Ecology-Killing one unwanted species gives rise to another | Science and Technology

IN hierarchy Among the concerns of conservationists, animals often seem to outperform plants. For example, wild mice that live on the island after being accidentally introduced by a passing ship are furious because of the damage they do to local wildlife. Over 100 island-based animals are extinct or threatened by these rodents. Birds are especially at risk due to egg loss and snuggling. However, the impact of invaders on the local flora has not been well investigated.

The main sources of nutrients for rats are seeds and fruits, which is a surprising omission. However, it was partially modified by a project carried out by Ana Miller-ter Kuile at the University of California, Santa Barbara. Ms. Miller-ter Kuile’s focus was on Palmyra, an atoll, one of the furthest land spots in the Pacific Ocean.And as she explains BiotropicaBy focusing on atoll vegetation, she showed how extensively rats can affect the ecosystem of isolated islands. But she also showed that getting the problem back to the status quo is not as easy as expected.

Palmyra, an American territory, is located at the northernmost tip of the Line Islands. At this time, there are no permanent residents of humans. But it always hosts the scientific foundation that is home to dozens of researchers. But during World War II, it was the location of the Navy Air Force Base. Then came the mouse, along with the ships, planes, and personnel who serviced the base.

Due to the damage caused by these rodents, the elimination of rats from such small islands has become like a cottage industry in recent years. In this way, more than 400 people were freed from their epidemic. Palmyra’s turn is scheduled for 2011, and Ms. Miller Turquile saw this as an opportunity to observe how local plants react.

In 2007, she and her colleagues set up seven vegetation surveillance plots on the atoll. The area of ​​each parcel is 300 square meters. Four years later, they observed the plants in these plots until the moment it rained from the sky in the form of a poisoned bait station for the fate of Palmyra rats. The success of this bombing on rats was confirmed the following year by installing additional feeding stations. None of the stations were touched. The animals are gone. Miller-ter Kuile and her colleagues returned to monitoring their plans after waiting another three years for things to settle. They did so for another four years.

Good deeds are not punished

The difference this second time was obvious. During both studies, researchers focused on young trees. Between 2007 and 2011, they found that the mass of such trees remained unchanged. It increased 14 times between 2014 and 2017. Ironically, however, the main beneficiaries of this expansion were coconut trees.

Coconut trees grow naturally on the Pacific islands, but Palmyra palm trees are aliens, like the rats that once lived there. They are descendants of palms imported to make copra plantations. Before people became interested in this place in the 1850s, it is believed that Palmyra’s coconut trees were about 4,000 mature trees. Copra agriculture changed this, and the last flattening effect was abandoned many years ago, resulting in a coconut tree population of over 53,000 in 2005. Now that the mice are gone, Ms Miller-ter Kuile’s research suggests that this population will grow even larger.

Even in the absence of mice, the Palmyra ecosystem is unlikely to return to its pre-Lapsaria state without human help. In 2019, Nature Conservancy, an American charity that now owns most of the atoll, will uproot coconut tree buds to give opportunities to other species, especially the devil’s claws with fun names. Further projects have started. It remains to be seen whether removing coconuts in this way will also have unintended consequences.■■

This article was published in the Science and Technology section of the printed version under the heading “Rats, Palms, Palmyra Island”.

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