Establishing seed addition transects

As part of the 2020 NSF grant to study fire effects on plant reproduction and population dynamics, we are implementing a seed addition experiment in numerous remnants. From previous studies, we know that fire can improve recruitment which is important for population growth. However, our previous observations of recruitment in remnants conflate the amount of seed entering the seed bank and the seedlings emerging from the seed bank. The goal of this seed addition experiment is to help us directly quantify the effects of fire on seedling emergence and early seedling fitness. We will use these data to parameterize demographic models for Echinacea.

For the seed addition experiment, we established 76 transects distributed across 32 prairie remnants with Echinacea. Transect locations were determined by generating an ordered list of random points (random integers corresponding with MN state plane coordinate system) within each remnant and selecting the first 2-4 random points that were located within ~5m of an adult Echinacea but avoided dense patches of flowering plants where we may have difficulty distinguishing experimental seedlings from natural recruits. Each transect originating at a random point is 4-m long and contains four 1-m segments. Most transects extend North from the random point but some extend East (in sites where North-South transects may span an entire ditch). One segment per transect was chosen at random to be planted in fall 2021 and one transect chosen at random to be planted during fall 2022. The study includes 9 sites burned during spring 2021 as well as 7 sites slated to burn during spring 2022.

Over the past week, I have been using a GPS unit to stake the transect locations. I marked the start and end point of each transect using a blue pin flag and installed nails at 1-m intervals using measuring tape (this will facilitate the use of meter sticks and/or measuring tapes in the field). We used 4 inch galvanized common nails. Pro tip: these nails were considerably less expensive at Fleet Farm than other vendors. I plan to finish setting up transects either this afternoon or tomorrow afternoon. Our goal is to begin sowing seeds later this week.


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