Tree islands restore nature in oil palm plantations
Research team led by Göttingen University investigate native species recovery in Sumatra
image:
Industrial oil palm plantation in Jambi, Sumatra
view moreCredit: Gustavo Paterno
Southeast Asia’s tropical forests are renowned for their biodiversity, but at the same time face significant threats from the expansion of oil palm plantations. With global demand for palm oil rising, the urgency for effective restoration strategies in these landscapes has become critical. A long-running experiment led by Göttingen University, Germany, and including the IPB University, Bogor and Jambi University in Indonesia, has investigated how ecological restoration promotes biodiversity recovery in oil palm plantations in Sumatra. Their findings reveal that establishing islands of trees within large oil palm monocultures can promote the recovery of native tree diversity through natural regeneration. The results were published in Science.
The international research team established 52 tree islands of varying sizes and diversity of planted trees in a conventional industrial oil palm plantation in Sumatra, Indonesia. This innovative experimental setup provided valuable insights into how initial restoration decisions influence biodiversity in oil palm-dominated landscapes. For instance, standard plantation management usually includes suppression of the undergrowth by using large amounts of herbicides and fertilizers. However, a diverse range of native species successfully colonized the tree islands, including trees that are endemic to Sundaland, meaning that they are only found in this region. Within just six years, many of these trees have already begun fruiting, with some exceeding 15 meters in height. Interestingly, alien species – meaning those not native to the study region – represented only ten percent of the natural regeneration in the restored areas.
The study highlights that tree islands accelerate the natural regeneration of native species, through the establishment of species from seeds that have arrived for example by wind or bird. This process enhances functional and evolutionary diversity, both crucial for building resilient ecosystems capable of withstanding climate change. Dr Gustavo Paterno, postdoctoral researcher at Göttingen University and lead author of the study, says: “An important finding to inform plantation management is that larger islands of trees, particularly those over 400 m², are essential for endemic and forest tree species that struggle to find suitable habitats within conventional oil palm plantations.” He adds: “Increasing the area of restoration leads to a surprisingly high increase in diversity.”
The research showed that starting with a higher diversity of planted native trees on each island can lead to a greater variety of ecological plant strategies colonizing the tree islands. “The more tree species you begin with, the more functionally diverse the restored ecosystem will become over time,” explains Professor Holger Kreft, Head of Göttingen University’s Biodiversity, Macroecology and Biogeography research group. “Our study demonstrates the potential of tree islands to transform biodiversity-poor agricultural lands into ecosystems teeming with biodiversity and native plants.” The team found, however, that despite these promising results, biodiversity levels in restored areas were still much lower than those in undisturbed forests, highlighting the urgent need to protect remaining forest patches with their irreplaceable conservation value.
This research was made possible thanks to the German Research Foundation (DFG) through the Collaborative Research Centre "Ecological and Socio-economic Functions of Tropical Lowland Rainforest Transformation Systems (EFForTS)".
Original publication: Gustavo Brant Paterno et al. Diverse and larger tree islands promote native tree diversity in oil palm landscapes. Science, 2024. DOI: 10.1126/science.ado1629
Southeast Asia’s tropical forests are renowned for their biodiversity, but at the same time face significant threats from the expansion of oil palm plantations. With global demand for palm oil rising, the urgency for effective restoration strategies in these landscapes has become critical. A long-running experiment led by Göttingen University, Germany, and including the IPB University, Bogor and Jambi University in Indonesia, has investigated how ecological restoration promotes biodiversity recovery in oil palm plantations in Sumatra. Their findings reveal that establishing islands of trees within large oil palm monocultures can promote the recovery of native tree diversity through natural regeneration. The results were published in Science.
The international research team established 52 tree islands of varying sizes and diversity of planted trees in a conventional industrial oil palm plantation in Sumatra, Indonesia. This innovative experimental setup provided valuable insights into how initial restoration decisions influence biodiversity in oil palm-dominated landscapes. For instance, standard plantation management usually includes suppression of the undergrowth by using large amounts of herbicides and fertilizers. However, a diverse range of native species successfully colonized the tree islands, including trees that are endemic to Sundaland, meaning that they are only found in this region. Within just six years, many of these trees have already begun fruiting, with some exceeding 15 meters in height. Interestingly, alien species – meaning those not native to the study region – represented only ten percent of the natural regeneration in the restored areas.
The study highlights that tree islands accelerate the natural regeneration of native species, through the establishment of species from seeds that have arrived for example by wind or bird. This process enhances functional and evolutionary diversity, both crucial for building resilient ecosystems capable of withstanding climate change. Dr Gustavo Paterno, postdoctoral researcher at Göttingen University and lead author of the study, says: “An important finding to inform plantation management is that larger islands of trees, particularly those over 400 m², are essential for endemic and forest tree species that struggle to find suitable habitats within conventional oil palm plantations.” He adds: “Increasing the area of restoration leads to a surprisingly high increase in diversity.”
The research showed that starting with a higher diversity of planted native trees on each island can lead to a greater variety of ecological plant strategies colonizing the tree islands. “The more tree species you begin with, the more functionally diverse the restored ecosystem will become over time,” explains Professor Holger Kreft, Head of Göttingen University’s Biodiversity, Macroecology and Biogeography research group. “Our study demonstrates the potential of tree islands to transform biodiversity-poor agricultural lands into ecosystems teeming with biodiversity and native plants.” The team found, however, that despite these promising results, biodiversity levels in restored areas were still much lower than those in undisturbed forests, highlighting the urgent need to protect remaining forest patches with their irreplaceable conservation value.
This research was made possible thanks to the German Research Foundation (DFG) through the Collaborative Research Centre "Ecological and Socio-economic Functions of Tropical Lowland Rainforest Transformation Systems (EFForTS)".
Original publication: Gustavo Brant Paterno et al. Diverse and larger tree islands promote native tree diversity in oil palm landscapes. Science, 2024. DOI: 10.1126/science.ado1629
Islands of trees in an oil palm plantation
Caption
Area being prepared for a second-generation oil palm plantation in Jambi
Credit
Gustavo Paterno
Journal
Science
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Diverse and larger tree islands promote native tree diversity in oil palm landscapes
Article Publication Date
14-Nov-2024
