The NYS DEC is soliciting comments on their proposed regulations of invasive species through today (12/23/2013). I'll share my perspective on black locust that I sent in response to the request for input. I offer this here in case (1) someone can expand on what I've argued or (2) someone notes a shortcoming of my argument in which case I'm especially interested.
A link to the report http://www.dec.ny.gov/animals/63402.html
A link to the proposed regulation http://www.dec.ny.gov/regulations/2359.html
I am writing to express my concern that black locust (Robinia pseudoacacia) is listed as a “regulated” species, in fact that it is listed at all. My arguments for this perspective are numerous, but I frame them below in an ecological and economic context. I appreciate the sensitivity that surrounds this discussion, but feel strongly that the negative attitudes towards black locust are unwarranted. I offer these observations based on my Karner Blue butterfly habitat research in the Albany pine bush in the early 1990’s, my training as a forest ecologist, and my work with NY woodlot owners and farmers as the NYS Extension Forester. Even knowing what I know about its role in the sand plains and impact on Karner Blue butterfly habitat, I feel it is one of our most important hardwood trees. The classification of black locust seems unjustified, and more generally the listing of black locust of “invasive” is questionable.
I understand that black locust lacks explicitly documented historical record from within the state, which forms the primary basis to argue that it be considered non-native. I also am familiar with its potential to frustrate land and habitat managers in the area of the Hudson River sand belt that corresponds to habitat for the Karner blue butterfly. I suspect that the strongest argument for listing black locust as an invasive species is based on the observations and experiences of land managers/conservations who work with the Karner blue butterfly. In my experience and research in this area (Smallidge, Leopold, and Allen 1996. J. Appl. Ecol. 33:1405-1419), black locust could be effectively managed. Past land uses have exacerbated the abundance of black locust, but this has relevance and bearing only as a human artifact not as a condition of the species. As I illustrate below, the arguments for black locust as an invasive species are insufficient in consideration of its life history and the given the burden placed on those who work with and benefit from black locust.
- For the plant species that are listed as either prohibited or regulated and that I have knowledge, all have native distributions outside of the United States; black locust being the singular species with a US distribution but that is listed as invasive. The known native distribution of black locust (USFS Silvics Manual) reports black locust from PA and within two counties of the NY southern tier border. The demarcation of the true boundary, given a reasonable margin of error (see #2 below) is tenuous. An eastern species such as black locust should be viewed with criteria that are distinct from a species that might have a fully southern or western historic native distribution.
- Commonly, the historical record of the native range of black locust is based on original land surveyors. Land surveyors would provide surveys of “warrant maps” when requested for parcels of land given to Revolutionary War soldiers or other citizens (Abrams and Ruffner, 1995. Can J. For. Res. 25:659-668). Other surveys were by county surveyors as lands were settled. In these cases, witness and common trees were noted, and these form the basis for much of the basis of the historic distribution of trees. The species documented by early land surveyors (Abrams and Ruffner 1995, and citations therein, notably Siccama 1971) comprise almost entirely shade tolerant species, or shade intolerant species that are longer-lived then black locust (e.g., eastern white pine). This isn’t surprising given black locust is highly sensitive to shade and propagates by disturbance. These characteristics would make black locust an improbable survey witness tree given pre-settlement forest conditions. However, the soil and site conditions where black locust occurred, at the interface of the Allegany Front and Ridge and Valley provinces in these early surveys, are replicated well into NY. This provides reasonable doubt that the historic range of black locust stopped abruptly just south of the NY border despite the similarity of growing conditions across the state border.
- Of the prohibited and regulated plant species on the proposed list for which I have familiarity, black locust is oddly the only species that is intolerant of shade and which has fairly restrictive regeneration criteria. Other listed woody, shrub and herbaceous species have broader ecological amplitude. I have not made a formal categorization of black locust according to Grime’s triangle of plant strategies (Grime, J. P. 1979. Plant strategies and vegetative process. Wiley, NY). However, black locust would seem to fit well as a ruderal species (i.e., short lived and requiring disturbance) while most other forest invasive species would be some combination of strategies related to successful competitors and/or stress tolerators (e.g., Norway maple, Japanese knotweed, Japanese barberry). From this I question the ability for black locust to effective sustain any vegetation management complications it possess while established. In the absence of sustainable problems at a given geographic point, its role as an invasive species is questionable. There is no doubt that black locust can reproduce effectively following cutting, but equally valid is the recognition that black locust disappears without disturbance. This is a succession limited species. I’m not aware of other invasive plants with a similar pattern. Goals to develop and maintain artificially high levels of early successional habitat should not disparage black locust because it responds to similar treatments.
