Allelopathy in Northern Temperate and Boreal Semi-Natural Woodland

Abstract

Allelopathy has been widely investigated in forest ecosystems around the world. This ecological process takes part in the vegetation dynamics and partially explains the success or failure of seedling establishment and survival. Therefore, allelopathy could be a common cause of natural regeneration failure, due to adverse impact of understory species directly on trees species (inhibition of germination and seedlings primary growth). This problem has been investigated mainly in coniferous forests, but it also occurs in deciduous forests. Furthermore, allelopathy can involve forest soil microorganisms. They can act as allelochemical mediators, where they are able to inactivate these compounds by means of metabolization, as they are able to produce biologically active compounds using inactive molecules as a substrate. Special attention is given to mycorrhizal fungi and mycor-rhizae, because, in theory, they are able to protect seedlings against allelopathy. Applied aspects of allelopathy in forest ecosystems are also presented, with two main goals: (1) how to reduce the adverse impact of such interactions (chemical and mechanical control of allelochemicals plant producer, afforestation with selected mycorrhiza), but also (2) how to use allelopathy as a tool for forest management. Suggestions to improve the study of allelopathy in forest ecosystems and prospects for future investigations conclude this review.