High dissimilarity within a multiyear annual record of pollen assemblages from a North American tallgrass prairie

• Published in: Ecology and evolution Vol. 6; no. 15; pp. 5273 - 5289
• Main Authors: Commerford, Julie L., McLauchlan, Kendra K., Minckley, Thomas A.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.08.2016; John Wiley and Sons Inc
• Subjects: Climate change; Composition; Ecological research; Fire; grassland; Grasslands; Great Plains; Herbivory; Historical account; Hydrologic data; Mathematical analysis; Original Research; Pollen; Prairies; Precipitation; Sediments; Signatures; Spatial data; Studies; Tauber traps; Terrestrial environments; Topography; Traps; Variability; Vegetation; Kansas; United States > US; Norway; North America; Europe; Finland; USA, Kansas, Konza Prairie; USA, Kansas; Tauber traps; herbivory; Great Plains; pollen; grassland; Fire
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.2259

Grassland vegetation varies in composition across North America and has been historically influenced by multiple biotic and abiotic drivers, including fire, herbivory, and topography. Yet, the amount of temporal and spatial variability exhibited among grassland pollen assemblages, and the influence of these biotic and abiotic drivers on pollen assemblage composition and diversity has been relatively understudied. Here, we examine 4 years of modern pollen assemblages collected from a series of 28 traps at the Konza Prairie Long‐Term Ecological Research Area in the Flint Hills of Kansas, with the aim of evaluating the influence of these drivers, as well as quantifying the amount of spatial and temporal variability in the pollen signatures of the tallgrass prairie biome. We include all terrestrial pollen taxa in our analyses while calculating four summative metrics of pollen diversity and composition – beta‐diversity, Shannon index, nonarboreal pollen percentage, and Ambrosia:Artemisia – and find different roles of fire, herbivory, and topography variables in relation to these pollen metrics. In addition, we find significant annual differences in the means of three of these metrics, particularly the year 2013 which experienced high precipitation relative to the other 3 years of data. To quantify spatial and temporal dissimilarity among the samples over the 4‐year study, we calculate pairwise squared‐chord distances (SCD). The SCD values indicate higher compositional dissimilarity across the traps (0.38 mean) among all years than within a single trap from year to year (0.31 mean), suggesting that grassland vegetation can have different pollen signatures across finely sampled space and time, and emphasizing the need for additional long‐term annual monitoring of grassland pollen. Grasslands have been historically influenced by multiple abiotic and biotic drivers, including fire, herbivory and topography. Here, we evaluate the influence of those drivers on grassland pollen (a key proxy for interpreting grassland composition throughout the past), while quantifying the amount of spatial and temporal variation in those pollen assemblages. We examine a four‐year annual record of modern pollen data from Kansas, and find significant but varied influence of fire, herbivory, and topography, as well as high variability in pollen assemblage composition across the study area.