In increasingly fragmented landscapes, it is important to understand how mature forest affects adjacent secondary forest (forest influence). Forest influence on ecological succession of beetle communities is largely unknown. We investigated succession and forest influence using 235 m long transects across boundaries between mature and secondary forest at 15 sites, sampling a chronosequence of three forest age classes (5-10, 23-29, and 42-46 years since clear-cutting) in tall eucalypt forest in Tasmania, Australia. Our results showed that ground-dwelling beetle communities showed strong successional changes, and in the oldest secondary forests, species considered indicators of mature forest had recolonized to abundance levels similar to those observed within adjacent mature forest stands. However, species composition also showed forest influence gradients in all age classes. Forest influence was estimated to extend 13 m and 20 m in the youngest and intermediate-aged secondary forests, respectively. However, the estimated effect extended to at least 176 m in the oldest secondary forest. Our environmental modeling suggests that leaf litter, microclimate, and soil variables were all important in explaining the spatial variation in beetle assemblages, and the relative importance of factors varied between secondary forest age classes. Mature-forest beetle communities can recolonize successfully from the edge, and our results provide a basis for land managers to build mature habitat connectivity into forest mosaics typical of production forests. Our results also indicate the importance of forest influence in determining potential conservation value of older secondary forest for beetles.
Bibliographical noteFunding Information:
This project was funded by the Australian Research Council Linkage Grant LP100100050. We thank Tom Spies and Jerry Franklin for their advice. We also thank Kaely Kreger and Bianca Deans for field/lab assistance and soil data, Kevin Bonham and Lynne Forster for assistance with beetle identification and sorting, and Peter Harrison and Russell Thomson for statistical advice. We also thank Forestry Tasmania for financial and logistical support and access to the Tasmanian Forest Insect Collection (TFIC).We are grateful for reviewer comments that improved the manuscript.
© 2015 by the Ecological Society of America.
- Forest influence
- Gradient forests modeling
- Litter input
- Secondary forest