The purpose of this observational study is to describe the dynamics of ecosystem succession. The change in the number, type, and amount of plant and grazing animal species is monitored in more than 20 fields. These fields were previously cultivated, but then abandoned from agriculture at various times in the past. The fields were left undisturbed for plants to develop from seeds within the soil or brought into the fields by wind or animals. Permanent transects have been established in these abandoned fields for purposes of sampling in a consistent location from year to year. Permanent plots along these transects have been used to sample soil nutrients, (in particular, nitrogen) abundance of vegetation, species composition and herbivore populations. The sampling occurs approximately every 6 years. In the initial survey, 100 quadrats of size 1 by 0.5 m were sampled per field in 23 different fields.
Past work at CDR and elsewhere has demonstrated an overriding influence of fire frequency in maintaining prairie openings and oak savanna at the prairie-forest border. Fire regimes harm some types of species while favoring others and drive light and nutrient dynamics, which in turn drive community functional attributes and diversity levels. Ultimately, fire frequency interacts with climate, N deposition, land use, and biotic invasion to determine the outcomes of tree-grass interactions and the dynamics of vegetation at ecotones such as the prairie-forest border in Minnesota.
In 2006 each field was divided in half, and one half randomly chosen for periodic prescribed burning (a fire every other year). We anticipate that the burned half will continue succession to prairie grassland while the unburned half will become white pine stands if seed sources are nearby, or will otherwise undergo extremely slow succession to oaks.
from: Inouye, R. S., N. J. Huntly, D. Tilman, J. R. Tester, M. Stillwell, and K. C. Zinnel. 1987. Old-Field Succession on a Minnesota Sand Plain. Ecology 68:12-26. 10.2307/1938801
Transect and Plot Information
Four permanent 40m long transects were laid out in each field. Twenty-five quadrats (plots), 1 by 0.5 m, were permanently marked every 1.5m along each transect. The 0.5m side of the plot was parallel to the transect line. The first plot is 1.5m from the zero end of the transect. These plots were made permanent in 1993 and designated by rebars placed at 2 diagonal corners of the plot.
Field Operations: Prescribed Burning
In 2006 each field was divided in half, and one half randomly chosen for periodic prescribed burning (approximately a fire every other year), see table below. All transects in Field 26 are excluded from burning.
E054 and E014 “Successional Dynamics on a Resampled Chronosequence” are spatially related.
Competition and biodiversity in spatially structured habitats
1994 Ecology 75 (1), 2-16
Deficits of biodiversity and productivity linger a century after agricultural abandonment
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Contingent factors explain average divergence in functional composition over 88 years of old field succession
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