Planting for an Uncertain Future
Islanders viewing the Land Trust’s tree and plant sale inventory may have noticed among the native plants on offer at least one non-native tree. (Whether or not a plant is “native” can sometimes be complicated.) It’s the conifer known as lodgepole pine.
Why would a landowner want to plant non-natives like this one when given the chance to plant natives instead, apart from wanting some ornamental effect? Simple answer: climate change. The general contours of Island weather in our altering climate are often summed up in the succinct if frightening, phrase, “hotter, drier summers alternating with colder, wetter winters.” (The shoulder seasons of spring and fall are growing shorter as a result of the intensification of the other two.)
Some landowners want to anticipate the effects of these changes on their property’s native flora. So they plant so-called “neo-natives”—plants from climates akin to the one the Island has started experiencing—hoping these plants will do well under our new conditions. Lodgepole pine may turn out to be one such successful newcomer.
A benefit of this strategy may be the preservation of plants that won’t survive in their current regions. Many plants are already “migrating” in response to climate change. For example, in the Northern Hemisphere, some are spreading northward of their current range seeking more moderate versions of the conditions they evolved for, while dying out in their range’s more inhospitable southern end. When we select these plants for our property, we’re participating, intentionally or not, in what scientists call “assisted migration.” As expected, this action is controversial because it encourages the spread of what is technically an invasive species.
But the dark truth behind this practice, controversial or not, is that many of our native plant species may go extinct under the pressure of climate change, and, the thinking goes, if we want healthy vegetation, it’s going to have to consist, at least in part, of these non-natives better adapted to the new conditions here.
Rather than go overboard at the annual tree sale and choose a plant palette exclusively of these possibly welcome refugees, however, the safer bet would be to continue planting natives and only intersperse some of these warmer-climate plants as a hedge (pun intended or not). The full contours of the Island’s climate future are still unfolding, and you wouldn’t want to go all-in on any bet placed against an uncertain future. Selecting a mixture of thus-far reliable plants like Douglas-fir and ocean spray, with some non-natives like lodgepole pine added, seems a safer strategy.
