Wednesday, August 3, 2016

Distant Volcano eruptions help Saguaro Nursery baby booms ?

The Ideal Baby Saguaro Cacti Tree Nursery
Image - Kathleen Ferris - City of Phoenix, Arizona

John & Heidi @ StatusGo
The prime nursery habitat for growth and development of a baby Saguaro is supposed to be under a Palo Verde or Mesquite tree. Although as you can see here in the photo at right, a small saguaro can be found nestled under a bursage nursery plant. This one here is supposed to be 25 years old, though it's certainly small for that age. There appears to be a number of ecological & climatic variables which can either help  or hinder in the development of a baby Saguaro. I miss the deserts southwest and yes, I still freak people out here in Scandinavia when I mention missing deserts. Their opinion of deserts is that nothing if anything good lives there, it's hot & hostile with a plethora of things which will stick you, stab you and bite you. Nurse Tree facilitation is an important ecological process whereby these woody plant protégé species (mentors like Palo Verde & Mesquite) enhance the growth and survival of their understory apprentice species. Without this relationship, the Saguaros would almost never exist on their own in many areas. But then this is true of most life on Earth which thrives by means of mutualism. And yet there appear to be acceptions to this rule as a new study references volcanes with extremely huge eruption events which can trigger a temporary global cooling trend coupled with heavier than normal rainfall years. More on that later. First let's understand how those baby Saguaros [which at germination look like helpless miniature succulents] make a go of it under harsh desert conditions. 

Image - Mine (June 2016)

Image - Mine (June 2016)
My wife and I visited the Tucson-Sonora Desert Museum this past June 2016. We were fortunate enough to see all of the Saguaros in most of Arizona actually in bloom. Not only still blooming, but also ripening fruits which were split open and being fed upon by Doves, Cactus Wrens, Sparrows, etc. Even Arizona Cardinals. Now after all that dining and given the usual rapid digestion birds have, it is clear they would be flying from shrub to shrub and desert tree to desert tree and as they do, they'd take a poop. That poop would contain all the Saguaro seeds which would hit the ground and later be triggered to germinate once the first monsoonal thunderstorms move in north from Mexico. 100s, maybe 1000s of seed germinate with only a handful of them being able to survive. Take note below of the many different bird species which love the Saguaro Cacti fruits. Also take note that many of them also love the Saguaro flowers as did many insects we saw at the Museum. Apparently it's not only the Mexican Fruit Bat that pollenize them. Another etched in stone paradigm regarding insistence of how some plants replicate and spread themselves bites the dust. The scientific consensus as approved by the prevailing Orthodoxy won't like this.

Image - Margarethe Brummermann (June 2014)

The obvious result would be years later a few of the Saguaros seedlings would be successful enough to make it on their own, eventually to outlive the mother tree Blue Palo Verde which may only live 50 or 60 years. Easy for a 150+ year old Saguaro to outlast.

Image - Saguaro National Park

Image - James Brooks
Of course the obvious conclusion here is that not long after all manner of desert birds dine on the juicy ripe and luscious Saguaro fruits, they need to go poop later. They generally do so within a tree or shrub's canopy. As is evident from the Palo Verde Nurse tree example above, a couple decades back some bird or birds used this tree as a roost and did their business. The immediate result was these little tiny ice plant looking things popped up by the 100s all over the place and then it was a simple numbers game for survival after that. Incredibly, it takes only a couple of days for germination to occur. I have also found this to be the same thing with regards other desert trees of the pea family like Palo Verde, Mesquite, Ironwood etc which often germinate during the wet monsoon season and develop rapidly thereafter. This is important that their genetic programming has such instructions for rapid development because in their preferred harsh environment there is only a small window of time before conditions change to one in which they could otherwise become toast. Below is a link to Southwest Cactus LLC live feed of a Cactus shade house nursery where various cacti seed are germinated.

Animation by KanyonKris

Facilitation or Competition - Which ?

Image - Gila Bend Shell Station
I've used this same animated illustration above many time before to illustrates the play of Hydraulic Lift & Redistribution. So it's logical that given desert trees like Mesquite, Paloverde & Ironwood perform the task of hydraulic life and redistribution of deep underground water to shallower rooted shrubs and perennial plants, it would be easy to assert the same benefit would apply to these young newly emerged Saguaro seedlings. This same pattern would also clearly help many to establish themselves over a period of years. Like one of my latest posts on Biomimicry on replication of companion planting found in nature, these trees are programmed to mutually cooperate for each other's success. Ignorance of this behavior or phenomena has done major harm in land management over the past 100+ years. The package at right I picked up at a Gila Bend Shell Truck Stop to plant back home here in Sweden. I'll keep things up to date on that. I've used this same long time Souvenir gift pack brand before and their seeds  germinate extremely well in the vermiculite mix provided. But on the fact about shaded light, when I first planted some of these back in the late 1980s, they looked identical to the seedling emergence you see a couple photo up on the right. After a month I thought that  perhaps desert plants instead of being in the shade and protection of my livingroom, just might enjoy life on the porch railing for about an hour in sunshine. It was morning and not at all hot. After an hour I brought them back inside and the next day I saw they had all been fried. Lost every single one of them. So I understood the Nurse plant protection thingy concept, but not out in far western Arizona where I saw Saguaros along Interstate 8 growing straight up out of bare desert varnish rock and lava fields. No mother trees or nurse plants, just barren high intense heat environment. So how does that work ? Take a look at the gallery landscape below of what I'm talking about.

