The Conservation Lands Experiment (CLE) was established in 2015 to test the consequences of intra- and inter-specific diversity in seed mixtures used to establish restored prairie plantings. It is based on a crossed manipulation of the number of seed sources per species (1 vs. 3; intra-specific diversity) and the number of species (inter-specific diversity) used in seed mixtures, across 12 prairie plantings ranging from 0.2 to 3.5 ha in area.
During the 2015 growing season, 12 herbaceous fields located within Kellogg Biological Station (10 fields) and the Kellogg Bird Sanctuary (2 fields) were prepared for planting by mowing the existing vegetation and applying glyphosate-based herbicide twice. Eleven of the 12 fields were previously cultivated and one had no known history of cultivation (“No Till”); all supported old field plant communities dominated by non-native plant species before planting. To initiate restoration, a modified Truax seed drill was used to install prairie seeds at a rate of 330 seeds/m2 into each field in 2015, following the growing season (first two weeks of December).
The experiment tests the effects of intra-specific diversity for 12 “focal” prairie plant species, each of which was purchased from three different locations in the central USA: locally (sourced from the geographically nearest location possible), from more distant, but climatically similar locations (Wisconsin, Minnesota, Illinois, or Iowa), or from southern locations (Missouri or Iowa). Seeds were acquired from seed producers in each region and all seed sources were confirmed to be local to the respective seed producers, prior to planting. Fields were randomly assigned to be planted either with seeds from one source (low intra-specific diversity; n = 6; 2 fields of each source), or with a seed mix that combined all three sources for each focal species (high intra-specific diversity; n = 6 fields). Intra-specific diversity was manipulated at the field level to reduce gene flow between high and low intra-specific diversity treatments. Fields are separated by ~75–2750 m.
To test the effects of inter-specific diversity, half of each field was planted with the 12 focal species and half of each field was planted with the 12 focal species plus 58 additional prairie plant species (70 species total). One half of each field was randomly assigned to each inter-specific diversity treatment (n = 12 for each inter-specific diversity treatment). The additional species were sourced from various locations across the Midwest, with each species sourced from a single location. All seed mixes contained the same total density of seeds, resulting in a greater per-species seeding density for the 12 focal species, in the low inter-specific diversity treatment. Both the low and high inter-specific diversity seed mixtures contained C4 and C3 grasses, legumes, and non-leguminous forbs native to the region.
Following planting, each field was mowed to facilitate prairie plant establishment by reducing competition from non-prairie (weedy) plant species during August 2016 and 2017. Starting in 2019, each field received a prescribed burn during the late dormant season (April). Prescribed burns have since been conducted every two years during this time.
Within two weeks of planting, 2.25-m2 vertebrate consumer exclosures were installed at the center and 1.5m from the edge of each half-field (n = 48 total). Exclosures consist of 110–120-cm-tall fences of 6.35-mm wire mesh, buried 10–20 cm underground, to impede entrance by digging mammals. Fences have 10 cm of metal flashing at the top, to prevent entrance by climbing small mammals. Each exclosure has a paired “pseudo-exclosure” (non exclosure plot) with only three walls and holes in the bottom to allow entry for vertebrates, controlling for fencing effects. The identity of the exclosure and pseudo-exclosure were randomized within each pair. Netting was placed on top of each exclosure to prevent bird access after planting and removed after the first growing season.
Maps:
Information:
- Publications (search under Conservation Lands Experiment)
- Species List