Greetings! We are monitoring several indigenous colonies of Ram’s Head Lady’ Slipper orchids. Our measures are plant height, length of lowest leaf, width of lowest leaf, number of leaves, and presence of a flower. My question is this: Using these measures, how can we quantify the “health” of each plant, and the “health” of a colony of plants? If there are generally-accepted methods of quantifying plant/colony “health” using other measures, we would also appreciate hearing about such measures. Thanks!
That’s a good question!
I don’t think you can quantify the health of your plants in an absolute way. That is, knowing that the plants have leaves 5 cm wide and stems 10 cm tall is not going to be enough information to determine if they are ‘healthy’. Even if this is significantly smaller or larger than other sites, it could just reflect differences in soil or other conditions.
However, if you track the size over time, that might be a very useful measure. Knowing that your plants are getting shorter from year to year, or are flowering less frequently, would be important in determining if their health is declining. This is the basis of population viability analysis, or stage-based demographic studies.
I would contact the North American Orchid Conservation Center; someone within their network is likely to be able to offer monitoring protocols.
It would be good to know what proportion of flowers go on the produce full seed pods, and reach the stage of releasing the seeds.
As well as assessing individual plants, maybe it would be useful to monitor the health of the population and of the habitat. For example, are there seedlings and immature plants present that will go on to flower in future years? If all your plants are robust and flowering, that isn’t a healthy population because it means there is no recruitment of young plants.
I see from Wikipedia it tends to grow on Sphagnum mounds. Are there nearby Sphagnum mounds that don’t currently have the orchid, which would give the orchid population scope to expand? If not, is that because of something that you could reverse, such as removing scrub that has covered former Sphagnum patches?
Fixed point photography of the habitat can be very useful, even if you don’t know what you are looking for when you start. It will show you changes a few years later that you maybe wouldn’t otherwise have noticed were happening.