[nafex ibiblio list] Alternatives to Autumn-olive (and the negative ecological impact of Autumn-olive)
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Mon Jan 9 13:06:48 EST 2012
Autumn-olive (Elaeagnus umbellata) [when it (easily) escapes cultivation into the wild] crowds our our native species, recruiting even on sites (as long as in good sun) that are low in fertility - sites to which native plants (often very rare ones) are adapted; so, in such cases, Autumn-olive not only takes up niches that could have, otherwise, been a spot for native plants (plants which are ecologically more beneficial - since birdfood is not everything.. you have to consider that many native insects rely upon specific native plants to feed from and will not utilize exotic invasives, such as Autumn-olive). Next, which is an easily over-looked fact: Autumn-olive is a considerable threat to native plants that are specially adapted to comparatively infertile sites not just because it is so successful at propagating itself and growing quickly - and densely causing shade to the herbaceous-layer, but because it is so successful at enriching the soil with nitrogen: so, after the Autumn-olive dies or allows some light to pass through it's canopy while it does persist, what will grow on that site is not your uncommon native flower, grass, or sedge - or tree/shrub seedling, but some exotic invasive weed that, although it couldn't recruit or thrive well on that site before the introduction of Autumn-olive, now can do so - thank's to the nitrifying of the soil.
Now, there are native and other non-native nitrogen-fixing shrubs - these have about the same effect (and usage potential) as the invasive nitrogen-fixing shrubs and trees, but will not easily escape your planting and become invasive.
NATIVE SHRUBS -
Elaeagnaceae (Oleaster Family)
Silver buffaloberry (Shepherdia argentea) - for colder regions; excellent edible fruit - edible but be cautions.. not edible in large quantities; thorny for hedges.
Russet buffaloberry (Shepherdia cadandensis) - for colder regions; bitter fruit - edible but be cautious.. not edible in large quantities; NOT thorny
Silverberry (Elaeagnus commutata) - for widespread conditions; heard the berry is not that good
Legumosa/Fabaceae (Bean family)
Amorpha fruticosa - nice flowers, magnetic butterfly host to the species that utilize it, etc.
Guomi (Elaeagnus multiflora) - for widespread conditions; berry is like a larger, better Autumn-olive; thorny; selected cultivars readily available; doesn't send-out adventitious roots to colonize
I suspect that seabuckthorn/seaberry (Hippophae rhamnoides) has the potential to become an alien invasive in parts of the U.S.; it is in Canada and the U.K.
As for nitrogen-fixing trees, jujube (Ziziphus jujuba) - non-native; only plant honey-locus and black locust (toxic) where native, as it is an invasive U.S. native that will naturalize quickly.
Not all members of the bean family (Legumosa/Fabaceae) are nitrogen-fixing (i.e. the native - Red-bud, Cercis spp. is not).
And you have all sorts of bean family native herbaceous plants, like Cassia spp. and Senna spp.
I bet that Autumn-olve (and the Russian-olive, E. angustifolia - also invasive) might be a little better of a nitrogen-fixer then most (?) of these more ecologically considerate and responsible choices, but the compromise is well-worth it if you're a nature fan; and I read some research papers on buffaloberries (Shepherdia spp. - above).. it looks like they put out a ton of nitrogen, so maybe they would be just as effective, as long as you are in a colder zone then say 7 - I'm growing it with good results, so far, in 7a/6b.
Steve; NJ 6b/7a
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