[HN Gopher] The Saguaro Solution: Can replanting cacti restore a...
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The Saguaro Solution: Can replanting cacti restore an ecosystem
ravaged by fire?
Author : onychomys
Score : 14 points
Date : 2022-09-30 18:32 UTC (2 days ago)
(HTM) web link (www.biographic.com)
(TXT) w3m dump (www.biographic.com)
| clumsysmurf wrote:
| In the mountain preserve nearby, many (if not most) of the
| saguaros have been killed by a fungus spread by moths. I expect
| the landscape to become mostly shrubbery soon with or without
| fire.
| zasdffaa wrote:
| I don't understand, vegetation in that desert is pretty scarce,
| so what's burning so hot it can kill cacti.
|
| As for the cacti, if anyone reads this who can tell me this is
| wrong: chop up an existing saguaro into sections a foot or two
| long then simply chuck them on the ground. They will root then
| start tillering. Doing this at the right time of year, a few
| months before rain, will allow them to root then become
| established.
|
| Disclaimer - I'm not a cactus, or an expert in saguaro. My advice
| in this area is going to be poor. Especially as I'm a brit who's
| never been there.
|
| Edit: it's in the article, substantial amounts of non-native
| grasses. I'm really surprised established saguaro can't cope with
| that, but I guess they just can't.
| mythrwy wrote:
| That will work with many cactus but not saguaro. They must be
| started from seed and the large ones can be well over 100 years
| old.
|
| (source: I moved and planted saguaro professionally for like 5
| years).
|
| Another note (in case anyone is interested). I experimented a
| lot with germinating saguaro seed back in those days and found
| a method that produces high germination rates.
|
| I fermented the seed within the crushed fruit with a little
| sugar and water for a week or so. Then dried the pulp and
| extracted the seed. Then put the seeds in a water bottle with a
| handful of sand. Then put water in the bottle and shook it
| vigorously for 10 minutes or so. Then poured it out and dried
| it. I planted the dried sand/seed together because it was hard
| to separate out the tiny seeds. Plant very shallow. Mist
| several times a day and keep the tiny seedlings well shaded
| with filtered light.
|
| Small saguaro need a "nurse plant" i.e. they will start under a
| bush with filtered light, and by the time they are big enough
| to poke through they can handle full sun (4 or 5 years).
|
| I think this method somewhat duplicates passing through an
| animals digestive tract, then the action of being tumbled over
| rock and sand during torrential seasonal rain.
| zasdffaa wrote:
| > source: I moved and planted saguaro professionally for like
| 5 years
|
| OK, I'm pretty well destroyed here! Great comeback.
|
| Regarding your germination notes, I would suggest contacting
| suitable cactus organisations. Here in the UK there's one
| (british cactus society) also a major cactus grower in
| Matlock Bath (http://www.abbeybrookcacti.com/) and any
| suitable over there in the US. What you've got may be
| valuable info.
|
| re. germination, you might want to play with ethylene as it's
| a plant hormone associated with ripening and germination -
| crushed fruit might very well emit ethylene
| (https://en.wikipedia.org/wiki/Ethylene_as_a_plant_hormone).
|
| I wonder, how do baby saguaro respond to grafting onto
| vigorous rootstock? Is that a possible avenue?
| prova_modena wrote:
| Sonoran desert resident here. Not to be rude, but your comment
| is informed by some common misconceptions about the desert and
| cacti that would be cleared up by reading the very good article
| linked here.
|
| It's a common misconception that the desert is barren with
| scarce vegetation. Saguaro habitat can include areas which are
| almost continuously vegetated, including palo verde and
| mesquite trees and all manner of grasses, shrubs and smaller
| cacti. There's a good pic in the article of an unburned area
| that shows this (about 1/3 down the page). Even in less
| vegetated areas, seasonal rains can cause bursts of growth that
| then dry out and fuel fires. Certain invasive species
| exacerbate this issue, as mentioned in the article.
|
| 1-2 foot chunks sectioned from a saguaro trunk will quickly
| die. The plant's "spongy interior" mentioned in the article
| will dry out if cut like this. Mature cactus can be
| transplanted but require special care and support as it takes a
| long time for them to get rooted. I'm not sure if saguaro arms
| or larger sections can be transplanted independently as
| "cuttings". Even if it's technically possible its not common as
| the mature plants are extremely slow growing and relatively
| fragile. There are also some state laws around removal and
| destruction of saguaros that would likely restrict a plan like
| this.
