The effects of anthropogenic land cover change on pollen-vegetation relationships in the American Midwest

Kujawa, Ellen Ruth; Goring, Simon; Dawson, Andria; Calcote, Randy; Grimm, Eric C.; Hotchkiss, Sara C.; Jackson, Stephen T.; Lynch, Elizabeth; McLachlan, J. S.; St-Jacques, Jeannine Marie; Umbanhowar, Charles E.; Williams, John W.

doi:10.1016/j.ancene.2016.09.005

Cited by 26 publications

(23 citation statements)

References 70 publications

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“…We also set a hiatus in the cores from the Northeast and upper Midwest when European settlement was indicated in the age controls, because accumulation rate increased significantly after European settlement 34,35 . This pattern of increasing accumulation rates is apparent in many cores across eastern North America and may be due to a number of factors, including increasing erosion, but is also due to sediment compaction and de-watering with depth and basin dynamics 36 .…”

Section: Methodsmentioning

confidence: 99%

Bayesian ages for pollen records since the last glaciation in North America

2019

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Terrestrial pollen records are abundant and widely distributed, making them an excellent proxy for past vegetation dynamics. Age-depth models relate pollen samples from sediment cores to a depositional age based on the relationship between sample depth and available chronological controls. Large-scale synthesis of pollen data benefit from consistent treatment of age uncertainties. Generating new age models helps to reduce potential artifacts from legacy age models that used outdated techniques. Traditional age-depth models, often applied for comparative purposes, infer ages by fitting a curve between dated samples. Bacon, based on Bayesian theory, simulates the sediment deposition process, accounting for both variable deposition rates and temporal/spatial autocorrelation of deposition from one sample to another within the core. Bacon provides robust uncertainty estimation across cores with different depositional processes. We use Bacon to estimate pollen sample ages from 554 North American sediment cores. This dataset standardizes age-depth estimations, supporting future large spatial-temporal studies and removes a challenging, computationally-intensive step for scientists interested in questions that integrate across multiple cores.

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Section: Methodsmentioning

confidence: 99%

Bayesian ages for pollen records since the last glaciation in North America

2019

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“…inability to identify pollen to the species level, rather than only to genus level in species-rich genera like Quercus, Davis 1983), temporally varying pollen-vegetation relationships (Kujawa et al 2016), and both false-positive and false-negative errors (i.e. These include poor taxonomic resolution (i.e.…”

Section: Paleoecological Datamentioning

confidence: 99%

“…These include poor taxonomic resolution (i.e. inability to identify pollen to the species level, rather than only to genus level in species-rich genera like Quercus, Davis 1983), temporally varying pollen-vegetation relationships (Kujawa et al 2016), and both false-positive and false-negative errors (i.e. evidence of species' presence in a location where it was not; lack of evidence in a location where the species truly was, sometimes called 'cryptic' refugia).…”

Section: Paleoecological Datamentioning

confidence: 99%

Inference of biogeographic history by formally integrating distinct lines of evidence: genetic, environmental niche and fossil

