Almost all land plants are connected together by an underground network of symbiotic fungi called mycorrhizae. There are thousands of different species of these symbiotic soil fungi which entangle...

plant science discussion, then after I post your answer I will send you someone else's post because I need to reply to two students


Almost all land plants are connected together by an underground network of symbiotic fungi called mycorrhizae. There are thousands of different species of these symbiotic soil fungi which entangle plants’ roots living between and within their cells. A spider web of tiny fragile fungal cells tunnel through the soil linking all of the plants together. The fungi draw carbohydrates from the plants and the plants in turn collect nutrients and water from the fungi. As much as 80% of a plant’s nitrogen and phosphorous plus minerals like copper, iron, potassium, zinc, calcium and sulfur can come from the mycorrhizae. But can plants share their resources with each other via the fungal grid? Biologists have long suspected so. Scientists in Switzerland have now traced carbon molecules slowly moving by cytoplasmic flow from tree to tree by this underground fungus pipeline (Klein et al., 2016). It has been estimated that up to 4% of the forests’ carbohydrate production from photosynthesis passes along this superhighway. Klein and his coworkers started their experiments by blowing “standardized” CO2 through a system of thin perforated tubes interwoven among the needles of Norway pine trees. They followed carbon 13 atoms (using the technique of stable isotope labeling) as they were picked up during photosynthesis and passed from CO2 into sugar and other organic molecules. The labelled CO2 was not detected in the air of neighboring trees or on the ground so the scientists felt secure that only the test trees were receiving the labels. This meant that when the carbon 13 label was detected in neighboring trees, the scientists could safely conclude that the molecules had been transported between plants by way of the soil network and not by way of the air. Interestingly, some of these adjoining trees participating in the exchange were European Birch and Larch trees, completely different species than the pine (Figure 1). The researchers became satisfied that the fungus was indeed the pipeline when they found that labelled organic molecules were detected in the mushrooms of fungi that were linked to the Norway Pine. These are called ectomycorrhizal mycorrhizae because they live on the surface of roots and between the root cells. They did not find labelled carbon in mushrooms that were not part of the mycorrhizae network but were soil fungi that break down dead organisms (i.e., saprotrophic fungi). Figure 1. The interconnections of mycorrhizae and trees in a forest. Mycorrhizae are involved but other soil fungi are not. Organic molecules can be exchanged between different species of trees via this route. Carbon and nutrient flow tends to move from trees which are in the sun to trees that are shaded and from older trees to seedlings. From: Van der Heijden, M. 2016. Underground networking. Science 352: 290–1. Reprinted with permission from AAAS.   In another important related study, researchers in British Columbia studied the fungal and Douglas fir tree interactions in a 30 × 30 meter plot of ground (Beiler et al., 2010). They collected samples of two mycorrhizal species connecting the various trees. They determined that all of the 67 trees in the plot and 64 trees outside were interconnected in a complex network (Figure 2). Trees of all ages were involved but the oldest trees had the most connections; one 94 year old “hub tree” connected to 47 other trees by way of 8 mycorrhizal individuals of one fungus species and 3 of the other. In principle chemical products could be interchanged throughout the system. Figure 2. Diagram of a 30 m × 30 m plot in a Douglas fir tree forest of British Columbia. Each green circle is a tree and the various lines depict the connections between individual trees by the mycorrhizae. The tree at the lower right of the diagram (indicated by an arrow) is connected with 47 others in the plot. From: Beiler et al., 2010, “Architecture of the wood-wide web,” New Phytol   After you finish reading the case studies above, follow the link below to watch a TED talk from one of the researchers: How Trees Talk to Each Other (Links to an external site.)   Based on what you read and watched, answer the discussion questions below: 1.Explain how this sharing of resources evolved. What possible advantage could there be to organisms sharing resources? 2.In the TED Talk, Dr. Simard makes the assertion that “trees talk.” Based on the case study above, the TED talk, and what you’ve learned in lecture, explain the processes by which communication occurs amongst the trees. 3.Why is clear-cutting a less efficient strategy for logging? What would you recommend is a better strategy and what are the benefits to both the logging industry and the ecosystem?