Date: 19th May 2024
Think rats
Think conifer seeds as a tasty morsel for their sharp little teeth and high energy lifestyle.
Tom Carlin from Scion and a group of science partners from Scion and Lincoln University have been trying to better understand how many wilding conifer seeds survive to germinate as this is a key part in understanding the weed life cycle puzzle. They investigated the contribution that seed predators have on reducing invasive alien conifer seed survival across both invaded and uninvaded habitats in Aotearoa New Zealand.
Examples of Pinus contorta seeds on sticks that were a -undamaged, b – hollowed out, c – missing, d -damaged, or e – missing with damaged sticks. These damage categories were used to assist in seed predator identification
The research was conducted at Flock Hill station in Canterbury in beech forest, pasture and tussock environments as well as aerially and ground-controlled conifer areas. The team found that introduced mammals, particularly rodents, were the primary seed predators of invasive conifers. Seed predation pressure was highest in herbicide treated invasive alien conifer forests, indigenous beech forests, and managed pasture containing grazing livestock.
Indigenous tussock areas support fewer vertebrate seed predators and as a result are particularly vulnerable to conifer invasion. The majority of seed predation occurs within the first two weeks post-dispersal.
These results suggest that introduced mammal control operations, which are essential to protect endemic New Zealand species, will likely result in increasing invasive conifer populations by reducing seed predation pressure. Seed predation varies greatly between habitats, suggesting invasion and reinvasion rates are higher in ungrazed areas of lower forest density that support fewer introduced mammals.
Few, if any, native species provide significant seed predation pressure on wilding conifers, which gives worrying implications for unintended consequences of invasive mammal control operations on wilding conifer populations.
This is a paper that is well worth reading. It’s attached below so find a nice comfy seat and have a good read. Congratulations to Tom and the team for getting this paper published in Biological Invasions an international journal which focuses on patterns and processes of biological invasions.
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