Being in the upper foliage of a redwood tree, 250 feet above solid earth opens up a different world. Below, where earthly creatures dwell, there is very little direct sunlight in a dense redwood grove. Above the light-blocking branches in the sun-drenched world of treetops, food of plants is abundant and bright creating conditions that are suitable for other types of plants. These plants often grow in “canopy soils” formed by years of leaves and debris falling on wide branch tops.
Plants growing on other plants are referred to as epiphytes. A wide variety of epiphyte species have been described from the redwood canopy. My graduate studies focused on ferns. In particular, I studied how tree structure influences where and in what quantity the epiphytic fern called Leatherleaf fern thrives. Leatherleaf ferns accumulate over the years into huge, car-sized mats of growth if conditions are right. This fern is almost exclusively an epiphyte, but several other ground dwelling ferns will grow in the treetops as well.
A number of epiphytic shrubs like salal, as well as two species of huckleberry, are frequently seen growing in the canopy. Eating freshly picked huckleberries while hanging from a rope 250 feet above the ground is oddly satisfying. I have seen several species of trees growing as epiphytes in the thin canopy soils on branches. In Humboldt Redwoods, where conditions are drier, epiphytic plants are not as abundant or varied as they are further north (or in the tropics) where more rainfall moistens the canopy. One 30-foot-tall Western Hemlock tree, was sighted growing with its roots over 100 feet off the ground in Prairie Creek and many others have been recorded by other researchers in the crowns of redwoods.
Though we always climbed to a chorus of birdsong, birds were surprisingly difficult to see through the thick foliage. Just like on the ground, the discerning ear can identify many bird species without ever seeing an individual. Many organisms have been discovered living off ground with adaptations for surviving on branches.
Even though there may be soil and sunlight, water is critical. Rainfall runs off a tree pretty fast so many epiphytes have evolved thick leaves that don’t give off water as fast. Even so, canopy soils can hold impressive amounts of water sponge-like for days. Water may trickle from fern mats weeks after the last rainfall. Because of this, fern mats are magnets for many kinds of animals in the leafy heights. A beautiful flying squirrel nest built into a fern mat was a cool find. Perhaps the most impressive animal I came across was the wandering salamander - an arboreal specialist that spends its entire life in fern mats. A wide variety of invertebrates are found off ground also. Mites, spiders, centipedes, springtails, snails, are all abundant in fern mats. The list of canopy dwellers keeps growing as exploration continues.
Mark Bailey has a Master’s Degree in Biology from HSU studying forest canopy biology. He currently teaches biology astronomy and chemistry at Eureka High School. Mark lives in Kneeland.
This article is part of a series about Natural Life of the Lost Coast, a project of the Lost Coast Interpretive Association. If you are interested in contributing an article to this bi-weekly column about the plants, animals and human history of the Lost Coast Region, contact Cathy Miller at cathymiller50@gmail.com.
photo captions:
1. The amazing view from the top of a redwood.
2. Looking up near the top of Paradox.
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