蜜柚直播

鈥淭he mesquite trees are wonders of their kind. 鈥� There were some whose trunks at the base scaled over four feet in diameter. The large bases branched a few feet into several limbs 15 or 18 inches in diameter,鈥� Willard was quoted in the book, 鈥淩equiem for the Santa Cruz.鈥�

For many decades, this mesquite bosque, covering seven square miles, was a mecca for bird lovers and scientists. From 60 to more than 70 bird species were known to have bred there at various times from the turn of the 20th century until the 1940s, and well over 100 species total lived there. The bosque helped make the 蜜柚直播 area one of the ornithological capitals of the Southwest.

But the introduction of large-scale groundwater pumping in the 1920s and onward, coupled with widespread tree-cutting for firewood and power supplies, destroyed the bosque by the 1960s, said the Santa Cruz book, written by four longtime 蜜柚直播-area scientists.

Now, with perennial water flowing once again on the Santa Cruz at San Xavier Road, and small cottonwood shoots starting to reappear, will this bosque come back?

The most likely answer is that something significant and possibly exciting will return. But it鈥檚 not certain if it will be a replica of the historic bosque, several experts told the 蜜柚直播, or how long any restoration will take.

One expert, 87-year-old riparian ecologist Roy Johnson, who studied birds there in the late 1950s, admitted, 鈥淚 just don鈥檛 know. I can鈥檛 think of any other place that I鈥檝e seen that happen to make a prediction. I don鈥檛 know of another case I could look at as a model.鈥�

This will be a new ecosystem, and it is anyone鈥檚 guess how it will develop, said retired hydrologist Robert Webb, who with Johnson co-authored the 2014 鈥淩equiem鈥� book along with Julio Betancourt and Ray Turner.

Another uncertainty is that right now, 鈥渨e really don鈥檛 know where the groundwater is coming from鈥� that is supplying water to the aquifer under the river, Webb said. While the sources of the water recharging the aquifer are known, their relative contributions aren鈥檛 clear. Learning that 鈥渨ould require a major groundwater study,鈥� Webb said.

The Great Mesquite Forest, as it was called, won鈥檛 return exactly as it was, said Eric Holler, a retired U.S. Bureau of Reclamation engineer involved in Santa Cruz River management issues for a quarter-century.

That鈥檚 because of a wide variety of societal changes in the 蜜柚直播 area including suburbanization and industrialization, and because of several different actions at play today involving groundwater use and recharge in that area, he said.

But if the groundwater levels keep rising, Webb said, 鈥渋t will be amazing. Because in the desert, just add water and Mother Nature will take care of the rest.鈥�

鈥淭he most picturesque鈥�

The mesquite bosque itself lay just east of what鈥檚 now considered the San Xavier area of the Tohono O鈥橭dham reservation. It was sandwiched between the saguaro-packed Martinez Hill east of the river and Black Mountain to the river鈥檚 west.

It got early, major notices from Western explorers, travelers and military officials in the middle of the 19th century.

In 1846 during the Mexican War, U.S. Army Lt. Col. Philip St. George Cooke found the mesquite grove near San Xavier so thick that he feared it would provide enemy troops cover for an ambush, wrote 蜜柚直播 archaeologist Deni Seymour in an unpublished paper on the river鈥檚 environmental history.

John Russell Bartlett, an artist, historian and U.S.-Mexican boundary commissioner, rested at the forest in the 1850s and called this area of the Santa Cruz valley 鈥渢he most picturesque and beautiful we had seen,鈥� says the 鈥淩equiem鈥� book.

For the San Xavier people living near the river, the mesquite bosque, along with canopies of cottonwood, willow, hackberry and walnut trees, provided shade, resources and a sense of place, Seymour鈥檚 paper said.

By the early 1900s, what was then called the Great Mesquite Forest had become one of the Southwest鈥檚 best studied places for birds, the 鈥淩equiem鈥� book said. By 1936, aerial photos showed it extended 6.75 linear miles.

In 1917, scientist William Dawson led a party of five scientists into the bosque and reported, 鈥渢he humble mesquite 鈥� rises here to the dignity of a real tree, matchless for size and extent, (and) contained trees sixty and seventy feet in height and up to three feet in diameter,鈥� the 鈥淩equiem鈥� book says.

Ornithologist A.C. Bent came there a few years later and reported, 鈥渢he forest was rich in bird life and the air was filled with their music.鈥�

I-19 construction was death knell

The forest started to decline in the 1930s and 鈥�40s, first from woodcutting that knocked over some trees towering more than 65 feet high, the book said. The trees grew back but at 15 to 20 feet tall.

Groundwater pumping then lowered the water table under the bosque, by nearly 30 feet from 1930 to 1940 alone, the book said.

Yet by 1958, when ecologist Johnson spent the first of three years in the forest as a University of 蜜柚直播 zoology graduate student, the forest still teemed with birds, even with the bosque spanning one-third of its original size.

Water was gone from the river but the water table remained high enough to support mesquites with roots 60 feet underground.

Johnson was a master鈥檚 degree student working under Professor Joe Marshall, a co-author of the pioneering 鈥淏irds of 蜜柚直播鈥� book and a student of the forest himself back in the 1930s.

鈥淚t was very thick, when you got in there, you could hardly see more than 50 feet. It was the biggest place for birds I think I鈥檝e ever seen 鈥攃ertainly in the U.S. and maybe some places in the tropics,鈥� Johnson said.

And, 鈥測ou had insects galore in the forest鈥� providing bird food, he said.

The death knell for the forest came first when the state built Interstate 19 through the area in the early 1960s, drawing more people and industry, he said.

鈥淚 don鈥檛 know, with the city of 蜜柚直播 growing like it did, it couldn鈥檛 be helped,鈥� Johnson recalled. 鈥淚t was, so to speak, progress.鈥�

What鈥檚 next?

Today, even with cottonwood shoots, cattails and sunflower plants back in the river, it will take 鈥渄ecades鈥� of sustained recharge of the aquifer to re-elevate the water table to levels that sustained the entire mesquite bosque, said Julie Stromberg. She is a retired 蜜柚直播 State University life sciences professor and riparian ecologist.

While the water table is even with the river in spots, it鈥檚 still up to 100 or more feet deep away from the banks where the bosque once stood.

The riparian vegetation is extending itself up and down river, but not yet laterally alongside it, she said, noting that the mesquite forest back in 1951 was five miles wide.

鈥淭his is not to say that we shouldn鈥檛 try! Better now than later or never!鈥� Stromberg added in an email to the Star.

Hydrologist Webb said, 鈥淲e will not restore the Great Mesquite Forest. What we鈥檒l get is something new and different and quite possibly very exciting.鈥�

One reason that the forest won鈥檛 become a replica of its past glory is that today, the river is both wider and deeper than it used to be, restraining potential future plant growth, he said.

鈥淪econd, the climate is different now, warmer and in some years at least drier,鈥� he said.

Former reclamation official Holler is more optimistic. Today, he notes, the aquifer in and around San Xavier is being replenished due to reduced pumping and more Central 蜜柚直播 Project water use to the river鈥檚 west, east and south.

Over the long term, water levels will rise to uniform levels and reach equilibrium compared to what鈥檚 being pumped out, he said.

River restoration work could help, along with the building of flood control structures, he said.

Eventually, he said, 鈥渨e can expect a lush and abundant mix of mesquite, cottonwood and willow vegetation.鈥