires. Using standard techniques for the analysis of charcoal …
Testing the Landscape Reconstruction Algorithm for spatially explicit reconstruction of vegetation in northern Michigan and Wisconsin
The Landscape Reconstruction Algorithm (LRA) overcomes some of the fundamental problems in pollen analysis for quantitative reconstruction of vegetation. LRA first uses the REVEALS model to estimate regional vegetation using pollen data from large sites and then the LOVE model to estimate vegetation composition within the relevant source area of pollen (RSAP) at small sites by subtracting the background pollen estimated from the regional vegetati…
The response of a jack pine forest to late-Holocene climate variability in northwestern Wisconsin
Terrestrial plant communities have the potential to respond to climate change rapidly, if dominant species are killed by a series of extreme events, or slowly, if the cumulative effects of shorter-term climate fluctuations result in long-term compositional change. We used pollen and charcoal records from a lake and a testate amoebae-derived history of water-table depth in a nearby peatland to assess the response of the jack pine-dominated forests…
Interpretation of charcoal morphotypes in sediments from Ferry Lake, Wisconsin, USA
We describe five common charcoal morphotypes observed in late-Holocene lake sediments from northern Wisconsin and compare them with charcoal produced by burning modern plant material. Our experiments show that grass cuticle, conifer wood and leaves of some broadleaved taxa all produce recognizable charcoal types that are preserved in sediments. We use the identification of charcoal morphotypes to enhance our interpretation of a previously publish…
Detecting differences in vegetation among paired sites using pollen records
The ‘Qualitative Assessment of Difference’ method (QAD) is proposed to objectively detect differences in the relative abundance of vegetation between paired sites using pollen percentages. This method corrects for intertaxonomic differences in pollen productivity and neutralizes influences of background pollen on pollen representation of vegetation, using an inverse form of the Extended R-value model. We test the method using modern pollen-vegeta…
Late-Holocene vegetation and fire history from Ferry Lake, northwestern Wisconsin, USA
We used charcoal and fossil pollen to investigate how fire, vegetation and climate have interacted over the past 2300 years at Ferry Lake, located on a sand plain in northwestern Wisconsin. Pollen analysis shows a rapid transition from oak (Quercus spp.)-dominated woodland to a relatively open pine (Pinus spp.) forest at 1450 cal. yr BP, and a more closed-canopy pine forest beginning about 700 cal. yr BP. We calculated accumulation rates of 125-2…
Mid-Holocene climate and the hemlock decline
Eastern hemlock (Tsuga canadensis) expanded rapidly across Upper Peninsula Michigan from ~6500 to 5500 cal. yr BP, followed by a sudden decline of hemlock pollen percentages that lasted over 1000 years. Hemlock declined throughout its range, apparently due to insect/pathogen outbreaks, which may have been affected by regional climatic shifts. Modern analogues were used to reconstruct submillennial climatic trends from fossil pollen sites spanning…
Effect of pollen from regional vegetation on stand-scale forest reconstruction
To investigate the influence of regional pollen inputs on reconstructing local vegetation, we compared modem pollen assemblages deposited in forest hollow sediments from two study areas, Michigan and Wisconsin. Local forest-stand composition (within 50 m) at all sites is dominated by hemlock and northern hardwood trees, but the regional abundance of tree taxa in the two study areas is not the same. Modern pollen assemblages differ between the two…
Identifying forest stand types using pollen from forest hollows
Methods of interpreting pollen assemblages in sediment were examined using surface samples from 66 small forest hollows in Michigan and Wisconsin. All canopy trees in the surrounding 50 m were measured to provide detailed information about the source vegetation of each surface pollen assemblage. Basal area of trees in each forest sample was used to classify them into six stand types: hemlock-dominated, sugar maple/hemlock mixed, sugar maple-domin…
Pollen Source Area and Pollen Productivity
1 Although fossil pollen from forest hollows (~ 5 m in diameter) is often interpreted as a record of stand-scale forest changes, this assumption has not previously been tested by comparing pollen percentages in modern sediment to vegetation from a range of sampling radii. I compared pollen in surface sediment with distance-weighted basal area of trees in radii from 10 to l00 m, to test a model (Sugita 1994) that predicts the 'relevant pollen sour…
