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2 February 2011

Foliage vs. Geology: Plants on volcanoes

What plants really do like to live on volcanoes – and what kinds have I come across? Plant types on volcanoes could be divided into two rough categories: rock and soil dwellers. A rock dweller might thrive on a young or an old volcano, but plants that need soil are only going to do well on an older volcano (which has had time to form soil), or a tropical one (where soil formation is accelerated because of the climate). Volcanic rocks are often (but not always) full of vesicles, which makes them porous and ideal for retaining water. Volcanic soils are generally referred to as andisols, which are soils that form on volcanic ash and contain volcanic glass and compounds of elements such as Fe, Al and Si. (Ions of those elements, which are released by leaching and weathering of volcanic rock, can form complexes with organic matter; in addition to an andisol’s ability to retain water, this can make for very fertile growing conditions.) Andisols in the US are, not surprisingly, concentrated in the Cascades and northern California – where we have large stratovolcanoes and an excellent supply of volcanic ash.


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11 February 2008

Holy Smoking Breadfruit, Batman!

Judging from the sudden dropoff of comments, people are a little stumped on exactly what got dropped in a lava flow in Friday’s geopuzzle. So, here’s the answer: Breadfruit. ( At least, that’s what the locals said. I was skeptical, since breadfruit is usually pretty smooth, and these appear to have some pretty prominent spiky parts, but there was a garden nearby that had some immature breadfruit growing in it, …


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18 January 2008

Cactus? Or not a cactus? Dangerous plants of Big Bend

While in Big Bend, and especially when going off-trail to do mapping exercises, it’s extremely useful to keep an eye out for the desert flora. Because, as Edward Abbey liked to say, “everything in the desert either bites, stabs, sticks, stings or stinks.” (We listened to a nice ranger talk on cacti in which this quote came up, along with “Cactus? Or not a Cactus?”) Desert fieldwork becomes, therefore, an …


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