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Thursday, April 30, 2015

Voices of the Future (4) - Invasive Plants in Pennsylvania

by Zachary Byers
Forestry major, graduating December, 2016
zrb5057@psu.edu

Our nation’s lands hold a wealth of diversity, impacted by the lifestyles and cultures of the people occupying it. While many of these additions have allowed America to grow and prosper, throughout the years there have always been a number of missteps. One of the clearest representations of this is the number of aggressive exotic plant species that continue to threaten and cause problems within our native landscape, known as invasive plants. The vast majority of these species, such as Garlic Mustard or Japanese Barberry, were introduced to the land on purpose. The reasons for doing so very greatly, from being ornamental to being a quick source of nutrition or even in hopes of preserving soil or water quality.

It’s not that these invasives are inherently bad; they simply cause too much stress in an environment where it can impact other species. The idea can be very straightforward, and even be explained in no more than two minutes like in the video below:



One of the greatest misconceptions that are often found when dealing with invasive species is that many still confuse them with ‘exotic’ species. An exotic plant species is any plant that does not natively originate from our area. An invasive plant species goes another step beyond, as a plant that was not only brought to our land from somewhere else, but also poses a threat to our lands or our other existing native species. For most agencies and legislative policies dealing with invasive plants, their management is typically similar. They are to be removed or controlled depending on how much of a threat they present on the other species in the area. Total systematic removal of invasive species on most federal and state lands is relatively uncommon, species being suppressed by various land management techniques as they are seen to pose a potential threat.

One of the most essential tasks in making sure that invasive species are well understood is being able to explain why they’re considered ‘invasive’ in the first place. At first glance, many invasive species may seem completely harmless, and could even have some degree of biological and aesthetic value within an ecosystem. There are several exotic species that exist within our lands now that aren’t considered invasive, and they are allowed to live in our ecosystems for precisely this reason. Unlike typical exotic species, invasives can cause a great deal of stress on our existing native species. They occupy living space, can take up resources needed to grow and develop, compete for natural roles within the ecosystem, and some even create secondary plant compounds which actively act to displace other species within reach.

The issue that’s most commonly dealt with by certain areas is not over whether or not invasive species should be controlled or even eradicated in a general sense, so much as whether or not some species are truly invasive. This means that invasives have to be handled more on a species to species basis, rather than taking the same action for any plant with the same designation. Multiflora rose, for example, is a species that has been established within our state from Asia and was spread for the sake of soil conservation and to provide ‘living barriers’. Since its establishment it’s been valued further as cover for small game, aesthetic beauty and a source of forage. The issue lies in the plant’s heartiness, far exceeding American native roses while netting into large shrubby masses which can act as barriers and prove very difficult to remove once established.

With similar differing qualities in mind it isn’t uncommon to find two individuals who differ greatly on the value of an ‘invasive’ plant in their ecosystem. This indecision often leads to difficulty agreeing on how to properly manage the plants beyond continual suppression, and makes the possibility for wide-scale eradication highly unlikely.

Of course, on the topic of large-scale eradication…would such a thing even be possible? Most invasive species still exist within our lands today because they’re so resilient against both man and nature’s attempts to remove them. In fact, you could go onto just about and piece of state or federal land with a checklist of invasive species, and spend hours ticking off examples dotted here and there. While in a perfect situation it would be great to pluck every threatening bush, stump or blade of grass from an area, it’s just not feasible.

But, there is one promising method that has started to make a comeback within our state. After many long years of suppressing fire from our natural environment, the practice of prescribed burning has been allowed and is slowly but surely becoming more frequent in our forests. Regardless of what opinions people may have on the use of fire, it is easily one of the most promising methods we have towards stemming the impact of invasive plants. Our native species have not yet lost their predisposition towards handling and recovering from low-intensity burns, and many invasive species have little to no tolerance from fire even in their native ranges. It’s true, running the entire state’s understory under a cleansing blaze would still not be a total end-all solution to our invasive plant problems. It will, however, provide us with an extremely valuable way to bring highly-damaged regions back into our control.

In a way, invasive plant species are likely to be our environment’s “criminals” forever, murdering native species and stealing valuable resources. If we were to leave the lands to follow nature’s course, then over time evolution would probably equalize these invasives until they were a part of our native ecological balance…but allowing this would cost us a great deal of the species that we cherish so deeply. In my opinion ‘policing’ invasive plant species as we have for years truly is our only option. We are more conscientious about the presence of hazardous life in our ecosystems now than we have been in the past. These invasive species are not strangers to us now. We know what they are, and we have the tools we need to keep them in line. All that’s left for us is to stay mindful, and do all we can to keep that long list of invasive plants from getting any longer.

2 comments:

Jeff Wartluft said...

I am generally against invasives, but we need to realize that they provide some benefits too. Norway maple and Tree of Heaven make decent firewood. Tree of Heaven grows in places where native species don't seem to adapt, and help prevent erosion. Japanese Knotweed blooms and makes good honey at a time when many other honey producing plants are not flowering.

Andy B. said...

Strongly agree with your conclusion.