3 results
Holocene Soil Development on Till and Outwash Inferred from Lake-Sediment Geochemistry in Michigan and Wisconsin
- Holly A. Ewing, Edward A. Nater
-
- Journal:
- Quaternary Research / Volume 57 / Issue 2 / March 2002
- Published online by Cambridge University Press:
- 20 January 2017, pp. 234-243
-
- Article
- Export citation
-
Two geochemical techniques from soil mineralogy were used with lake sediment to reconstruct soil development in the catchments of two lakes—one on outwash and the other on till—in the Great Lakes region. A sodium pyrophosphate extraction provides information about leaching of exchangeable and organically complexed cations from terrestrial sources, while an acidified ammonium oxalate extraction removes mineral materials without well-developed crystalline structure that are indicative of podzolization. More evidence of pedogenesis is preserved in sediment of the lake on outwash—likely a result of greater retention of material within the soil profile in the catchment on till. This difference between the records suggests that excessively well-drained (leaky) catchments may provide better records of soil development than those with higher water-holding capacity. Evidence of acidification and podzolization appeared first at the lake on till and 4500 years later at the lake on outwash. Both records reveal a late Holocene intensification of weathering that coincided with a regional climatic change to greater moisture availability. The variability in weathering rates observed presents a more complex picture of weathering than the simple exponential functions often assumed in chronosequence studies. Use of lake sediment records provides better temporal resolution of significant events in soil formation than could be achieved using a chronosequence approach.
7 - Interactions between Precipitation and Vegetation Canopies
- from Part III - Coupling Hillslope Geomorphology, Soils, Hydrology, and Ecosystems
-
- By Alexandra G. Ponette-González, University of North Texas, Holly A. Ewing, Bates College, Kathleen C. Weathers, Cary Institute of Ecosystem Studies
- Edited by Edward A. Johnson, University of Calgary, Yvonne E. Martin, University of Calgary
-
- Book:
- A Biogeoscience Approach to Ecosystems
- Published online:
- 27 October 2016
- Print publication:
- 13 October 2016, pp 215-253
-
- Chapter
- Export citation
-
Summary
Introduction
When we see a tropical rainforest, intensively managed cropland, or grazed pasture from a distant view (Figure 7.1), we are seeing a critical component of the ecosystem – the vegetation canopy. At the most basic level, vegetation canopies are composed of leaves, twigs, branches, and often epiphytes (plants that grow on other plants, such as bryophytes, ferns, lichens, and orchids, and generally access water and nutrients from the atmosphere). However, many would agree that canopies are more than just a simple collection of these components (Parker, 1995). This relatively thin boundary between the atmosphere and biosphere regulates exchanges of matter, energy, and information across the air-land interface and has been the subject of significant research in biogeoscience, ecology, geoinformatics, and atmospheric science over the past three decades (Lovett and Lindberg, 1993; Parker et al., 1995; Baldocchi et al., 2002; Lefsky et al., 2002; Nadkarni et al., 2011).
In this chapter, we examine the canopy as a locus for interaction with the atmosphere – primarily with precipitation. How do vegetation canopies influence the form, amount, and chemical composition of precipitation inputs to ecosystems? What methods are used to measure and model precipitation-canopy interactions? What role do geographic factors play in altering spatial and temporal patterns of precipitation inputs to and underneath canopies? To answer these questions, we look to studies from around the globe, particularly those in forests, the vegetation type whose canopies have been most widely studied. After a brief description of vegetation canopies, we review common materials emitted to the atmosphere and the ways in which they are deposited before exploring the interactions that take place within the canopies themselves.
Vegetation Canopies
In the study of precipitation-canopy interactions, it is useful to think about the canopy as a three-dimensional porous layer with passive and active surfaces (Parker, 1995). Canopy structure – the position, extent, quantity, type, and connectivity of the aboveground components – can be described using a variety of metrics, including maximum tree height, canopy cover, and leaf area index (leaf area per ground area), to name a few (Parker, 1995). Often, canopies are described in terms of their aerodynamic roughness, which refers to how the physical surface at the top of the canopy interacts with the atmosphere, and which is related to the height, density, and distribution of canopy elements (Oke, 1987).
Contributors
-
- By Hamid M. Abdolmaleky, Cory Adamson, Paola Allavena, Dimitrios Anastasiou, Johanna Apfel, Surinder K. Batra, Mark E. Burkard, Amancio Carnero, Michael J. Clemens, Jeanette Gowen Cook, Isabel Dominguez, Jeremy S. Edwards, Wafik S. El-Deiry, Androulla Elia, Mohammad R. Eskandari, Aurora Esquela-Kerscher, Manel Esteller, Rob M. Ewing, Douglas V. Faller, Kristopher Frese, Xijin Ge, Giovanni Germano, Daniel A. Haber, William C. Hahn, Antoine Ho, Christine Iacobuzio-Donahue, Sergii Ivakhno, Prasad V. Jallepalli, Rosanne Jones, Sharyn Katz, Arnaud Krebs, Karl Krueger, Arthur W. Lambert, Adam Lerner, Holly Lewis, Jason W. Locasale, Giselle Y. López, Shyamala Maheswaran, Alberto Mantovani, José Ignacio Martín-Subero, Simon J. Morley, Oliver Müller, Kathleen R. Nevis, Sait Ozturk, Panagiotis Papageorgis, Jignesh R. Parikh, Steven M. Powell, Kimberly L. Raiford, Andrew M. Rankin, Patricia Reischmann, Simon Rosenfeld, Marc Samsky, Anthony Scott, Shantibhusan Senapati, Yashaswi Shrestha, Anurag Singh, Rakesh K. Singh, Gromoslaw A. Smolen, Sudhir Srivastava, Simon Tavaré, Sam Thiagalingam, László Tora, David Tuveson, Asad Umar, Matthew G. Vander Heiden, Cyrus Vaziri, Zhenghe John Wang, Kevin Webster, Chen Khuan Wong, Yu Xia, Hai Yan, Jian Yu, Lihua Yu, Min Yu, Lin Zhang, Jin-Rong Zhou
- Edited by Sam Thiagalingam
-
- Book:
- Systems Biology of Cancer
- Published online:
- 05 April 2015
- Print publication:
- 09 April 2015, pp ix-xiv
-
- Chapter
- Export citation