Negative effects on the forests include selective browsing, soil erosion, depletion of nutrients and compaction of the topsoil. Forest grazing frequently causes slow or no regeneration, poor forest conditions and, in extreme cases, potential ecological disasters. With their ability to climb through trees, goats have a particularly damaging effect on conifers; not only do they browse the foliage but they also strip off the bark. In Mediterranean areas forest restoration of former grazed areas is somewhat complicated in that the ecologist is often faced with the dilema of having to control the biuld up of combustible materials which can become a severe fire risk.