How Climate Change Affects Invasive Species
New Behaviors
Warmer temperatures bring longer growing seasons. Purple loosestrife, a flowering plant that inhabits temperate zones, is invasive on several continents. In parts of North America, it has started blooming and releasing its seeds up to 24 days earlier than it did 100 years ago. This has allowed the flowers to invade wetland habitats and disrupt water flow, choke out natives such as cattails, and affect the life cycles of waterfowl, amphibians and algae.
Populations of “sleeper” species, which are nonnative but not-yet-invasive species, can be triggered into becoming so if conditions are right. For example, several types of introduced warm-water fishes live in chilly Lake Tahoe in the United States. Their populations are kept in check only by cold temperatures. With Lake Tahoe warming rapidly, they’re poised to become an invasive species.
Expanding Ranges
Warmer temperatures also mean species can spread northward. For example, mosquitos have begun moving north, potentially bringing diseases with them. Burmese pythons in Florida and feral hogs in Texas are following the same trend.
Warmer temperatures also melt sea ice, creating new shipping routes by which invasive species can travel on boats. Extreme weather events like hurricanes damage tree canopies and allow noxious weeds to take over the understory, and wildfires help cheatgrass proliferate.
Drought-stressed trees become a perfect habitat for certain insects. In Canada, the brown spruce longhorn beetle will attack both healthy and sick trees but performs best when infesting trees dying from drought, wind damage or defoliators.
Flexible Adaptations
How do invasives dominate ecosystems?
Invasive species often have physical or behavioral advantages over natives. Invasive aoudads, also called Barbary sheep, will aggressively chase native bighorn sheep away from water sources. Drought conditions are exacerbated by climate change, but aoudads’ aggression and high heat tolerance give them a competitive edge over bighorns.
Another way climate change affects invasive species is by accelerating the spread of the diseases they carry. Already struggling in part due to climate change, bighorns are also more susceptible to the pneumonia-causing bacteria that aoudads harbor, further reducing their populations.
As carbon dioxide levels rise, invasive plants can grow bigger and faster than their competition. They are spurred on by warm weather and often sprout and grow leaves before native species have a chance to poke through the soil, monopolizing nutrients and sunlight. Some invasive plants can even resist pesticides by absorbing less poison sprayed on their leaves during drought conditions.
Finding Solutions
There are many possible solutions to the problem of invasive species. First, if you have an invasive animal on your property, you can call someone to remove it.
If you have an unwanted pet, give it to a rescue center or sanctuary rather than releasing it into the wild. There are enough nonnative snakes in the grass as it is. This goes for fish, too. Keep cats indoors or in a catio and don’t let your dogs roam outside your yard.
Dig up invasive plants from your property as you notice them. Bag them, leave them in the sun to dry and throw them in the trash. Plant native flowers and shrubs in your yard to give them a head start and bolster the ecosystem. If you grow ornamental plants, confine them in pots or raised beds so they don’t escape.
It may be a little gross, but do your part to squish invasive insects such as spotted lanternflies in the U.S. They seriously damage crops such as grapes, apples and blueberries. If you’re in Europe, swat tiger mosquitoes on sight.
Climate change is affecting the behavior and spread of invasive species, but you can still make a difference by helping to curb their population growth. Humans got themselves into this mess and can get themselves out of it.