Question: What is a word that means "periodically purged" or "cleansed by fire"?

Answer: 
*[Swailing](http://scienceray.com/biology/ecology/swailing-hazard-reduction-burning/)* is the term used by the forestry community to describe the process of using intentional controlled burns to reduce the hazards of forest fires and to encourage new tree growth. 

Usage of *swailing* appears particular to wooded parts of the UK (except, naturally, Scotland, where it is called *[muirburn](http://www.scotland.gov.uk/Publications/2011/08/09125252/0)* or *moorburn*). *Controlled burn* is more common in the US. *Prescribed burn* is also common in Australia.

An elegant pen could make fine use of *swailing* in a literary context, but it may send readers running for a dictionary -- and, unfortunately, the reputable entries for *swailing* seem to be few.
The word *[salamanderize](http://books.google.com/books?id=BKMvAAAAYAAJ&pg=RA1-PA38&lpg=RA1-PA38&dq=%22salamanderize%22&source=bl&ots=rkjgr86STR&sig=cE6QXLWJ4gj8_q-fjYzqbFVpnZk&hl=en&ei=jz-yTtypOfTZiALtwY2DAQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEYQ6AEwAA#v=onepage&q=%22salamanderize%22&f=false)* has been used with that sort of meaning (regenerate, rejuvenate), but I think in more recent usage just means to burn up without regeneration. ![date heading - 26 Dec 1914 Electrical World](https://i.stack.imgur.com/EZ9pd.jpg)!['New coils for old' ad in Electrical World](https://i.stack.imgur.com/M7a7J.jpg)

There are several mystical terms that reflect the concept, named with catch-phrases like *fiery rebirth*, *Phoenix rising* and *star fire cycle*. Less-mystical phrases include *fire cycle* (meaning the actual cycle of fire and regrowth in forests), *rising from the ashes*, *tried in the crucible*, and *purified by fire*. The latter two phrases appear in or stem from Proverbs 27:21 and Zechariah 13:8-9 respectively.

*[Serotiny](http://en.wikipedia.org/wiki/Serotiny)* is a related but plant-specific term: "an ecological adaptation exhibited by some seed plants, in which seed release occurs in response to an environmental trigger, [...] The most common and best studied trigger is fire". Etymology from [wordnik](http://www.wordnik.com/words/serotinous): "Latin sērōtinus, coming late, from sērō, at a late hour, from sērus, late."

The term *pyriscence* refers in the main to seed release triggered by fire. Also (mis)used in reference to release due to dry conditions, which more properly is xeriscence.

Pyriscence looks like a word that ought to mean what you want, except it doesn't.