Hoban

Dawson

Robinson³

et al. 2019

Ecography

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A primary focus of historical biogeography is to understand changes in species ranges, abundance and genetic connectivity, and changes in community composition. Traditionally, biogeographic inference has relied on distinct lines of evidence, including DNA sequences, fossils and hindcasted ecological niche models. In this review we propose that the development of integrative modeling approaches that leverage multiple distinct data types from diverse disciplines has the potential to revolutionize the field of biogeography. Although each data type contains information on a distinct aspect of species' biogeographic histories, few studies formally integrate multiple types in analysis. For example, post hoc congruence among analyses based on different data types (e.g. fossils and genetics) is commonly assumed to indicate likely biogeographic histories. Unfortunately, analyses of different data often reach discordant conclusions. Thus, fundamental and unresolved debates continue regarding speed and timing of postglacial migration, location and size of glacial refugia, and degree of long distance dispersal. Formal statistical integration can help address these issues. More specifically, formal integration can leverage all available evidence, account for inherent biases associated with different data types, and quantify data and process uncertainty. Novel, quantitative integration of data and models across fields is now possible due to recent advances in cyberinfrastructure, spatial modeling, online and aggregated ecological databases, data processing and quantitative methods. Our purpose is to make the case for and give examples of rigorous integration of genetic, fossil and environmental/ occurrence data for inferring biogeographic history. In particular, we 1) review the need for such a framework; 2) explain common data types and approaches used to infer biogeographic history (and the challenges with each); 3) review state-of-the-art examples of data integration in biogeography; 4) lay out a series of novel, suggested improvements on current methods; and 5) provide an outlook on technical feasibility and future opportunities. Ecography E4 awardGlossary ABC (approximate Bayesian computation; also see Box 1) -a simulation-based statistical method that approximates the likelihood of a model through comparisons of summary statistics calculated from simulated and observed data. Biogeographic history -the study of processes and patterns related to: geographic range shifts, contractions and expansions; demographic fluctuations; locations of refugia; and migration patterns. Bottleneck -a drastic reduction in population size that often also results in a loss of genetic diversity; colonization at a continental scale often involves serial bottlenecks. Coalescent theory -a body of theory that uses probabilistic models to reconstruct the genealogy of a sample backward in time from the sampled lineages (present) to the most recent common ancestor (past). DRM (dynamic range model) -a hierarchical Bayesian approach to estimate paramet...

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“…In an effort toward consistency and uncertainty quantification, age-depth models were refit for all pollen records in the spatial domain using Bacon (Blaauw and Christen 2011). Age-depth model construction methods and results are described in more detail in Goring et al (2019) and Kujawa et al (2016). We follow radiocarbon and paleoecological convention of representing time as "years before present," where present is fixed at the year 1950 (Vogel 1969).…”

Section: Pollen Recordsmentioning

confidence: 99%

Quantifying trends and uncertainty in prehistoric forest composition in the upper Midwestern United States

Dawson

Paciorek

Goring

et al. 2019

Ecology

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Forest ecosystems in eastern North America have been in flux for the last several thousand years, well before Euro‐American land clearance and the 20th‐century onset of anthropogenic climate change. However, the magnitude and uncertainty of prehistoric vegetation change have been difficult to quantify because of the multiple ecological, dispersal, and sedimentary processes that govern the relationship between forest composition and fossil pollen assemblages. Here we extend STEPPS, a Bayesian hierarchical spatiotemporal pollen–vegetation model, to estimate changes in forest composition in the upper Midwestern United States from about 2,100 to 300 yr ago. Using this approach, we find evidence for large changes in the relative abundance of some species, and significant changes in community composition. However, these changes took place against a regional background of changes that were small in magnitude or not statistically significant, suggesting complexity in the spatiotemporal patterns of forest dynamics. The single largest change is the infilling of Tsuga canadensis in northern Wisconsin over the past 2,000 yr. Despite range infilling, the range limit of T. canadensis was largely stable, with modest expansion westward. The regional ecotone between temperate hardwood forests and northern mixed hardwood/conifer forests shifted southwestward by 15–20 km in Minnesota and northwestern Wisconsin. Fraxinus, Ulmus, and other mesic hardwoods expanded in the Big Woods region of southern Minnesota. The increasing density of paleoecological data networks and advances in statistical modeling approaches now enables the confident detection of subtle but significant changes in forest composition over the last 2,000 yr.

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The effects of anthropogenic land cover change on pollen-vegetation relationships in the American Midwest

Cited by 26 publications

References 70 publications

Bayesian ages for pollen records since the last glaciation in North America

Bayesian ages for pollen records since the last glaciation in North America

Inference of biogeographic history by formally integrating distinct lines of evidence: genetic, environmental niche and fossil

Quantifying trends and uncertainty in prehistoric forest composition in the upper Midwestern United States

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