As they enjoy their ecotourism vacation in the forests of southeastern Peru, visitors who look up into the rainforest canopy as they walk the forest trails in Tambopata will be struck by the many different types of spiny, succulent plants that cover the branches and trunks of trees, their variety of forms silhouetted against the tropical sky.
These are the members of the bromeliad family that grow as epiphytes (plants with no attachment to the ground). While these so-called “air plants” account for more than half of the estimated 3000 bromeliad species known to exist, in fact bromeliads are such a large, successful and highly diverse family that they also thrive as lithophytes (plants that grow among rocks) and as terrestrial, or earthbound, species.
Among the people of North America and Europe, probably the one species of bromeliad they are familiar with is the domesticated pineapple. In fact, the thousands of species of bromeliad that form the Bromeliaceae family are all native to the Americas, with the exception of one species which is native to Africa.
The tropical rainforest canopy is home to many species of bromeliads. The waxy foliage of these bowl-shaped plants gathers and stores water efficiently. Some species of bromeliad can contain several liters of water, making them the ideal host plants for hundreds of species, ranging from insects to frogs. Unlike those species of vines which exist as parasites, bromeliads do not harm their host trees.
When it rains, bromeliads are highly efficient at channeling water into their funnel-like centers, and some species contain water year-round. These constitute an important water source for larger canopy-dwelling animals, as well as for bromeliad frogs, particularly during the long months of the Amazon dry season. In the rainforests of South America, the density of bromeliad species is so great, that across a single hectare of forest they are capable of sequestering several thousand liters of water.
In recent decades, researchers working in the Amazon basin have begun to turn their attention to the forest canopy. This work has led to a greater understanding of the importance of bromeliads to the teeming life of the forest. The unique architecture of bromeliads means that they function as tiny, self-contained ecosystems that fulfill a crucial role in the life cycles of many of the creatures who inhabit the upper reaches of the complex structure of the rainforest.
The animals that depend on the ponds created by bromeliads range from the birds that swoop down to sip from them, to the frogs and insects that swim, hunt and raise their young in these year-round, reliable water sources.
Other, tiny, animals that make their home in bromeliads include beetles and ants. And at a microscopic level, each bromeliad may be home to literally hundreds of microbes and protozoans. In this way, bromeliad ponds serve as an essential source of life in the canopies of tropical forests, and as a vital component of the forest’s flora.
So-called “tank bromeliads”, which trap water in the tank formed by the youngest leaves of their tight crowns, vary enormously in size, ranging from just 8 centimeters (3 inches) to one meter (three feet) across. While such variety creates a broad range of habitats that support an enormous array of creatures, at the same time bromeliads also play host to other plants, ranging from algae to predacious, insect-eating plants.