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 agricultural use at various times since 1927, with the most recent fields abandoned in 2015. The fields were left undisturbed for plants to develop from seeds already present in the soil (the “seed bank”), or that were 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. Each field includes 100 plots (called “quadrats” in some publications) of size 1 by 0.5 m, grouped into four transects of 25 plots each.
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. These effects are especially important at Cedar Creek, because the site is located at the boundary “ecotone” between forest and prairie biomes. Fire regimes harm some types of species while favoring others, and fire has major impacts on light availability and nutrient dynamics, which in turn can drive changes in community functional attributes and diversity. Ultimately, fire frequency interacts with climate, nitrogen deposition, land use, and biotic invasion to determine the outcomes of successional forest-grassland interactions..
In 2006 each field was divided in half, with one half left as a “control”, and the other subject to prescribed burning (a controlled fire roughly every five years). Findings from other sites suggest 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. However, preliminary results from Cedar Creek have shown that at least some unburned sites have remained tree-free for almost a century - suggesting that factors such as drought or herbivore pressure from deers may also play an important part in maintaining open grassland landscapes along the prairie-forest ecotone.
Aboveground plant biomass is sampled annually in more than 20 fields from 4 permanently marked 3m x 4m plots in each field. The fields included in this study are 4, 5, 10, 24, 26, 28, 35, 39, 41, 45, 53, 70, 72, 77, 600, 601 and the Lawrence strip (all of these sites except the Lawrence strip are also sampled for species-level percent cover in Experiment 014). In each plot, aboveground biomass is harvested once per year around the second to third week in July, sorted to species-level, dried, and weighed.
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
In 1988 3m x 4m plots were established at the ends of E014 transects in fields 4, 5, 10, 24, 26, 28, 35, 39, 41, 45, 53, 70, 72, 77, and (separately) in the Lawrence strip. Two new fields were added, 600 (abandoned in 2014), 601 (abandoned in 2015). The E054 plots are located either near the E014 quadrats 1 or 25, depending on their orientation (see table).
Field Operations: Prescribed Burning
In 2006 each field was divided in half, and one half was chosen for periodic prescribed burning (approximately a fire every five years). As a result, two of the four E054 plots in each field are burned, and two are left unburned as controls. All transects in Field 26 and the Lawrence Strip (LS) are excluded from burning. Burn records are contained in the Method Tables.
Subsurface Soil Carbon and Nitrogen Losses Offset Surface Carbon Accumulation in Abandoned Agricultural Fields
Y Yang, JMH Knops
2023 Ecosystems 26 (4), 924-935
Synchrony matters more than species richness in plant community stability at a global scale
E Valencia, F De Bello, T Galland, PB Adler, J Lepš, A E-Vojtkó, ...
2020 Proceedings of the National Academy of Sciences 117 (39), 24345-24351
Deficits of biodiversity and productivity linger a century after agricultural abandonment
F Isbell, D Tilman, PB Reich, AT Clark
2019 Nature Ecology & Evolution 3 (11), 1533-1538