Decrease grass seeding rates, but increase graminoid diversity
The draft document supports the current paradigm that calls for lowering grass seeding rates to encourage greater forb dominance. The “less grass” paradigm assumes less grass equates to greater forb densities. In a linear way, this assumption seems to make sense. Lowering grass seeding densities has become a standardize procedure for “high quality” restoration for more than a decade. In the early 1990s we planted approximately 4 to 8 species of warm season grasses at rates between 8 – 16 pounds per acre. Today, many of these same species are planted at rates between a few ounces to a few pounds per acres; however, it’s still primarily the same 4 – 8 warm season species.
While I support lowering seeding rates, specifically for warm season heavy soil species, I think we should consider increasing the diversity of graminoids in our design as a means to encourage greater forb diversity. This may seem counter-intuitive, but complex systems, such as ecosystems, often require counter-intuitive analysis. After all, there are more than 200 grass plus another 200 sedge species native to the Midwest region. Even if only 10% of these graminoid species were present in any one place at any one time, we should still consider planting a minimum of 30 to 50 graminoid species. Yet the “less-grass” narrative prevails, to the point that I recently heard a refuge manager boast of planting “only two species of grass”, in a Central Illinois grassland.
Instead of less grass, maybe we should consider planting a greater diversity of graminoids in our restorations. I suggest mixes should include several graminoid species from a variety of phenological guilds, in theory to amplify niche partitioning so no one species is allowed to dominant any one space and time. Graminoids should be viewed as a companion species to forbs, providing a matrix which facilitates forb membership in the community. Warm season grasses facilitate warm season forbs and cool season grasses facilitate cool season forbs. Therefore our design should include early spring, mid spring, late spring, early summer, mid-summer, late summer species, early fall, mid fall, and late fall graminoid species.
Part of the solution involves moving beyond the current Midwest paradigm that only considers warm season C-4 grasses native to the region. We also need to consider the cool season species in our design, especially since the cool season, both the vernal and autumnal periods combined, occupy approximately 135 days while the warm season species occupy approximately 75 days of the growing season. Also, since warm season species are not shade tolerant, because grazing animals in the hot summer shade didn’t allow warm season species to evolve shade tolerance, the cool season graminoids represent the dominant graminoid of the grazing lawn. We can’t propagate a strong cool season forb community without propagation a co-companion graminoid matrix.
This forces us to consider species from genera including: Poa, Festuca, and Agrostis in our plantings. These grasses are the perfect companion plants for many of our cool season forbs. The current “warm season” narrative considers cool season species belonging to aforementioned genera “exotic”. From where this narrative emerged is unknown and more careful research finds many cool season genera, species, or races, or strains cirrcumboreal. For example, species in the genus Poa, or the bluegrasses, are considered exotic in the Midwest, but research finds a strong Poa component throughout every grassland/savanna community in the northern hemisphere, but supposedly not here in the Midwest. If we accept this narrative, then we conclude the Midwest is the only grassland in the Northern Hemisphere that never evolved a Poa component, or for that sake a cool season graminoid community. Therefore the longer cool season period, in the Midwest, was devoid of a graminoid community.
In This Series
A Plan For A Better Future: Creating a Unified Pollinator Ecology
Premise 1: Pollinators are grazers
Narrative 2: The most powerful terrestrial ecosystem on earth, the Grazing Lawn
Premise 3: Cool season species are cool too
Premise 4: Decrease grass seeding rates, but increase graminoid diversity
Premise 5: Functional groups, niche theory, and seed mix design
Premise 6: Relax the current punitive genotype restrictions
Premise 7: High density patch planting
Premise 8: Nitrogen pollution is a serious threat to pollinators
Premise 9: Make hay, not war
Premise 9: More pollinator habitat through more frequent fire.
Premise 10: Afforestation, an unknown but significant threat to pollinator survival