Modelling: biological productivity, structural resistance, reproductive model

[Tony Croft aka hamadryad]

O.K, please continue....

 

this thread might help explain the science in what i see happening to the "subsidence" reductions on oak mainly, they get done every three to five years and the stress and constant relience on stores weakens them and eventualy, as with one of ours (insurance compulsary condition) is now very very close to the end of its tether, its such a shame.

[Marcus B-T]

OK, we have a very basic model here that describes the inter-relationships between each of the pools and even with a basic model like this it starts to raise some very interesting questions. First is partitioning of carbon between each of the pools. What are the controlling relationships. Initailly all the net carbon (P') production will go into the transient transport pool which I have defined as part of storage S. Then we could look at the partitioning as a kind of pecking order, there will be initially a large demand from B (biological pool) and/or R (reproduction) depending on the timing of flowering. However, trees are a bit chicken and egg. Their perennial biology means that there will be overwinter storage pools which will contribute to B and R so infact the early growth, i.e. leaf emergence and/or flowering will be fueled by stored carbon. Then later after S has kick started the process there will be contributions direct from P' with S used for a brief period. Then stem extension and later leaf growth will be heavily influenced by P'. Timing of stem extension, leaf area duration, flowering and seed production are big issues here.

 

We haven't even started on roots yet!

[Tony Croft aka hamadryad]

so just to get this clear in my head, what are we trying to do here?

[Marcus B-T]

A number of things. All this info has been in my head for some time but is more use written down in some form. But it may not be correct so putting it up here makes it both accessible and subject to review. By having the model we can compare the collated knowledge to experiences and management outcomes. This helps remove some of the guess work. It will also point out the knowledge gaps and where knowledge is thin. So keep posing questions and i will keep building.

[Tony Croft aka hamadryad]

O.k Im not 100% certain where this is going, but i think its going to help what is done by gut instinctintuition uptill now.

 

basicaly I think your trying to work out how we can quantify whento prune, when to remediate soils and more importantly when pruning might be more detrimental than benificial.

 

As a gut thing I know when A tree is struggling, for various reasons, drought, fungi pruning regimes etc

 

I know the trees carbs are stored in the stem and roots during dormancy, and hence a good idea to prune in winter before flush.

 

I know when a tree is stressed due to declining i know when the tree is likley to benifit from pruning even in decline as at the right point this encourages new growth from dormant regions and shortens transport distances and gives the tree a second innings.

 

BUT sometimes I get this wrong, or rather im FORCED to overide gut instincts, sometimes by men far more qualified than i, and the trees suffers as a result, iether now or goes into terminal decline.

 

That proscess takes a long time and often it is long after the work has been done and little attachment is made to the contractor/consultants, this needs to change, but we need a model such as this proposal and we need some form of "forensics" to evaluate how why and when a thing started the chain of downward spiraling

[RobArb]

good read so far:thumbup1:

[Marcus B-T]

The term dormant can be misleading. Firstly what do you mean by this? Even when there are no leaves on trees they can still have periods of growth in the roots and cambium (work by Shigo, and also a Swiss guy whose name escapes me for the moment), also the the transport of resourses to storage pools and also their maitainance over the winter takes up energy. Then which species are we talking about? Some coniferous species show very little dormancy in the UK. Also even with deciduous trees can have only brief periods of revalive inactivity. Although leaf abscision may be temeprature /and/or light triggered any true dormancy is probably controlled by temperature and may be a temperature/pressure thing as has been show in Sugar Maple. This whole dormancy thing is perhaps the first area where information is a little thin but I might be wrong. Some of the research is probably quite old so if anyone out there knows of any good references on this let me know please.

[William]

Some of the research is probably quite old so if anyone out there knows of any good references on this let me know please.

 

T A Villiers Dormancy and the survival of plants (Studies in biology series) - old but good and availale for a reasonable 1p on Amazon.

[Marcus B-T]

Hi, thanks for the ref, I Will get it out at the British Library next time I am down there. Larcher is the name of the Swiss guy by the way, look up his book Physiological Plant Ecology, it is a fantastic read. Also the work of the great Neil Turner from Australia is worth looking up, particularly his work on drought adaptations.

[Marcus B-T]

We have our basic model in place and it is time dependent, so the next step is to put in some contols. I will be using developmental switches based on light intensity and temperature, so that for each developmental change you can have temperature, light or both as the switches. This means we can introduce things like bud break, flowering and leaf fall based on temperature and/or light. More on this later. I will code this all up over the comming weeks so that we can all play about with it and compare outcomes.

 

I will leave the partitioning of roots and shoots out just for the moment to keep it simple.