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.

The disturbance that ground-based extraction operations can imply on the forests ecosystem is an issue which demands more attention. Skidding and forwarding are the two most common ground-based extraction systems. While skidding implies to partially or fully dragging the logs on the ground, in forwarding, timber is transported on a deck thus avoiding direct contact with the soil. Generally, skidding is considered to be more impactful than forwarding in relation to the amount of disturbance on forest soil and residual stand. However, the framework depicted in current literature is not so strict. While skidding actually implies a higher level of damage to residual stand, the situation concerning disturbance to forest soil is much more complex. The dissimilarities in the results from various studies on this topic have shown the level of complexity. The lack of research investigating the consequences of the two extraction systems on the overall forest ecosystem is evident. Only a few studies were focused for example on the implications on biodiversity. However, the beneficial effects of best management practices, such as the application of snatch blocks during winching or positioning brush mats on the skid trails/ strip roads to reduce soil compaction, have been clearly demonstrated.