Global controls of forest line elevation in the northern and southern hemispheres

We explored whether the independent evolutionary history of extratropical forests in the southern and northern hemispheres affects the temperature–elevation relationship of mountain forest lines. We compiled 115 forest line descriptions from the literature, covering the major extratropical mountain ranges of the world. We related forest line elevation to thermal regimes using mean annual temperature adjusted to sea level (MAT) and seasonal thermal amplitude (STA, mean of the warmest month minus the mean of the coldest) obtained from a global climate database.