Geese are overlooked dispersal vectors for vascular plants in archipelago environments. (2nd May 2019)

• Record Type: Journal Article
• Authors: Hattermann, Dirk; Bernhardt‐Römermann, Markus; Otte, Annette; Eckstein, Rolf Lutz
• Editors: Henrik Bruun, Hans
• Is Part Of: Journal of vegetation science. Volume 30:Number 3(2019:May)
• Page Start: 533
• Page End: 541
• Publication Date: 2019-05-02
• Subjects: Baltic Sea -- dispersal traits -- endozoochory -- greylag goose -- indicator species -- island plant populations -- long‐distance dispersal -- seed dispersal -- semi‐natural grasslands -- waterbirds; Plant ecology -- Periodicals; Plant communities -- Periodicals; Plant populations -- Periodicals; 581.7
• DOI: 10.1111/jvs.12742
• Languages: English
• ISSNs: 1100-9233

Abstract

Abstract: Question: We addressed the importance of gut‐mediated dispersal by greylag geese for vascular plants in archipelago environments and asked: (a) What proportion of the local species pool is dispersed by geese? (b) Which plant traits characterize species dispersed by geese? (c) Which plant communities are likely to benefit from endozoochory by geese? Location: Three Swedish Baltic archipelagos. Methods: Goose droppings were collected on 45 islands. Plants germinating from the droppings represent the endozoochorous species pool (ESP). On 108 islands, the presence of vascular plants was recorded in each habitat. These species represent the island species pool (ISP). Differences in functional traits between ESP and ISP were expressed as effect sizes and tested using meta‐regressions. Using indicator species analyses and indicator species for managed semi‐natural grasslands, we identified the primary habitats of the ESP. Results: Geese dispersed viable diaspores of 97 plant species, which represents 22% of the ISP. Most ESP species were typical for small islands. Geese dispersed a higher proportion of graminoids and less woody plants, higher proportions of chamaephytes and therophytes and less phanerophytes; annuals and bi‐annuals were significantly overrepresented. On average, seed volume of the ESP was 95% smaller than that of the ISP. About 51% of all ESP species were dispersed in at least two archipelagos. Geese showed a bias towards species of rocky shore habitats. Conclusion: Geese potentially disperse large amounts of diaspores of many terrestrial island plant species. Through their feeding behaviour, geese select species with certain suites of traits from the regional species pool. Plant dispersal by geese may benefit plants species of rocky shores, but species of formerly managed semi‐natural grasslands may also find refuge sites on epilittoral shores after goose‐mediated dispersal. The relative importance of geese as dispersal vectors may increase under on‐going land‐use changes and cessation of grazing networks. Abstract : We show that geese may disperse in their gut at least 20% of the regional flora in northern archipelagos. Through their feeding behaviour, geese select seeds of plants with a specific suite of traits from the regional species pool. The importance of geese as a dispersal vectors may increase in these archipelago landscapes since grazing by livestock is declining.