| mythrwy wrote:
| I've tried to root saguaro cuttings and was unsuccessful. I
| didn't use rooting hormone. (I had permits to move or destroy
| the saguaro, each of which had to be tagged and recorded).
|
| Perhaps it's "possible" with some technical or hormonal
| manipulation but doubt they would grow to full size and
| somewhat doubt it's possible at all. Otherwise commercial
| growers would do it (large saguaro for landscaping can be
| very expensive).
|
| Other cactus (particularly the Opuntia, prickly pears and
| cholla) will propagate very easily from cuttings and do so in
| nature.
| zasdffaa wrote:
| Yeah, opuntia pads do root easily. I also won't have them
| in the house any more. Guess why (shudders with memories of
| pain)
|
| But other columnar cacti do root easily, eg. trichocereus
| (though it's is a mountainside cactus not desert) and I've
| rooted a few others of similar shape over the years, so I
| mistakenly assumed saguaro would as well.
| mythrwy wrote:
| Yep, San Pedro in particularly root really well from
| cuttings. (I won't ask "why" you were rooting trichocerus
| lol).
|
| But Saguaro are quite different. They have an internal
| woody skeleton. I think they are the only member of their
| genus. At any rate I failed completely to root them and
| all cuttings died. I've also seen them fallen over but
| not dead in the wild many times and they didn't root at
| the point they touched the soil.
|
| It's a completely understandable assumption that they
| would root from cuttings though as many other cactus do.
| zasdffaa wrote:
| Rudeness entirely deserved, should have read the article more
| carefully, thanks. Actually the pics I can see don't show
| much vegetation around the base. It could be that they just
| aren't evolved to deal with fire ie, dried out bases. Anyway
| you know your stuff and I don't.
|
| > 1-2 foot chunks sectioned from a saguaro trunk will quickly
| die. The plant's "spongy interior" mentioned in the article
| will dry out if cut like this
|
| I'm deeply surprised. Can the ends be cauterised to prevent
| this?
|
| > the mature plants are extremely slow growing
|
| I understand they are at the start of their lives and end,
| but I thought in the middle there was a burst of growth,
| otherwise how could they reach their large sizes?
|
| > There are also some state laws around removal and
| destruction of saguaros
|
| Hadn't considered this. Very good point indeed.
|
| Thanks for a thoughtful, tolerant reply
|
| (edit: "Sonoran desert resident here". I envy you)
| mythrwy wrote:
| Growth rate is a function of water. If you water saguaro
| well (but not enough to rot the roots) they actually grow
| reasonably quickly for a large cactus. But, over-watering
| can cause them to split so it's a very fine line.
|
| This is one of the reason saguaro (and other cactus) have
| ribs. So they can expand and contract as they store/use
| water.
|
| In nature they grow when it rains, which is not that often
| in their native climate.
|
| Their roots go out quiet a ways, fine roots go out around
| as tall as the plant is, but they are surprisingly shallow.
| A large specimen can weigh several tons. This large shallow
| root system allows them to capture much shallow monsoon
| rain.
|
| When we moved them, we took off all roots leaving only the
| large base roots maybe 2 or 3 feet from the trunk. We would
| have to brace them for a few years before they established
| enough of a root system to hold themselves up.
| dylan604 wrote:
| >I understand they are at the start of their lives and end,
| but I thought in the middle there was a burst of growth,
| otherwise how could they reach their large sizes?
|
| They are really old?
|
| https://www.epicroadtrips.us/2020/tucson_potpourri_1/saguar
| o...
| verisimi wrote:
| Aren't quite a lot/all ecosystems already capable of recovering
| from fire?
| verisimi wrote:
| > Many ecosystems evolved to live with wildfire, but the
| Sonoran Desert is not one of them. Saguaros have no defense
| against fire, and no ability to rebound from fire damage.
| Gordonjcp wrote:
| Moorland such as you get in Scotland, where people want to
| "rewild" it by planting massive amounts of non-native trees to
| claim giant tax breaks, do just fine getting set on fire every
| so often.
|
| Left wild you end up with heather growing over a metre deep in
| some places, and then a thunderstorm at just the right wrong
| time will set it all off, and then you've got thousands of
| acres of burning oily woody stuff that you simply cannot
| extinguish.
|
| But hey let's just bang on about "greedy farmers burning away
| all the wildlife for grouse moors". Pretty sure I'd have seen
| at least one grouse shoot in 40-odd years of living in the
| area.
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