Suspended in three-dimensional space, hanging gardens of epiphytes are like coral reefs in the sky, creating opportunities for a whole community of life. In tropical cloud forests, and in some wet lowland forests, epiphytes create a continuous mat long branch and trunk surfaces, like green upholstery along the stems. Epiphytic mosses and liverworts form the matrix in which vascular plants such as orchids, bromeliads, and ferns grow.
The roots of these vascular plants knit together and create a network of clasping cords which hold together large amounts of "crown humus". This arboreal soil is composed of the decomposed material; is very similar in texture and content to the upper 10 centimeters (2.5 inches) of soil on the forest floor. It is derived from the death of the epiphytic plants that die in situ and undergo decomposition. The material tends to be much more acidic than its forest floor counterparts, but still contain adequate amounts of nitrogen, phosphorus, and other nutrients to support the vibrant life of the epiphytes.
“These mats are just full of roots. They sort of knit the soil together. It smells great! It’s has this very earthy smell. There are lots of invertebrates, insects, earthworms, that live in this material high above the forest floor. You have to get up here. You have to look in these plants. You have to look in this soil to figure out what’s going on up here…N. Nadkarni, Heroes film.
The nutrient needs of the epiphytes are also met by the interception and retention of nutrients contained in mist, rain, and fog. Precipitation contains dilute amounts of nutrients dissolved in it, and many epiphytes are efficient at capturing atmospheric moisture and straining the nutrients from it. Thus in tropical cloud forests, where as much of 40% of the incoming moisture comes into the system in the form of mist and wind-blown fog, canopy-dwelling epiphytes can function like giant sponges in the treetops, intercepting and hanging onto these nutrients.
"The daily misting provides just what epiphytes need. Mosses catch droplets drifting past. With each drop, they gather a bit of dust, some from as far away as the Sahara desert. Soil builds up, and the hanging gardens grow in size and diversity, building more soil. A kiss from a desert wind, blown wet and warm, feeds the forest."
“A really amazing thing about these moss mats are that they can actually nourish the tree itself. They can feed the tree. Some species of tree can sprout roots from their own branches and trunks that go into the soil and take in food and water. And so, the epiphytes are getting support, they’re getting their place in the sun, but the tree is getting nutrients and water from the mats that the epiphytes make. So it’s like the epiphytes are paying rent to a landlord- a really amazing situation!” N. Nadkarni, Heroes film
