And the LORD said unto Joshua, Stretch out the spear that is in thy hand toward Ai; for I will give it into thine hand. And Joshua stretched out the spear that he had in his hand toward the city.
And the ambush arose quickly out of their place, and they ran as soon as he had stretched out his hand: and they entered into the city, and took it, and hasted and set the city on fire.
And when the men of Ai looked behind them, they saw, and, behold, the smoke of the city ascended up to heaven, and they had no power to flee this way or that way: and the people that fled to the wilderness turned back upon the pursuers.
And when Joshua and all Israel saw that the ambush had taken the city, and that the smoke of the city ascended, then they turned again, and slew the men of Ai.
And the other issued out of the city against them; so they were in the midst of Israel, some on this side, and some on that side: and they smote them, so that they let none of them remain or escape.
And the king of Ai they took alive, and brought him to Joshua.
And it came to pass, when Israel had made an end of slaying all the inhabitants of Ai in the field, in the wilderness wherein they chased them, and when they were all fallen on the edge of the sword, until they were consumed, that all the Israelites returned unto Ai, and smote it with the edge of the sword.
And so it was, that all that fell that day, both of men and women, were twelve thousand, even all the men of Ai.
For Joshua drew not his hand back, wherewith he stretched out the spear, until he had utterly destroyed all the inhabitants of Ai.
Only the cattle and the spoil of that city Israel took for a prey unto themselves, according unto the word of the LORD which he commanded Joshua.
And Joshua burnt Ai, and made it a heap for ever, even a desolation unto this day.
And the king of Ai he hanged on a tree until eventide: and as soon as the sun was down, Joshua commanded that they should take his carcass down from the tree, and cast it at the entering of the gate of the city, and raise thereon a great heap of stones, that remaineth unto this day.
-Joshua 8: 18 - 29
When Captain John C. Frémont first beheld the Joshua tree, he saw not what the Mormons are purported to have seen in its limbs: the spear-tip of Joshua in its sharp leaves, bent and raised at the enemies of God, relentlessly held aloft until the inhabitants of Ai were slain, stones of the city were heaped the scattered desert rocks and their king was dangled from the upper reaches of a tree perhaps not so different than the giant yucca itself. Frémont noted only “their stiff and ungraceful forms” and declared the Joshua tree “the most repulsive tree in the vegetable kingdom.” His contempt was mild compared to the violent myth behind the honorific given by the Latter Day Saints.
When a pack mule toppled over a cliff, Frémont lost his botanical collection, including the information gathered regarding the Joshua tree. The yucca was finally described by modern science in 1871 after samples were collected during a War Department railroad survey of the Southwest.
Of course, Native Americans knew and made use of Yucca brevifolia for centuries before the colonials encroached. Its more fibrous matter was woven into baskets and shoes, and its seed-filled pods were broken open and eaten. The seeds are actually large berries.
Another inhabitant of the Southwest was fond of, perhaps even dependent on, the edible parts of the Joshua tree. The fruits, flower stalks and leaves of the yucca have been found in the ancient, “poorly digested” dung of the Shasta ground sloth, Nothrotheriops shastensis, the smaller cousin of the more famous ground sloths, Megatherium sp. The fossil record reveals a much larger distribution of the Joshua tree in the Pleistocene, and scientists suspect that these megaherbivores (and perhaps others like them) were responsible for its dispersal during that period. The Shasta ground sloths disappear from the fossil record around the end of the Pleistocene, which happens coincide with growing populations of humans and a cooling climate, possible factors that led to its extinction. At the dawn of the Holocene (~11,700 ya), amid a very rapid warming period, the southern reaches of the Joshua tree's distribution were significantly reduced.
The Joshua tree never recolonized the historical extent of its distribution. With the ground sloth missing from its adapted dispersal methods, it relies on rhizomes and seed-caching rodents for expansion. Holocene migration rates have been demonstrated to be significantly lower than in the Pleistocene, a maximum estimate of 2 m/yr. With the threat of the effects of climate change looming again, and the Joshua tree's ability to disperse already impaired, concerns about its future have sparked new studies looking at how another warming period will affect the organism.
By the end of this century, suitable habitat for the Joshua tree could be reduced to only 10 percent of its current range, again impacting the southern stands most severely, but this time with a far more limited capacity for distribution. Most likely we'll see similar effects on the animals that depend on Y. brevifolia like the Yucca moth and Xantusia vigilis, the Desert night lizard.
While these models are predicting steep declines, it's important to note that a large portion of these future sustainable population areas are on federal lands. According to Cole et al.:
96% (739 km2 out of 772 km2) of the area predicted to allow survival of current stands, and 91% (378 km2 out of 414 km2) of the area predicted within the range of natural migration are on Federal lands which are not expected to be at risk of development or urbanization. Further, 83% of the areas predicted as potential relocation sites (17,909 km2 out of 21,578 km2) occur on Federal lands.
Obviously, this is good news. If we see these predicted extremes, such a massive reduction of stands, relocation will most certainly be integral to saving the Joshua tree, and the less red tape to cut through, the better.
It's interesting that most of the summaries of the natural and cultural history of the Joshua tree do not actually detail the Biblical story of Joshua at Ai. They mention the prophet and a general notion of gesticulation or a raising of arms to the sky, not the hand of a warlord gripping a divine incitement to slaughter. Some accounts claim that the limbs of the Joshua tree waved the Mormons on, like beacons in the desert. Referencing Mormon history, the conflicts, deception and blood spilled, the ugly results of that journey, the Joshua tree seems more of a sinister portent than a curious waymark.
A note: Chris has written extensively on the Joshua tree. Anyone interested in learning more should head over to his blog.
Cole, K., Ironside, K., Eischeid, J., Garfin, G., Duffy, P., & Toney, C. (2010). Past and ongoing shifts in Joshua tree support future modeled range contraction Ecological Applications DOI: 10.1890/09-1800.1