Ecological Values
Certain trees provide disproportionately large ecological benefits, supporting a vast array of other species.
Some trees produce food (in the form of fruits, flowers, leaves or seeds) in much greater quantities than others. For example, Simarouba amara, from South and Central America, provides nectar and pollen for bees and moths, fruit consumed by monkeys and birds and seeds eaten by leafcutter ants. It also grows new leaves every year that are consumed by various caterpillars and, at the end of its life, its dead bark is consumed by termites.
The morphology of certain species may also be of high ecological importance. Trees with hollows in their trunk or branches provide shelter and nesting space for scores of species. In New South Wales, Australia, only certain tree species (often native eucalypts) provide suitable hollows for the over 170 vertebrate species dependent on them.
Certain trees also make significant ecological contributions by affecting nutrient levels in the soil. Trees from the pea family (Fabaceae) form root nodules that host a type of bacteria known as Rhizobia that in turn captures nitrogen in the surrounding soil.
The potential loss of ecologically valuable tree species would have wider knock-on effects on biodiversity and humanity. Below we highlight just a few ecologically valuable trees under threat:
The makore (Tieghemella heckelii) and the moabi (Baillonella toxisperma)
These species are two large trees from Central Africa that provide an important food source for forest elephants and small mammals. Logging threatens the survival of both trees, limiting their ability to provide an important food source for the forest’s mammals.
The pokemeboy tree (Acacia anegadensis)
The species is confined to two small Caribbean islands: Anegada and Fallen Jerusalem. The tree plays an important ecological role, promoting the succession of vegetation in degraded areas. Tourism development and invasive species are pushing the species towards extinction.
No other species would feel its loss greater than the Anegada iguana (Cyclura pinguis). The lizard, itself numbering less than 200 individuals, is dependent on the pokemeboy tree as a source of food and shelter.
The huarango tree (Prosopis pallida)
This species is native to semi-arid areas of Colombia, Ecuador and Peru. The tree plays a critical ecological role, supporting nitrogen fixation and, with the longest roots in the world, pulls up groundwater to allow other plants to grow in an extremely dry climate.
Archaeologists now believe that excessive logging of the huarango tree led to the ecological devastation that ultimately caused the sudden downfall of a pre-inca civilisation, known as the Nasca. Today the species remains under conservation attention in its natural habitat, but is highly invasive elsewhere in the world.