Lepš, Jan, and Aleš Lisner. "Resistance and Resilience of Species Composition: Thirty Years of Experimental Mismanagement and Subsequent Restoration in a Species Rich Meadow." Ecology and Evolution 15, no. 2 (2025): e70923.

 

What They Did

The authors studied the changes in species composition of plots in a meadow in the Czech Republic over 30 years. The plots had a total of eight different treatments, determined by the combinations of mowing or not, fertilizing or not, and removing the dominant species (Molinia caerulea) or not. After baseline data was collected, the researchers followed the treatment protocols for 22 years, then restored traditional management (i.e. mowing, no fertilizer, no dominant species removal) for 8 years to see how the communities recovered.

They found the largest impact on species richness from fertilizing. Plots that were fertilized also did not fully recover by the end of the experiment; the researchers suggest the long-term changes in soil nutrients as an explanation. Plots that were simply left alone (i.e. no mowing, fertilizer, or dominant species removal) had a smaller decrease in species richness than those that were fertilized and also recovered faster and more completely when mowing was resumed.

The plots that were both mowed and had dominant species removal had a greater “effective species number,” a metric that includes species evenness rather than just number of species. The plots with just mowing and those with just dominant species removal had a lower effective species number than those with both treatments, but higher than the fertilized plots. All plots, regardless of treatment, experienced a significant change in species composition from the baseline over time; the authors suggest that this was due to a decrease in groundwater availability resulting from climate change.

Further Exploration

I was surprised that mowing was standard for species diversity management in the Czech meadows. After all, nature carried on just fine for millennia before humans came along with their tools. Here in the southeastern United States, it’s more likely for mowing to be avoided to preserve species diversity in some semi-natural areas, such as power line corridors.

On the other hand, prescribed fire is a relatively common management technique, and nature got on fine before humans started setting fires, too. In the case of prescribed fire, part of the purpose is to replace the natural fires from things like lightning strikes. Since humans typically don’t want wildfires near their homes and workplaces, natural fires are often suppressed. This both changes the species composition and tends to increase the buildup of combustible material, making fires more destructive when they do occur. Prescribed fire is one way to partially mitigate the effects of human fire suppression.

 I wonder if mowing replaces some other natural process, such as grazing by large herbivores. According to a site called Conservation Evidence (see https://www.conservationevidence.com/actions/133), more intensive agriculture has reduced the species richness of grasslands in Europe, so there’s a benefit to having managed semi-natural areas with a greater variety of herbaceous species.  I also remember learning in grad school that Europe has a much longer history of intensive human influence on the landscape. It’s less clear how much the indigenous peoples of the Americas changed their environment, but that’s a rabbit hole for another day!

Image credit: Jan Lepš

Update: 2/22/2025

I routinely contact the corresponding authors on the papers I write about in order to give them the opportunity to correct any mistakes and make sure I'm using their work fairly. This past week, I received a response from Dr. Lepš, who had this to say about mowing as a land management practice (quoted with permission): "Regarding the mowing – it is very traditional in Central Europe, scythe is known here for more than two millennia. Hay-making was very traditional way to get fodder for cattle – I attach pictures (from the year 2000) in Slovakia with mown meadows and traditional way of drying hay. As a matter of fact, the traditionally managed hay meadows are among the most species rich communities at the scale of 1m^2  – you can see https://www.preslia.cz/article/90." Dr. Lepš was also kind enough to share some photos from the research locality and gave permission to post, so I replaced the previous photo.