PARENT SESSION
Organized Oral Session 5: Biome and Coastal Models for Local Sites and Biosphere Regions
Organized by: JS Olson and D Ojima
Friday, August 8. 9:00 AM to 12:00 PM, SITCC Meeting Room 106.
Equations and rates of change for C3 and C4 grasses and classic sand dune successions.
Olson, Jerry*,1, Oikawa, Takehisa2, Lee, Giljae2, Mo, Wenhong2, 1 Universityof Tennessee-Knoxville, Knoxville, Tennessee, USA2 Tsukuba University, Tsukuba, Ibaraki 305, Japan
ABSTRACT- Holistic and reductionist models nearly merge in abstractions for pioneer ecosystems: e.g. dunes with few species. Many models simulate rates of change of leaves, stems, and roots, (state variables C1/C2/C3), and litter and humus pools (C4,C5 residues), initially encompassing their decomposers. Marram grasses (Ammophila spp.), lyme grasses (Leymus spp.), and some Elymus spp. use cool seasons for rapid expansion (positive feedback). These thrive during and soon after rapid sand buial (Olson 1958a-d; 1997). Lee and Oikawa's (2002) "Sim-CYCLE Eddy" has an explict compartment C6 here for C4 grasses (e.g. sand reed, Calamovilfa longifolia; little bluestem Schizachyrium scoparium = Andropogon scoparius) which overtake the C3 pioneers on classic Great Lake and Great Plains dunes. Here concepts of succession reached America from Denmark (Cowles 1899, 1901; after Warming 1891, 1895). Ishikawa compared C3 and C4 behavior on beach dunes of Ibaraki, Japan. Sea oats (Uniola paniculata)), like sand reed, resists erosion as well as burial by waves and wind. Sim-CYCLE Eddy has an explicit compartment for reproductive parts (C7), peaking in summer. One or more, or all, herbivores may sometimes be aggregated in pool #C8. Animal residues, in C9, preferably treated collectively, suggest estimated total consumpton. Do C8,C9 paths often hasten recycling significantly in pioneer or later successions of Shelford's (1913) Indiana age sequence of Animal Communities in Temperate North America? Fire does hasten carbon cycling in oak savannas (Quercus velutina...) and open dune woodlands (Pavlovic et al.). Fuller modeling calls for a) explicit loops for burning (Itoh and Oikawa 2002, Itoh et al. 2003 this session); b) slow and rapid partitions of stem, root, litter and humus compartments; separate decomposers (e.g. GTEC of Post et al. 1997, 2002); c) multi-element cycling (Parton et al. 1987, 1989; Ojima et al. 2002, 2003 this session; Olson 1963a,b; 2002); and d) grid arrays of modules for landscapes, regions or the biosphere. Model projections have broader implications for management choices: for park, educational, amenity, forest and grazing resource values, and harbor/strand/resort protection.
Key words: sand dune successional rates, management policy implications, ecosystem simulation models, C3, C4 grassland metabolism