A perspective on black locust

[Peter Smallidge]

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

my comments...

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.

 Ecological

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.

Economic

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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
7. 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....
8. Black locust amends the soils through nitrogen fixation and provides nutritious forage and fodder for ruminant livestock.
9. 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. 

[Brett Chedzoy]

Black Locust is back in the news, making the new DEC list of regulated "invasive" plants.  Of particular concern to me as a forester and agroforester is the language copied below from the document:

What is the difference between prohibited and regulated invasive species? Prohibited invasive species cannot be knowingly possessed with the intent to sell, import, purchase, transport or introduce. In addition, no person shall sell, import, purchase, transport, introduce or propagate prohibited invasive species. Regulated invasive species, on the other hand, are species which cannot be knowingly introduced into a free-living state, or introduced by a means that one should have known would lead to such an introduction, although such species shall be legal to possess, sell, buy, propagate and transport. What species have grace periods established in the regulations? A one-year grace period is included in the regulations for Japanese Barberry

Complete list: http://www.dec.ny.gov/docs/lands_forests_pdf/isprohibitedplants2.pdf

I interpret this as meaning that it's not illegal to plant Black Locust in NYS.  Thoughts?

Copied below are some earlier email discussions with other foresters that never made it on to the forum:

Forester #1: I’m a cooperating forester and am commenting on the inclusion of black locust trees as a “regulated” invasive species.  For the record, I do not agree that this species should be regulated.  It is a native species of the USA and some sources have it as native to the Alleghenies, which, if not in NY, then damn close.

 

I’ve been around this species all my life; first in central New Jersey where I grew up, and now in NY for the past 20+ years.  This species was one included in my college education for Dendrology.  There was never any mention of it being a serious problem in any manner.  I’ve seen some small stands (an acre) or less, usually around old agricultural or abandoned lands, where it had spread as an early successional species; as would poplars, birches and many other species.  However, I have never heard of or seen any situation where this species is problematic in a broad sense.  To the contrary, I recently (2 months ago) had a local wood buyer inquire if I new of any black locust that was available for logging.  The wood of this species is one of the best ever for natural resistance to wood decay.  As such, it is highly regarded and sought for many uses.  It’s much better than cedar for structural strength and I’ve used it myself for a number of building projects over the past 30 years.  I could show you a some black locust pilings I buried for supporting a deck I built 30 years ago in NJ that remain rock-solid to this day, whereas parts of the deck supported by these pilings made of pressure treated wood (with the old arsenic recipe no less) have had to be replaced – and these treated parts were not in contact with the ground, like the locust is.  Not far from this site, I could also show you the remains of a summer bungalow that used black locust as supports and some of them remain solid and in the ground, since they were installed over 100 years ago.  It’s also excellent firewood and has a long history of other uses where a hard, durable wood was required.

 

Black locust is not shade tolerant like Norway Maple and will not invade an established woodland.  In addition to the useful wood, the roots fix nitrogen in the ground and the seeds are eaten by many species including quail, dove, squirrels, and rabbits.  Deer also eat the young shoots and bees make a high grade honey from its nectar.

 

Invasive?  As a forester, I can tell you our native American beech is much more a problem in our forests than black locust will ever be.  If you are going to include species on your invasive species list based solely on this characteristic, you have to include the beech (and see what kind of broad-based reaction you get then!!!).  To the contrary, this characteristic of the black locust is valued for reclaiming “wasteland”.  I’ve seen it planted to reclaim strip-mined areas in PA because it is tolerant to poor and dry soils.

 

Some content from the web:

 

• It is valuable as an      aggressive, rapidly growing invader species that controls erosion in road      cuts, abandoned fields, strip-mined areas, logged forests, and fireswept      areas. Initially colonizing by seeds, it also suckers from the roots,      forming pure stands and snuffing out competitive weeds and woody plants.      Trees of sufficient size are valued for their logs, which make fine      fenceposts, poles, or railroad ties due to the anti-rotting properties of      the olive-green wood. (http://ohiodnr.com/trees/locust_bk/tabid/5380/Default.aspx      )

 

• This is      considered the most durable wood of any species in North America. It is      used in making fence posts, tree nails, rungs of ladders and policeman's      clubs. It has high fuel value. One cord nearly equals 1 ton of      anthracite coal. (http://mdc.mo.gov/your-property/problem-plants-and-animals/nuisance...      )

 

Of course, leave it to the bureaucrats (no offense intended . . . ) to come out with contradicting information.  The content below (bulleted) is from the USDA Forest Service (http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/robinia/pseudo... )  This site also will show you with a map that it is native in the Allegheny Mtns.

 

• Black locust is      not a commercial timber species but is useful for many other purposes.      Because it is a nitrogen fixer and has rapid juvenile growth, it is widely      planted as an ornamental, for shelterbelts, and for land reclamation. It      is suitable for      fuelwood and pulp (my highlights)      and provides cover for wildlife, browse for deer, and cavities for birds.

 

(Not commercial?  Since when were fuelwood and pulp classified as not commercial?  I’ve also seen hardware stores with sawn and shaped black locust for sale as fencing.)

