Dicromantispa interrupta

Dicromantispa interrupta

Monday, June 19, 2023

Torrey Squirrels

Question: Can the Eastern gray squirrel (Sciurus carolinensis) be employed in the assisted migration of Torreya taxifolia? 

Historically, Torreya Guardians have been wary of seed predation on Florida torreya by the gray squirrel because of their appetite for its large seeds. However, my brief literature review indicates that the gray squirrel may be useful to Guardians, as this rodent is known to distribute significant numbers of the large seeds of torreyas and other species into microhabitats conducive to torreya establishment, bury seeds to suitable germination depths, cull seeds containing seed-predator insects & other debilitating factors, and occurs within a suitable geographical range. Therefore, I have assembled the information below so that Torreya Guardians can take a closer look at the roles that the gray squirrel might provide in (1) enlarging the geographic range of the Florida torreya northward of the presumed range of the torreya pathogen and (2) significantly increasing the torreya populations within that enlarged range.

Torreya Guardians already know that the Eastern gray Squirrel can affect our assisted migration tactics. This rodent (1) raids mother trees of their seeds, (2) steals potted seeds, and (3) caches seeds in developed areas and wildlands that can germinate and grow into naturally occurring individuals and colonies. Although we know this third thing, and we are happy about it when new seedlings “volunteer,” we have historically focused on the first two annoyances. In my view, this is because our historical charge has been to propagate and migrate, and obviously, we cannot increase the population until we learn how to propagate and nurture it. I believe we have now done those two things well enough to start looking at natural colonization strategies.

Being a wildlife biologist who sees mammals as the natural dispersers of Florida torreyas – not wind or water or birds – I suggest that wildlife biologists assess the potential for expanding (1) colony sizes of existing artificially planted trees, (2) leapfrog colonizations near existing artificial individuals and colonies, and (3) large-scale colonizations within national and state forestlands. However, as Daniel Boone exhorted, we must be sure we are right before we go ahead. My literature research indicates that there is only one good candidate for spreading the Florida torreya in the Eastern U.S., and that is the Eastern gray squirrel. Ergo, I have focused below only on that species.

The gray squirrel forages for, among other things, the relatively large seeds (= fruits, nuts) of trees such as the walnut (Juglans nigra), hickories (Carya spp.), oaks (Quercus spp.), and chestnuts & chinkapins (Castanea spp.). Chestnut trees historically were particularly reliant on gray squirrels, but the pines, beech, hazel, and oaks also benefit greatly, and so probably does the Florida torreya.

Foraged seeds that contain seed-predator insects are eaten immediately, whereas pristine seeds are stored for later consumption, especially as winter food. Seeds are stored individually via burial to depths of at least one inch, one source claiming below the frost line. Seeds may also be deliberately cracked before burial, it is said to prevent germination. Seeds are generally stored relatively closely to the finding gray squirrel’s nest tree, but can also be dispersed over an area of up to seven acres. One study revealed that gray squirrels can re-find up to two-thirds of the nuts they buried.

Gray squirrels employ a mnemonic storage technique called “spatial chunking” (also seen in rats), where seeds are sorted and buried according to size, type, and possibly taste and food value. By spatial chunking, zoologists mean that, for instance, hickory nuts will be buried in one area and oak acorns in a separate place. It has also been found that gray squirrels store preferred seeds in wide open spaces, possibly to increase a robber’s risk of predation when randomly foraging away from cover. Presumably, the storing squirrel experiences less risk because it knows where its seeds are buried, can go directly to them, and thus be less jeopardized by predators.

Another way that gray squirrels try to prevent neighboring squirrels from stealing their stores is the tactic of “deceptive caching;” that is, they only pretend to bury a nut, especially if they see another squirrel watching them.

Gray squirrels immediately consume insects they serendipitously find imbedded within seeds. Furthermore, while nest-caching squirrel species store pristine and insect-containing seeds together and thus increase seed-feeding insect populations, the gray squirrel’s habit of storing only pristine seeds and storing them separately acts to limit seed-predator insects. This practice could also limit seed-fungi infestations, which is another potential subject for research.

