Interactions between plants and their neighbours



  • Pedro J. Aphalo, PhD, Docent (Senior Lecturer, project leader)
  • Tarja Lehto, PhD, Docent (Senior Researcher)
  • Risto Rikala, PhD, (Senior Researcher)
  • Carlos Ballaré, PhD, (Senior Researcher)
  • Riitta Tegelberg, PhD, (Postdoc)
  • Tania de la Rosa, MSc, (now PhD, former doctoral student)
  • Kira Maisniemi (MSc student)


  • Rodolfo Sánchez, PhD (Professor)
  • Jorge Casal, PhD (Associate professor)
  • Ana Scopel, PhD


In this project, research centres on the study of `The role of information-acquiring systems in plant-plant interactions’. By information-acquiring systems we understand sensory mechanisms such as those mediated, for example, by phytochrome. In plant-plant interactions we include both negative ones, such as competition, and positive ones like facilitation.

The kinds of phenomena under study are: (1) Interactions between individuals in a pure stand. (2) Interactions between different plants species. (3) Scaling up of individual plant responses to stand behaviour. The kinds of mechanisms to study are: (1) photomorphogenesis, (2) allocation of resources (photosynthates and mineral nutrients) within individuals and capture of resources by individuals, and (3) effects of plants on the canopy microclimate (including light quality).

Work is mainly on plant-plant interactions mediated by light transmitted signals, and under current environmental conditions. Part of the research is applied, and related to forest tree nursery problems such as the management of growth density of seedlings and its consequences for performance after outplanting.


  1. To elucidate how the response to signals of neighbours (e.g. shade avoidance) depends on which resource restricts growth (e.g. light vs. nitrogen).
  2. To quantify the stabilizing role of the “shade avoidance response” on the size structuring of canopies.
  3. To elucidate how the responses of individuals to the presence of neighbours contribute to properties and behaviour of canopies.
  4. To assess how canopy conditions in tree nurseries affect performance of the seedlings after outplanting.


The information being obtained is useful: (1) for mechanistically predicting/modelling canopy properties and behaviour based on the eco-physiology of the individuals; (2) to improve crop and forest management practices so that (a) weed control can be done with a much reduced, or without, use of chemical herbicides, (b) maximum stand uniformity can be achieved even after disturbances early in the season/life-cycle, and (c) to attain high seedling densities in forest tree nurseries without compromising performance after outplanting.


Plant species studied include trees of commercial importance in Finland (birch, pine, spruce). In the future our work may be extended to species particularly easy to work with (e.g. arabidopsis, tobacco) and include the study of mechanisms for which we will make use of manipulations of the of the plant genotype in addition to experimental manipulation of environment. Mutant and transgenic lines could be used to study how disabling the response of the individuals to particular environmental signals affects the behaviour of the plant stand. The main measurement techniques used are: growth analysis, gas-exchange, microscopy, stable isotopes, chemical analyses and micro-meteorological methods.

Current status

Currently our activity on this subject is not intense, mainly writing up of results from long-term measurements of out-planted seedlings and writing of results from experiments on the effects of green light on the growth and morphology of Fuchsia plants. With different intensity at different times, this “project” has been almost continuously active since 1992. Initially it was funded by the Finnish Forest Research Institute, and later by different private foundations.


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