Pinus contorta cone scale fertility is similar between two Aotearoa New Zealand sites despite fourfold difference in seed potential

Non-native conifers are some of the most invasive weeds in Aotearoa New Zealand (A-NZ). One species, Pinus contorta, has undergone known reproductive trait shifts since its introduction to A-NZ that increase the number of seeds produced per cone compared to its native range. Seed potential is partially determined by the number of fertile cone scales, however prior studies in A-NZ have only considered the number of cone scales rather than their fertility. This preliminary study investigates cone scale fertility across two A-NZ sites known to differ in their seed potential (Lake Pukaki and Craigieburn). As expected, cones from Craigieburn contained four times fewer filled seeds than cones from Lake Pukaki but, surprisingly there was no difference in the proportion of fertile scales between the two sites. Notably, the number of fertile scales at both A-NZ sites was almost double that reported in the native range. Further work is required to understand whether this finding is consistent across A-NZ or influenced by within- or between- tree factors (e.g. cone location in the crown), and comparisons with data from the native range are required to understand whether the higher cone scale fertility in A-NZ represents a trade-off against cone-defences (e.g. scale thickness).