Changes in forest structure and composition after fire in tropical montane cloud forests near the Andean treeline

Abstract

Background: In tropical montane cloud forests (TMCFs) fires can be a frequent source of disturbance near the treeline.

Aims: To identify how forest structure and tree species composition change in response to fire and to identify fire-tolerant species, and determine which traits or characteristics are associated with fire tolerance.

Methods: Shifts in forest structure and diversity were assessed on 15 paired plots in burnt and unburnt (control) forests, along a fire chronosequence. Species were classified as fire-sensitive, fire survivors or fire thrivers, using a fire tolerance index. Regression and tree analyses were used to determine which traits contributed to the fire tolerance of species.

Results: There were more small- and medium-sized trees in the burnt plots independent of time since the last fire. There were shifts in family importance value and in species diversity among the plots. Of the 73 species analysed there were 39 fire-sensitive species, 19 fire survivors and 14 fire thrivers. Sprouting ability and biomass showed a positive relationship with the fire tolerance of species.

Conclusions: There were immediate as well as long-term (up to 15 years) effects of fire on forest structure and species composition, suggesting that TMCFs take more than 15 years to regenerate from a fire. Long-term studies are needed to fully understand regeneration patterns of TMCFs after fires.

Keywords:

• bark thickness
• fire sensitivity
• Peruvian Andes
• species diversity
• sprouting, tree size
• wood density

Acknowledgements

This project was funded by the UK Natural Environment Research Council (NERC Grant NE/G006385/1). The authors are very grateful to the Amazon Basin Conservation Association (ACCA) for logistical support, especially to Karen Eckhardt for providing the resources for meeting local communities. We thank the local communities of Sunchubamba, Challabamba, Pilco Grande and Japu, who very kindly allowed us to work in their land. Authors are also grateful to Machu Picchu Historical Sanctuary and Manu National Parks officers and forest rangers for their valuable logistical support. YM is supported by the Jackson Foundation and the Oxford Martin School. The authors wish to thank the anonymous reviewers and Dr Sam Moore for their useful comments and suggestions that improved the quality of the manuscript.