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Invasive Species

Invasive Species and Climate Change


An invasive species is a plant, animal, or any other organism that causes ecological or economic harm in a new environment where it is not native. Not all new species are therefore defined as invasive. An example of an invasive species in New Hampshire is the emerald ash borer, which is killing native ash trees. As the temperature increases, ash trees become stressed and even more susceptible to dying due to infestation by the ash borer.



Woolly adelgid nymphs on hemlock

How Invasive Species Affect Wildlife


Many invasive species are currently limited by temperature, and are likely to expand northward into New Hampshire as a result of warmer temperatures caused by climate change. Climate-related disruptions such as large storm events and drought may also introduce species and create conditions that allow invasive species to proliferate.


From the northern forests to the seacoast invasive species may change the plants and animals we see in New Hampshire. Warmer winter temperatures will allow the northward migration of the hemlock woody adelgid. Loss of hemlock would have dramatic effects on forest composition and wildlife habitat. The wasting disease pathogen Labyrinthula zosterae, which has decimated eelgrass beds in the past, is likely to become more of a problem because it prefers waters with higher salinity, which is expected in some estuaries because of sea level rise and warmer water. Climate change could create conditions that result in human-caused illegal introductions of non-native species that are better adapted to warmer water to flourish. West Nile virus will likely become more of a threat if milder winters facilitate continued mosquito survival and breeding. Floodplain habitats may experience increased erosion due to flooding and provide more disrupted environments allowing invasive plants such as glossy buckthorn to take hold. Control of invasive species could also affect non-target organisms if used improperly.


What NH Fish and Game Is Doing in Response to Invasive Species


New Hampshire Fish and Game works to manage its Wildlife Management Areas (WMA) to create habitats healthy enough to resist invasive species and to control those invasive species that are already present. Fish and Game, the NH Natural Heritage Bureau, and the Great Bay National Estuarine Research Reserve have teamed up with community members, natural resource managers, and academics to develop a plan for the control of upland, wetland, and intertidal invasive plant species.


Invasive Species and People


Invasive species can change the face of wildlife habitats and cause significant economic harm, such as the Asian longhorned beetle, which attacks a variety of hardwood trees impacting the forestry and logging industries. Managing invasive species is a complex process that requires careful planning and professional advice to make sure you do not make the problem worse by causing the species to spread or doing harm to the habitat where it is found. It is best to monitor and control populations when they are small.


Taking Action

  • Learn to identify invasive species.
  • Develop a plan to manage invasive species on your land in consultation with experts.
  • Promote native plants and wildlife.
  • Attend an invasive plant work day.
  • Engage with a local school on a citizen science project to inventory and map invasive species.
  • Plant a pollinator garden with native species.
  • Obey all state quarantines.
  • Volunteer with projects to help control invasive species.
  • Follow expert guidelines on not spreading invasive species
  • Educate yourself and share your understanding with friends and family about how climate change affects wildlife and habitats.       
  • Start planning now for good ecological health and get involved in your local community by addressing potential climate change issues in your town or region.       
  • Support and volunteer for environmental and conservation organizations that address climate change impacts to wildlife and habitats.
  • Become a citizen scientist and help collect data on plants, wildlife, water, and weather.