Fire severity effects on resprouting of subtropical dune thicket of the Cape Floristic Region

PeerJ

article

Tiaan Strydom¹  Tineke Kraaij¹  Mark Difford²  Richard M. Cowling² 

[1] School of Natural Resource Management, Nelson Mandela University;African Centre for Coastal Palaeoscience, Nelson Mandela University

关键词: Biome boundaries;    Coastal dunes;    Fire frequency;    Fire severity scoring;    Pre-fire shrub size;    Thicket-fynbos mosaic;   

DOI  :  10.7717/peerj.9240

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

It has been hypothesised that high-intensity fires prevent fire-dependent fynbos from being replaced by fire-avoiding subtropical thicket on dune landscapes of the Cape Floristic Region (CFR). Recent extensive fires provided an opportunity to test this hypothesis. We posit that (1) fire-related thicket shrub mortality would be size dependent, with smaller individuals suffering higher mortality than larger ones; and (2) that survival and resprouting vigour of thicket shrubs would be negatively correlated with fire severity. We assessed survival and resprouting vigour post-fire in relation to fire severity and pre-fire shrub size at two dune landscapes in the CFR. Fire severity was scored at the base of the shrub and categorised into four levels. Pre-fire size was quantified as an index of lignotuber diameter and stem count of each shrub. Resprouting vigour consisted of two variables; resprouting shoot count and resprouting canopy volume. A total of 29 species were surveyed. Post-fire survival of thicket was high (83–85%). We found that smaller shrubs did have a lower probability of post-fire survival than larger individuals but could detect no consistent relationship between shrub mortality and fire severity. Fire severity had a positive effect on resprouting shoot count but a variable effect on resprouting volume. Pre-fire size was positively related to survival and both measures of resprouting vigour. We conclude that thicket is resilient to high-severity fires but may be vulnerable to frequent fires. Prescribed high-intensity fires in dune landscapes are unlikely to reduce the extent of thicket and promote fynbos expansion.

【 授权许可】

CC BY