Gray squirrels are important in forest regeneration, much more so than other North American squirrel species. Of all the North American squirrel species, only the gray squirrel stores most of its hoard in individual caches scattered over a wide area in locations that include those that do not already have forest tree cover. Studies show that gray squirrels bury 97% of the seeds they find and immediately eat only the 3% that contain insects. Studies show widely variable rates of gray squirrels’ re-finding their caches, one being 70% and another only 36%. The remaining seeds were eaten by other animals (one study lists 20%) and only 10% germinating. Nevertheless, those that do germinate are likely to be the ones furthest from the nest tree and thus naturally disseminated. The net effect of planting so many healthy & insect-free seeds is that vigorous & genetically superior trees are selected for in the forest regeneration process.

Other North American species of squirrels tend to use nest caches. For example, the red squirrel (Tamiasciurus hudsonicus) stores most of its seeds in tree cavities and buries only 11% of them. Seeds stored in tree cavities will not germinate nor aid in forest regeneration. The red squirrel is thus considered a seed predator and not a forest regenerator.

Similarly, the Indochinese flying squirrels (Hylopetes phayrei) and particolored flying squirrel (Hylopetes alboniger) in southern China’s rain forests chew two grooves in the shells of smooth, egg-shaped or rounded nuts to wedge them firmly between branch crotches. The grooves hold the nut between the branches much like a sturdy mortise-tenon joint that carpenters use to attach legs onto furniture. They choose smaller saplings, placing caches roughly 2 m above the ground and 10-25 m from the nearest nut-producing tree. This makes sense in their humid environment, as a seed stored in the ground or dead log would rapidly either rot or germinate, and a seed falling out of a tree crotch would be quickly found and eaten by other herbivores. Thus, these two squirrel species are also seed predators.

Answer: Gray squirrels are expected to disperse the Florida torrey regardless of our intentions, so plant one and just stand back!

Saturday, June 3, 2023

The Vertical Forest

The Hanging Gardens of Babylon are famous, although no one knows where they were physically located. There is even some doubt whether this garden ever actually existed, as it was only the Babylonian priest Berossus who wrote in 290 BCE from first-hand (?) sightings. Regardless, so many of us want it to be true, and try to make it true of our own ‘castles,’ even if only in small part. 

I have mixed feelings about it. I love plants. Plants are gods, replacing wastes with the vapors and substances needed by the living. We keep small plants indoors for their ambiance, and larger perennials in landscaping features to hide rude concrete and steel and to provide for wildlife. But we fear large trees next to our houses and paved driveways, and are right to eschew them. Only shrubs and small tree species are allowed within falling-limb and pavement-buckling distance of most abodes. But mirages of hanging gardens still sway in the whims of my daydreaming mind.

An Italian architect named Stefano Boeri and his staff designed two residential towers in Milan, Italy, called Il Bosco Verticale, or The Vertical Forest. At 80 m and 112 m in height, they host appx 20,000 plants in balcony containers. This greenery is comprised of perennial herbaceous flowers, shrubs, and small and medium-sized trees. I think it also includes lianas, but that is not stated in media articles. The two towers are sweet, if not exactly lush. For example, the greenery is in spots rather than sweeps and washes, as it appears that nothing is allowed to grow on exterior walls. Furthermore, gardener pruning keeps plants well separated.


The carbon footprint of the spectacle has been assessed, concluding that it would take many decades for its flora to offset construction impacts and maintenance costs. This is in large part due to the additional structural needs for supporting the heavy weight of the plants and their containers, potting media, and water. In addition, the large balconies, being appx 40% of the total floor space, are quite heavy.

Another limit on the carbon footprint offset is the need for three gardeners working nearly year-round to clip the flora. Firstly, most plants really do not need to be clipped. Secondly, this keeps exterior walls possibly overly exposed to the elements. Thirdly, gardeners are expensive. Are three gardeners working nearly year-round really necessary? For example, one video depicts gardeners pruning low-growing flowering plants even though most perennial cultivars exhibit self-limiting growth simply by dying back in the winter. Planting small and medium-sized trees also appears to be a mistake, both because of their weight and the need for artificial irrigation and pruning. Shrubs grow plenty large on balconies, and annual pruning easily ensures that they do not grow too heavy.

