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The effect of heat and smoke on the soil seed banks of heathlands on permanent freshwater swamps
Author(s) -
Trezise James E.,
Facelli Jose M.,
Paton David C.,
J.P. Davies Richard
Publication year - 2021
Publication title -
austral ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.688
H-Index - 87
eISSN - 1442-9993
pISSN - 1442-9985
DOI - 10.1111/aec.12957
Subject(s) - threatened species , swamp , endangered species , vegetation (pathology) , ecology , biology , native plant , germination , seedling , rare species , plant community , critically endangered , introduced species , habitat , species richness , botany , medicine , pathology
In South Australia, Swamps of the Fleurieu Peninsula are critically endangered due to past vegetation clearance and changes in hydrology, but still contain a high diversity of threatened plant species. This vegetation community provides habitat for 82 threatened ground‐stratum plant species, including the nationally critically endangered subshrub Hibbertia tenuis which is endemic to these swamps. With infrequent burning, native ferns and taller shrubs outcompete these species. We conducted glasshouse trials to determine the potential of fire to regenerate threatened and other swamp plant species. Soil samples from eight swamps were used in germination trials with half of each sample treated with heat plus smoke, and half left untreated. Samples were spread onto trays ( n = 188), and seedling emergence was recorded for twelve months. Emergence was dominated by native species (2649 seedlings m −2 ) compared to exotics (675 seedlings m −2 ). In total, 48 native and 25 introduced species germinated, with 21% of germinated native species absent from the above‐ground vegetation. The dominant native fern Gleichenia microphylla did not emerge from any soil samples, indicating that recovery likely lags behind that of ground‐strata species, giving them time to establish and set seed before being outcompeted. Thirty‐four rare or threatened species germinated, including five species absent from above‐ground vegetation. Of all native species that emerged, only five were confined to heat plus smoke treatments, suggesting most species will regenerate without fire if overstorey competition is reduced. However, seedling emergence of native shrubs/subshrubs more than doubled with the fire treatment. Of particular importance, H. tenuis showed an 18‐fold increase in germination when treated with heat plus smoke. This study supports the utility of ecological burns as a management tool to regenerate threatened plant species in long‐undisturbed peaty heathlands on permanent swamps.