North American Fruit Explorers mailing list at ibiblio

[Steven Covacci <filtertitle@aol.com>]

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.
A short-list:
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.

NON-NATIVE SHRUBS-

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