Lava tube passages tend to be fairly close to the surface, generally with less than 20 feet of overburden and sometimes less than a foot! Trees growing above the passage will often send down roots in search of water. In Hawaii, where the first 4 photos were taken, it is the ohia ohelu tree whose roots are most common, often forming a feathery jungle in the cave passage. When exploring the caves, care must be taken not to damage the roots. Not only is that not good for the trees, but the roots themselves are host to a complex and fragile community of cave-adapted insect life. Often these insects are endemic species found in only a few caves in an area.

In rain forest environments, roots may extend down into caves through skylights as in the fifth and six photos.

Photo 7 is the only non-Hawaiian cave I’ve seen with extensive roots, in a California lava tube.

AUTHOR: Dave Bunnell