Getting rid of ivy!!

[Mark J]

14 minutes ago, CambridgeJC said:

Before someone takes this out of context I am NOT saying ivy kills all trees…just those on which it creates a sail for the wind to bring it down. And I fully accept not all those are healthy trees. But more and more will succumb to ivy canopy growth as time goes on. 

Why do you think there are so many unhealthy trees which succumb to ivy?

[CambridgeJC]

2 minutes ago, Mark J said:

Why do you think there are so many unhealthy trees which succumb to ivy?

Because that’s what other contributors are saying. They are the arborists…not me. See earlier posts here. 

[Mark J]

1 minute ago, CambridgeJC said:

Because that’s what other contributors are saying. They are the arborists…not me. See earlier posts here. 

Sorry, what I meant was: what do think is causing all these trees to become so physiologically stressed that ivy has an opportunity to thrive? Plants are opportunists.

[agg221]

42 minutes ago, CambridgeJC said:

Before someone takes this out of context I am NOT saying ivy kills all trees…just those on which it creates a sail for the wind to bring it down. And I fully accept not all those are healthy trees. But more and more will succumb to ivy canopy growth as time goes on. 

You are presenting that as a statement of fact, rather than a hypothesis. There is an interpretation of your statement which is a truism - over time, more trees will grow, more ivy will grow and hence more trees will be covered in ivy and fall in that condition. The questions of significance are how to quantify coverage, how to quantify and differentiate between situations (e.g. species, location, health etc) and whether a greater percentage of trees with a given status are in a given condition.

 

For example, I could argue that a smaller percentage of trees in residential areas are covered in ivy than 50yrs ago. I cannot test that statement but it is likely to be true if I define 'residential' as within defined residential zones, since settlements have generally grown larger, reducing the boundary to area ratio and most unmanaged trees (e.g. hedges) are likely to be around boundaries. Also significantly, the attitude to trees, the generally litigious culture and the ability to do something about them means more large trees are removed from residential areas. Finally, this period represents the rise of leylandii, with over 55M of them planted (2011 figure). These are clonal and hence always planted, so generally in residential areas, and tend to be too dense to support ivy. Therefore, based on the above, I am likely to be correct in my statement without even leaving my armchair!

 

Your previous posts also suggest confirmation bias in that you are agreeing with people who indicate ivy to be a threat and disagreeing with those who do not. The point of good scientific practice is to formulate a testable hypothesis and objectively test it. Of course, most people have a preconception as to what they will find, but it is important to remain objective in the test method, particularly so if you believe you have a significant preconception to make sure that the data is not skewed. If, as you indicate earlier in this thread you have only been researching this subject for a few weeks, I suggest a longer study is needed, taking into account more evidence, before diving in with a strong opinion.

 

I would be particularly cautious regarding dismissal of knowledge gained from books - the books you have been pointed at were written by leading authorities based on many years of practical observation. That does not automatically mean that everything they have written is correct of course - for example my own observation is that Richens contradicts himself at one point in 'Elm' which is generally regarded as authoritative on that subject. If he was around to discuss the point then I would gladly have done so. However, this does not diminish my view of him as the leading authority. Taking a contradictory view to the prevailing understanding is valid but only based on substantial evidence.

 

My anecdotal observation is that ivy appears to be a contributory factor in accelerating the demise of trees, but that is analogous to the role of a co-morbidity in humans such as age or diabetes. Whether the co-morbidity is stress or age, and whether the outcome without ivy would have been retrenchment or failure, is a more complex point.

 

Can I suggest that reviewing the existing evidence (literature review) followed by formulating and sharing a testable hypothesis for peer review on this site would be a constructive route forward? These are, after all, the first two steps in any well constructed research project.

