Thursday, February 23, 2017

A Tiger in Winter

When someone mentions a tiger the first thing that comes to mind to most of us is the large striped Asian predator. Usually we think of tigers prowling the jungle; but Siberian tigers, the largest of all tigers, actually inhabit far eastern Russia where winters can be severe and the snow deep.

However, Siberian tigers aren’t the topic here.

It was February and I was repotting several amaryllis bulbs that we had overwintered in the basement. Amaryllis, which are not hardy here and must be overwintered indoors, produce spectacular flowers that can easily reach eight inches in diameter. These bulbs originated from several that Gerald (see this previous post) had given me a number of years ago.

The potted bulb had been in the basement since early October, without water. As I took the bulb and dry soil out of the pot what also emerged was a tiger in the form of a six-spotted tiger beetle –

Tiger beetles are extremely active predators of spiders and small insects both as adults and larvae. They spend their larval stage in burrows in the ground with only their heads exposed; there they wait for passing prey which they grab with their large mouthparts.

Adult six-spotted tiger beetles are bright metallic green (occasionally blue), typically with six white spots on their elytra (wing covers). They frequent paths and quiet roads in wooded areas where they dash about as they pursue and capture prey. Tiger beetles are so fleet of foot that their speed is said to be the equivalent of a human running at 700 miles an hour.

This tiger beetle undoubtedly created its larval burrow in the amaryllis’ pot when it was outside in the garden last summer, came in with the pot and pupated, changing into an adult in the pot in the basement.

Northcentral Pennsylvania has had unusually warm weather this February (the climate is changing) so perhaps the tiger beetle will survive outside.

If it does, this may be the last thing some unlucky insect or spider will ever see –

Thursday, February 16, 2017

From the North I

Our son and his family live far to the north, on the side of a large mountain with many different habitats – the valley at its base, on its slopes and on its peak. For several years I’ve had a couple of camera traps there to capture photos of the wildlife that lives on their property or wanders through.

My primary targets are the predators that inhabit this large tract of wild country, but there's a lot of other interesting wildlife. Here are some of the photos from a camera trap set at a fallen tree: the blue jay that stopped by –

And the red squirrel caught in mid leap to the same tree trunk –

That old fallen tree really attracts wildlife, a raccoon (one of many raccoons photographed there) –

 A white-footed mouse (also one of many) –

And the long-tailed weasel that came to hunt the mice –

And even a young white-tailed deer that inspected the fallen tree –

Then checked the camera trap -

A subsequent post on In Forest and Field will feature photos from another location on their property.

Thursday, February 9, 2017

Oak Tales

The dead white oak stood along a seldom-traveled township road where it had caught the eye of someone with a chainsaw who needed firewood. The first time I saw the tree it had been felled and all that remained was the stump and the smaller branches.

Whoever cut the tree was pretty good with a chainsaw so the stump was quite smooth. The tree’s annual rings, formed each year as the tree grows in diameter, spoke of its life. Oak trees in temperate areas like northcentral Pennsylvania form annual rings that can usually be seen clearly. The wood that is formed in spring consists of large-diameter vessels that are easily seen with the naked eye; wood formed in the summer consists of vessels of much smaller diameter.

The width of annual rings depends on the many things that impact the tree’s vigor: on the availability of water and nutrients, competition from neighboring trees, defoliation by insects or disease, damage from ice storms or logging, root damage from flooding or soil compaction – or a host of other factors.  

Looking at the annual rings on this stump, it was obvious that there was a great range in the width of the tree’s annual rings –

The outer inch of wood, the tree’s sapwood, was deteriorated due to decay, but the heartwood was sound and undecayed (the heartwood of white oak is decay resistant because the vessels are blocked by deposits, called tyloses, that block fungi).

The age of the tree at the time it died can be determined by counting the annual rings. Although a few of the annual rings were difficult to distinguish, it appears that the tree was 112 or 113 years old when it died. The annual rings became markedly narrower during the last 25 years of its life, probably due to competition from surrounding trees. 
Much more interesting is the tree’s remarkably slow growth from age 45 to age 62. What happened to put a brake on its growth in 1949 and then suddenly speed the growth up in 1966? It could be any one or a combination of quite a few things that stressed the tree, reduced its vigor and slowed its growth.

Many years ago I was visiting a landowner whose family had kept meticulous records of activities in their woodland; he showed me a stump that had a very similar pattern in its annual rings. He’d counted the rings in the stump and realized that the sudden jump in the annual rings' width occurred nine years after his grandfather had sold timber thereby removing some of the competition from adjacent trees that had been cut.

The nine year delay was apparently the time it took for that tree to add leaf surface to its crown following the logging and then begin growing more rapidly. Perhaps that’s what happened with this tree as well – which still doesn’t explain a sudden tremendous spurt in growth rather than a slow acceleration as the leaf surface gradually expanded year by year.   

Unfortunately, although this stump has a story to tell there’s no way to interpret the tale without a detailed history of the weather, insect defoliation, and logging that could tell us more about the life of this tree.

Thursday, February 2, 2017

Beware the Sun

That bright orb in the sky, that average star in an ordinary galaxy, that object we call the sun is what makes most life, as we know it, possible on this otherwise unremarkable planet. We have so much to thank the sun for: the temperature of our atmosphere; the energy supply that allows plants to photosynthesize and, directly or indirectly, feeds almost everything on earth; the light that enables us to see and enjoy the beauty of the things around us. But the sun can also “do us dirt” to the point that we should be careful.

H’s stepfather was an interesting person in many ways – he loved his hometown and his garden, he was on his own from age 12, and he was blind in one eye. He was blind in that eye because as a young man he looked directly at the sun and burned his retina so badly that he had absolutely no vision in the affected eye. So, don’t look at the sun!

There are much more subtle and common ways that glorious star can and does harm us. The sun’s invisible ultra-violet rays are reported to be a major factor in the development of the cataracts that impact the vision of so many of us as we age.

The other major adverse impact the sun has on us is caused by those same ultra-violet rays. Ultra-violet rays striking us penetrate the skin to varying degrees and damage the cells’ DNA. That damage creates mutations that can result in skin cancer of several kinds. Physicians report that both basal cell carcinoma and squamous cell carcinoma are caused by exposure to ultra-violet rays.

For over 50 years I’ve been spending the majority of both my professional and recreational days in forest and field. Except in winter’s cold, on most of those days I went without a hat of any sort, it’s only been for the last 15 years that a hat has regularly been atop my slowly balding pate. More recently I’ve adopted broad-brimmed hats to replace those baseball-style caps.

And for the last few years at each of my annual visits to the dermatologist one or more precancerous lesions or basal cell carcinomas have been removed. Some by surgical excision and some by freezing; this is one of the most recently frozen carcinomas after four days, a touch of frostbite –

Just about a year ago a more serious squamous cell carcinoma was removed by a special surgical technique that resulted in 22 tiny sutures on my cheek –

A year later the incision has completely healed and the scar is barely visible.
Those of us who work and play outdoors know that our skin will take a beating over the years: insect bites, adverse reactions to plants like poison-ivy or stinging nettles, lots of cuts and scrapes, frostbitten ears or noses and the possibility of skin cancer.

The sun is not just a harmless source of heat and light; it damages us also – so beware the sun!