Image - World Heritage Commitee - NordEnergiThe 37th session of the UNESCO World Heritage Committee made the decision to make the El Pinacate and Gran Desierto de Altar Biosphere Reserve in Mexico the latest site to achieve World Heritage Status.

Image - Feargus Cooney
See, I can understand and relate to Nurse Plants or Mother Trees. Aside from the obvious shade factor provided for such a tender delicate Nursery for baby Saguaros from intense Summer heat, there is also the mechanisms of  "Hydraulic Lift and Redistribution" which provides valuable moisture brought up from subterranean sources, redistributes it through lateral roots further connected to an elaborate mycorrhial grid network no doubt plugged into the lateral root systems of young Saguaros. But in clearly moonscaped surface environments like the Pinacate Volcanic Lava fields which mostly lack pronounced Nurse Trees/Shrubs, how does establishment take place here ? I get the fact that seed germination happens anywhere  under good monsoonal rainfall events, germination is a matter of two days. But it's that critical three years of good luck and beyond that is the puzzle. This far western Arizona landscape is not the vibrant green living desert of of Tucson which is also strategically located right smack in the middle of the Monsoonal moisture superhighway. Look below at a few other examples of large Saguaro Cacti in areas far removed from the ideal Tucson Mesquite and Palo Verde forests and see that they actually thrive there. 

Photo by Leonora Torres

Saguaros in Lava fields of the 
Gila-Pinacate Biosphere Reserve

Image - Taly Drezner

Kofa National Wildlife Refuge - Yuma county, Arizona

Saguaro cacti are the tallest things standing at Kofa National Wildlife Refuge, near Yuma, Arizona. The cultural icon is a keystone species of the Sonoran Desert, serving as perch, nesting site, shelter, thermal refuge, and food for the birds and other animals in the desert ecosystem. So how do they establish themselves beyond the germination period ?

Image by Geologist Dan Lynch

Tecolote Volcano - Pinacate Volcanic Field
How Saguaro seed germination and establishment take place in areas where very little Nurse Trees & Shrubs are found and in a landscape that is basically volcanic fields with Desert Varnish. Remember, they start out life as an Iceplant mimic!

US Fish & Wildlife Serivce - Kofa National Wildlife Refuge

Here is a paragraph from the research done by Taly Drezner about the perfect location for the study of Saguaro seed germination and establishment within the Kofa National Wildlife Refuge. It was the perfect place to study Saguaro survival under extreme conditions.
"To investigate her hunch, Drezner went to Kofa National Wildlife Refuge near Yuma, Arizona, where limited water pushes the physiological limits of the saguaro, to sample the age structure of the local cacti. Rainfall at Kofa is a third of other locations in the Sonoran. Cacti do not have rings, like trees, that make age simple to gauge. Drezner estimated the ages of 250 cacti based on meticulous calculations of local growth rates using a model she pioneered. She added data from 30 locations in the Northern Sonoran Desert and compared the generational cohorts of the cacti to climate datasets for the region and the annual Weighted Historical Dust Veil Index, an indicator of volcanism."
So the idea here is that volcanic events, like the eruption of the Mexican volcano, El Chichón in 1982, have a major impact on global climate cooling. Hences delicate Saguaro seedling survival in hotter areas without nurse plants or trees like western Arizona's Kofa Wildlife Refuge require something uniquely different as far as climatic circumstances. 

Now think in terms of  large  historical Volcanic eruption events ? 

Photo by 
So these volcanic eruption events tie in to Saguaro establishment successes ? Remember the 1982 eruption of El Chichón, the largest volcanic disaster in modern Mexican history. ? That powerful 1982 explosive eruption of high-sulfur and other particulates high into the upper atmosphere effected the global climate. The total volume of material from the El Chichón eruption was much smaller than the other infamous eruption of Pinatubo of the Philippines in 1991. That powerful eruption pumped enormous volumes of ash injecting significant quantities of aerosols and dust into the stratosphere. Sulfur dioxide oxidized in the atmosphere to produce a haze of sulfuric acid droplets, which gradually spread throughout the stratosphere over the year following the eruption. I remember how you could see these high atmospheric ring anomalies around both the sun and moon for two or three years. The effect was a cooling trend, hence references today by global leaders on geo-engineering projects to replicate what these volcanoes did to climate past, instead of actually stopping what cause the climate change. The Mexican Volcanic eruption coincided with an El Nino weather pattern we had in the early 1980s in the southwest which gave massive amounts of rainfall and flooding. I also remember the monsoonal thunderstorm events where stronger and more completely widespread as opposed to the usual isolated incidents common with Southwestern monsoons in Summer. So it's not under the realm of possibility that Saguaro establishment success was positive during a two or three year window period. Too bad this info was not available back then to research those years in the Kofa Mountain area. Here is what Taly Drezner further says on the subject:

