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Plan Your Project Success

There are several ways to approach invasive plant management that will help lead to a more successful project. Most depend on the location of your site and distribution of invasive plants present, but consideration of plant species ecology and management difficulty is also important.

 

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Early Detection and Rapid Response

autumn olive

Numbers represent location and populations of autumn olive in New Hampshire. Although common in the southern part of the state, autumn olive remains an early detection species for the White Mountains northward.

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Early detection and rapid response to prevent, or slow, a new invasive species coming into an area is the single most important strategy when planning invasive plant management projects. It is much easier to remove a few plants of an “early detection species” to stop it becoming established than to tackle a species that has firmly taken root throughout an area.

 

Early detection and rapid response can take place within any sized area you select. You could choose a local watershed, town forest, parcel of conservation land, Wildlife Refuge, or even a single flower bed within your own backyard.

 

man with sunflower

Prioritize Areas of Disturbance
knotweedThis small stand of knotweed below an outflow pipe into the East Branch of the Saco river will likely be the source of new populations that establish downstream. Select image for larger size. Photo credit: Rachel Stevens

Invasive plants are early colonizers of disturbed soils, so being proactive and trying to manage populations before a timber harvest, construction project, or other disturbance takes place can be a very effective strategy.

 

A timber harvest exposes the forest floor to additional light so any seeds present are likely to grow vigorously. As construction machinery moves soil around a site, seeds and fragments of invasive plant can be moved to previously uninfested parts of the property. Machinery can be the source for invasive plant populations starting in completely new areas if not washed thoroughly before leaving a site.

 

Disturbance can have natural as well as human-related origins. Floodplain forests are particularly subject to infestation by invasive plants as flood events can wash seeds and stem fragments from upstream banks and carry them to into these adjacent areas.

Protect Priority Habitats First

priority habitats

Selecting habitats that are a priority to you is a good place to start managing invasive plants. In this example, a homeowner decided to start with population “A” which is located next to a wetland and leave population “B”, which is next to the house, until later.

 

Selecting habitats of priority within your project area is a good place to start targeting invasive plant management efforts. It could be a habitat relatively uncommon in New Hampshire, for example pine barrens or salt marshes, or it could be an area you are particularly fond of, such as the wetlands or a meadow on your property.

 

The NH Natural Heritage Bureau maintains an online list of exemplary natural communities for each municipality, along with rare plants and animals. They advise prioritizing areas that support globally rare natural communities or species, followed by high quality examples of common communities and state rare plants and animals, and finally areas that are particularly rich in biodiversity.


Start at the Headwaters and Work Downstream

Downstream

Starting invasive plant management with population “A” before “B” prevents reinfestation from upstream.

Starting at the headwaters prevents reinfestation from upstream populations of the same species. This is particularly true in areas that are prone to flooding and high bank erosion. This is just as important a strategy for a major river such as the Androscoggin, Connecticut, Merrimack, or Saco as it is for a small order stream that drains from a local beaver impoundment.

 

 

 

Start with Small Populations First, or Geal with "Spot Fires"

success

Starting with the small population “A” is more likely to result in early success.

In an area that has multiple sized populations of invasive plants, it often makes sense to start with the smallest first. The smaller a population, usually the less effort is needed for eradication. Early removal also prevents its growth into a large population that is more challenging, and costly, to tackle.

 

In some cases, an invasive plant population may be expansive and too challenging to control with the resources currently available. In this situation, it makes sense to draw a ring around the core infestation and focus on managing newly establishing populations, often called spot fires, at the periphery until resources are available to tackle the core patch fully over a committed number of years. When you do decide to tackle an extensive population, start on the outside of a large stand and work in towards the middle.


Proximity to Other Populations

Invasive plant management commonly takes place on a property of single ownership. However, it is important to be aware of populations of the same species on surrounding properties that may be close enough to reinfest a successful invasive plant management project on your land. If such populations exist, consider reaching out to the neighboring owner(s) and see if they are interested in beginning management on their property too. This will allow effective invasive plant control on your land to remain sustainable for a much longer period.

 

other properties

Starting work on your property “A” may only make sense if surrounding landowners on property “B” also want to participate.

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Plant Distribution Pattern

An invasive plant species that is distributed throughout a large area will take much more time to get to than one that is densely clumped together. This will increase the volunteer time needed to complete a project and is a substantial part of the cost when hiring a commercial applicator. For this reason it may make sense to start with the clumped species first.

 

distribution

In southern New Hampshire a barberry population would be much more costly to control than an equal number of honeysuckle bushes. Barberry is spread by birds eating its seeds, so is commonly found as single or few plants spread throughout an entire forest compared to honeysuckles which are usually found in clumps, often radiating out from an old cellar hole.

 

Species Ecology and Management Difficulty

An invasive plants’ seed bank duration, mechanism of spread to new areas, germination success, and shade tolerance are some of the key factors that combine to determine how difficult it will be to tackle successfully. Depending on the invasive plant species present within the project area you select, you may choose to focus first on species that are easiest to control.

 

For example, invasive bush honeysuckles produce seeds prolifically, but these remain viable only for a short time. In contrast, garlic mustard seeds can sprout for up to 10 years, so having a plan to keep checking back for a decade is the only way to be sure any population has been eradicated for good.


 

 

 

 

 

 

 

 

 

 


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Picking Our Battles

 

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