On 29 August at 10:15 Maria Abakumova will defend her doctoral thesis „The relationship between competitive behaviour and the frequency and identity of neighbours in temperate grassland plants“.

Supervisors:
Prof. Kristjan Zobel, University of Tartu, Estonia
Dr. Marina Semchenko, University of Manchester, UK

Opponent:
Dr. Bodil K. Ehlers, University of Aarhus, Denmark 

Summary:
​Plants are sessile organisms and can react to surrounding environment by morphological plasticity. They respond plastically not only to the abiotic environment, but also to the identity of neighbours (individuals of the same or other species, relatives or non-relatives). Plant responses to neighbours are shaped by evolutionary processes as plant species are exposed to the neighbours of a certain identity during many generations. The findings of this thesis are based on the field study of seven semi-natural grasslands in Estonia and pot experiments conducted in a common garden. We found that plants were able to discriminate between different types of neighbours (the same or another species, kin or nonkin) only when these neighbours were common in the plants’ home environment. We also found that plants could avoid competition with kin and show more aggressive behaviour towards nonkin. However, kin recognition is not easy to detect among grassland species, because it may depend on different factors, including the density of neighbours, and can elicit species-specific responses that vary in magnitude and direction. We discovered that plant ability to compete with other species varied with species reproductive strategy and dispersal. Species that reproduce by seed have a low degree of conspecific aggregation in the field (e.g., legumes) and were on average stronger competitors than species that reproduce clonally and form clumps of the same species. As a rule, plants grew better with the neighbour type that they encountered most frequently in nature. Each plant community has its own formation history and is subject to evolutionary processes that shape the patterns of species spatial distribution, neighbour recognition and species co-existence. Plants’ ability to recognize their neighbours and interact with them in a more or less aggressive manner depending on species reproductive strategy expand our understanding of the complexity of plant behaviour.