Red Trillium (oil on canvas 5 x 7 in.) SOLD!
As we duck under the branches of trees by the road and step through the bordering stand of Equisetum hyemale, the leafless horsetail that is "put together" like drinking straws inserted end to end, the forest is still there - the old Maples, Beeches, and Basswoods standing tall, older ones lying all over, and young ones growing up around them. But the forest floor is an even sea of Trout Lily leaves. My first thought is "Where's the diversity?" I expected to see all of my old friends the forest floor herbs, bloming or sprouting - Wild Ginger, Squirrel Corn, Twin Flower, Bunchberry, Star Flower, Cohosh, and Wild Ginger. Trilliums Bloom here and there, mostly white in small groups of 4 or 5, and some single Red Trilliums at the bases of trees. Fred saw one Cohosh down by the pond, and one clump of Jack in the Pulpit near where I settle to paint this Red Trillium.
Tell-tale crumbles of soil peek from between last year's dry fallen leaves. Last year's leaves seems to be all there are.... the rest has been pulled underground and consumed by invasive aliens. Earthworms have been here for as long as the Europeans who brought them, but increasingly we've noticed that they are changing the ecology of forest floor, first in urban parks and now even in protected old growth forests!
I rise from my crouched painting position to stretch and drink hot tea from a thermos, and turn a log segment to see if there are any snails. At least ten earthworms flinch and retreat into their holes, and the dark earth is well churned. Wayne Grimm introduced us to this special forest in 1975, and I remember the deep layers of leaf litter he sifted through in search of tiny snails - leaf litter that was home to complex communities of everything from nematodes to springtails to sowbugs to centipedes, to salamanders. Today we find no salamanders, no snails, and of slugs, only a few shiny black Deeroceras laeve and a juvenile Arion sylvaticus.
On Sunday, 13 June, the Macnamara Field Naturalists Club took a field trip to the Shaw Woods to have a look at the leaf litter fauna with Rob Lee, the flora with Eleanor Thomson, and forest bird ecology with Kathryn Lindsay. Like us, they didn't find many Plethodon, but they did encounter two of each of the colour phases, so we've got two samples separated by 30 years, and the observed ratio has changed from 1/13 (in 1975) to 2/2. Four is a small sample size, but Fisher's Exact test gives a probability of only 0.108 that's it's the same as the 1975 ratio.
ReplyDeleteLeadback/redback morph ratios in Plethodon cinereus were an infant concern of mine, so I consider...
Gibbs, James, and Nancy Karraker. 2006. Effects of Warming Conditions in Eastern North American Forests on Redback Salamander Morphology, Conservation Biology 20(3):913-917, June 2006.
http://www.cnah.org/pdf_files/596.pdf
...one of the most exciting scientific papers of recent years. Their finding was that the leadback/redback ratio in this species had increased with, but faster than, increasing temperature over the course of the 20th century. I've mused about the possibility that the excess increase in the leadback morph, above that predicted by climatic warming, may be due to the effects of Earthworms in warming the soil, and in the Shaw Woods we find this result in an Earthworm-ravaged, but otherwise protected, oldgrowth woods, where reduction in litter depth by Earthworms is the main observed long-term disturbance. So, as always, we need bigger sample sizes, from more sites where Plethodon were collected in the past!