The effects of harvest frequency on coarse woody debris and its use by fauna

Context: Forest harvest practices have the potential to alter habitat available to forest fauna. One aspect of harvesting practice that has received little research attention is the effect of multiple rotations on available habitat, and its use by fauna.

Aims: We examined one component of habitat that is critical to many taxa, coarse woody debris (CWD). In forests of north-eastern New South Wales, Australia, we aimed to assess whether harvest (moderate intensity for saw-logs) frequency influences CWD levels, and whether fauna activity on CWD varies with harvest frequency and with CWD attributes.

Methods: Using habitat surveys and camera trapping, we compared CWD quantity and quality in unharvested sites with those that had been harvested once, twice and three times, and assessed fauna use of CWD.

Key results: We found significantly greater volume of non-hollow CWD, and of medium-sized pieces (15–30 cm diameter), in sites harvested three times versus unharvested sites. Camera trapping showed that the activity and composition of fauna were similar across these harvest treatments. Our results also found that a broad range of fauna used a variety of logs, including large and small logs in various states of decay.

Conclusions: Consistent with other Australian studies, our results suggested that there are no detectable impacts of harvesting on hollow or large CWD. Further studies using radio-tracking or similar methods are needed to more comprehensively assess how CWD is used by fauna.

Implications: CWD was used broadly by a range of species and should be targeted for retention under ecologically sustainable forest management practices to ensure that it continues to be present in harvested landscapes. This is particularly important in places where an intensification of practices is being considered.