Working for Water
Part of the Water: H2O = Life exhibition.
Around the world, ecosystems are being disrupted by invasive plants--species purposely or accidentally imported to a place where they lack natural enemies. What's more, many of these species are especially thirsty. This means they can siphon off water needed by other organisms, including people, and can crowd out the native plants better adapted to existing rainfall conditions.
South Africa is fighting back with an ambitious invasive species control program, Working for Water. By hiring jobless people to remove invasive plants, the program has cleared more than one million hectares (2.5 million acres) of these thirsty plants, and provided important economic benefits for the local community. Though sometimes faulted for inadequate scientific monitoring, Working for Water is a success on many counts. But clearing is only part of the job. If native species aren't replanted and maintained, thirsty invasives can come roaring back.
Every Drop Counts
Water in South Africa is an especially precious commodity. The country has only two large rivers, the Orange and the Vaal, and much of the land gets little rainfall. In some areas experts think invasive plants account for up to one-third of estimated total water use.
River Restoration
Cutting invasive trees yields ecological benefits, and profits from selling the cut wood aid local communities. Some experts argue that the Working for Water strategy of invasive tree cutting is more effective--and cheaper--than dam building as a way of increasing water supply.
Half the Water
Invasive species are a particular problem for the water supply in the Cape Province in southwestern South Africa. The region supports a unique plant community, the fynbos (FAIN-boss), that is well-adapted to dry conditions. Invasion by non-native woody species, which require more water than native plants, can lead to dramatic declines in stream flow--up to 50 percent by some estimates.