Fire is an important driver of community composition and structure in Mediterranean ecosystem shrublands; however, little is known about how riparian habitats in Mediterranean ecosystems respond to fire. We investigated post fire recovery in Fynbos riparian habitats 10 months after fire on the Erste River and one of its tributaries in the Jonkershoek Nature Reserve in the Western Cape Province of South Africa. We addressed the following questions: 1) How does stream size influence fire intensity and re-sprouting habit? 2) How does proximity to the water influence resprouting habit and mortality? 3) Do dominant species in the riparian Fynbos exhibit a similar response to fire? We sampled 20 transects perpendicular to the stream channel on the Erste River and its tributary Langsrivier. Transects were sampled in 1 m2 plots, and distance from the water was recorded for each plot. For each woody species in the plot, we recorded number of stems, largest re-sprouting and non-re-sprouting- stem, type of re-sprouting, degree of canopy damage and smallest branch diameter.
Results/Conclusions
Stream size appears to influence fire intensity; the mean diameter of the smallest branch was significantly larger in the tributary, Langsrivier. Dominant species at both sites included Brabejum stellatifolium, Meterosideros angustifolia and Erica caffra. Proximity to the water decreased the percentage of individuals experiencing total canopy damage along the Erste River, but not in Langsrivier. Surprisingly, mortality was higher along the Erste River. Erica caffra exhibited the highest mortality at both rivers, and 100% of the individuals on Langsrivier were killed. Re-sprouting habit differed between the two rivers. Only 14% of the individuals at the Langsrivier site had crown sprouting or epicormic sprouting as compared to 52% of the individuals at the Erste River site; basal re-sprouting was more common in individuals on Langsrivier where 88% of individuals had basal re-sprouts as compared to 51% at the Erste River site. The results of this study suggest that an increase in fire frequency could eliminate Erica caffra which has been identified as a key species in riparian habitats.
