In the misty rainforests of southern Chile, we have discovered a crucial shift in the forest’s food web as we go higher into the mountains. We studied two types of mistletoe, which are parasitic plants. In the lowlands, a generalist mistletoe thrives on many tree species, while a picky, specialist mistletoe only grows on beech trees (Nothofagus) found higher up. As elevation increases, the lush, evergreen forests give way to colder, deciduous beech forests. This change causes the lowland mistletoe to disappear, leaving only the specialist beech mistletoe at the highest elevations.
Here’s the critical finding: the variety and abundance of other fruit-bearing plants drop dramatically on the mountain slopes. This makes the remaining mistletoe’s berries disproportionately vital for birds and small marsupials that depend on fruit. In the highest forests, this single mistletoe species provides over half of all fleshy fruit available. Essentially, as the mountain environment gets tougher, this parasitic plant transforms from just one fruit source among many into a keystone resource, holding the entire frugivore community together and highlighting how environmental pressure can amplify a species’ ecological role.
You can read the full article here: https://doi.org/10.1002/oik.11886