- From my knowledge of black locust, I am not aware of allegations for it being perceived as a problematic plant outside of the Hudson River sand belt and perhaps Long Island. Black locust can be found throughout most of the rest of the state yet without documentation of being troublesome. In all areas, black locust provides important economic functions. The point here is that the geographic ratio of areas with problems is a small percentage of the area with economic and ecological benefit.
- Although native species are not under consideration, listing a species such as black locust (in light of arguments made here) doesn’t pass the “straight face” test when it is considered against the significant and widespread problems caused by native species such as American beech, striped maple, eastern hophornbeam, and most rhizomatous ferns. These species, though officially native, have significantly greater capacity for ecological hardship and without any or many redeeming attributes. Although NY law specifies the definition of an invasive species, regulatory agencies need to develop and apply guidelines in a way that makes sense in the broader context of ecological and sustainable management.
- Overarching in the discussion of economic values of black locust is its widespread availability throughout NY. As such, it becomes accessible for local production and use, and as a locally sourced product. Its value to local use, local economies and local communities cannot be ignored. These factors contribute to its role in on-farm endeavors that would typically be poorly documented, and in local cash sales that also (albeit illegally) might be underreported.
- The same author who provides the historic distribution of black locust (A. Little, as cited in the USDA Silvics Manual) also includes black locust in “Important Forest Trees of the United States” (1978 USDA Agric. Handbook 519) that includes species of commercial importance. Black locust has a well-established economic importance.
- Black locust makes the best fence posts of all eastern species. Fence posts are important for locally sourced agricultural enterprises related to livestock, vegetable production (as deer fence), and grape production. Black locust has the highest rot resistance plus wood properties that allow for it to pound easily with mechanical fence post drivers.
- Because of the rot resistance of black locust, it is preferred as a source for exposed wood elements. For construction and building projects that will avoid chemically pressure-treated lumber, black locust is a preferred option. A lumber mill near Ithaca (T. Brown www.locustlumber.com, pers. comm. 2013), who I believe commented in response to the DEC Invasive Species report, described the very high demand by architects and engineers because of the rot resistance and engineering attributes of black locust. He reports, from his mill alone, sales of 150,000 to 200,000 board feet per year.
- Because of its fast growth and specific gravity, it has the ability to quickly sequester carbon. Because its products are long-lived (e.g., fence posts, decking, etc.) the sequestered carbon remains out of cycle for long periods of time.
- Black locust is reported to be the most dimensionally stable hardwood after drying. Other attributes of black locust as a wood are highly favorable. The potential for expanding the demand of black locust is significant. More details about its engineering properties are here http://www.thag-o-mizer.net/Hardwood.html
- Black locust has the highest BTU rating of any species. This makes it a favorable species for wood heat, and other applications of woody biofuel utility. http://www.daviddarling.info/encyclopedia/W/AE_wood_heat_value_BTU....
- Black locust amends the soils through nitrogen fixation and provides nutritious forage and fodder for ruminant livestock.
- I am unaware of any other eastern hardwood that has the black locust’s profit potential for forest owners and farmers. The life cycle of locust lends itself to profitable commercial production associated with its fast growth, management options, and variety of products. Through either natural or artificial establishment, black locust will grow quickly. Within as little as 10 to 12 years following natural reproduction methods, locust of post size can be harvested. This provides cash flow early in the rotation and fairly quick recovery of any establishment costs. While thinning for posts, high quality and well-formed stems can be released from competition for sunlight and allowed to develop into higher value sawlogs. Two or more thinning s for posts are feasible within a forest stand as the higher quality sawlogs are encouraged.