Strawberry Guava and Red Vented Bulbul

Strawberry guava (Psidium catteianum), also known as waiwai in Hawaiʻi, is a worldwide threat to native tropical forests. This attractive tree with abundant fruit was brought to the Hawaiian Islands in 1825. This native to Brazil is a threat to Hawaiian forests in many ways. The strawberry guava is a fast growing tree that forms dense thickets that crowd out native species. The strawberry guava has deep roots that lower the water table. Studies show that forests infested with strawberry guava lose 27% more water than a healthy native ‘ōhia forest. The strawberry guava releases allelochemicals into the soil which inhibits the growth of other plants nearby. The abundant fruit feeds rats, feral pigs, invasive fruit flies, and non-native birds.

The Asian red vented bulbul (Pycnonotus cafer) was introduced to the Hawaiian Islands as a pet. It was released into the wild in the mid-1950s on O‘ahu. The red vented bulbul competes aggressively with other birds for food and space. It is a pest that damages agricultural fruit and flowers. It also spreads seeds from invasive species like the strawberry guava.

One way to control invasive species is to exploit them. The leaves can be brewed into a medicinal tisane. The strawberry guava fruit is very plentiful, delicious, and can be harvested for food. Removing fruit reduces the population of invasive animals.

The wood of the strawberry guava is especially good for smoking meats and barbecue. It also makes good charcoal. Charcoal, or bio-char, can be used to remediate soil where strawberry guava has been cut down. The bio-char absorbs the allelochemicals left by invasive plants, and allows native plants to re-establish.