Invasive plants

“On a global basis…the two great destroyers of biodiversity are, first, habitat destruction, and second, invasion by exotic species…” – E.O. Wilson (Strangers in Paradise, 1997)

As with other post-agricultural land that has not immediately been converted to other purposes, the old fields of our conservation area have been invaded by non-native plants that have few natural enemies in our region.  These are plants that each have at least one, but usually more, of the following characteristics that allow them to out-compete native plants.

  • They produce prodigious amounts of fruit and have high germination rates.
  • They shade out native plants, and often maintain their leaves longer than native plants.
  • They alter  the soil chemistry, often releasing toxic chemicals, so that native plants won’t grow around them.
  • They are more tolerant of  extremes in light, moisture, and temperature than native plants.
  • Because they didn’t evolve in this region, they no longer have the natural enemies  that co-evolved with them.

So, why not allow these superior non-native plants to take over the fields and spread into established woodlands, wetlands, and other natural areas?  Aside from any aesthetic tastes, historical importance, or nostalgia we might have for our native plants,  our native wildlife depends on them.  Our native insects and other animals evolved with native plants, often requiring specific plants to survive.  The loss of one native plant species could cause the extinction of one or more native insects that rely on it for food or reproduction.  Though insects may not be our favorite creatures, birds and other animals depend on them for survival, and other plants, including the food crops that we depend on for survival, depend on insects for pollination. The point is that we can’t afford to allow our native plants and animals to become extinct, and many argue that exotic species invasion is a leading cause of  wildlife extinction.

Biological pollution

In their new regulations on prohibited and regulated invasive species, the New York DEC calls invasive species “a form of biological pollution.” If we choose to accept that definition, our conservation areas are quite polluted, probably no worse than most other  properties with similar histories, but if they are to be called “conservation” areas, they should probably be held to higher standard and be kept as free of pollution as is practical.

Our most obvious invasive plants

The following plants have all been seen at one or more of out conservation areas.  They are listed in the order of their New York State relative invasiveness rankings. (100 would be as bad as any invasive plant could possibly be, and 0 would indicate no foreseeable problems in New York.) These rankings are shown in parentheses after their species names. Because they are state-wide rankings, the numbers don’t necessarily indicate their prevalence in this area or even their true potential for being a problem in any specific area. There are probably many plants that should be on this list that haven’t been noticed. If you have any to add, please contact us.

  1. Autumn olive – Elaeagnus umbellata (94)
  2. Common reed – Phragmites australis (92)
  3. Japanese barberry – Berberis thunbergii (91)
  4. Purple loosestrife – Lythrum salicaria (91)
  5. Multiflora rose – Rosa multiflora (89)
  6. Pale swallowwort – Vincetoxicum rossicum (88)
  7. Exotic bush honeysuckle – Lonicera tatarica, morrowii, & ×bella (86)
  8. Garlic mustard – Alliaria petiolata (84)
  9. Black locust – Robinia pseudo-acacia (81)
  10. Common/European buckthorn – Rhamnus cathartica (81)
  11. Curly pondweed – Potamogeton crispus (80)
  12. Knapweed – Centaurea stoebe, diffusa & psammogena (79)
  13. Mugwort – Artemisia vulgaris (79)
  14. Privet – Ligustrum vulgare and/or obtusifolium (68/77)
  15. Canada thistle – Cirsium arvense (71)
  16. Myrtle – Vinca minor (57)
  17. Bird vetch – Vicia cracca  (54)
  18. Wild parsnip – Pastinaca sativa
  19. European dewberry – Rubus caesius (ID uncertain)
  20. February daphne – Daphne mezereum

Invasive plants of concern.

These are plants that are known to be in the general vicinity,  but which have not yet been reported at any of the  town conservation areas.  Of course they are likely to be found in one or more of the areas in the future.  Please report sightings of these plants in any of the areas (just contact us, including as specific a location as possible).

  1. Japanese/giant knotweed – Falopia japonica & sachalinensis (98)
  2. Asian bittersweet –  Celastrus orbiculatus (87)
  3. Norway maple (including the widely planted ‘crimson king’) – Acer platanoides (82, DEC regulated)
  4. Winged burning bush – Euonymus alatus (81)
  5. Giant hogweed – Heracleum mantegazzianum (72)

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