Interpretation of charcoal morphotypes in sediments from Ferry Lake, Wisconsin, USA
We describe five common charcoal morphotypes observed in late-Holocene lake sediments from northern Wisconsin and compare them with charcoal produced by burning modern plant material. Our experiments show that grass cuticle, conifer wood and leaves of some broadleaved taxa all produce recognizable charcoal types that are preserved in sediments. We use the identification of charcoal morphotypes to enhance our interpretation of a previously publish…
Late-Holocene vegetation and fire history from Ferry Lake, northwestern Wisconsin, USA
We used charcoal and fossil pollen to investigate how fire, vegetation and climate have interacted over the past 2300 years at Ferry Lake, located on a sand plain in northwestern Wisconsin. Pollen analysis shows a rapid transition from oak (Quercus spp.)-dominated woodland to a relatively open pine (Pinus spp.) forest at 1450 cal. yr BP, and a more closed-canopy pine forest beginning about 700 cal. yr BP. We calculated accumulation rates of 125-2…
Identifying forest stand types using pollen from forest hollows
Methods of interpreting pollen assemblages in sediment were examined using surface samples from 66 small forest hollows in Michigan and Wisconsin. All canopy trees in the surrounding 50 m were measured to provide detailed information about the source vegetation of each surface pollen assemblage. Basal area of trees in each forest sample was used to classify them into six stand types: hemlock-dominated, sugar maple/hemlock mixed, sugar maple-domin…
Mid-Holocene climate and the hemlock decline
Eastern hemlock (Tsuga canadensis) expanded rapidly across Upper Peninsula Michigan from ~6500 to 5500 cal. yr BP, followed by a sudden decline of hemlock pollen percentages that lasted over 1000 years. Hemlock declined throughout its range, apparently due to insect/pathogen outbreaks, which may have been affected by regional climatic shifts. Modern analogues were used to reconstruct submillennial climatic trends from fossil pollen sites spanning…
Effect of pollen from regional vegetation on stand-scale forest reconstruction
To investigate the influence of regional pollen inputs on reconstructing local vegetation, we compared modem pollen assemblages deposited in forest hollow sediments from two study areas, Michigan and Wisconsin. Local forest-stand composition (within 50 m) at all sites is dominated by hemlock and northern hardwood trees, but the regional abundance of tree taxa in the two study areas is not the same. Modern pollen assemblages differ between the two…
Detecting differences in vegetation among paired sites using pollen records
The ‘Qualitative Assessment of Difference’ method (QAD) is proposed to objectively detect differences in the relative abundance of vegetation between paired sites using pollen percentages. This method corrects for intertaxonomic differences in pollen productivity and neutralizes influences of background pollen on pollen representation of vegetation, using an inverse form of the Extended R-value model. We test the method using modern pollen-vegeta…
The effects of anthropogenic land cover change on pollen-vegetation relationships in the American Midwest
Pollen Source Area and Pollen Productivity
1 Although fossil pollen from forest hollows (~ 5 m in diameter) is often interpreted as a record of stand-scale forest changes, this assumption has not previously been tested by comparing pollen percentages in modern sediment to vegetation from a range of sampling radii. I compared pollen in surface sediment with distance-weighted basal area of trees in radii from 10 to l00 m, to test a model (Sugita 1994) that predicts the 'relevant pollen sour…
Identifying forest stand types using pollen from forest hollows
Methods of interpreting pollen assemblages in sediment were examined using surface samples from 66 small forest hollows in Michigan and Wisconsin. All canopy trees in the surrounding 50 m were measured to provide detailed information about the source vegetation of each surface pollen assemblage. Basal area of trees in each forest sample was used to classify them into six stand types: hemlock-dominated, sugar maple/hemlock mixed, sugar maple-domin…
Effect of pollen from regional vegetation on stand-scale forest reconstruction
To investigate the influence of regional pollen inputs on reconstructing local vegetation, we compared modem pollen assemblages deposited in forest hollow sediments from two study areas, Michigan and Wisconsin. Local forest-stand composition (within 50 m) at all sites is dominated by hemlock and northern hardwood trees, but the regional abundance of tree taxa in the two study areas is not the same. Modern pollen assemblages differ between the two…
