Now that temperatures are dropping and we are in late fall/early winter (although it seems as though it has just become fall down here in Tennessee), you might be wondering if there is a difference in how invasive and native plants respond to autumn. Or maybe you weren’t, but you are now! In ecology, “phenology” is the word we use to describe the seasonal changes in organisms. This might include the timing of emergence of insects, of bird migrations, or of plant aging, which is called “senescence”. As you know, in deciduous forests, many plants drop their leaves in the winter. This is usually caused by changes in light levels. As the days get shorter, plants respond by reabsorbing nutrients from their leaves, and then dropping them to prevent damage from frost and freezing temperatures in the winter. At this point they are no longer doing photosynthesis, which is the process by which plants make energy from sunlight. Different species respond in slightly different ways and often their leaves senesce at slightly different times. Dr. Jason Fridley from Syracuse University studies the differences in phenology between native and invasive plants. From his research, we know that in the deciduous forests of the eastern United States, invasive plants such as honeysuckle remain photosynthetically active for an average of four weeks later into the fall than native plants! This delayed phenology gives invasive plants access to more sunlight because the sun isn’t being absorbed by leaves of natives. They can make energy for a longer amount of time, which may give them an advantage over some native plants. Basically, they can take advantage of a longer growing season! Although this is likely not the only means by which these invasive plants have an advantage over natives, it is definitely an important factor. When you walk around outside in late fall, keep an eye out for those invasive plants with delayed phenology that are still photosynthesizing! For more reading, here is a link to Dr. Fridley’s article: http://www.nature.com/nature/journal/v485/n7398/full/nature11056.html
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Morgan RochePhD student in Ecology and Evolutionary Biology at the University of Tennessee, Knoxville Archives |