ACORN review: To what extent can we consider animal logging as a low-impact harvesting system?

Animal logging is one of the most ancient wood extraction methods and it is still applied in different parts of the world, including industrialised countries. Animal logging is often imagined as a low-impact method and sometimes, or rather often, it is recommended as a best-management practice. However, the literature findings depict a more complex scenario, and the goal of the present review is to shed light on the topic of environmental sustainability of logging operations performed by animals. Usually, animal logging causes less pollutant emissions and less damage to the residual stand in comparison to ground-based mechanised extraction methods. However, when applied in commercial forestry interventions such as coppicing, animal logging showed levels of soil compaction in line with those of ground-based machinery like tractors, skidders and forwarders. Specifically developed trials revealed that in the animal skid trails a strong disturbance to the soil microarthropod community occurred. Furthermore, the soil features in the animal trails seemed to get worse over time after logging, thus suggesting the possible presence of strong localised erosion along these trails. Despite the strong need to further investigate this topic, concerning the ecological aspects of forest soil which were generally neglected by the literature, the use of animal logging can be recommended in the case of small-scale forestry with wooden material sparsely located throughout the logging site. In the case of commercial logging on steep slopes instead it is recommended to replace animal logging with cable-based extraction systems. • Logging operations by the use of animals are still very common. • Animal logging causes lower emission and less damage to the residual trees than machinery. • Animal logging can cause disturbance to soil physicochemical and biological features. • Animal logging is recommended for isolated pockets of timber to be harvested. • Cable systems should be preferred to animal logging on steep slopes. [ABSTRACT FROM AUTHOR]