Environmental considerations from legislation and certification in managed forest stands: A review of their importance for biodiversity

• We review environmental considerations in forestry with Sweden as a case study.
• Environmental considerations in forestry have support in the scientific literature.
• Retention levels in Sweden are low compared with ecological thresholds.
• There is a need to better adjust the levels above thresholds from empirical studies.
• The allocation of consideration in and among landscapes needs to be improved.

Negative impacts of forestry on biodiversity have been addressed through environmental considerations held within legislation and various forest certification protocols. We used Sweden as a case study where a long history of forestry aiming at sustained yield of wood fiber has resulted in landscapes with low quantities of old growth structures e.g. dead wood and old forest, but where environmental considerations have been implemented during the last two decades. We reviewed the scientific literature for studies evaluating the environmental considerations included in the Swedish Forestry Act and FSC, compared individual metrics and benchmarks, identified thresholds as well as identified specific gaps missing from current regulations (missing factors/areas of improvement). All environmental considerations listed in the Swedish Forestry Act were found to be relevant for conservation. The strongest scientific support for their importance in maintaining biodiversity in managed landscapes was found for dead wood, tree retention and habitats for sensitive species, including edge zones and woodland key habitats. However, suggested levels fall below identified thresholds. Retention of small habitat patches can provide a life-boat function for some red-listed species, but the long term survival of these populations is uncertain. Tree species composition was also found be important, and in the boreal region the proportion of deciduous trees is a key factor. For some environmental considerations, there is too limited information from the scientific literature to evaluate their importance in relation to the current levels, e.g. consequences of clear-cut size and shape, and forest roads. Similarly, damage to soil and water affect biodiversity through drainage, leakage and sedimentation, but the effects vary considerably and are often diffuse. There is a need to better adjust the levels of environmental considerations above thresholds from empirical studies. However, it will be impossible within current regulatory framework to maintain all species in all landscapes. Therefore, the allocation of environmental consideration among stands, landscapes and regions need to be considered. Evenly dispersed retention might always stay below suggested thresholds with limited contribution to ecologically sustainable forest ecosystems. More flexibility, where the sum of conservation measures in the landscape as opposed to measures in individual stands are considered, would result in better conservation strategies. This would mean that particular landscapes could be more intensively managed and in other more focus on biodiversity conservation could be taken.