Since learning about permaculture about three years ago, one of the most interesting questions for me has been how to adapt permaculture principles to a region where the natural climax ecosystem isn't forest but grassland.

Tallgrass prairie restoration has been a personal passion of mine for many years, so I sometimes shudder reading praise of the edge effect. For 15 years, "edge" to me has meant the spot where exotic grasses such as brome launch their invasions of my prairie. Brome is cool season grass and most native grasses are warm season, so if it is not regularly mowed or grazed during its growing season, brome can effectively shade out native grasses and wildflowers in spring, reducing the diversity and health of the prairie ecosystem.

Edge is also the enemy of native grassland birds, many of whom nest on the ground and use a needle-in-a-haystack approach to avoiding predation. Grassland birds equate trees and shrubs with predators, and few will nest in a grassland smaller than 40 acres in size. For a truly diverse and representative sampling, you need at least 100 acres, and to attract the species most sensitive to habitat fragmentation, studies have found that you still have only a 50% chance of seeing them at 250 acres! With 99% of the tallgrass prairie plowed under and converted to cropland (mainly corn and soy), you can probably imagine the shocking decline of grassland birds in the United States. Populations of some grassland songbirds are declining at a rate of up to 10% annually, others have declined up to 95% in 25 years.

Permaculture is infinitely more sustainable than the endless industrial monocultures currently covering the tallgrass region, but the problem of scale seems a serious one to me on several levels. The native flora and small fauna of prairies can't replace the multi-functional usefulness of trees and shrubs on as efficient a scale. With good design and planning, you can grow a productive forest garden in a suburban backyard. In order to gain an equivalent supply of food, energy, and shelter from a prairie, you'd pretty much need a bison. Bison are naturally migratory and do best on pastures of 5000 acres or more. (They can be raised successfully on much less, but will behave more like cattle in their grazing patterns, which is not as beneficial for prairie health and biodiversity.)

Another factor is the importance of fire to the prairie ecosystem. The tallgrass prairie is believed to have burned about every 3-4 years, some fires set by lighting, others by humans trying to attract bison and other grazing animals to the first flush of new growth. The fires converted 20-25% percent of grass biomass to charcoal, creating extraordinarily carbon-rich and fertile soils, but like bison, fire is poorly suited to suburbs and requires knowledgeable management even in larger tracts of land to avoid creating the raging 20 foot walls of flame that so terrified early European settlers to the plains.

For these reasons, I think a true prairie permaculture system that upholds the principles of Earth Care as well as People Care and Fair Share might require the creation of some form of cooperative to be capable of acquiring the scale of land required to live sustainably on the prairies. They would probably have to be designed around some central village like the Pawnee, Mandan, and other (primarily) sedentary tribes of the Plains, rather than the scattered homesteads common in the prairie region today. This could limit the use of trees and shrubs such as chokecherries and burr oak to one small area while leaving large tracts free of woody plants to provide habitat for grassland birds, bison, and other native species.

Such a system could even be combined with the Buffalo Commons idea proposed by Frank and Deborah Popper to develop corridors connecting prairie permaculture communities, public lands, and sympathetic private landhandholders in order to ultimately re-open the ancient migratory paths of the bison and pronghorn.

As mentioned on my profile, I have not yet been able to take a Permaculture Design Course, nor am I a professional in the field of habitat restoration or wildlife biology, so these musings are based only on my own self study of permaculture and prairie ecosystems. I would love to hear the thoughts, ideas, and criticisms of more qualified individuals.