"In the year after Krakatoa, summer temperatures in the Northern Hemisphere fell 1.2⁰C below average. The eruption violently disgorged tons of ash and sulfur dioxide gas into the stratosphere. Dust particles and sulfuric acid droplets rode winds through the upper atmosphere, conspiring in a haze that reflected sunshine and lowered global temperatures. Though not as disruptive as the “year without a summer” that followed the eruption of Mount Tambora in 1815, Krakatoa’s influence was seen and felt around the globe in vivid sunsets and stormy weather.  Southern California experienced a “water year” of record rainfall. Sulfate aerosols in particular can hang out in the atmosphere for years, and Krakatoa released an unusual abundance of sulfur. Typical temperature and weather patterns did not recover for years. For the saguaro, the perturbations appear to have amounted to a collection of “just right” conditions for new growth."   
"I started noticing that these saguaro age cohorts followed notable volcanic eruptions,” said Drezner. “I knew that volcanoes drive milder summers and winters, and typically more rainfall for an extended period—two to three years after the event, which is a perfect window of time for the saguaro to get established and have a chance to survive."  
 My own personal concluding comments
Image - Mine (2011)

Image - Mine (2012)
I enjoyed the article on possible potential for notable large volcanic events spewing tonnes of ash, aerosols, etc into the upper Stratosphere and effecting global climate by means of a cooling trend over a period of three years. It certainly seems logical. My own experience with a 12" tall Saguaro brought to me by friends in Tucson from a Nursery (complete with offical Arizona State legal paperwork of ownership) I planted on Rattlesnake Mountain in El Cajon would seem to confirm the idea that Saguaro baby booms come with more favourable weather. The weather in El Cajon just a little ways east from San Diego & the Pacific Ocean definitely is a radical change from Arizona. I planted the little Saguaro on a south facing slope which was remote and where no one ever ventured. I never once watered it. Planting a Saguaro and watering can lead to root rot. Just place it in the soil and leave it alone. There is enough energy & water within the cacti to trigger root growth into the soil without the need for any extra outside water. Once the root system infrastructure is established, they will quickly suck up any water and refill the plant's lost storage capacity. From my own observation every year for seven years after planting, the plant grew a little over a six more inches that first year after rains came and over a foot a year thereafter. At it largest height, the Saguaro was almost seven foot tall. Then some idiots with guns decided to target practice. The cactus died back to the ground and formed a large healed scab even with the soil. Much to my surprise the cacti resprouted with two new competing central leaders the following year and the above picture my friend took of me standing next to it in 2011. I haven't been back there since, so I am not even sure it is still there given the fact that below that point the Sky Ranch Housing development people used chainsaws and destroyed some 30' tall Torrey Pines which were planted at the same time as the Saguaro. Still, the change in climate proved beneficial to Saguaro growth and it's later development. Aisde from more target practice, it's real danger now is fire. I mean it is located in coastal sage-scrub. But Saguaros are not the only mystery of Cacti establishment in full blown baking desert Sun without Nurse plants. This Anza Borrego Desert barrel cactus in the photo at right  is yet another example of success under extreme southern exposure conditions down in the Anza Borrego Desert where Summertime Temps are often 110+ Fahrenheit (40+ celsius).

Animated Illustration - Rockland Saguaros
The illustration above is a good guesstimate of probably how the average Saguaro grows under normal growing conditions in the Sonoran Desert. But there are clearly variables which break that rule. Some smaller Saguaros in the Kofa Wildlife Refuge in far western Arizona under less favourable growing conditions may well be as old as some towering 45' giants around Tucson. Still, as the National Park Service photo below reveals, there are clearly strategies for successes where no Nurse Tree is available.

Image - Saguaro National Monument
Interesting Reading References: Distant volcanic eruptions foster saguaro cacti baby booms
James Brooks: Arizona Saguaro Cactus - Sustainable, Seed-Grown Plants 
 AZGeology: Pinacate in stereo by Dan Lynch
Perhaps something else could have factored in the changes in the Southwest - maybe local Volcanism around the year 1000 C.E. - give or take a few hundred years or so either way ??? Okay, that's another post.
Time out for some Saguaro Cactus Humor!
Photo - Saguaro National Monument

Prickly Pear Cactus emerges from the top of a Saguaro Cactus

Anyone remember the comedy Sci-Fi film, "Men in Black" ? There was a scene in the Cafe where an alien contact was killed by this enemy Cockroach Alien and his body mistakenly went to the City Morgue before the MIB guys could clean up the incident. Field agent 'J' (Will Smith) and Forensics Lab Laurel (Linda Fiorentino) watch as the dead corpse's head opens to reveals a tiny alien creature with a dire warning, and 'K' (Tommy Lee Jones) has to erase Laurel's memory. Remeber "Orion's Belt" ??? This is the first thing I thought of when I saw this over at the Saguaro National Monument pages. Clearly this is another bird pooping incident out there in the wild somewhere, only this time Prickly Pear tunas.

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