Invasives 2

My interest in plants began about 15 years ago when two students Alison Cella-Mowatt and Caitlin Lindé decided to do a independent study project on Native American medicinal plants. We naively hoped to associate these plants with specific environments and use them as possible predictors for locating Native American campsites. We learned a lot about the plants and environmental change over the last 15,000 years, but we were all surprised to learn the number of non-native species that make up the plant life of New England today. The girls went on to bigger and better things in college while the research they began research slowly grew to become a database of over 400 plants that have been or can be found at Sheep Pasture.

The database tells us that about 140 of Sheep Pasture's  plants are non-native. Of those less than 30 are considered invasive. The simplest definition of an invasive plant species is a non-native that has the ability to displace or diminish native species or limit species diversity or alter the balance of an ecosystem. That should eliminate species that, like us, have naturalized in the environment. People sometimes confuse weeds with invasive species. A weed has been humorously defined as any plant in a place where it doesn't belong. A carnation that pops up in a field of garlic is a weed, but it is not an invasive. In the world of birds a flock of Canada geese on a golf course can be a "weed," but a family of mute swans are invasive because they are non-native and uproot and damage pond vegetation and displace native species of waterfowl with their truly nasty dispositions. Back in the world of plants, for humans, no matter where it appears, poison ivy is a weed because it makes us itch. However, it's not an invasive because it's native and "fits" into the ecosystem.

Plantain is the common name for two non-native weeds. They may hold the record for being the first plants to be placed on a "watch list" for invasiveness-the Native American name for these two are white-man's footprint because the plant quickly took root wherever Englishmen walked due to the habit of plantain seeds sticking to shoes. Whether you recognize the name or not, you are familiar with these little immigrants. Here's their mugshots:

That's common plantain.

This shows English plantain flowers. The leaves are more lance shaped then common plantain. The two plants share a common genus Plantago, but have different reproductive strategies and somewhat different environmental needs. They have been around for so long in New England that it's impossible to tell if they displaced any native plants, but they seem to fit into the ecosystem pretty well. By this I mean local bugs eat them with the same verve as they do native plants. John Eastman's indispensable book The Book of Field and Bog notes fungi that attacks the leaves and seeds, flea beetles attack common plantain while the sap beetle prefers the English plantain. Everyone recognizes the wooly bear caterpillar and plantain is a favorite food plant for them. The seedpod weevil eats the seeds as do many birds, chipmunks, and mice. Grouse, rabbits, deer and domesticated grazers all eat the leaves. In other words plantains have biological controls that keep them in check and prevent them from becoming invasive.

We'll finally look at that Globe article, and it's so-called new view of invasives in tomorrow's blog. 

On Invasives 1

The Boston Globe published an article on invasive species Sunday that has elicited some comment. It is a not very well written example of sensationalizing journalism-sort of like all those articles that spotlight the one scientist (usually paid by an oil company) that is predicting a new Ice Age rather than global warming. Going to the abstracts of the underlying scientific journal articles we find the 19 scientists featured in the Globe opposed by an article signed by 141 other scientists. The Globe article is no longer easily available online, but since it was in the Globe, it will probably do much damage to the effort to control invasives. I intend to blog my views on this article tomorrow since invasive species control is a subject that has interested me for almost twenty years.

Today, I want to present an an interesting article from Scientific American that also relates to invasive species science. No scientists in the invasive species debate doubts the potential impact of introducing a new species onto an island. The arrival of Old World mammals and snakes to Pacific islands like Guam, Hawaii and New Zealand has had devastating effects on local bird populations, The cited article details scientific experiments that document the impact of bird extinction on the pollination of native flowers.

