Environment & Energy
Related: About this forumSince 1930s, Half Of California's Big Trees Gone; Potential Link To Drier, Warmer Climate
California has lost half its big trees since the 1930s, according to a study to be published Tuesday in the Proceedings of the National Academy of Sciencesand climate change seems to be a major factor.
The number of trees larger than two feet in diameter has declined by 50 percent on more than 46,000 square miles of California forests, the new study finds. No area was immune, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.
Many factors contributed to the decline, said Patrick McIntyre, an ecologist at the state Department of Fish and Wildlife who was the lead author of the study. Loggers targeted big trees. Housing development pushed into the woods. Zealous fire suppression has left California forests crowded with small trees that compete with big trees for resources. But in comparing a census of California forests done in the 1920s and 1930s with another survey between 2001 and 2010, McIntyre and his colleagues documented a widespread demise of big trees that was evident even in wildlands protected from logging or development.
The loss of big trees was greatest in areas where trees had suffered the greatest water deficit. The researchers estimated water stress with a computer model that calculated how much water trees were getting versus how much they needed, taking into account such things as precipitation, air temperature, soil moisture, and the timing of snowmelt.
EDIT
http://news.nationalgeographic.com/news/2015/01/150119-california-forests-shrinking-climate-drought-science/
Sopkoviak
(357 posts)Just don't coexist very well in California.
Say, isn't that what happened to Easter Island too?
The people finally mostly disappeared.
Now, let that be a lesson to ya.
hatrack
(59,587 posts)Kind of fits politics today, doesn't it?
OKIsItJustMe
(19,938 posts)December 10, 2013 8:41 AM ET
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Here's their argument: Professors Hunt and Lipo say fossil hunters and paleobotanists have found no hard evidence that the first Polynesian settlers set fire to the forest to clear land what's called "large scale prehistoric farming." The trees did die, no question. But instead of fire, Hunt and Lipo blame rats.
What's more, though the island hadn't much water and its soil wasn't rich, the islanders took stones, broke them into bits, and scattered them onto open fields creating an uneven surface. When wind blew in off the sea, the bumpy rocks produced more turbulent airflow, "releasing mineral nutrients in the rock," J.B. MacKinnon says, which gave the soil just enough of a nutrient boost to support basic vegetables. One tenth of the island had these scattered rock "gardens," and they produced enough food, "to sustain a population density similar to places like Oklahoma, Colorado, Sweden and New Zealand today."
According to MacKinnon, scientists say that Easter Island skeletons from that time show "less malnutrition than people in Europe." When a Dutch explorer, Jacob Roggevin, happened by in 1722, he wrote that islanders didn't ask for food. They wanted European hats instead. And, of course, starving folks typically don't have the time or energy to carve and shove 70-ton statues around their island.
One niggling question: If everybody was eating enough, why did the population decline? Probably, the professors say, from sexually transmitted diseases after Europeans came visiting.
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OKIsItJustMe
(19,938 posts)By Robert Sanders, Media Relations | January 20, 2015
[font size=3]BERKELEY Historical California vegetation data that more than once dodged the dumpster have now proved their true value, documenting that a changing forest structure seen in the Sierra Nevada has actually happened statewide over the past 90 years.
A team of scientists from the University of California, Berkeley, UC Davis and the U.S. Geological Survey compared unique forest surveys collected by UC Berkeley alumnus Albert Wieslander in the 1920s and 30s with recent U.S. Forest Service data to show that the decline of large trees and increase in the density of smaller trees is not unique to the states mountains.
[font size=1]Severe water stress (left red) since the 1930s mirrors the decline of large trees (right red) seen throughout the state, from the Sierra Nevada to the Coast Ranges.[/font]
Older, larger trees are declining because of disease, drought, logging and other factors, but what stands out is that this decline is statewide, said study leader Patrick McIntyre, who began the research while a postdoctoral fellow at UC Berkeley and now manages biodiversity data for the California Department of Fish and Wildlife. Forests are becoming dominated by smaller, more densely packed trees, and oaks are becoming more dominant as pines decline.
The authors found that the density of large trees declined in all regions of California, with declines up to 50 percent in the Sierra Nevada highlands, the south and central coast ranges and Northern California.
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