The Forestry Forum

General Forestry => Ask The Forester => Topic started by: straightree on July 02, 2007, 03:56:28 PM

Title: non native tree spieces
Post by: straightree on July 02, 2007, 03:56:28 PM
Over the past times there have been some instances of non native species that have proved to be invasive. Many of these were bushes or herbaceous, some trees. These examples are used to justify the recommendation, and sometime the enforcement, on a universal ban on non native tree species for reforestations or plantations.
I recognize the threat that lies inside the indiscriminate use of non native tree species, but I doubt that a universal ban has a sound basis. There are many species that have evolved in Europe that have good potential for USA, and also the other way. The use of the "American oak" (Quercus Rubra), as it is known in Europe, has a long positive history in that continent, the same for the black walnut tree (Juglans Nigra). Is it reasonable to forbid them inside protected areas, only because they are not native? I do not see any invasion threat, and think that they would contribute to the biological diversity.
I would advocate for a system that regulates the use of non native tree species in protected areas, but can not understand the present trend towards a universal ban.
I would appreciate to hear other opinions on the subject, particularly from people that have a different point of view.

Title: Re: non native tree spieces
Post by: Texas Ranger on July 02, 2007, 04:07:36 PM
Not sure that I can give you the definitive answer, but, much of the decision has to be based on the individual species.  We have had some success in the US with imported species, and some disasters.  Chinese Tallow comes to mind.  I think that should you import a species that has similar growth characteristics to native trees you will not have a "run away" invasion of alien species.

I would wonder if some of the fear on importation lies in cultural rather than biological resistance.  I cannot see red oak or black walnut as an invasive species, it lacks the rapid growth and spread of the true invaders, and here the Empress Tree comes to mind.  I would think that trees with light seed, cotton wood and sweet gum, would be closer to an invasive species.
Title: Re: non native tree spieces
Post by: Ron Wenrich on July 02, 2007, 05:10:58 PM
I favor a ban on shrubs, vines and most trees.  Too often they look good in someone's yard, but they end up doing a lot of damage by out competing the native species.  Often there isn't the check that was in place in the native ecosystem, so it takes off.

We have problems with ailanthus.  It has become a pioneer species with no redeeming value in either forest products or as wildlife food.  We also have Norway maple starting to invade from the suburbs.  It is an OK maple, but it is difficult to match to our native maples when sawn.  It takes up room that our native oaks and maples could use.

Russian olive will take over abandoned fields that used to be filled in with native red cedar.  Oriental bittersweet is now taking over trees.  You can follow the dispersal along main roads from cities. These vines will completely cover trees in a few years. 

Then there's the problem of bugs and diseases.  We've managed to kill our elms and chestnuts and have done some damage to our oaks and now our ashes.  All due to bugs or diseases that don't hurt the invasive plants, but sure plays havoc with the native species. 

I think if you want to have trees with similar characteristics of non-native trees, maybe we should try to alter the native tree genetics.  That's what has been done with our native chestnut.  We've bred some non-native blight resistance. 
Title: Re: non native tree spieces
Post by: Tom on July 02, 2007, 05:26:51 PM
I look at the term 'invasive' as something that, not only gets out of hand, but also interrupts the natural development of native life.

Paulownia has a market in the orient, but it is for slow grown trees.  Their attractiveness to farmers here is that they grow fast.  That is contrary to the market.  They have also  gotten out of hand in the USA and the mountains that once grew valuable hardwoods are being taken over by paulownia.  It's become a weed.  The same has occurred with Mimosa, Chinese Tallow, Eucalyptus, Hyacinth and many other plants, mostly garden plants.

My personal opinion is that valuable plant life may provide a crop for farmers where no crop currently exists and testing is the only way to know that a plant will not "take over".  To condemn a plant solely on its not being natural may not be the most intelligent way of handling it.

Still, we have been invaded by plants, insects, reptiles and warm blooded animals that were originally thought to be harmless by someone.  Some of those causing us the most fear now are the tropical fish and snakes that have been turned out into our waterways and swamps.  For a homeowner in Florida to be confronted with a Python is an example.

Black Walnut may be native in the USA, but there are places where it is a weed.  It is poisonous to horses.  Those who raise horse don't want any close by.  Black Walnut is also capable of keep other trees from growing in their close approximation, so they tend to be able to form clear stands.  That might not be worth the trouble to try to raise something like that in Spain.

The easiest answer is to forbid foreign plants and animals.  On a Governmental level that's about the best way to handle it.  Governments aren't known for their attention to detail and, unfortunately, birds, wind, wild animals and roots don't recognize artificial boundries like signs and fences.  There really isn't a protected or "controlled" area when it comes to wildlife.
Title: Re: non native tree spieces
Post by: Ianab on July 02, 2007, 05:39:40 PM
Strange situation is NZ. We have a lot of problems with imported species, very strict import controls (now) and yet 99% of our forestry industry relies on non-native species  :P

One thing that has happened is that we have just sped up the movement of species around the globe. It used to happen before, it just took ages and various freak happenings. This changes ecosystems as species re-shuffle themselves. Good or bad - depends on your outlook I guess.

Cheers

Ian
Title: Re: non native tree spieces
Post by: Riles on July 02, 2007, 07:10:52 PM
A guy fishing on the Catawba river here in NC caught a piranha the other day. Apparently it wasn't the first time it's happened. Says he won't be swimming there any more...
Title: Re: non native tree spieces
Post by: WDH on July 02, 2007, 08:12:17 PM
Some non native plants have had a huge positive effect on society, mainly food plants.  We don't hear much about the good ones.  Most people do not even recognize the good imports.

So, some good and some bad.  Completely banning all non native plants seems too extreme. 
Title: Re: non native tree spieces
Post by: straightree on July 06, 2007, 12:17:23 PM
Thank you for all the answers.

Yes in the past there have been successes and failures, regarding non native species. In Europe we have tomatoes, potatoes and corn, because they were brought from the Americas. In Spain the chestnut (Castanea Sativa) was introduced by the Romans. So it seems that all we need is to learn from past and amend. Is the same we do in other human activities. Roads are made more secure; cars introduce safety belts, ABS, and other improvements to make accident less probable, but no politic is forbidding riding cars because it is a risk.

Risks should be addressed, particularly those relative to invasiveness, and pests. But I think it is possible to do it in a responsible and effective way. In fact, the main useful non native species are already grown in local nurseries. Black Walnut or American Oak may be purchased in many nurseries close to my home. Probably the pests are propagated mainly by wood crates of imported goods, and tourists.
Title: Re: non native tree spieces
Post by: straightree on August 12, 2007, 03:06:34 PM
I have found an information that may be useful, since it gives considerations about when and how exotic species may be useful. I give the link to the net page. It belongs to Pro Silva, an European organization active on forestry practices that are environment friendly.

This is the link http://ourworld.compuserve.com/homepages/J_Kuper/Page4_E.htm.
Title: Re: non native tree spieces
Post by: WDH on August 12, 2007, 05:32:18 PM
Straightree,

Very informative link.  This is a thorny question.  Some exotics like Eucalyptus in Brazil and Radiata Pine in Australia and New Zealand have created new economies.  The world is now too accessible to simply ban everything, so a good set of policies are needed.