Q&A

In the tropical cloud forests where I have worked, I rarely see any fruiting bodies of macrofungi. But we do know that many species of canopy-dwelling plants – and the canopy roots of host trees – are mycorrhizal, which means that fungi have relationships with these plants’ roots. But very little is known about tropical canopy fungi. Here is a reference.

More is known about canopy fungi and their importance in temperate forests of the Pacific Northwest. Here is another source.

One way that epiphytes benefit their host trees is by attracting pollinators and fruit dispersers. In one of our studies in Monteverde, Costa Rica, we found that over ½ of all foraging visits of birds were to the epiphytes, not just the host trees. So epiphytes sustain populations of these essential animals. In addition, epiphytes have evolved to capture nutrients that are dissolved in rain and mist, and which come into the forest from outside the ecosystem. Eventually, when the epiphytes fall to the ground, those nutrients become available to terrestrially-rooted trees. Also, some trees put out roots from their own branches and trunks into the mats of epiphytes and the canopy soil they create. So the tree gets a direct nutrient benefit from the canopy plants it supports!

I was in my first year of graduate school when I climbed my first tree in Costa Rica – 24 years old!

Great question. In the Pacific Northwest, and, increasingly in other regions, forestry regulations require that foresters provide “leave trees” in clearcuts, trees that grew up in the primary forest. These are called “legacy structures” and they help to provide some elements of old growth forests in the matrix of young, regenerating forests. They provide a source for seed from the cones they continue to produce. They also provide habitat for birds and mammals that depend on old growth trees. These rules also require foresters to provide other legacy structures, such as fallen logs and standing dead trees (“snags”) that provide nesting and feeding spots for cavity nesting birds and mammals. In some cases, foresters inject fungi into these snags to speed up the process of decomposition, softening the trunk and making it more useable for animals.

 Trees provide oxygen, shade, and habitat for many other animals and plants. They also stabilize soils and prevent run-off and flooding. We have seen the consequences of losing trees on hillsides  -- landslides and loss of soils. We still have a lot to learn about the consequences of losing trees, but there are definite negative effects in terms of loss of ecological, and well and aesthetic and spiritual benefits.

It depends on where you are! In the tropics, it is never cold, but it rains a lot, and if you are sitting in the canopy and getting soaking wet, it can be chilly! Sometimes, if it is a very sunny day, it is much hotter in the canopy than on the forest floor, because the forest floor is shaded by leaves and branches. If you climb trees in temperate of boreal (arctic) forests in the winter, it can get very cold!

As a kid, I always wanted to support and protect trees, but didn’t quite know how, because I was just a kid. Now that I am a grown up, I can do things like earn money with my job to give to conservation groups. I can give talks and write books that help people understand how important trees are and why all of us should support them.

I have seen many sloths in the tropical forest where I work --- usually 10-15 each year. I see raccoons and their relatives on the ground also, may 20-30 a year.

I was in third grade (8 years old) when I first started climbing the maple trees in my front yard.

In tropical cloud forests and temperate rainforests, canopy soils are similar to terrestrial soils in some ways, but different in others! They both contain high levels of organic matter, and similar nutrients (nitrogen, phosphorus, magnesium, calcium, potassium, and many other “micronutrients”.  But canopy soils are more acidic and support different forms of nutrients, for example, the form of nitrogen is dominated by ammonium (a positively-charged ion) rather than nitrate (a negatively charged ion. They have similar amounts of microbial biomass, but the groups of microorganisms differ strikingly. Here is a research article.

The current estimate of the total number of trees on Earth is 3.04 trillion. A study was done in 2015 to assess the world population, using satellite imagery and “truthing” expeditions on the ground. The researchers also estimated that the planet had about 6 trillion trees before humans began doing agriculture. About 15 billion trees have been cut down each year, and with tree planting at about 5 billion/year, we are losing about 10 billion trees annually. Here is that research study.

Great question! In the temperate rainforests of the Pacific Northwest and places like Haida Gwaii, the greatest accumulations of canopy soil – and prevalence of canopy roots  - are in the crowns of hardwood trees like bigleaf maple and red alder. However, we have documented cases of canopy roots occasionally in conifer trees such as spruce and western red cedar.  Hard to say for sure why this is, but I imagine that bigger accumulations occur on hardwoods because their branches are broader and more horizontal. And because during the winters, when the environment is very wet, deciduous trees have much more light coming through their crowns than do evergreen trees, so their crowns are darker, and less conducive to rapid moss growth. But that is a good research question to pursue!