Climate proxies

Using the traces of soil biota as proxies to measure climate

Ichnologic signatures in Dryland settings

 Principal Investigator: Dr. Stephen T. Hasiotis, The University of Kansas, Department of Geology http://www.ku.edu/~geology/People/regular.html

Co-Investigator: Dr. Mary. C. Bourke, Trinity College, Dublin (formerly, Smithsonian Institution)

Funding was provided by the Scholarly Studies Program at the Smithsonian Institution (2002) to MB.

Project Summary: A well-defined relationship exists between climate, hydrology, soils, and biodiversity. This relationship is also articulated as net primary productivity (NPP) in an ecosystem. NPP is largely based on the diversity and abundance of plants and the rate that they bind energy or create organic material by photosynthesis, providing the base energy for food webs that support organisms in above- and below ground ecosystems. Organisms are distributed laterally and vertically within these ecosystems as juxtaposed biotopes across alluvial environments. The major control on NPP and biotic distribution is climate and is expressed as temperature, precipitation, evapotranspiration, and solar radiation. Similar controls also impact soil formation and include topography, parent material, biologic activity, climate, and time.

Figure 1: Various beetle and moth larval burrows in the inter-bedded modern (<50 yrs) sand and silt floodplain deposits on the Ross River, central Australia.

 

Figure 2: Remains of a termite fungal garden excavated from the nest near Ross River Homestead, Central Australia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Biota are indirectly and directly related to the substratum through feeding, dwelling, locomotion, reproductive, and searching behavior manifested as tracks, trails, burrows, nests, and roots. These behaviors are known also as trace fossils and they have various impacts on the formation and destruction of soil features. Thus, the bioturbation patterns that occur in proximal to distal alluvial and aeolian deposits can be used as proxies to the moisture and climatic conditions under which they are formed. Furthermore, the bioturbation patterns produced by soil biota should be able to be used to distinguish between areas that receive moisture delivered directly to the environment, as precipitation compared to environments that receive most of it moistures from external sources such as stream flow and overland flow (floods). The Simpson Desert is an excellent area to study spatial and temporal bioturbation patterns in fluvial and aeolian environments in the semi-arid to arid climates. We focus on modern fluvial environments south of Alice Springs and the MacDonald Ranges in central Australia. This type of research has not previously been attempted and the information from trace fossils, soils, biodiversity, and other physical and chemical data can be used to differentiate between climate and groundwater controls.

Figure 3. Scorpion burrows. A-B. Cast of a modern scorpion burrow from the Simpson Desert about 50 miles south of Alice Springs, Northern Territory, Australia. C-D. Crescent-shaped entrance of a scorpion burrow (C) prior to pouring the fiberglass into the burrow, and its excavation (D) (From Hasiotsis and Bourke, 2005).

 

Figure 4. Dr. Steve Hasiotsis excavating modern ant nest in base of a ~60,000 year old soil.

 

 

 

 

 

 

 

 

 

 

 

Conference abstracts

Hasiotis, S.T., and M.C. Bourke, (2005) Differentiating between cricket, spider, scorpion, and skink burrows in dryland environments, Simpson Desert, Northern Territory, Australia, in American Association of Petroleum Geologists, Annual Convention, Calgary.

Hasiotis, S.T. and Bourke, M.C. (2005) Distribution of traces in dryland fluvial systems, Australia. 8th International Conference on Fluvial Sedimentology. The Netherlands.

Papers

Hasiotis, S.T. and Bourke, M.C (2006). Continental trace fossils and museum exhibits: displaying organism behavior frozen in time. The Geological Curator 8, 211-226. PDF