Mid-Holocene climate and the hemlock decline
Eastern hemlock (Tsuga canadensis) expanded rapidly across Upper Peninsula Michigan from ~6500 to 5500 cal. yr BP, followed by a sudden decline of hemlock pollen percentages that lasted over 1000 years. Hemlock declined throughout its range, apparently due to insect/pathogen outbreaks, which may have been affected by regional climatic shifts. Modern analogues were used to reconstruct submillennial climatic trends from fossil pollen sites spanning…
Detecting differences in vegetation among paired sites using pollen records
The ‘Qualitative Assessment of Difference’ method (QAD) is proposed to objectively detect differences in the relative abundance of vegetation between paired sites using pollen percentages. This method corrects for intertaxonomic differences in pollen productivity and neutralizes influences of background pollen on pollen representation of vegetation, using an inverse form of the Extended R-value model. We test the method using modern pollen-vegeta…
Late-Holocene vegetation and fire history from Ferry Lake, northwestern Wisconsin, USA
We used charcoal and fossil pollen to investigate how fire, vegetation and climate have interacted over the past 2300 years at Ferry Lake, located on a sand plain in northwestern Wisconsin. Pollen analysis shows a rapid transition from oak (Quercus spp.)-dominated woodland to a relatively open pine (Pinus spp.) forest at 1450 cal. yr BP, and a more closed-canopy pine forest beginning about 700 cal. yr BP. We calculated accumulation rates of 125-2…
Interpretation of charcoal morphotypes in sediments from Ferry Lake, Wisconsin, USA
We describe five common charcoal morphotypes observed in late-Holocene lake sediments from northern Wisconsin and compare them with charcoal produced by burning modern plant material. Our experiments show that grass cuticle, conifer wood and leaves of some broadleaved taxa all produce recognizable charcoal types that are preserved in sediments. We use the identification of charcoal morphotypes to enhance our interpretation of a previously publish…
The response of a jack pine forest to late-Holocene climate variability in northwestern Wisconsin
Terrestrial plant communities have the potential to respond to climate change rapidly, if dominant species are killed by a series of extreme events, or slowly, if the cumulative effects of shorter-term climate fluctuations result in long-term compositional change. We used pollen and charcoal records from a lake and a testate amoebae-derived history of water-table depth in a nearby peatland to assess the response of the jack pine-dominated forests…
Testing the Landscape Reconstruction Algorithm for spatially explicit reconstruction of vegetation in northern Michigan and Wisconsin
The Landscape Reconstruction Algorithm (LRA) overcomes some of the fundamental problems in pollen analysis for quantitative reconstruction of vegetation. LRA first uses the REVEALS model to estimate regional vegetation using pollen data from large sites and then the LOVE model to estimate vegetation composition within the relevant source area of pollen (RSAP) at small sites by subtracting the background pollen estimated from the regional vegetati…
Charcoal signatures defined by multivariate analysis of charcoal records from 10 lakes in northwest Wisconsin (USA)
We show how sedimentary charcoal records from multiple sites within a single landscape can be used to compare fire histories and reveal small scale patterns in fire regimes. Our objective is to develop strategies for classifying and comparing late-Holocene charcoal records in Midwestern oak- and pine-dominated sand plain ecosystems where fire regimes include a mix of surface and crown fires. Using standard techniques for the analysis of charcoal …
The effects of anthropogenic land cover change on pollen-vegetation relationships in the American Midwest
Late-Holocene climate changes linked to ecosystem shifts in the Northwest Wisconsin Sand Plain, USA
Records of century-scale climate variability in the Upper Midwest generally agree that moisture availability increased between 4000 and 3000 cal. yr BP (calendar years before present = 1950 CE), and that there were large, frequent droughts 1000–700 cal. yr BP followed by wetter/cooler conditions. Variability among regional sites, however, remains problematic. In this study we reconstruct climate on the Northwest Wisconsin Sand Plain (NWSP), USA, …
Geography (12 obras) · Biology (10 obras) · Environmental Science (10 obras) · Pollen (10 obras) · Ecology (9 obras) · Geology and Paleoclimatology Research (9 obras) · Physical geography (9 obras) · Vegetation (pathology (7 obras) · Archaeology (6 obras) · Holocene (6 obras)