Logged forests have reduced seedling density, reducing the probability for the next generation to emerge. Photo Credit David Bartholomew |
Rainforest seedlings are more likely to survive in natural forests than in places where logging has happened – even if tree restoration projects have taken place, new research shows.
Scientists monitored over 5,000 seedlings for a year and a half in North Borneo.
They studied a landscape containing both natural forest and areas logged 30 years ago – some of which were recovering naturally, while some had been restored by methods including tree planting.
A drought had triggered “mast fruiting” across the region, with trees simultaneously dropping fruit en masse and new seedlings emerging.
At first, both natural forest and restored forest had similarly high numbers of seedlings, compared to naturally recovering forest – suggesting restoration activities enhanced fruit production.
But these benefits did not last: low seedling survival in the restored forest meant that, by the end of the study, similarly low numbers of seedlings remained in restored and naturally recovering forest. Seedling populations remained higher in natural forests.
Together, these results show that regeneration may be challenged by different factors depending on the restoration approach – seed availability in naturally recovering sites and seedling survival in sites where planted trees have matured. These differences may have longer-term implications for how forests can deliver key ecosystem services such as carbon sequestration.