Dirk Hattermann, Markus Bernhardt-Römermann, Annette Otte & Rolf Lutz Eckstein
Since plants do not move, they have to adapt to changing environmental conditions on the spot or disperse their seeds by means of wind, water or animals to escape unfavourable conditions. Seed dispersal is especially important in archipelagos, which consist of a mixture of plant communities on a mosaic of islands, separated by seawater.
Seed dispersal in the gut of geese may play a major role for island plant
This paper addressed the potential of the Greylag Goose (Anser anser) for internal dispersal of plants in three archipelagos along the Baltic coast (Stockholm, Västervik, Blekinge) to answer the following questions:
(i) What proportion of the island species is dispersed by geese?
(ii) Which functional characteristics are typical for plants dispersed by geese?
(iii) Which plant communities are likely to benefit from internal dispersal by geese?
We first recorded the presence of higher plants in nine island habitats on 108 islands during the growing seasons in 2015 and 2016. This island species pool comprised 428 plant species.
Secondly, goose droppings were collected on vegetation-free rocks along the rocky shores of 45 islands from June to August 2016. The dried droppings from each island were crumbled, thinly spread on top of sterile potting soil in germination trays, and these placed randomly in a temperature-controlled greenhouse. All seedlings emerging from the droppings were identified and counted. All vascular plant species germinating from goose droppings represent the goose-dispersed species pool.
Finally, we compared goose-dispersed plants and all occurring species per island with respect to plant characteristics. The relation between goose-dispersed plants and plant species per island is shown in the diagram. Averages larger than zero indicate higher values or higher proportions of a plant characteristic in goose-dispersed plants than in the island species pool and vice versa.
Geese dispersed viable dispersal units (“diaspores”: seeds, fruits) of 97 plant species, which represents at least 22% of the island species pool. Geese dispersed a higher proportion of grass-like plants and
This is a plain language summary for the paper of Hattermann et al. published in the Journal of Vegetation Science.