Old Field Ecosystem

The hypothetical S. IN ecosystem that is the subject of this web site consists of a variety of plant types occurring in different abundances and proportions throughout the areal extent of the old field. Some parts of the the field may be dominated by a pine forest, another a grassy area with a grove of sumac. Another place may have an older yellow poplar or black cherry surrounded by redbud, dogwood, autumn olive thickets or sassafras groves. Yet another, may consist of red cedar, grasses, and prairie wildflowers. In some portions of the field, their may be a Autumn olive tree with 4 meters diameter crown surrounded by grasses. Some areas may have high species richness, while in others it is low.

These vegetation distribution patterns may be caused by a combination of a large number of factors, including:

The diagram below illustrates some of this interrelatedness and ecosystem complexity. The table beneath the figure describes the ecosystem processes that occur at the locations numbered on the figure.

Map ID	Activity	Related Work	References
0	Energy from the sun - used by plants for photosynthesis, warming and drying the soil, providing the timing for plant life histories
1	Weathering of Bedrock Contributes ions, soil pH, soil Phosphorus, the soil texture and clay content. Multiple Scales of Soil Heterogeneity	McCormick's Creek State Park Section is example of Limestone weathering;Velbel - Coweeta work, Hobbie - Glacial history effect on pH in tundra, Gabe Fillipini - P in soils, Knops and Tilman - N and C	Hobbie et al., 2002; <br> Knops and Tilman, 2000
2	water enters and moves down through the soil profile, translocating clays and cations, Litter accumulates and is decomposed and N2 air penetrates soil, then n-fixation or ammonification and nitrification make N available to plants	Watershed analyses of basins involved in research	Eidem et al., 1999; Schlesinger, 1997
3	Soil is thin on upper and mid slopes (due to erosional dynamics) - groundwater moves downslope eventually to move into a nearby stream	Johnston - Soil + regolith thickness mapping	Taylor and Eggleton, 2001
4	Oxidized zone in soil above eroded bedrock fracture intersections - groundwater recharge of fractures in bedrock?	hydrologic variability - specifically hydraulic conductivity on large scales (very detailed)
5	Thicker bottomland soil, contains some alluvial sediment. Moisture Contents expected to be higher at this location	Johnston - Soil + regolith thickness mapping
6	Grasses and Red Cedars are some of the dominant vegetation on the higher elevation portions of the field. Succession has occurred much slower in these portions of the field than in others.	Tilman, Gross, other Old - Field Work
7	Invasive shrubs and vines such as Autumn Olive exist throughout pilot study field (Griffy Preserve)	Luke and Keith Clay - Invasives
8	Seed pool and bank are important determinants of which plants will colonize where in a field
9	lower S facing slope vegetation is likely on thinner soil
10	Sumac groves dominate some areas
11	Higher pH if on Limestone, High Biodiversiy
12	Plant communities in the bottom lands are expected to be more diverse than those of the mid-slopes and hilltops
13	recharge of fractures in bedrock
14	Much of the water that moves through this system will find its way into the stream. Plant roots tap into pockets of Nutrient. Multiple Scales of Soil Heterogeneity		Collins and Wein, 1998
15	AMF mutualistic associations help plants	Jim Bever - AMF
16	Plants give off CO2, they transpire, Soil bacteria transform NO3- to N2 (process called denitrification)	Jean Bahr - denitrification in Riparian wetland	Schlesinger, 1997
17	History of Land use strongly influences the system
18	The system teaches us restoration and sustainability	Holl - Coal Mine Reclamation,	Holl, 2002

An Upland, Old-field Ecosystem of Southern Indiana