A regional assessment of the Pteridium aquilinum growth and phenology: a case study in Southwestern Asia

Pteridium aquilinum is one of the most widespread, invasive species in the world, frequently invading disturbed land where it often reduces biodiversity, crop yield, and economic value. Most research on P. aquilinum has been conducted in temperate climates, with limited information available on the spread of the species in areas with semi-arid or Mediterranean climates. Here, we present a regional assessment of the growth of P. aquilinum in Mazandaran Province, northern Iran. P. aquilinum frond and rhizome growth was assessed at 15 sites covering its regional geographic range and a range of elevations, climate types, soil properties and land-uses. Frond phenological change over the growing season was also measured at three sites at different elevations. Results showed that P. aquilinum invasion is not restricted by land-use, elevation, and climate type. P. aquilinum produced 23-42 fronds m(-2) with a height of between 78 and 275 cm and 4 to 21 t ha(-1) frond biomass and 1.3-18 t ha(-1) rhizome biomass. Sites at high elevation had the greatest dormant bud number indicating a potentially greater resistance to control treatment. A novel result was that P. aquilinum biomass produced a bimodal response for soil carbon, nitrogen and pH, but soil phosphorus produced greatest biomass at low concentrations. Phenological analysis of fronds showed a site-dependent, non-linear, sigmoidal pattern for biomass and frond height; asymptotes for frond biomass and frond height reached 1700 g m(-2) and 110 cm and became stable after 170 and 180 Julian days, respectively. The phenological results indicate that treatments targeting fronds to control P. aquilinum invasion should be applied after 180 Julian days when maximum transfer of resources from fronds to rhizomes occur. These results provide for the first-time information on the spread of P. aquilinum in northern Iran from a growth and phenological perspective of both fronds and rhizomes and indicate that any human changes in natural ecosystems up to an elevation of 2100 m could facilitate further invasion.

Automated summary

Pteridium aquilinum is a widespread invasive species that often reduces biodiversity, crop yield, and economic value. A study in northern Iran found that the spread of P. aquilinum is not limited by land-use, elevation, or climate type. This study provides valuable information about the growth and phenological patterns of P. aquilinum in northern Iran.