Biomedical subjects
Kurt O Reinhart
Publications and source records attributed to Kurt O Reinhart.
Soil biota and invasive plants.
Interactions between plants and soil biota resist invasion by some nonnative plants and facilitate others. In this review, we organize research and ideas about the role of soil biota as drivers of invasion by nonnative plants and how soil biota may fit into hypotheses proposed for invasive success. For example, some invasive species benefit from being introduced into regions of the world where they encounter fewer soil-borne enemies than in their native ranges. Other invasives encounter novel but strong soil mutualists which enhance their invasive success. Leaving below-ground natural enemies behind or encountering strong mutualists can enhance invasions, but indigenous enemies in soils or the absence of key soil mutualists can help native communities resist invasions. Furthermore, inhibitory and beneficial effects of soil biota on plants can accelerate or decelerate over time depending on the net effect of accumulating pathogenic and mutualistic soil organisms. These 'feedback' relationships may alter plant-soil biota interactions in ways that may facilitate invasion and inhibit re-establishment by native species. Although soil biota affect nonnative plant invasions in many different ways, research on the topic is broadening our understanding of why invasive plants can be so astoundingly successful and expanding our perspectives on the drivers of natural community organization.
Invasion through quantitative effects: intense shade drives native decline and invasive success.
The effects of invasive nonnative species on community composition are well documented. However, few studies have determined the mechanisms by which invaders drive these changes. The literature indicates that many nonnative plant species alter light availability differently than natives in a given community, suggesting that shading may be such a mechanism. We compared light quantity (photosynthetically active radiation, PAR) and quality (red: far-red ratio, R:Fr) in riparian reaches heavily invaded by a nonnative tree (Acer platanoides) to that in an uninvaded forest and experimentally tested the effects of our measured differences in PAR and R:Fr on the survival, growth, and biomass allocation of seedlings of the dominant native species and Acer platanoides. Light conditions representative of the understory of Acer platanoides-invaded forest decreased survival of the native maple Acer glabrum by 28%; Amelanchier alnifolia by 32%; Betula occidentalis by 55%; Elymus glaucus by 46%; and Sorbus aucuparia by 52%, relative to seedlings growing in PAR similar to that of native understories. In contrast, Acer platanoides and the native shrub Symphoricarpos albus were not affected by reductions in PAR. Acer platanoides seedlings and saplings are uniquely adapted to shade relative to native species. Acer platanoides was the only species tested that decreased allocation to roots relative to shoots in the invaded forest vs. the native forest light conditions. Therefore it was the only species to demonstrate an adaptive response to the particular light environment associated with Acer platanoides invasion as predicted by optimal partitioning theory. The profound change in light quantity associated with Acer platanoides canopies appears to act as an important driver of native suppression and conspecific success in invaded riparian communities. Further research is necessary to determine whether the effect of nonnative plant-driven changes on light quantity and quality is a widespread mechanism negatively affecting resident species and facilitating invasion by nonnatives.