A Satyrium coriifolium orchid erupts from the fire-cleared sands of a recently-charred fynbos hillside. The fan-shaped leaves belong to a Watsonia, which is a Gladiolus relative. The specific name of coriifolium means leathery leaf, which is apt.
The Cape fynbos ecosystem is home to a surprising number of orchids, at least several hundred species. One of the showiest is the terrestrial orchid Satyrium coriifolium. Growing on seasonally dry sandy sites, these noticeable blaze orange flower spikes bloom particularly well after a fire, as do many other Cape bulbs. Living in a habitat not usually seen as suitable for any orchid, much less such a handsome one, the flowers are often pollinated by sunbirds. Here several plants show off right by the roadside as we drove to Cape Town past a recently-burned area. They were joined by at least a dozen other bulbs, and numerous other fire-stimulated species, including several other orchid species.
I visited the Plants ZA site (a great online resource for identifying and growing many South African plants) and read about this species before writing this post. The Satyrium orchids have not been domesticated much but it is possible for an experienced grower to cultivate them in a pot. They need specific climate conditions, including a strict warm dormancy period in summer, during which they should not be watered or else they will probably rot. It’s not an easy plant to grow in captivity.
A colony of orchids blooms post-fire. They may have had some difficulty flowering successfully in the years immediately ahead of the burn last autumn since the taller woody vegetation would have outcompeted the smaller orchids in size. But with those plants temporarily knocked back, the orchids have a chance to do well for a few years.
Many plants in fire-dependent ecosystems are stimulated by burning, often from the combustive chemicals contained within ash and smoke. These orchids bloom more heavily and have greater seedling survival rates in the few years after a fire than plants in not-recently-burned areas do. Removal of larger plants that compete for sun, water, and nutrients helps smaller fynbos species survive and contributes to overall diversity as long as fires are not excessively frequent. Diversity suffers if fires happen too often; ironically it also suffers if they are not frequent enough. Ideal fire return periods vary with precise fynbos type, but averages between 10 and 30 years to support optimal habitat and growth conditions over time for a wide variety of plants.
Detail of the delicate floral structure of the Satyrium coriifolium orchid. I love this color!
Can you give the link to Plants ZA please? Also I assume these fires are naturally occurring?
Some of the fires are natural but in many places, as everywhere humans live, most are artificial. The difference between natural and artificial fires has to do with causes, timing, and frequency, as obviously a fire burns either way. Natural fires would have occurred in the late summer and early fall, just prior to fall and winter rains, and the plants would have been ready to sprout back form bulbs, crowns, and seeds just in time for the rainy season without a long dry period exposing the seeds and roots to herbivores and seed predators. But with humans in the mix, fires can start at any dry time of year, sometimes late spring, which leaves many plants and the soil exposed to harsh summer conditions for months and months that is abnormal. This stresses the survival of certain species beyond that which is natural for them.
Plus with humans, fire frequency tends to be much greater. Natural might be once every 10 to 30 years, which varies with ecosystem type and locality and species composition. Spacing the fires far enough apart to allow for everything to have a chance to grow to maturity and reproduce is beneficial to the system. But when fires happen too often (every 2 to 5 years) many species reliant upon seed production are eliminated since the plants cannot grow to maturity in time to set seed crops before being burnt prematurely. After a couple of cycles of this, many species are drastically reduced or even made extinct.
So while fire is important and necessary to the fynbos and similar ecosystems (like California chaparral) there is a balance of how often it happens and when it should occur. Too frequent and wrong timing of the year are both harmful, and ironically too infrequent a burn cycle can also be detrimental, and that’s another factor to consider. How long it’s been burned since the last time is also important because it affects fire intensity. As you may know, humans try to suppress fires in some places and that leads to lack of regeneration, decrepitude, high concentration of fuel sources, which then lead to truly raging, devastating fires when they inevitably occur again. When fires are too intense, they can kill things that might otherwise have survived a smaller fire that happened a bit sooner (as in years ago) or at a more benign time of year.
There is no single fire regime that works for every species and every subtle vegetation type perfectly. but by so radically affecting the timing of fires, humans have really altered many ecosystems, and often for the worse.
Here’s the link:
http://pza.sanbi.org/satyrium-coriifolium
I was afraid you would say that about the fires! Such an amazing natural phenomenon. But I hate that humans screw it up as with so many of nature’s ways!
Thanks for the web site info.
We have a terrestrial orchid that looks almost exactly like this Satyrium here in central Mexico at elevations of 1500 – 2000 mts. elevation. When in flower (Aug.-Sept.), I´ll post a pic for you.
Wow, that’s great, I would love to see it. Not sure if the comments section will enable posting of pics though, but if you can find the Latin name I can google it.