posted 7 years ago
For the tree communication part of your question, the answer is "we* are just learning now the intricacies of plants communicating with other plants and the soil microbiome".
There is quite a lot of experimenting yet to get started to arrive at some of the answers, this is something we all are thinking of as "In its infant stage", so much has to be done to come up with an experiment that can produce reproducible results, it can take up to a year just to get a study off and running, then you have at least a year of data collection followed by calculations so that you can come up with the probable relationships and methods of communication, which are all chemical and electrical by the way.
What we do know is that plants secrete sugars (mostly complex but some are simple) that bacteria come to feed on, we also know that there are some electrical signals that accompany the secretion of these exudates.
The electrical signals are either positive charged or negative charged, each calls out to different bacteria as well as alerting fungi, amoeba, nematodes, flagellates, and other organisms of the microbiome that live in and create the soil complex.
As these organisms react to the signals and food exudates they communicate with electrical charges and chemical secretions to each other at the same time, this sets up the chain reaction of bacteria eating the exudates, the fungi, amoeba, flagellates and nematodes all join the "feeding frenzy" that results in the nutrients the plant needed and called for to become available, all the excess nutrient is then re ingested by the microorganisms and thus is ready for a new call from the plants. Some fungi live in close contact with the root systems, others actually invade the root cells, fungi will also engulf those nematodes and flagellates that could be considered predatory or parasitic, thus rendering them into food for the fungi, this also releases nutrients that the bacteria will gobble up and hold within their structure with any excesses put back out for other bacteria to consume.
It is currently thought that it is mycorrhizal fungi that help pass signals from plant to plant just as they provide nutrients to their host root, these have the capability to pass along electrically charged ions, passing them from one host root to another.
It should be mentioned here that these fungi hyphae can be multiple host (plant) with one end around or inside one trees root system and the other end functioning the same way in another trees root system thus if one tree sends an electrical or chemical signal it will almost immediately be picked up by any other tree serviced by another part of the hyphae complex of that fungi.
* the biology and horticultural scientific community.
Redhawk