On December 12 at 10:15 Anu Lepik will defend her doctoral thesis „Plant competitive behaviour: relationships with functional traits and soil processes"
Dr. Marina Semtšenko (University of Manchester), Prof. Kristjan Zobel (University of Tartu)
Dr. Erik Trond Aschehoug (Norweigian University of Life Sceinces)
All plants need roughly the same resources to survive and reproduce. To be successful members in a community, plants have to be good “fighters”, capturing resources at the expense of their neighbours, and be resilient “sufferers” in order to withstand suppression from neighbouring plants.
One aim of my doctoral thesis was to determine which belowground traits enhance species’ ability to suppress and tolerate neighbours. It turns out that a larger and wider root system hampers neighbouring plants’ growth the most. On the other hand, plants with less branched and deeper root systems are better at tolerating competitive pressure from neighbouring plants. Plants can use different approaches to increase their competitive ability, this in turn enables the opportunty for different species to stably co-exist in the same community.
In the second experiment, we used novel methods to examine how plant root systems occupy soil space and defend it from competitors. We examined eight common grassland species and found that these species lacked territorial behaviour as their foraging areas overlapped extensively in species mixtures. However, several species defended their core foraging areas to some extent by aggregating their roots and preventing invasion by other species.
We also wanted to find out how widespread kin recognition is in plants and how plants modify their morphology in response to kin. It appears that kin recognition may not be very common in grasslands. According to our results, only one speies of eight, Trifolium repens, exhibited clear responses to neighbours of different genetic relatedness and showing cooperative behaviour towards kin by reducing competition and investing more into seed production.
Kin recognition in plants may have wider implications at the ecosystem level, including changes in interactions with soil microorganisms. We found that kin recognition may be important in species-poor plant communities where genetic diversity in the dominant plant species influences the chemical composition of dead plant material which in turn modifies microbial activity in the soil.