The western and southern sides, which lie in the rain shadow of the central highlands, are home to dry deciduous forests, spiny forests, and deserts and xeric shrublands. Due to their lower population densities, Madagascar's dry deciduous forests have been better preserved than the eastern rain forests or the original woodlands of the central plateau. The western coast features many protected harbors, but silting is a major problem caused by sediment from the high levels of inland erosion carried by rivers crossing the broad western plains.