Spring 2017 Seminar Series
W"o"rming up the formerly glaciated world
Earthworms came with reindeer herding, plows, fishing rods, houses, and brackish water - but then went further!
January 25th | 3:30 PM | 375 Borlaug Hall
Many studies have shown that formerly glaciated forests in N. America had evolved without native earthworms since the last glaciation, but that this status-quo had been dramatically altered with the introduction of European earthworms over the past decades to centuries. We take this new perspective of earthworms as introduced species and bring it across the Atlantic to the formerly glaciated regions in N. Europe. A series of field works in N. Sweden and Finland reveals that, despite the long history of human presence in the region, active earthworm invasions are still on-going and even accelerating beyond the margin of lands under direct human influence. Preliminary data suggest that the effects of earthworms on Fennoscandian forest soils are similar to those in N. America at least in the time scales of years to decades, including the removal of litter layer, facilitation of carbon-mineral interactions, and homogenization of soil horizons. We are intrigued to ask how these short-term changes accumulate over centuries to millennia, the time scale of arrival and expansion of agriculture in the region, which leads us to a provocative possibility that fertile mull soils may have formed partially because earthworms arrived with agrarian populations then went further to colonize and transform the forests beyond human reach.
Earthworms and Earth history
An introduction to the evolutionary history of earthworms, their ecological functions, and interactions with humans.
February 8th | 3:30 PM | 375 Borlaug Hall
Dr. Samuel James | University of Iowa
Earthworm phylogeny is the starting point for understanding biogeography and the changes in faunas of earthworms over time. With the advent of human commerce and higher-intensity disturbance regimes, those faunas began to change radically. However there have been long-term relationships at lower intensities, such as may occur in the Amazon Dark Earths of Brazil. With molecular resources we can now begin to put finer resolution on the naming and blaming of earthworms involved in recent changes in soils and ecosystems.
Soil lead distributions across scales in the Twin Cities Metropolitan Area
February 22nd | 3:30 PM | 375 Borlaug Hall
Dr. Nic Jelinski | Department of Soil, Water, & Climate | University of Minnesota
Far from being static repositories of the urban lead inventory, soils represent a dynamic pool of lead that can be re-mobilized through anthropogenic activities, particularly with increasing interest for utilizing urban soils for food production. Understanding metro-wide and property-scale distributions of soil lead is critical for minimizing health risks from soil lead. Management recommendations and land-use siting strategies for urban soils at the scale of individual households can affect ambient lead exposure and have a continuing impact on human health. In this work, we review the current state of knowledge and investigate the distribution of soil lead individual households throughout the Minneapolis-St. Paul (Minnesota) Metropolitan Area through linked transect and core sampling. Through the in-situ use of portable X-Ray Fluoresence (pXRF), we reveal fine-scale patterns in both the spatial and depth distribution of soil lead. Our data show that over half of investigated cores now have their maximum lead concentrations at depths deeper than 10cm, to 20 or 40 cm in some cases, suggesting ongoing physical or chemical processes which are redistributing lead in urban soils. These processes have important implications: if anthropogenic lead inputs have been distributed deeper into the soil over time through biotic and abiotic agents, concentrations of lead at the surface may have been diluted, so that decades-old predictions of the surficial concentrations of soil lead may overestimate the current loading and risk at the surface. Understanding the depth distribution of lead is also important for making better recommendations for urban agricultural uses of soil, where contaminant screening in the top portion of the soil may not accurately reflect the total lead loadings that will be made available once the soil is mixed more deeply.
North Central United States: Climate, Runoff, and Flooding
March 8th | 3:30 PM | 375 Borlaug Hall
Dr. Karen Ryberg | USGS, Bismarck, ND
Can't be there in person? Stream it live on WebEx.
The north central United States is subject to a great deal of natural climate variability, as well as potential anthropogenic influences from land-use and climate change. Weather patterns, short-term or longer-term persistent conditions, either of which can result in flooding, are influenced primarily by regional atmospheric and oceanic circulations and this presentation will describe some typical patterns in the north central US. Then, the presentation will show how climate variability affects seasonal runoff. Next, regional changes in seasonality and timing of peak streamflow will be shown. Finally, this work will be placed in the context of longer-term information from tree-rings and compared to other studies.
March 22nd | 3:30 PM | 375 Borlaug Hall
Watch the 5 minute talks and Q&As on YouTube:
- Kelley Wells
- Emerson Souza
- Brian Barber and the Soil Testing & Research Analytical Laboratory
- Brian Bohman
- Ke Xiao
- Nathaniel Baeumler
- Zichong Chen
April 5th | 3:30 PM | 375 Borlaug Hall
Stacy Nordstrom | Department of Soil, Water, & Climate | University of Minnesota
Want to see the slides and figure out how they are made? See the file below.
With an outside look on the scientific community and a love of great presentations, Stacy Nordstrom will be giving fresh ideas on how to make the most of communication opportunities. With easy, actionable ideas, get tricks for improving your slides, media interactions, and web presence.
Emerging Issues in Soil & Water
Sources of Sediments and Phosphorus to Lake Winnipeg: Matching Causes with Cures
Dr. David Lobb and Dr. Donald Flaten | University of Manitoba, Canada
April 21st | 2:00 - 4:00 pm | 335 Borlaug Hall
Air pollutants change composition of floral scents and increase insect foraging times
May 3rd | 3:30 PM | 375 Borlaug Hall
Flowers produce and emit odors that play crucial roles in plant-insect interactions. Oxidants such as ozone, hydroxyl radical, and nitrate radical can deleteriously impact plant-insect interactions as they readily react with floral odors and change the chemical composition of the original scents. In polluted air masses, reactions chemically destroy floral odor plumes and reduce the distance that scents travel from their sources. During the seminar, experimental and theoretical results will be presented to evaluate the hypothesis that elevated concentrations of air pollutants deleteriously impact insect pollinators and plant communities due to reduced quality and quantity of floral odor mixtures. In one study, an insect failed to detect its host plant when ozone mixing ratios exceed 80 parts per billion (ppbv) because chemical reactions altered the quality and the quantity of scents. In polluted environments, insects may not recognize the plant-emitted scents because the proportion of each chemical species in the plume is modified by chemical reactions. Results from a three-dimensional numerical model indicate that insect foraging times significantly increase in polluted environments due to scent plume degradation of the floral scents. Results also indicate that increased levels of air pollutants could perniciously contribute to the observed declines in the insect pollinators and reduced pollination efficiency done by insect pollinators.