Small rodents encourage the formation of scrublan...( After two years of research over fiv...)

After two years of research over five degraded landscapes in the National Park of Sierra Nevada (Granada), scientists have established for the first time that field mice base their diet on holm oak and pine seeds, causing a deterioration of the habitats and an extension of scrubland in the forests.

The trees in the forests such as the holm oaks, rowans and pines have unexpected predators which are impeding their expansion over the mountains. In 98.5% of cases it is field mice and other rodents which eat a large proportion of the seeds which have been scattered before they are able to germinate.

Luis Matas is the main author of the work and a researcher for the Land Ecology Research Group at the University of Granada. "If the choice of the seeds they eat is not random, in other words, they eat the seeds of a determined species more often, this will be reflected in a greater emergence of seedlings among those species which are eaten less, which could alter the structure of the plant community", he told SINC.

Between 2004 and 2005, the research team exposed the seeds of six species to the predators and analyzed the numbers which were eaten. "Some species were ravaged much more than others, and this selection pattern was maintained in the different habitats throughout the two years of study", explained Matas.

The new research, recently published in Plant Ecology, shows that this phenomenon is constant in time and in the different landscapes and habitats. In this sense, according to the researchers, "the species which undergo the highest rate of depredation are the dominant arboreal species (the pine, holm oak and rowan), while the scrubland species suffer much less consumption".

The rodents prefer the seeds from the holm oak, quercus ilex, of which a total of 77.4% are eaten, the pine, pinus sylvestris, (73.3%), and the rowan, sorbus aria, (69.2
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