Trees. They might be the first image that pops into mind when picturing Mother Earth. They symbolize life and growth, wisdom and power, protection and happiness, and ultimate resilience. They filter our air, protect the land, provide homes and food for animals, fungi and other plants, and breath-taking naturescapes wherever they gather.
I grew up in Vermont and New Hampshire and the trees made up my backyard and playground. In the summer I would build little houses in the knots of old trees and wait for fairies to arrive. As fall rolled in my mum and I would collect bags of colorful leaves from the ground and modge-podge them, freezing their beauty in time. During winter I’d marvel at the pines and fir trees and their ability to stay green through the bleak season. However as climate change has shifted our seasons and weather in the Northeast, I have wondered how my leafy friends will fare as the future changes.
Trees are often touted as a climate solution because of their ability to act as a carbon sink, but they aren’t immune to the effects of a warming planet. Wildfires, droughts, insects, and deteriorating air quality all add complexity to the challenges that trees are facing. If we’re going to rely on trees to protect us, then we should protect them too, right?
Conservation of forests is the first important step in giving trees a fighting chance to win over the effects of global warming. Whether in situ through onsite conservation efforts like national parks or ex situ like seed saving, protecting the biodiversity of forests is crucial in keeping them in the fight against climate change. But is preserving and protecting the species that make up forests enough?
This led me to research happening right now in New Hampshire. Studies are being conducted in a 7,800 acre “Experimental Forest” to see which local, and perhaps not so local, species might thrive in the future NH climate. The idea is that the researchers want to help forests be more resistant to climate and environmental stressors by introducing trees that will thrive in the new conditions brought to a region in coming decades. By examining places that have climates similar to what models predict for New Hampshire, researchers are assessing various tree species that might soon call the granite state home. Possible contenders are the Northern Red Oak, and Eastern White Pine, as these trees are well suited for droughts. This work is an example of a process called assisted migration, where humans aid the relocation of a species.
As interesting as I found the work being done in my home state, I definitely found myself questioning why humans needed to get involved. Trees have been around a lot longer than we have, with ancestors of modern trees appearing about 385 million years ago. They lived with dinosaurs, survived ice ages, and have played a major role in Earth’s climate for millenia. Surely, these resilient species know more about migration and adaptation than we do.
The difference now is that climate change is moving faster than trees can act. We have data from tree migration that has occured in the past by analyzing fossil pollen records. As the last ice age began to recede, trees migrated North following in the footsteps of the ice. It took the spruce and birch trees about 12,000 years of northward migration to arrive at their current location. Yes trees can migrate, but we don’t have that kind of time anymore. On top of that, humans have created physical barriers through development that block trees' ability to move freely.
Given this dilemma scientists and foresters have proposed the idea of assisted migration. There are three levels to this proposed solution that differ based on how far the species is moved from their natural habitat. The first two techniques mimic closely what would happen naturally, if the seeds were being spread by the wind and animals instead of by the hands of humans. This means that the trees are moved within, or just outside of their established range. The third however, seems to put us more in a position of playing God and relocating species far from where they would naturally end up, and where I start feeling more hesitance.
We already have a history of moving species to where we believe they would be beneficial, and being incredibly incorrect. Take Buffelgrass for instance. Brought from Africa to the Southwest U.S. by the Federal Government for cattle forage and erosion control, it quickly became an invasive species that now threatens native ecosystems. In terms of assisted long-distance migration, picking a spot for relocation depends on our ability to determine which ranges will become habitable as well as which species might become invasive. Climate change is unpredictable and figuring out how places will change requires coupling climate and terrestrial models, which researchers are working on but have yet to perfect.
My initial response to this was we should just keep our hands off and leave the forests to figure it out for themselves. Haven’t humans done enough meddling with the environment already? But the discussion is more complicated than it may at first seem. An important argument for lending trees a helping hand is that the ‘natural baseline’ is already altered because of the actions of humans. Inactivity could result in loss of species that would have echoing impacts throughout ecosystems. While assisted migration is in essence a type of geoengineering (which can be a scary concept) we as a species have been geoengineering the climate by injecting the atmosphere with greenhouse gasses and altering the landscape of the surface of the Earth. With countries around the world continuing with this polluting ‘geoengineering’, now does not seem like the time to draw the line at helping trees find habitable homes.
That being said, the research on tree migration still seems to be in the early stages. In order to avoid doing more harm than good when moving trees we must know more about how local climates will shift and how to best introduce species so that they work with, and not against, the existing environment. I believe that as studies such as the one in New Hampshire continue to uncover the viability of assisted migration, conservation and seed saving must remain top priority so that we don’t lose species while waiting to make a move.
When and how should humans get involved with environmental processes that we have already altered? The topic of tree migration, while niche, speaks to broader discussions that will continue to become more relevant in the coming years