The videos and articles I have seen do not mention how the plants get watered. Watering can be done automatically with drip irrigation systems, or by shunting rainwater into plant containers, or by choosing drought-tolerant cultivars that are fine when watered only when it rains. Too, water is heavy, so keeping plants small and maintaining only relatively small plant containers reduces the load on and size of such balconies.

Thus, the building’s carbon footprint can be reduced substantially by growing smaller, more drought-tolerant plants in smaller containers on smaller balconies.

Another weakness of the Milan Vertical Forest is the value placed on the amenity that the vegetated balconies were supposed to offer residents. The architect doubtless envisioned residents having breakfast and dinner there, relaxing outdoors with a good book, or perhaps having a smoke while enjoying the scenery. However, Milan’s climate is evidently too chilly for most of the year, so residents remain nearly entirely indoors when home. Conversely, some cities are simply too hot for hanging out outside during summer.

After I ran across and enjoyed several Vertical Forest articles and videos, several people coincidentally posted articles on it on Facebook. A bunch of sharks on one site piled on the idea in a virtual feeding frenzy, falling all over themselves to pan the idea. It never ceases to amaze me that invention is literally always attacked by those who are unable to understand that prototypes are deliberately designed to find their own flaws so that future editions can be informed and become better. You can see some of that in the above text where I mention how some of the invention’s flaws can be easily mitigated. So, I decided to review the cartilaginous fish attacks to see if they had come up with any issues that I could not think of potential solutions for off the top of my head. Here goes:

AM: “Structure engineer had their math cut out on this project…”

Buford: Hmm, what does this comment mean, anyway?


WS: “I can only imagine the insect problem in this building.”

Buford: Why would the “insect problem” be any different in this building than in any other city building? For one thing, if this building were plopped down anywhere that I have ever lived, it would have many birds and lizards consuming the insects. Whatever, there are more plants around my single-story house than there are on the balcony of any of the vertical forest’s apartments. Dumb.


MO: “When good intentions go bad..roots verses concrete.. good luck if you’re living in that.”

Buford: Roots are not a problem in the proper plant containers. Duh.


AR: “It may work if it was designed for that purpose the roots may be controllable with the hydroponic system however all that being said moisture and concrete are not long term friends…”

Buford: Hydroponic systems are heavy and would have large labor costs in a vertical apartment forest. FYI, concrete and moisture are actually lovers – concrete continues to set long after you think it is dry. Indeed, concrete sets better underwater than under air. And anyway, if moisture were such a problem with buildings, then why is it so popular as a construction material all over the world? Do your due diligence.


PM: “…the cyclic loading from winds going through the trees couldn't possibly have been accounted for.”

Buford: This comment cracks me up. LOOK at the picture! In the first place, there is no more windage with than without the veggies. Secondly, PM is evidently not really aware of just how thorough professional architects are. THEY do THEIR due diligence.


WL: “In fact it might not even be possible to safely construct and operate such a building. The water it would require would be terribly heavy and difficult to manage.”

Buford: In fact, it was indeed safely constructed and is currently being safely operated because it was designed by architects who did their homework, and it was permitted by professionals who did their due diligence, too.


MEW: “This cannot be a good thing.”

Buford: What cannot be a good thing? We cannot read your mind.


MMB: “Well, you also need to look at the long term side effects...”

Buford: What long-term side effects? Oh, and can MMB possibly imagine that one of the purposes of prototypes is to “look at long-term side effects?”


BKB: “…it wouldn't last one windstorm in Alaska…”

Buford: This comment cracks me up. BKB apparently thinks something like this might even be designed for an Arctic or Antarctic locale (!); or that it is not a good idea for Miami or Houston because it wouldn’t be a good idea in Alaska, or something…

You get the picture. These people haven’t a clue about architecture, irrigation, plants, insects, birds, concrete, windage, logic, grammar… My suggestion to the OP of the thread is to delete asinine comments and Block dummies. That is what I do on my FB page. That way, thoughtful, informed, educated, progressive people could share reasonable information.