Seed germination and climate change

What will happen to native plant populations with climate change? My project seeks to answer this question by looking at a subset of native plant species that are commonly found throughout most of the country. We are testing how the germination responses of seeds respond to different length “winters” and incubation temperatures, in order to look at how they might respond to climate change. For this project, I got the opportunity to do field work, in addition to working in the labs at the Chicago Botanic Garden.

In the field, we were scouting natural areas for populations, which consisted of searching prairies and woodlands for the seven species we wanted to find, assessing phenology and fruit set of the plants, taking GPS coordinates and eventually collecting seeds at that location. This project is looking at populations located along a latitudinal gradient, which means the plants have experienced different climates. This allows us to see how different populations of plants are locally adapted to their climate zones. Our sites are located in Minnesota, Illinois, and Missouri, which all have different plant hardiness zones (USDA 2012). Plant hardiness zones are calculated using the average annual minimum winter temperature.

We started our population scouting in Minnesota, where we found many of the target species, but not all of them. Each site we visited was slightly different, so we were never sure what we would find. Also, each species flowers at a different time, and it can be difficult to see the plants when they are not in flower, especially when we were driving along the roadsides searching for populations. Whenever we were driving, we were also searching for our plants because many of our plants like the moist and sunny conditions that roadsides provide. While in Minnesota, we visited the Minnesota Landscape Arboretum, which has many of the species we were looking for! The Arboretum was beautiful; it was also full of wild geese and their newly hatched babies. One of the problems we ran into at the Arboretum was that although the species we were searching for were in the prairies, many of them were planted. The trouble with planted prairies is that you don’t know where the seeds came from. We are looking for native populations because they exhibit local adaptation to the regions climate. Planted prairie seeds could be from local populations, but they could also be from far away, and it is often hard to track where the seeds originated. While in Minnesota, we also got to see bison that were visiting a state natural area for the summer. The bison are used in prairie management for grazing and also used for meat consumption. This combination allows the prairie to benefit and supports a local and sustainable meat source that requires little upkeep. The manager of the natural area drove us in a small golf cart right up to the herd, which visits for the summer to graze the prairie.

After Minnesota, we scouted for populations in Missouri. Despite some promising leads from local botanists and land managers, the first few days of our scouting was unfruitful. We went to many different areas and didn’t find the species we were looking for. One species we were looking for was Penstemon digitalis, which is an incredibly common species that were abundant in Minnesota.  It was discouraging at first because the species is so common and should have been easy to find. A little more research proved useful in finding what we wanted. We decided to use herbarium specimens of our species and search for the locations where they were collected and we got some advice from George Raven, a distinguished Missouri botanist. Our hard work paid off and we finally had success at a huge conservation area that had a tiny unmanaged prairie. The prairie loop was just 0.2 miles long, but on the trail we found an abundance of Penstemon! It was very exciting and unexpected from the area we were searching!

Population scouting was a rewarding experience. It showed me how difficult it can be to find sample populations to collect seeds to use in the lab. Often, as students, we are given the materials that we want to test and don’t think about where they come from. This field work showed me how it is that people who have been biologists for many years just know about certain populations. Sometimes it takes a lot of hard work and perseverance to find what you are searching for, but it is rewarding when you finally find what you want!