From below, the tropical forest canopy looks like a giant puzzle backlit. A thin, bright light profile insulates each other tree. Biologists call this trend as “the crown shyness”.
The tops of the tropical forests are home to more than 40 percent of all terrestrial species in the world. Flying toucans and monkeys jumping through the trees. But for coatis, opossums and tiny ants, each tree is an island.
Despite their tendency to be timid, some trees remain connected through a complex network of woody vines.Stefan Schnitzer, STRI research associate and professor at Marquette University, was the author of a series of articles showing that the vines and lianas are taking over many tropical forests. To find out what could be the impact of this mess, lianas cut all the trees in a section of the forest and elsewhere left the lianas.
Since long ago, one of the rules of ecology is that large islands surrounded by water–those have more species than smaller islands. This also applies to isolated patches of forest surrounded farmland: large patches of forest species generally have small patches.
“Nature is so variable, sometimes it is frustrating trying to explain even what seems obvious pattern,” said research associate at STRI, Steve Yanoviak, who is also a recipient of the Department of Conservation Tom Wallace at the University of Louisville . “In this case, we were very happy to see that something as complicated as diversity in the tropical forest canopy could be explained simply watching the trees as islands”.
Yanoviak spends as much time as you can climb the treetops, where he studied the communities of tropical insects, mosquito larvae and dragonflies that breed in tiny pools of water that form in the center of the plants growing in the branches, and ants that plan back to the tree trunk when off of it.
The doctoral student Yanoviak, Ben (Max) Adams compared the number of ants in more than 200 trees representing more than 30 tree species. Adams and his assistants used a mixture of honey and meat (ham, tuna or chicken) as bait to catch 128 species of ants. The bait is a very effective way to determine which species of ants live in a tree because it provides a combination of carbohydrates, salts, fats and proteins.
From below, the tropical forest canopy looks like a giant puzzle backlit. A thin, bright light profile insulates each other tree. Biologists call this trend as “the crown shyness”.
They collected 92 species in trees with lianas against 58 in trees without lianas. They found that on average, from 2 to 20 different species of ants living in a single tree crown. Larger trees tend to be home to more species of ants than smaller trees, but only when the trees are not connected by lianas. Trees connected to other trees by vines and lianas had more than 10 species of ants, while connectionless trees had an average of 8 species of ants.
Trees with lianas tend to have more species of ants that forage alone seek food, rather than foraging in groups like other ant species. And species of ants that build large colonial nests were equally common in trees with and without lianas.
Next time, think about the vines as if they were telephone wires or those lines on a map showing the geographic connections between cities across the web. Understanding why these connections matter is especially important in a world where continuous timber harvesting and road construction break these vital connections.
Source: STRI / DICYT
