Search

Remote sensing was used to map the invasion of yellow-flowered legumes on the Central Plateau of New Zealand to inform weed management strategy. The distributions of Cytisus scoparius (broom), Ulex europaeus (gorse) and Lupinus arboreus (tree lupin) were captured with high-resolution RGB photographs of the plants while flowering. The outcomes of herbicide operations to control C. scoparius and U. europaeus over time were also assessed through repeat photography and change mapping. A grid-square sampling tool previously developed by Manaaki Whenua—Landcare Research was used to help transfer data rapidly from photography to maps using manual classification. Artificial intelligence was trialled and ruled out because the number of false positives could not be tolerated. Future actions to protect the natural values and vistas of the Central Plateau from legume invasion were identified. While previous control operations have mostly targeted large, highly visible legume patches, the importance of removing outlying plants to prevent the establishment of new seed banks and slow spread has been underestimated. Outliers not only establish new, large, long-lived seed banks in previously seed-free areas, but they also contribute more to range expansion than larger patches. Our C. scoparius and U. europaeus change mapping confirms and helps to visualise the establishment and expansion of uncontrolled outliers. The power of visualizing weed control strategies through remote sensing has supported recommendations to improve outlier control to achieve long-term, sustainable landscape-scale suppression of invasive legumes. [ABSTRACT FROM AUTHOR]

We assessed the degree of pollen and fruit-dispersal limitation in the endemic gynodioecious New Zealand tree fuchsia Fuchsia excorticata over several seasons and at 17 sites throughout New Zealand. The flowers were visited mainly by two endemic honeyeaters (bellbirds and tui), and in some cases very frequently by silvereyes, which also occasionally rob nectar from flowers. We confirmed that hermaphrodites account for more than half the plants in all populations, are fully self-compatible, and can autonomously self in the absence of pollinators (especially in plants with smaller herkogamy). Fruit production in hermaphrodites and (particularly) females was frequently pollen-limited (mean Pollen Limitation Indices of 0.17 and 0.40, respectively), and was correlated with visual assessments of pollen loads on the stigma, a useful index of pollinator service. A comparison of the proportion of ripe or overripe fruit on branches exposed to birds versus branches enclosed in wire cages showed that uncaged fruit on Kapiti Island is removed almost as soon as it is ripe but on the mainland it persists for much longer. The proportion of ripe or overripe compared to green fruit is therefore an approximate index of dispersal service. Both indices may be useful to managers concerned with measuring the level of mutualism service provided by native birds. [ABSTRACT FROM AUTHOR]