By Thembi Borras
An ever present reason for the decline of a tree is old age. The age after which trees decline varies with species and site quality. In forestry terms, some identify this age as being synonymous with the culmination of mean annual increment (CMAI), which is defined as the age at which the stand volume production rate is maximized. Although we like to call it the "Golden Years" for ourselves foresters offer the term "senescence" for this stage in the life of a tree.
What got me thinking about senescence was my visit in April to the Mendocino Coast Botanical Gardens to see the bishop pine, which was prompted by one of the volunteers. He wanted to have more information for patrons when they asked about the health of the bishop pine, which he said they often do.
Of the 47 acres that comprise the Mendocino Coast Botanical Gardens, several acres support a relatively even aged overstory of bishop pine, some of which have died and been topped or removed for safety. Several bishop pines display dead brown branches within the living crown, otherwise known as flagging and many of the crowns appear to be thinning.
Typically, the number of years a tree has lived, alone, will not cause flagging or death. Instead age yields a weakened state that invites a myriad of biological agents and when combined with harsh environmental conditions and animal damage may lead to the demise of a tree.
Too much water can also tip the balance. For example, shore pine on the west side of Highway 1 just north of the Albion River Inn started dying several years ago. According to Jack Marshall, Forest Pathologist at the California Department of Forestry and Fire Protection, the mortality agents are the pine engraver beetle and sour sap beetle. The shore pines follow a watercourse, which is likely receiving increased water due to a change in the water drainage pattern.
If the bishop pine at the Mendocino Coast Botanical Gardens will run their course in the next few decades the question becomes how can the next generation be encouraged without the benefit of fire, which bishop pine needs to regenerate. Bishop pine seeds are stored in closed cones until the cones are opened during fire or very hot conditions when large numbers of seeds are released to inhabit the disturbed ground.
A portion of this production was gleaned from the website: http://en.wikipedia.org/wiki/pine.
May 14, 2006
Poison Oak
By Thembi Borras
It is a test of your mettle as a forester to get up in the middle of the night to call owls, to weather winter storms checking road drainage and stream crossings, to wipe blue paint off your face when you mistakenly stand downwind, to be dirty, to run property line down 100% slopes, to crawl or throw yourself at old growth huckleberry and to run cruise lines through poison oak. These experiences are badges of merit. However, having chewed the field challenges of the "dirt" forester, I could do without the poison oak. Oh I suppose I could also do without the 100% slopes, but everything else I embrace and is balanced by the perfect spring days spent on gentle terrain in the woods.
When people find out I am the poster child for poison oak sensitivity, their first question is how can you be a forester here in poison oak country. A rigid multi step routine, supported by a type A personality and obsessive compulsive disorder generally keeps me poison oak free unless it is above shoulder height.
The culprit is a chemical called urushiol found in the sap of poison oak. Ironically, human bodies, which defend against urushiol, contract the aggravating symptoms, whereas the bodies of the 3% of humans that are "immune" do not defend against the chemical. According to Terry Kratwurst in her article on this subject in the June/July issue of Mother Earth News: "Within 15 minutes after you get the substance on you, it's carried into the dermis (the inner skin layer) and bonds with skin protein to form an antigen. The first time this occurs, nothing obvious happens- no one is "born sensitive" to urushiol….But sooner or later most people's immune system develops some degree of distinct biological distaste for the urushiol spawned antigen. At that point, whenever the antigen's presence is detected…T-cells rush to the hated invader and attack, releasing chemicals that literally destroy the surrounding skin…better known as poison oak dermatitis."
The most frustrating aspect of contracting symptoms is questioning the source. Since there is a lag of as long as 4 days from the time you encounter the chemical to the time symptoms manifest you can imagine the speculation. Was it the dog I petted three days ago? A perfect ending to this story would be a cure, but after having tried pharmaceuticals and homeopathic remedies there is no magic cure and unless I want to move to Nevada the only State entirely free of species containing urushiol I will live with it, buck up and stop complaining.
It is a test of your mettle as a forester to get up in the middle of the night to call owls, to weather winter storms checking road drainage and stream crossings, to wipe blue paint off your face when you mistakenly stand downwind, to be dirty, to run property line down 100% slopes, to crawl or throw yourself at old growth huckleberry and to run cruise lines through poison oak. These experiences are badges of merit. However, having chewed the field challenges of the "dirt" forester, I could do without the poison oak. Oh I suppose I could also do without the 100% slopes, but everything else I embrace and is balanced by the perfect spring days spent on gentle terrain in the woods.
When people find out I am the poster child for poison oak sensitivity, their first question is how can you be a forester here in poison oak country. A rigid multi step routine, supported by a type A personality and obsessive compulsive disorder generally keeps me poison oak free unless it is above shoulder height.
The culprit is a chemical called urushiol found in the sap of poison oak. Ironically, human bodies, which defend against urushiol, contract the aggravating symptoms, whereas the bodies of the 3% of humans that are "immune" do not defend against the chemical. According to Terry Kratwurst in her article on this subject in the June/July issue of Mother Earth News: "Within 15 minutes after you get the substance on you, it's carried into the dermis (the inner skin layer) and bonds with skin protein to form an antigen. The first time this occurs, nothing obvious happens- no one is "born sensitive" to urushiol….But sooner or later most people's immune system develops some degree of distinct biological distaste for the urushiol spawned antigen. At that point, whenever the antigen's presence is detected…T-cells rush to the hated invader and attack, releasing chemicals that literally destroy the surrounding skin…better known as poison oak dermatitis."
The most frustrating aspect of contracting symptoms is questioning the source. Since there is a lag of as long as 4 days from the time you encounter the chemical to the time symptoms manifest you can imagine the speculation. Was it the dog I petted three days ago? A perfect ending to this story would be a cure, but after having tried pharmaceuticals and homeopathic remedies there is no magic cure and unless I want to move to Nevada the only State entirely free of species containing urushiol I will live with it, buck up and stop complaining.
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