# ISA certification challenge questions



## ArborM (Apr 30, 2012)

I am working through the ISA certification guide and I am looking for a few good answers to a couple of the challenge questions to chapter one: 

Question #1: Does a branch higher in a tree receive direct nourishment from lower branches? Discuss the vascular structure of trees and how it relates to branch attachment? 

Question #2: Armillaria Mellea has been described as an "opportunistic" fungus that functions both as a mycorrhizae and a disease. How might this be explained? 

Anyone insight would be much appreciated!


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## Carburetorless (Apr 30, 2012)

ArborM said:


> I am working through the ISA certification guide and I am looking for a few good answers to a couple of the challenge questions to chapter one:
> 
> Question #1: Does a branch higher in a tree receive direct nourishment from lower branches? Discuss the vascular structure of trees and how it relates to branch attachment?



No, the branch only receives as much nourishment as it is capable of producing. 



> Question #2: Armillaria Mellea has been described as an "opportunistic" fungus that functions both as a mycorrhizae and a disease. How might this be explained?
> 
> Anyone insight would be much appreciated!



I think that means that it can attack the tree locally at a wound site, and can also spread and affect the various compartments of the tree, such as the root system, and can spread from one tree to another via pollination, touching limbs, or touching roots and so on.


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## Jed1124 (Apr 30, 2012)

ArborM said:


> I am working through the ISA certification guide and I am looking for a few good answers to a couple of the challenge questions to chapter one:
> 
> Question #1: Does a branch higher in a tree receive direct nourishment from lower branches? Discuss the vascular structure of trees and how it relates to branch attachment?
> 
> ...



Let me give #2 a shot. Armillaria is opportunistic as it acts as both a parasitic fungus in soil toward root function and also a beneficial micorrhiza. It will be prolific and attack newly planted trees after an area has been cleared because it is feeding on dead roots in the soil. Beech ,oaks and pines need micorriza in soil or they will begin to wane. So it can be both beneficial and detrimental to new tree growth. I did cheat and consulted Shigo's New Tree Biology Dictionary! Just happen to be reading it lately:msp_biggrin:


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## ROPECLIMBER (May 1, 2012)

(1) No, the branches of the trees are autonomous meaning they produce more than they need, when they are not producing enough to sustain themselves and the tree as a whole the branch protection zone closes off and eleminates that branch, exceptions would be codomenant branches but which are both in competition and have no true branch union or BPZ.The BPZ is at the brach collar to protect the parant stem and the tree as a whole, the xylum cunducts nessesary elements and moisture up to the leaves as long as the branch is producing (see Transperational Pull), much like the absiccion zone at the leaf of decididous trees the BPZ will close off when the transperational pull has not been "up to parr" this also helps "seal off" aginst any secondary vectors of patogens that may be attracted to the weaker stem or branch. The Phloeum transports the sugars down the branch utilizing what is needed and storing the rest but all with gravity, the only time energy is spent to recover carbs stored is in reciptation wich actually cost energy to convert the stored carbs into usable sugars and this process requires oxygen which the tree gets from the macropores in the soil, see soil compaction,construction damage,root structure,4 primary functions of the roots,
(2)Armillaria Mellea is opertunistic as it utilizes the sugers, that the new root growth excretes in the soil.The roots invest the sugars to promote micro biological break down in an attempt to create usable nutrients,the funi is a parrasite and a fungi but since it actully helps more than it takes it creates the Mycorrhizea symbosis, meaning that both benefit more than they pay, the fungus feeds on the sugars and in return breaks down the existing elements in the soil to a more usable level and helps with absorption of the now more usable nutients and more attainable mosture. by affixing itself to the roots the fungus helps the roots absorb more than they and specifically more usable substance than they could if solo,
think of sybosis as two people coming to the table with 2 and both leaving with 4, doesnt make sense in a humans selfish mind does it.
The fungis is like a barker for a store front it needs the store to pay him but his sales amount to more than his pay,
however if the store closes the barker continues working and brakes down the store front and makes it usable for other store fronts, 
Paul


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