[MPWG] [PCA] Electronic Public Discussion: Evaluating the Invasive Potential of Imported Plants

[Bob Beyfuss]

Hi Steve
I agree with much of what you say below, in particular the part about 
ecosystems not being static! This is my point entirely! If a natural event 
such as a forest fire burns up a forest, It will soon be colonized 
(invaded?) by new species of plants that were not there before the fire. 
These plants may be considered as "exotic" to that forest ecosystem since 
they were not there before the fire but moved in afterwards as result of 
the fire. Whether those plants were present nearby 100 years ago or 400 
years ago makes no difference. The process of colonization followed by 
succession is exactly the same whether the pioneer species are native from 
400 years ago or introduced 100 years ago. . The big question is "what is 
native?" or how long does a plant or animal have to be here before it is 
considered "native". Policy makers (not scientists, scientist know that 
picking dates like this is not at all scientific) have 
"arbitrarily"  chosen the time period of somewhere around the year 1600 AD 
as the beginning of "exotic" plant importations and hence invasions. This 
is almost as stupid as saying that black locust is an "invasive, exotic" 
plant species in NY State when it is "native" to Pennsylvania. Yet black 
locust is "listed" as such by the Invasive Plant Council of NY.  I have 
issues with "lists" like these.
The Asian peoples that colonized the United States before European 
settlement brought plants with them and many of those plants became 
naturalized and since they were here before 1600 they are now considered as 
"native".  The plants they brought in had the same virtues or vices as 
plants imported since 1600. Undoubtedly they affected the previously 
"native" ecosystems just like the post 1600 plants have affected the 
current "native" ecosystem. As you point out, these systems are not static. 
They are constantly changing whether due to natural events such as fire or 
wind or tides, or man made events such as acid rain, global warming, 
paving, selective herbicides etc. Policy makers have decided that "we like 
these ecosystems that have been here since 1600 and we will are trying to 
protect them from the invasive plants". But it is the environment that 
ultimately determines whether any given plant will survive or not. The 
plants that appear succeed or fail based on the environment that is 
"currently" in place. When the environment changes, so too will the species 
composition.
The Catskill Mountains of NY State where I live used to be called the "Blue 
Mountains" because of the blue like haze they presented from a distance. 
That color was due to the fact that the predominant tree species was 
hemlock associated with beech. Settlers cut down almost all the "native" 
hemlock  for the tanning industry. Since the environment was drastically 
changed by removing the hemlock the tree species that succeeded them was 
not hemlock but sugar maple. The Mountains no longer projected the blue 
haze and now they are called the Catskill Mountains. In this situation 
sugar maple may be considered an "exotic invasive" species since it has 
clearly changed the ecosystem it replaced. Sugar maple did not "destroy" 
the native environment any more than garlic mustard will "destroy" the 
current environment but it will surely change it.
I have no problem with people trying to  preserve a "current" ecosystem 
because they happen to like that ecosystem but this is purely an arbitrary 
decision and not how nature works. If you want to get rid of a particular 
plant, that is fine with me, but don't force me to cater to your whim. To 
pretend that preserving a current ecosystem by banning plants that "might" 
be successful in it is bad, very bad policy.
This policy diverts sparse resources from far more pressing environmental 
concerns, like global warming and other habitat alterations caused by 
humans that are correctable by means other than banning plants. As Jean 
pointed out, when a coal company blows the top off a Mountain, we should be 
happy that anything grows back! I would much rather have Norway Maple 
growing along the street than no tree at all. This policy also assumes that 
someone in Washington or Albany or some other state capital is able to 
distinguish "good" plants from "bad" plants. I sincerely hope that 
scientists don't make judgmental calls about "good and bad"  plants. In 
science there are no "good" or "bad" plants. There are just plants with 
different characteristics. Yes, purple loosestrife will displace many other 
species of plants and form almost a monoculture for a period of time. No 
one really knows how long that period of time will be. It might be 50 years 
or maybe even 100 years but if there is anything we know for sure, we know 
that it will not be there forever.  To label purple loosestrife as a "bad" 
plant overlooks its good points. It makes wonderful honey, it does provide 
food for many species of wildlife as do the much maligned "exotic" 
honeysuckles, Autumn olive, multiflora rose, etc. By banning plants simply 
because they are exotic and may be potentially invasive, what potentially 
valuable plants are we excluding? Should people like Liberty Hyde Bailey, 
Thomas Edison and the many, many other botanists who made collecting trips 
abroad be condemned as evil people because they brought back new plant 
material? Should the pilgrims have been forced to leave behind the plants 
they used in the old world?  90% of the food we eat and a substantial 
amount of the plants we enjoy horticulturally are "exotic".
The county executive in NY who "banned" the use the use of all but native 
plants in any county landscaping projects should be "banned" from drinking 
coffee, tea, orange juice, milk and beer. He should not eat beef, chicken, 
pork, bread, tofu, rice, apples, oranges, kiwi fruit, mangos, avocados, 
lettuce, onions, garlic, cabbage or any of it relatives. He should remove 
his Kentucky bluegrass lawn, all his spring flowering bulbs, most of his 
shrubs and most of his other landscape plants as these are all "exotic" 
species. Failure to do so makes him a hypocrite in my opinion.

Robin wrote that some of these "exotics" have formed an almost impenetrable 
thicket on her property. Have you ever tried to walk through a "native" 
rhododendron thicket in Virginia or North Carolina? A botanist I know who 
works in the Smoky Mountains calls these thickets "Rhododendron hell" but 
they are "native". A rose by any other name still smells sweet.