 

                         Also from the USDA FS site (with my highlights):

• Black locust is a pioneer type, usually      man-influenced, and temporary. It follows disturbances and may be natural or planted.      The type is found locally throughout the Eastern United States and in      southern Canada. Black locust makes up a majority of the stand during      early stages but is short lived and seldom matures to a sawtimber stand. A wide variety of species      become associated with black locust and usually replace most of it.

 

• Reaction      to Competition- Black      locust is very sensitive to competition and is classed as very intolerant      of shade (44). It is found in closed forest stands only as a      dominant tree. Reproduction is not successful until perturbations create      openings in which black locust, because of its rapid juvenile growth, can      compete successfully. In open areas, dense herbaceous growth often      prevents seedling establishment (37). On spoil banks in Illinois, survival      rate of planted black locust was 83 percent on sparsely vegetated sites      but was only 31 percent on densely vegetated sites (5).

Forester #2:  Here are my quick two cents regarding Black Locust.  From a pragmatic financial point of view Black Locust has the potential to produce more forest income per acre than a lot of other species currently tracked on the stumpage report.  Here are the reasons.

            1.    The species can and does replace exotic tropical hardwoods such as Ipe for upscale outdoor applications in a vastly more sustainable manner.

            2.    As previously mentioned by Mr. Statts it is also more viable than pressure treated for longevity plus it is a far more environmentally benign option than pressure treated lumber.

            3.    It grows much faster than other higher value species based on stumpage price.  I recently measured a 21inch diameter Black Locust stump on my property that was only 33 years old.  A comparable sugar maple would be at least 100 years.

            4.    Mills specializing in Black Locust are rumored to be paying up to $400 per thousand for high quality logs at the landing.

Based on this information one could grow 3 equal aged harvestings of Black Locust in the time it takes to grow one equal aged harvesting of Sugar Maple.  The Sugar Maple would have to be sold at $1200 per thousand to equal the value of the Black Locust produced over the same time period and because of the time value of money the comparison would be even more in favor of Black Locust.  While it is currently possible to obtain these prices for premium Sugar Maple other species such as Ash and Birch, to name a couple, can’t match the value of Black Locust.

In my opinion the value of Black Locust in the marketplace is likely to increase significantly going forward as its environmental advantages become more widely recognized.  Other more traditional species are unlikely to experience a general continued market improvement because of their historical uses and are instead subject to the well known “in and out of favor” traditional pricing.

I do not know what the upshot of the “invasive” classification would mean but it is clear to me that limiting a landowner’s potential forest based income is probably not the best alternative.

 

[Brett Chedzoy]

I asked Nicole Horowitz  from NY Farm Bureau's Public Policy department for some clarification on this.  Her response is below (phew!)

A “free living state” would not mean a farm or technically anywhere else in NYS. The Adirondacks are the best example because they are the essence of free-living and the need for non-introduction of a potential invasive species. A free living state would not be a farm as it is technically a controlled environment as are people’s yards and communities (as anything planted in a town or city is done by/with a landscaper to choose plants and trees that would provide a benefit to the area). Essentially the goal of regulating is to educate the customer on purchasing the product and what it would potentially do to the environment if they planted it in an inappropriate place.

[John McNerney]

I don't know how I missed this when it was first posted. What was the result of the proposed legislation? Is Black Locust now regulated?

I think it is a vastly under-rated species by many foresters. There is a reason that many old farms had a planted stand of Black Locust - it's an incredibly useful wood. If I had found the stand of it on my property sooner, my deck would be made out of it. The structural members of the shade pavilion we recently constructed are Black Locust harvested from about 100' from where the pavilion stands. We've used Black Locust logs for parts of the obstacle course we built in our woods. The leftovers from these projects make good firewood. Finally, as others have noted, it's great having a natural alternative to pressure-treated lumber (the Red Cedar growing on our property lacks the form and strength for many of our projects).

[Carl Albers]

I have been observing different stands of black locust now for many years.  The characteristics of individual trees, straightness, growth rate, smoothness of the bark, resistance to the locust borer, etc. are all no doubt affected by soil type, drainage, soil organic matter and soil pH.  If one is interested in starting a black locust plantation for timber production plant on the best soil you can find.  Preferred would be a well-drained soil, high in fertility and organic matter levels with a pH around 6.5.  In my opinion, timber characteristics are also very much influenced by genetics and if you look at different stands you will notice lots of variation in straightness, diameter growth, and how rough the bark is.  The latter is important because you can't make bark into boards.  So seed should be collected from isolated stands with superior timber-type characteristics.  I think it may make sense to establish black locust plantations in mixture with some other fast growing hardwoods, to shade the trunks and shade the ground early in the season as a way to discourage invasive shrubs - black locust leafs out late.  I don't know which hardwoods would work best?  Some ideas would be red oak, basswood, butternut and black walnut.  Butternut should only be planted on upland sites with good air drainage/circulation/movement as these are the only conditions that allow this species to fight off butternut canker long enough to produce timber.  Kenworthy is a butternut-Japanese walnut hybrid that is known to have good resistance to the butternut canker - don't know about timber form.  Butternut seedlings can be purchased from the Clements State Tree Nursery, WV Division of Forestry.  When collecting black locust seed from superior stands it is also a good idea to collect some of the soil from around these trees so that you can inoculate the seedlings with the Rhizobia bacteria that allows black locust to fix nitrogen.