Does the amount of trees retained at clearfelling of temperate and boreal forests influence biodiversity response?

The overall aim of our review will be to provide forest practitioners and conservationists in temperate and boreal forests with more detailed recommendations regarding the amount of trees that should be retained in order to achieve positive effects for biodiversity compared to traditional clear-cutting.Intensive forestry has modified forest landscapes worldwide, with a decrease in global forest extent (habitat loss) and an increase in habitat fragmentation, resulting in negative effects for biodiversity [1,2].Industrial forestry is common in different parts of the world, with more or less intense forest management and harvest for the purpose of producing pulp, timber and bioenergy. Clear-cutting is a traditional method of logging, i.e. the complete removal of the tree layer and a subsequent regeneration of even-aged stands. This practice has been controversial due to the simplification of forest structure and composition [3], and the type and intensity of disturbance that occur under industrial forestry can deviate dramatically from natural disturbance processes [4]. The resulting lack of complexity in managed stands and across forest landscapes feeds back on ecosystem processes and carries high risks of reducing several key environmental services [e.g. [5].A new forest management model – “retention forestry” – was introduced in northwestern North America about 25？years ago as a response to the rapid ongoing transformation and simplification of forests, and the need to create greater balance between wood production and biodiversity [6]. Retention forestry spread rapidly and was adapted to conditions in various regions of the world [7]. Prescriptions can vary in a multitude of ways with large variation in type, amount, and spatial distribution of retained trees to achieve different ecological outcomes. The primary goal is to provide for continuity in ecosystem structure, function, and composition between forest generations. Legacies, such as large old trees and dead