 

Alec

Edited February 19, 2022 by agg221

[openspaceman]

37 minutes ago, gary112 said:

John ,ivy is not a parasitic plant,you are wrong,check before you write 

You are engaging with experts in misinformation, such is social media

[CambridgeJC]

5 minutes ago, agg221 said:

You are presenting that as a statement of fact, rather than a hypothesis. There is an interpretation of your statement which is a truism - over time, more trees will grow, more ivy will grow and hence more trees will be covered in ivy and fall in that condition. The questions of significance are how to quantify coverage, how to quantify and differentiate between situations (e.g. species, location, health etc) and whether a greater percentage of trees with a given status are in a given condition.

 

For example, I could argue that a smaller percentage of trees in residential areas are covered in ivy than 50yrs ago. I cannot test that statement but it is likely to be true if I define 'residential' as within defined residential zones, since settlements have generally grown larger, reducing the boundary to area ratio and most unmanaged trees (e.g. hedges) are likely to be around boundaries. Also significantly, the attitude to trees, the generally litigious culture and the ability to do something about them means more large trees are removed from residential areas. Finally, this period represents the rise of leylandii, with over 55M of them planted (2011 figure). These are clonal and hence always planted, so generally in residential areas, and tend to be too dense to support ivy. Therefore, based on the above, I am likely to be correct in my statement without even leaving my armchair!

 

Your previous posts also suggest confirmation bias in that you are agreeing with people who indicate ivy to be a threat and disagreeing with those who do not. The point of good scientific practice is to formulate a testable hypothesis and objectively test it. Of course, most people have a preconception as to what they will find, but it is important to remain objective in the test method, particularly so if you believe you have a significant preconception to make sure that the data is not skewed. If, as you indicate earlier in this thread you have only been researching this subject for a few weeks, I suggest a longer study is needed, taking into account more evidence, before diving in with a strong opinion.

 

I would be particularly cautious regarding dismissal of knowledge gained from books - the books you have been pointed at were written by leading authorities based on many years of practical observation. That does not automatically mean that everything they have written is correct of course - my own observation is that Richens contradicts himself at one point in 'Elm' which is generally regarded as authoritative on the subject. If he was around to discuss the point then I would gladly have done so. However, this does not diminish my view of him as the leading authority on the subject. Taking a contradictory view to the prevailing understanding is valid but only based on substantial evidence.

 

My anecdotal observation is that ivy appears to be a contributory factor in accelerating the demise of trees, but that is directly equivalent to a co-morbidity in humans such as diabetes. Whether the co-morbidity is stress or age, and whether the outcome without ivy would have been retrenchment or failure, is a more complex point.

 

Can I suggest that reviewing the existing evidence (literature review) followed by formulating and sharing a testable hypothesis for peer review on this site would be a constructive route forward? These are, after all, the first two steps in any well constructed research project.

 

Alec

Alec is quite right but not about me dismissing those who do not support my contention. I am asking for data which both supports and refutes it. So far without much luck. I am attracting a lot of aggressive dismissal without supporting evidence myself. 
I am keen to ask for hard evidence. 
I do not dismiss text books written by authoritative persons but Knowledge moves forward and especially in the field of genetics and ecological environment. There is more being learned every day so not good enough to simply regurgitate so-called facts from the literature without a degree of caution. Learning can be uncomfortable for those who rely on previous knowledge without question. Learning consists of building on previous knowledge and modifying that if new evidence arises. But in principle you are completely correct. My quest is for this potential new evidence based simply on my personal observations which may or may not be consistent with an increasing threat from ivy for whatever reason, climatic or otherwise. 

[john87]

1 hour ago, gary112 said:

John ,ivy is not a parasitic plant,you are wrong,check before you write 

Strictly speaking maybe not, but it is not far from it..

 

john..

[john87]

Going off at a tangent...

 

Why does ivy grow up buildings and telephone poles?? What is in it for the ivy??

 

john..

[gary112]

1 minute ago, john87 said:

Going off at a tangent...

 

Why does ivy grow up buildings and telephone poles?? What is in it for the ivy??

 

john..

It,ll grow up most things,it just needs a support John

[Stere]

Plants tend to grow up towards the light.

 

Phototropism