Invasive species are changing the structure and function of our native ecosystems, there is a need for effective management of these species to protect ecosystem services and biodiversity. Through a desk study which collated all published research on the primary plant invader of forests across 25 U.S. states, Microstegium vimineum, Coweeta researchers showed how ecological theory can be used to inform land management; most importantly, that metapopulation theory can be used to focus management on specific areas where the invader grows well, and that eradication of the invader from these areas should reduce its abundance across the entire landscape by removing the source of its seeds.
The fact that M. vimineum does well in moist riparian and understory habitats initially surprised researchers, as the grass employs the C4 photosynthetic pathway generally considered an adaptation for dry environments and commonly associated with invaders of open habitat. Coweeta researchers synthesized all available information on the species’ life history and habitat characteristics with the goal of understanding of how the unique invader’s niche requirements affect its population dynamics, and how an understanding of these population dynamics through space and time could produce better management recommendations.
Their approach was unique in two ways: it did not use landscape position as a proxy for niche requirements and it emphasized stage-specific investigation of niche limitations. Using landscape position as a proxy for niche requirements fails to elucidate subtle differences in habitat requirements, such as light or soil moisture, that vary over heterogeneous landscapes. Emphasizing stage-specific habitat requirements allows researchers to differentiate varying needs during germination, growth, and reproduction, helping to elucidate temporal variation in population dynamics. In the case of M. vimineum, researchers were able to discover that the grass was able to disperse and thrive along sunny and sometimes wet roadside habitats, which then acted as a source population for interior sink populations- those in the interior of the forest- that would otherwise not be able to sustain themselves from year to year. Though the habitat conditions under the canopy were sufficient to allow growth and survival for the year, they were not adequate for seed production and dispersal. Overall, this research demonstrates that identification of niche requirements, specifically as they vary over key demographic stages (recruitment, survival, growth, reproduction, and dispersal), can be useful to identify effective and efficient management strategies- in the case of M. vimenium of focusing eradication strategies on source populations.