Biotic regulation: ignoring of excessive synthesised organic matter by immotile heterotrophs

[ap.vanduijn]

Dear Anastassia, dear all,

I have been struggling with heterotrophic organisms ignoring organic matter. Please find five quotes from your work below followed by my question at the end.

Best regards,

Arie

"Suppose that the concentration of atmospheric CO2 increases above the level optimal for the biota. To compensate this unfavorable change, the biota can, for example, increase the rate of biochemical synthesis P+ as compared to the rate of decomposition P− (G&M 2004; p.24)."

"In this particular example the heterotrophic organisms must ignore the excessive organic matter synthesized by autotrophic organisms and let it escape decomposition and leave the environment (e.g., by deposition in sediments) (G&M 2004; p.24)."

"All organisms of the immotile life find themselves under conditions when no free (i.e., unclaimed) space, matter or energy fluxes are available (“lack of affluence”) (G&M 2020; p.6)."

"Under the assumption that bacteria form a continuous cover both on land and in the sea (Sieburth, 1976) of thickness L = 5 · 10-5m (G&M 2000; p.84)."

"The layer of biomass of bacteria and fungi in soil is not thick (G&M 2000; p.84)."

Question:

From the quotes above I conclude that if the rate of biochemical synthesis increases as compared to the rate of decomposition, more free matter or energy fluxes will become available. As a result I would normally expect an increase in the rate of decomposition. However, it seems this is not the case. Is this in any way related to the availability of free space? Does more free space become available as well or is space to a certain extent limited? Can it be that space is the limiting factor that ensures that a possible change in the rate of decomposition does not keep up with the increased rate of biochemical synthesis? Thank you.

[ap.vanduijn]

Dear Anastassia, dear all,

While continuing my quest to understand the differences and similarities between immotile ecological communities (i.e. immotile autotroph plus immotile heterotrophs and small animals) and motile ecological communities (animal (host) plus immotile heterotrophs and parasites) with regards to how they each regulate their local environment (local outer environment or local inner environment) I stumbled onto something the connects to my question above and in particular why heterotrophic organisms ignore the excessive organic matter. I'm trying to compare, contrast and link different approaches: mainly biotic regulation of the environment/biotic sensitivity sensu G&M; flexibility sensu Bateson; and primary and secondary feedback sensu Ashby. Now within the toxicological sciences there has, during the past 20 years, apparently been a re-emergence of hormesis as a fundamental dose response model in the toxicological sciences (Calabrese, 2004). 

When I looked at the figure below from Calabrese's publication in Environmental Pollution I started to look at biotic sensitivity and biotic regulation in a different way. Still especially from the viewpoint of why heterotrophic organisms ignore the excessive organic matter. Does it perhaps make sense when I say that the initial non-response is the biotic sensitivity threshold. This is followed by a response (i.e. overcompensation) in line with Le Chatelier's Principle. However, if the dose crosses a certain threshold (e.g. excessive organic matter) it influences the environment of the soil microbiota to such an extent that for example it becomes toxic to a certain number of species thereby limiting their activity. This could be seen as ignoring excessive organic matter. A response to this change in the environment of the soil microbiome could subsequently be a change in species composition and result in a different pattern of decomposition P−. Does this make any sense to you?

[ap.vanduijn]

Dear all,

I just noticed that the figure I thought I pasted in my post above disappeared. I refer to figure 1 of page 380 of the attached publication.

Best,

Arie

[Anastassia Makarieva]

Dear Arie,

Thank you for your questions.

I think that it is essential to differentiate between the lack of abundance of energy/matter fluxes from the lack of abundance of energy/matter stocks. Stocks of energy-rich organic matter are abundant. We go to the forest and see a lot of organic matter, above the ground most of it is in the form of wood. In the ocean it will be in the form of dissolved organic carbon (DOC). Why don't heterotrophs eat it all away?

If we answer this question, we will understand why they ignore the excessive organic matter synthesized by the biota in response to environmental perturbations. The general answer is because they are programmed to act like this. Otherwise the biotic regulation would not work.

More specifically, it is relevant that the excessive biomass is produced in the form of poorly digestible material (indeed, it should be so!). It is a global process during which human food is becoming less nutritious as well.

Dong J., Gruda N., Lam S. K., Li X. and Duan Z. 2018 Effects of elevated CO₂ on nutritional quality of vegetables: A review. Frontiers in Plant Science, 9, 924. https://doi.org/10.3389/fpls.2018.00924

Best wishes,

Anastassia

ср, 6 янв. 2021 г. в 12:26, ap.vanduijn <ap.va...@gmail.com>:

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[Arie Pieter van Duijn]

Dear Anastassia,

You are most welcome. I am slowly trying to struggle my way forward to a more complete understanding of BRE. Thank you for your clarification. As usual it presented me with a new struggle. With regards to your ‘general answer’ it seems that I struggled with terms like ‘ignore’ because it sounds like immotile heterotrophs are making a conscious decision. To me it sounded like they woke up this morning and felt like eating a sandwich instead of porridge while environmental conditions are basically constant except for the presence of excessive organic matter. My error seems to be that I thought of the immotile heterotrophs as organisms separate from their ecological community instead of organisms as an integral part of their ecological community. The way I understand it now, we are not talking about just their individual program as separate from the joint program of the entire tightly correlated ecological community they are part of. Under normal conditions the competitive interaction between uncorrelated ecological communities results in the stabilizing selection of communities with the appropriate joint program. A change in environmental conditions like an increase in the level of CO2 leads to a change in both the quantity and quality of biomass. This leads to direct, but even more importantly to indirect effects (which are usually stronger compared to the direct effects) within the community. These indirect effects apparently include negative feedback on the feeding behavior of those immotile heterotrophs that are responsible for the decomposition of biomass and as a consequence the excessive organic matter is not all decomposed. Does the way I phrase it now make more sense?

Best wishes,
Arie

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Arie Pieter
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"Ambulator nascitur, non fit" (Thoreau 1854)