Paleoenvironmental reconstructions from cave sediments of the Moravian Karst, Czech Republic / by Pavel Sroubek.

This thesis presents a paleoclimatic/paleoenvironmental study conducted on clastic cave sediments of the Moravian Karst, Czech Republic. The study is based on environmental magnetic techniques, yet a wide range of other scientific methods was used to obtain a clearer picture of the Quaternary climate. My thesis also presents an overview of the significance of cave deposits for paleoclimatic reconstructions, explains basic environmental magnetic techniques and offers background information on the study area – a famous karst region in Central Europe with a rich history. In Kulna Cave magnetic susceptibility variations and in particular variations in pedogenic susceptibility yield a detailed record of the palaeoenvironmental conditions during the Last Glacial Stage. The Kulna long-term climatic trends agree with the deep-sea SPECMAP record, while the short-term oscillations correlate with rapid changes in the North Atlantic sea surface temperatures. Kulna Cave sediments reflect the intensity of pedogenesis controlled by short-term warmer events and precipitation over the mid-continent and provide a link between continental European climate and sea surface temperatures in the North Atlantic during the Last Glacial Stage. Given the number of independent climate proxies determined from the entrance facies of the cave and their high resolution, Kulna is an extremely important site for studying Late Pleistocene climate. In the interior of Spiralka Cave, a five meter high section of fine grained sediments deposited during floods yields information on the climatic and environmental conditions of the last millenium. In the upper 1.5 meters of this profile, mineral magnetic and other non-magnetic data indicate that susceptibility variations are controlled by the concentration of magnetite and its magnetic grain size. Comparison of our susceptibility record to the instrumental record of winter temperature anomalies shows a remarkable correlation. This correlation is explained by coupling of the flooding events, cultivation of land and pedogenetic processes in the cave catchment area. A combination of mineral magnetic and geochemical proxies yields a detail picture of the rapidly evolving climate of the near past and tracks both natural and human induced environmental changes taking place in the broader region.

Planting and production of switchgrass (Panicum virgatum L.) as a bioenergy crop in Michigan's Upper Peninsula

Switchgrass (Panicum virgatum L.) is a perennial grass holding great promise as a biofuel resource. While Michigan’s Upper Peninsula has an appropriate land base and climatic conditions, there is little research exploring the possibilities of switchgrass production. The overall objectives of this research were to investigate switchgrass establishment in the northern edge of its distribution through: investigating the effects of competition on the germination and establishment of switchgrass through the developmental and competitive characteristics of Cave-in-Rock switchgrass and large crabgrass (Digitaria sanguinalis L.) in Michigan’s Upper Peninsula; and, determining the optimum planting depths and timing for switchgrass in Michigan’s Upper Peninsula. For the competition study, a randomized complete block design was installed June 2009 at two locations in Michigan’s Upper Peninsula. Four treatments (0, 1, 4, and 8 plants/m2) of crabgrass were planted with one switchgrass plant. There was a significant difference between switchgrass biomass produced in year one, as a function of crabgrass weed pressure. There was no significant difference between the switchgrass biomass produced in year two versus previous crabgrass weed pressure. There is a significant difference between switchgrass biomass produced in year one and two. For the depth and timing study, a completely randomized design was installed at two locations in Michigan’s Upper Peninsula on seven planting dates (three fall 2009, and four spring 2010); 25 seeds were planted 2 cm apart along 0.5 m rows at depths of: 0.6 cm, 1.3 cm, and 1.9 cm. Emergence and biomass yields were compared by planting date, and depths. A greenhouse seeding experiment was established using the same planting depths and parameters as the field study. The number of seedlings was tallied daily for 30 days. There was a significant difference in survivorship between the fall and spring planting dates, with the spring being more successful. Of the four spring planting dates, there was a significant difference between May and June in emergence and biomass yield. June planting dates had the most percent emergence and total survivorship. There is no significant difference between planting switchgrass at depths of 0.6 cm, 1.3 cm, and 1.9 cm. In conclusion, switchgrass showed no signs of a legacy effect of competition from year one, on biomass production. Overall, an antagonistic effect on switchgrass biomass yield during the establishment period has been observed as a result of increasing competing weed pressure. When planting switchgrass in Michigan’s Upper Peninsula, it should be done in the spring, within the first two weeks of June, at any depth ranging from 0.6 cm to 1.9 cm.