PhD Estación Biológica de Doñana

Research, science, ecology, animal, plants, conservation, tips…

Barriers or corridors? The overlooked role of unpaved roads in endozoochorous seed dispersal

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After almost three years of fieldwork in the Doñana National Park, the results of our research are coming out.

We are assessing the effects of widespread human structures (specifically trails and firebreaks) on plant-animal interactions and how this third-order interaction affect plant communities and landscape structure. These human-made linear structures represent weaker landscape alterations than paved roads and highways, having probably subtle and unknown ecological effects. Therefore, we termed them “Soft Linear Developments” (SLD).

P1080641We found that, as a kind of avenue, SLD can promote the movement of some mammals such as rabbits and foxes, which positively select SLD verges for defecation. Interestingly, these mammals are usual fruit consumers, and often disperse countless viable seeds within their faeces, acting as natural gardeners. In the picture, a rabbit letrine placed in a SLD verge. On the left side, two small saplings of one typical rabbit-dispersed shrub in the area (Juniperus phoenicea subsp. turbinata) are growing.

Through such seed dispersal service, these animals can contribute to the creation and the expansion of plant populations along SLD verges and probably also along their surroundings. Thus, SLD verges can act as seed and plant corridors, helping to connect isolated plant populations.

P1040443As long as the community includes seed dispersers that positively select SLD for defecation, these structures can be used as management tools to promote reforestation of humanized landscapes, as well as to identify invasion pathways of mammal-dispersed alien plants. Prior to SLD construction or removal, we suggest to careful consider their potential advantages and disadvantages. Given their important ecological role in plant restoration, we suggest cautious management of seed dispersing wildlife (for example the red fox, in the picture, is severely hunted worldwide, despite they provide an important service for plant populations) and SLD verges (avoiding the use of herbicides and destructive mechanical methods).

These intriguing results have been recently published in the Journal of Applied Ecology, and are already available in “Early view”. You can see the abstract and get a pdf copy in the following link: http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12080/abstract

If you do not have access to the journal, please do not hesitate to ask me for a copy (suarezesteban.a@gmail.com).

In addition, you can find a great summary of our paper in the volume 496 (401) of Nature, in the “Research highlights” section. We hope to keep increasing our knowledge about the effects of human activities on terrestrial ecosystems, in order to improve their management and conservation, which is undoubtedly needed.

We are in debt with many people that, in one or another way, helped us to collect, process and present the data. We want to especially thank Gemma Calvo and the staff of Doñana Biological Reserve and Doñana Biological Station for they support.

Alberto Suárez-Esteban

https://sites.google.com/site/asuarezesteban/home

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