On Orchids and Fungi

It is no secret that orchids absolutely need fungi. Fungi not only initiate germination of their nearly microscopic seeds, the mycorrhizal relationships they form supplies the fuel needed for seedling development. These mycorrhizal fungi also continue to keep adult orchids alive throughout their lifetime. In other words, without mycorrhizal fungi there are no orchids. Preserving orchids goes far beyond preserving the plant. Despite the importance of these below-ground partners, the requirements of many mycorrhizal fungi are poorly understood.

Researchers from the Smithsonian Environmental Research Center have recently shone some light on the needs of these fungi. Their findings highlight an important concept in ecology - conservation of the system, not just the organism. Their results clearly indicate that orchid conservation requires old, intact forests.

Their experiment was beautifully designed. They added seeds and host fungi to dozens of plots in both young (50 - 70 years old) and old (120-150 years old) forests. They continued to monitor the progress of the seeds over a period of 4 years. Orchid seeds only germinated in plots where their host fungi were added. This, of course, was not very surprising.

The most interesting data they collected was data on fungal performance. As it turns out, the host fungi displayed a marked preference for older forests. In fact, the fungi were 12 times more abundant in these plots. They were even growing in areas where the researchers had not added them. What's more, fungal species were more diverse in older forests.

The researchers also noted that host fungi grew better and were more diverse in plots where rotting wood was added. This is because many mycorrhizal fungi are primarily wood decomposers. Nutrients from the decomposition of this wood are then channeled to growing orchids (as well as countless other plant species) in return for carbohydrates from photosynthesis. It is a wonderful system that functions at its best in mature forests.

This research highlights the need to protect and preserve old growth forests more than ever. Replanting forests is wonderful but it may be centuries before these forests can ever support such a diversity of life. Also, this stands as a stark reminder of the importance of soil conservation. Less obvious to most is the importance of decomposition. Without dead plant material, such fungal communities would have nothing to eat. Clearing a forest of dead wood can be just as detrimental in the long run as clearing it of living trees.

Research like this is made possible by the support of organizations such as the Native North American Orchid Conservation Center. Head on over to www.indefenseofplants.com/shop and pick up an In Defense of Plants sticker. Part of the proceeds are donated to this wonderful organization, which helps support research such as this! As this research highlights: What is good for orchids is good for the ecosystem.

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