In a nutshell, my main problem with this whole issue is that it is 
extraordinarily arbitrary and judgmental. European honey bees have 
displaced many, many other native pollinating insects but since we like to 
eat honey, that is OK? The multi colored Asian lady beetles has displaced 
virtually every other species of lady beetle in NY State but since the 
imported beetle eats fruit pest insects, that is OK too. Never mind that 
the "fruit" they are protecting are in themselves, exotic species. 
Scientists may observe nature and report that species A is now replacing 
species b,c or d. When scientists start saying that this is "bad" or "good" 
they are imposing their opinions and not their observations. When policy 
makers start making policies based on opinions, we suffer as a nation.

It is nice that in this Holiday season, some of us have time to engage in 
these interesting discussions. Happy Holidays to all of you, native 
Americans and exotics too!

bob

bium hirsutum, they were introduced as
>ornamental plants after European settlement. I'll add the
>introduced Spartina species and hybrids in Washington to my
>examples, introduced as packing material with  oysters
>imported from the eastern US and as an attractant to
>improve hunting for waterfowl.
>
>If you mean all of the other species in these systems
>(grassland/prairie and high and low salt marsh), in numerous
>ways. If you're asking for a quick dissertation on movement of
>plants and biogeography, sorry, I don't have time and I don't
>think its immediately relevant to your comment.
>
>My primary point here is that the belief that invasion and
>establishment of new plant species necessarily requires
>disturbance does not appear to me to be supportable. I think
>there are two underlying inaccurate assumptions: 1) The
>assumption that ecosystems do not normally undergo
>non-antropogenic cyclical disturbance at varying time scales;
>and 2) that in the absence of disturbance, new establishments
>are not possible.
>
>On 1, every system I'm familar with undergoes cyclic
>non-anthropogenic disturbance on time-scales ranging from
>centuries (i.e. fire in some forest types) to decades (i.e.
>windstorms in forest; major riverine flooding, etc.) to years,
>days and hours (i.e. tidal pulses in estuaries). I think that the
>perception of nature as a static, stable, unchanging entity is a
>culturally based popular myth that is not supported by the
>science.
>
>On 2, acceptance of this myth than leads to the conclusion
>that successful invasion and establishment must, in all cases,
>be associated with disturbance. However, I do not see
>support for this. While disturbance may increase the
>probability of successful establishment of new species, it is
>not always necessary. The two examples I originally provided
>support this conclusion, as does the hyper-sucessfull invasion
>and establishment of Spartina. Establishment of all three of
>these species results in major changes to the invaded
>systems. Cytisus scoparius shades out the native grasses and
>herbs, and its Nitogen fixation causes fundamental changes in
>soil chemistry that the native species cannot exploit as
>sucessfully as numerous exotic species (i.e. rhizomatous
>grasses of recent European origin). Epilobium hirsutum
>appears to have the potential to invade and convert huge
>areas of high salt marsh to extensive monocultures, displacing
>the existing (native) species. The Spartina species colonize
>low salt marsh and mud flats that were formerly mostly
>unvegetated, but highly productive of invertebrates that are
>key resources for numerous higher trophic levels. Spartina's
>presence than traps silt, increasing the vertical level of the
>substrate, and fundmamentally changing functions such as
>nutrient export and productivity.
>
>The changes outlined above from these successful invasions
>are detrimental to the previous communities in these
>systems; in come cases, the injury reverbrates much further
>(i.e. Spartina and Pacific Salmon). None of these invasive
>species is in any trouble in their native range. But the systems
>they are invading and changing are. Native prairies west of the
>Cascade Mountains in Washington have been reduced >90% in
>the <200 years since European settlement. Most high salt
>march in the Puget Sound region has been altered by diking and
>draining. Pacific Salmon have been similarly reduced and
>additonal impact to estuary function, structure, and
>productivity from Spartina act as another impediment to
>recovery.
>
>-Steve
>====================================================
>
> > Hi Steve
> > How did they get there in the first place?
> > Bob
> > At 08:37 PM 12/20/2006, you wrote:
> >
> > > > >>> Bob Beyfuss <rlb14 at cornell.edu> 12/19/2006 4:40 PM
> >>>
> > > > New or different plants do not displace established
>existing
> > >plants in healthy, undisturbed  ecosystems.
> > >
> > >My observation is that this is not so. I'll provide two quick
> > >examples.
> > >
> > >Cytisus scoparius (Scot's Broom) commonly invades and
> > >establishes on intact prairie (grassland) remnants in
>Western
> > >Washington.
> > >
> > >I'm currently watching Epilobium hirsutum (Hairy Willow
> > >Herb) increase exponentially (forming moncultures) in an
> > >undisturbed high salt marsh on Puget Sound. This species
>now
> > >covers more than 20 acres. It is not visible at all in aerial
> > >photographs from 1995.
> > >
> > >While disturbance may increase the frequency and success
>of
> > >colonization by new species, it is not always necessary.
> > >
> > >-Steve
> > >---------------------------------------------
> > >Frosty Hollow Ecological Restoration
> > >â•Ë›Helping Nature Healâ•Ë‡
>‡
> > >Box 53
> > >Langley, WA  98260
> > >=======================================
> >
>---------------------------------------------
>Frosty Hollow Ecological Restoration
>“Helping Nature Heal”
>Box 53
>Langley, WA  98260
>=======================================
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