I was at the Niobrara Valley Preserve this week. My son John and I went up for a kayaking trip, as well as for some work. Thursday evening, we went looking for bison, driving through the 10,000 acre east bison pasture. As the sun was going down, we hadn’t yet found any bison, but the prairie was gorgeous and we were enjoying the drive. We were near the far corner of the pasture when we spotted the primroses.
Fourpoint evening primroses (Oenothera rhombipetala) are having a good summer. Two years of abundant rain probably help with that – the plants are biennials, so they germinate one year and bloom the next, before dying at the end of their second season. Lots of rain means that a big number of seeds can successfully germinate and grow because moisture isn’t limiting. However, the huge patch John and I came across was influenced by more than just rain.
The primrose patch we found was hundreds of acres of almost solid yellow, and there was a distinct border to the patch. As soon as I saw it, I recognized it as the 2017 prescribed burn unit, which was burned in the spring of 2017 and then grazed by bison very intensively that year and again in 2018. It is recovering from that intensive disturbance, but the grasses are still weakened from that grazing impact, meaning greatly reduced competition for new seedlings of fourpoint evening primrose. As a result, some germinated in 2017 and bloomed in 2018, but many more germinated in 2018 and bloomed this year.
As the sun sank, I scurried around with my camera, trying to capture the incredible scene, while John patiently waited and wandered on his own. The next morning, I snuck out while he slept and caught the sunrise at the same location. In this post, I’m including just a few of the many many photos I took during those two short periods of time.
Today, we took a group of visitors out to see the same primrose patch. They were appropriately impressed… It’s always nice when prairie resilience displays itself in such an aesthetically pleasing way!