Allelopathy in northern temperate and boreal semi-natural woodland

Allelopathy has been widely investigated in forest ecosystems around the wo rld. This ecological process takes part in the vegetation dynamics and part ially explains the success or failure of seedling establishment and surviva l. Therefore, allelopathy could be a common cause of natural regeneration f ailure, due to adverse impact of understory species directly on trees speci es (inhibition of germination and seedlings primary growth). This problem h as been investigated mainly in coniferous forests, but it also occurs in de ciduous forests. Furthermore, allelopathy can involve forest soil microorga nisms. They can act as allelochemical mediators, where they are able to ina ctivate these compounds by means of metabolization, as they are able to pro duce biologically active compounds using inactive molecules as a substrate. Special attention is given to mycorrhizal fungi and mycorrhizae, because, in theory, they are able to protect seedlings against allelopathy. Applied aspects of allelopathy in forest ecosystems are also presented, with two ma in goals: (1) how to reduce the adverse impact of such interactions (chemic al and mechanical control of allelochemicals plant producer, afforestation with selected mycorrhiza), but also (2) how to use allelopathy as a tool fo r forest management. Suggestions to improve the study of allelopathy in for est ecosystems and prospects for future investigations conclude this review .