Ambon is an island in the Indonesian archipelago Moluccas, consisting of two peninsulas. The island has a length of 51 km, with a surface of 761 km2. The fact that Ambon is an island and relatively small makes it vulnerable to climate change, which is predicted to cause changes in multiple factors like temperature, sea levels and rainfall. Additionally, Ambon is exposed to an increased risk of flooding and damage from storm surges because of the earthquake frequency.
Mangrove forests provide a strong natural coastal defense, but these forests have been removed or degraded on many locations on the island. Due to the climate changes and the frequent occurence of natural disasters, there is an urgent need for restorations of these mangrove ecosystems. Restoring these ecosystems will provide additional coastal protection for Ambon.
Goal of our project
Based on our experience in Florida, we know that mangrove trees can be planted successfully with the help of BESE-elements. With this information, we installed BESE-elements on two locations to restore mangrove ecosystems on the island of Ambon.
Set-up
The restoration experiment was set up in March 2020 in collaboration with the local community and scientists of Universitas Pattimura. On two sites, a total of 24 modules were installed, each consisting of BESE-elements with 4 young mangrove trees and 6 propagules. In addition to the BESE-elements treatment, a similar amount of plants and propagules were planted in the bare sediment, as a control.
Preliminary results
The first results in May 2020 indicated that the mangrove plants in the BESE-elements were doing well. the young trees have grown and over 50% of the propagules survived and had grown leaves. By contrast, most of the controls without the BESE-elements support were lost.
Results 2022
In November 2022, after covid travel restrictions, we went back to Ambon. Unfortunately, the BESE-elements and mangroves planted in 2020 got destroyed by floating debris, primarily plastics. We only found one broken piece of BESE-elements.
New set-up
Back to the start, but with lessons learned. This time we choose three different locations for mangrove restoration with BESE-elements. A safe area, with a high chance to succeed was in Passo. A location with an intermediate chance to succeed was in Waai. A high-risk location with a low chance to succeed was at Pattimura research station, inner Ambon Bay. This last location is the same as in 2020. The difference is that at Waai and Pattimura research station a net was set-up and we cleaned the beach to prevent debris from hitting the BESE-elements again.
Each location has 10 plots with 6 BESE-elements with mangrove seedlings and propagules in the middle. At Passo and Pattimura research station we use Rhizophora apiculate, at Waai we also used Sonneratia alba and Ceriops tagal.
Measurements
We taught the students from Pattimura University how to do the measurements. After some practice they did the measurements perfect. They will do monthly measurements on the mangroves to monitor the success of the restoration effort.