What caught my attention was the mention of passenger pigeons, which used to exist in America by the billions, until they were shot into extinction by hunters. These missing birds were mast feeders eating hickory nuts, beech nuts, and chestnuts and spreading these seeds in their guano. What effect has the loss of the passenger pigeon had on our forests? The author of the article suggests the extinction might have contributed to forest loss, but I think this might be an unfair extension of the research featured in the article. In areas where flocks of passenger pigeons flew, they would often darken the sky with their numbers for hours according to early observers. Thus, it's unlikely that other mast distributors like chipmunks or squirrels have taken up the slack from their loss. However, to attribute forest loss to the passenger pigeon extinction is probably inaccurate. Forest loss was almost exclusively caused by the spread of agriculture. With agriculture's decline the forests are coming back, but with the absence of the passenger pigeon it's accurate to speculate that the composition of the forest has changed. One thing we know for certain-no one is getting their heads covered with poop from billions of pigeons!

Haymakers

Pushed the wrong button yesterday and erased the whole blog!

A haymaker is a wild swing used for a one punch knockout. The origin of the term comes from old time haymakers who swung a scythe in the same motion as the punch. Today's blog is about the "haymakers" faced by today's haymakers: poison ivy, nettles, and wasps.

At Sheep Pasture we try to balance our need for animal feed with the needs of various animals in the environment. If we hay too late, the nutritional value of the hay declines, but if we hay too early, ground nesting birds can lose their nests. As an earlier blog noted, turtles also cross our fields to find nesting spots and they have a hard time avoiding the blades of a mower. Just to make things more complicated, the bluebirds on our property like to hunt for insects in short grass so if we delay haying too long there is a possibility that second nestings could be negatively impacted. Finally, no matter when we hay, the many rodents in our fields suffer. Meadow voles are common in our fields and they and their young are often exposed by mowing offering a smorgasbord for hawks and foxes. To keep a year round population of these prey items, we leave reservoir areas unmowed around our biggest field.

Poison ivy makes things difficult for haymakers as they load the newly harvested bales into storage. Poison ivy causes it rash from an oil on the leaves. The rash appears four to forty-eight hours after exposure so you have sometime to limit or even prevent the damage. We use something called Tech-Nu which breaks up the oil and allows it to be washed away. You rub it on, let it sit for a minute or two, and then wash it off. It also works as a pretreatment for clothes. Tech-Nu is available at some garden centers and pharmacies. One should not use Tech-Nu within three days of using hydrocortisone ointments, another common treatment for poison ivy.

Before poison ivy appeared seemingly everywhere, nettles were the primary itch provoker in hay. Stinging nettle does its damage with hollow hairs that act like hypodermic needles to inject histamines and other chemicals that cause an immediate stinging sensation. Since the effect of the sting is immediate, Tech-Nu won't help. Rubbing on a hydrocortisone ointment helps take the sting out, but the most soothing folk remedy is the juice from crushed jewelweed.

Probably the most dangerous part of haying are wasps. Yellowjackets and their cousins the bald faced hornet make paper nest. Bald faced hornets make a ball nest in trees and woe to anyone who gets too close. These large wasps are extremely aggressive, attacking with little or no provocation anyone who closely approaches the nest. They will also pursue people for a substantial distance away from the nest. Each hornet can sting multiple times and has the most painful sting I have ever encountered.

Unlike bald faced hornets, yellowjackets most often make their paper nests underground. By the time July and August roll around, these nests can contain thousands of stinging insects. Vibrations in the ground can send these wasps into attack mode, but they are generally more peaceful the bald faced hornet. At Sheep Pasture, the dangerous time for yellow jackets is during baling. The tractor or baling machine hits the nest and the innocents in the hay wagon are the ones who suffer the wrath of the wasps. Louis Hain, our property manager, tells of the time when he looked back to see both people on the wagon jump off and run away as fast as they could to avoid what Louis said was an actual cloud of stinging insects.

Yellow jackets are well know visitors to picnics particularly in the late summer and early fall. This is because the adults normally feed on nectar and as flowers become less common, the insects are attracted to jams, jellies, and sweetened drinks. Yellow jackets hunt insects to feed their young and they are significant predators of many insect pests. Unlike other mud daubers and digger wasps who paralyze live prey to feed hatching eggs. Yellow jackets chew up the bugs before feeding them to their larva in the nest. The larva respond to this feeding by secreting a sweet juice that the adults drink.