NEBRASKAland Magazine is dedicated to outstanding photography and informative writing with an engaging mix of articles and photos highlighting Nebraska’s outdoor activities, parklands, wildlife, history and people.
Issue link: http://mag.outdoornebraska.gov/i/683373
JUNE 2016 • NEBRASKAland 61 and contribute to society in our own way. We have teachers, firefighters, police officers, postal workers, trash collectors and many others, and the combination of all of them makes an effective community. The loss of any of those important functions ripples through the community and weakens it. Fortunately, we rarely have communities with only one postal worker or trash collector. If someone is unavailable because they are sick, there is usually someone else who can step up and fill that role. Natural communities in prairies are very similar. Every species plays a unique role in the ecosystem, and the combination of all of those roles makes the community function. Predators, herbivores, pollinators, scavengers, nitrogen fixing bacteria and many others contribute to the prairie community, and they all rely on each other. Just as in human communities, there is redundancy within each of those roles so that if one species is unavailable for a while, others can fill in. In many ways, prairie species diversity starts with plants because the number of plant species in a prairie affects nearly every other group of organisms. Herbivores, for example, obviously rely on plants for survival, and need to have a constant supply, no matter what happens to a prairie. In dry years, many plant species go dormant during the middle of the summer, making them unavailable to herbivores (including livestock). Prairies with strong plant diversity, however, have plenty of other plant species that can thrive under those hot dry conditions, giving herbivores something to feed on – and also providing habitat structure for numerous other species of animals and insects. Fires, intensive grazing, diseases, and many other events will weaken or temporarily deactivate some plant species, but in a diverse prairie, there are always others to take their place. Pollinators are another group that relies on plant diversity. They also help preserve it. There are hundreds of bee species in Nebraska grasslands, along with numerous butterflies, moths, wasps, flies, and other pollinators. Some of those insects specialize on one plant species, or a particular group of species (sunflowers, for example, or legumes). Other pollinator insects visit different kinds of flowers day to day and season to season, depending upon what's available to them. When plant diversity is low, there are few choices for pollinators, and a relatively high likelihood that there will be periods of the year when nothing is available to eat – especially for more specialized pollinator species. Since pollinators are required for most prairie plant species to produce seeds, losing pollinators because of low plant diversity can mean losing even more plant diversity and create a self-perpetuating downward spiral. Plant diversity affects much more than just herbivores and pollinators. Plant diversity begets, and is begotten by, soil microbial communities that regulate soil productivity. A high number of plant species leads to high numbers of insect species, which provide all kinds of services that keep ecosystems humming along. The availability of lots of insect species also stabilizes the prey base for the wildlife that depend upon them, including most breeding bird species. Protecting and Building Resilience Ensuring that Nebraska's grasslands remain as resilient as possible means protecting the two biggest features that make them so – prairie size and species diversity. There are numerous economic, sociologic and other factors that lead to prairies being converted to row crop agriculture or other land uses, but the end result is the same: increased grassland fragmentation and decreased size and connectivity of remaining prairie patches. Restoring prairie habitat lost during periods of high commodity prices is exponentially more expensive and difficult than breaking it out, and the costs are shared well beyond the individual landowner who plowed up the grasses. Our best strategy, by far, is to do everything we can to protect what's left of Nebraska's prairies, especially in parts of the state where grassland still dominates the landscape. In parts of Nebraska where grassland has been highly fragmented by rowcrop agriculture, the strategic restoration of some prairie habitat can help rebuild resilience. This doesn't mean turning back the clock and trying to make the landscape look like it did before farming. Instead, it means looking for small but important opportunities to enlarge and reconnect some of the remaining prairie fragments. While we don't know how big a prairie needs to be to support the majority of species and ecological processes, we do know that bigger is better, and more connectivity helps species move around to find the habitat they need. Adding a little more prairie habitat adjacent to, and between existing prairies, can make a big difference to the species trying to survive there. When creating new prairie habitat, it pays to invest up front in the highest plant species diversity possible. Using seed mixes of 50 or more plant species helps ensure that there is a constant supply of flowering plants for pollinators and forage for herbivores. High plant diversity also means that invertebrates and soil microbes that are tied to particular species can find those hosts in the new habitat. More Pollinators rely on plant diversity, but a diversity of pollinators is also important to maintain diverse plant communities. A combination of both builds resilience.