How we found which traits predict pairwise interactions in a mountain grassland

The post provided by Hana Skálová, Tomáš Herben, Věra Hadincová, Sylvie Pecháčková and František Krahulec

This post refers to the article Which traits predict pairwise interactions in a mountain grassland? by Herben et al. published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.12872).

A long time ago, when personal computers were a real rarity and younger members of our team had only hazy ideas about science, a few interested people established several permanent plots in species-rich mountain grassland. They aimed to investigate whether and how fine-scale species interactions determine overall community stability. However, at the beginning, they had only vague ideas about how this can be done technically. At any rate, they stayed at that splendid site and have been making yearly vegetation records in fine-scale grids fixed at the same position since 1985.

In these grids we have been recording frequency of individual species at the top of vegetation season in mid-June, sometimes under the hot sun, sometimes in the cold fog. After the record, we clipped the vegetation to simulate traditional management.

After five to ten years we were not only able to identify juvenile and poorly developed individuals of all species, but also found considerable small scale spatio-temporal dynamics, with a number of nonrandom patterns (Herben et al. 1997). Despite this small scale dynamics, dynamics at larger spatial or temporal scales were generally small. This indicated that something interesting resides really at the small scale. So we wanted to continue.

However, as once pointed out by somebody wise, while the main problem of short-term experiments is to collect and analyze data, and to get it published, the main problem of long-term experiments is to survive. We were fortunate that we managed to persuade our funding bodies to support us. Of course, we did not ask for funding of “continuation of the recording”, but to run several spin-off short-term manipulative experiments.

The extraordinary spatio-temporal stability of the research team, i.e. persistence at one study site for 33 years, resulted in more than one-third of a million of plant ramets of about 60 species counted in the permanent plots. This is a massive data set that we were able to analyze using analytical techniques generally unheard of at the time when the plots were established. Thus we are able to reveal mechanisms acting in real field communities. Removal experiments permitted us to see how species behave under experimentally altered conditions and to determine how the fine-scale dynamics are mechanistically related to species growth and dispersal potentials. 

Finally, the wonderful richness of the data permitted us to tackle the old question whether all plant species compete just by size, or whether there are more intricate relationships involved. In the paper just published, we did not only detect an important effect of plant size on the interactions, but were also able to discern detectable signal of size‐unrelated predictors of how species interact, in a manner that points to possible mechanisms of within‐community niche differentiation.

Judging from the increasing number of interesting results that this data set is yielding, it is likely that even longer dataset will bring novelties at an increasing rate. However, despite considerable progress in medicine and especially in physiotherapy, we are afraid that another 30 years are not realistic for us. But we are not giving up – not only because of the findings and papers, but also because of the fun of going there and trying to understand (of course not only by these permanent plots) how the plant communities work. Cross fingers for our health, friendships and financing of our research!

Reference: Herben, T., Krahulec, F, Hadincová, V., Pecháčková, S., & Kovářová, M. (1997). Fine-scale spatio-temporal patterns in a mountain grassland: do species replace each other in a regular fashion? Journal of Vegetation Science, 8, 217-224. https://doi.org/10.2307/3237350

Brief personal summary: Tomáš Herben, Hana Skálová, Věra Hadincová, Sylvie Pecháčková and František Krahulec work at the Institute of Botany of the Czech Academy of Sciences based in Průhonice, Czech Republic. Tomáš Herben is also a professor at the Department of Botany, Faculty of Science, Charles University in Prague, Czech Republic. Since the beginning of our professional carrier, we have been interested in community dynamics and processes behind it, plant-to-plant and plant-environment interactions, and clonal plants. Besides this, Tomáš Herben studies evolutionary ecology of clonal growth organs and of perennial herbaceous plants in general, Hana Skálová invasive plants, František Krahulec plant breeding patterns and Sylvie Pecháčková works for The West Bohemian Museum in Pilsen, Czech Republic, where she developed an interactive exhibition of the underground world in plant communities.