Greetings Paul,
The term “introduced” as commonly used in forestry, ecology, horticulture, etc., infers that a particular species has become established outside its native range. There are many synonyms (e.g., non-native, invasive, exotic, etc.); however, certain synonyms may often have different inferred meanings. For example, the term “invasive” often (but not always) suggests that a particular species is both an introduced and an aggressive reproducing plant which often complicates management objectives because said plant can readily occupy a site or landscape and displace more desirable, native vegetation. A common, invasive species to Illinois is tree-of-heaven (Ailanthus altissima); tree-of-heaven is both invasive and exotic (i.e., non-native species introduced from outside the US). Note, some native species can be termed “invasive” in nature. Switch-grass, a native, perennial, warm-season prairie grass is often perceived by some natural resource managers as invasive because it has the potential to overtake a given site (if planted to heavy to switch-grass) and suppress other native grasses and forbs.
Another term commonly used in tree identification books is the phrase “naturalized”, which in essence means that a particular introduced species has become successful in reproducing in the wild without direct human assistance. A common, naturalized species to Illinois is Osage-orange (Maclura pomifera), which was introduced in Illinois by Jonathan Baldwin Turner. Osage-orange, a native tree in the US, is indigenous to Oklahoma, Texas, and Arkansas. White mulberry (Morus alba) is also a naturalized species common to Illinois, but unlike Osage-orange, white mulberry is an exotic species.
Direct seeding is still an appropriate afforestation/reforestation technique and this technique still has a niche in USDA tree planting programs such as the Conservation Reserve Program (CRP). Over the last few years, the number of acres planted to trees via USDA Farm Bill conservation programs has decreased primarily due to the huge success Illinois enjoyed during the 1990’s through 2005 via these federal and state conservation initiatives. In essence, a large majority of acres that were eligible for CRP are currently enrolled in USDA Farm Bill conservation programs. Now, you mentioned increases in agricultural commodity prices and I surmise this cyclical phenomenon and concomitant US biofuels initiative has caused a modest to significant decrease in USDA Farm Bill conservation program enrollment (although I would need to verify such a statement with actual data from the USDA Farm Service Agency).
Thanks for the question Paul!
