2023-09-18 11:54:21
Borneo Rainforest – FLICKR
MADRID, 18 Sep. (EUROPA PRESS) –
A twenty-year experiment has revealed that active replanting outperforms natural recovery in the restoration of cleared tropical forests.
Another conclusion is that the greater the diversity of replanted tree species, the faster the canopy area and biomass recover.
The results, published in the magazine in the magazine ‘Science Advances’underline the importance of preserving biodiversity in virgin forests and restoring it in logged forests.
Satellite observations from one of the world’s largest ecological experiments on the island of Borneo have revealed that Replanting cleared forests with various mixtures of seedlings can significantly accelerate their recovery.
The experiment was launched by Professor Andy Hector, from the University of Oxford (United Kingdom), and his colleagues more than twenty years ago within the framework of the SE Asia Rainforest Research Partnership (SEARRP). It evaluated the recovery of 125 different plots in an area of cleared tropical forest that were planted with different combinations of tree species.
The results revealed that plots replanted with a mixture of 16 native tree species showed faster recovery of canopy area and total tree biomass, compared to plots replanted with 4 or only 1 species. However, even plots that had been replanted with 1 tree species They recovered more quickly than those that had allowed themselves to be restored naturally.
The study’s lead scientist, Professor Andy Hector, from the Department of Biology at the University of Oxford, explains that the study “demonstrates that replanting logged tropical forests with diverse mixtures of native tree species get multiple benefitsaccelerating the restoration of tree cover, biodiversity and important ecosystem services such as carbon sequestration.”
According to the researchers, one of the most likely reasons for this result is that different tree species occupy different positions, or “niches”, within an ecosystem. This includes both the physical and environmental conditions to which the species adapts and its interaction with other organisms.
As a result, the diverse mixtures complement each other to increase the overall functioning and stability of the ecosystem. For example, some tropical tree species are more drought tolerant because they produce more protective chemicals, giving the forest the ability to recover during periods of low rainfall.
Professor Hector adds that “having diversity in a tropical forest can be compared to an insurance effect, similar to having a financial strategy of diverse investment portfolios”.
In turn, a diverse mix of trees can support a much wider range of animal life. For example, hornbills need mature trees with holes where females can nest.
Tropical forests cover only 6% of the planet’s land surface, but are home to around 80% of the world’s documented species (WWF) and act as important carbon sinks.
However, these critical habitats are disappearing at an alarming rate, mainly due to logging for timber and conversion to palm oil plantations. Between 2004 and 2017, 43 million hectares of tropical forests were lost, an area similar to that of Morocco (WWF).
Restoring logged tropical forests is a crucial component of efforts to address both the natural and climate crises. However, until now it was unclear whether the best way to achieve this was to let forests restore naturally (using dormant seeds in the soil) or through active replanting.
To investigate this question, the researchers collaborated with local partners to create the Sabah Biodiversity Experiment on 500 hectares of cleared forest in the Malaysian state of Sabah, on the island of Borneo.
They were divided into 125 experimental plots that were left to recover naturally or planted with mixtures of 1, 4 or 16 species of trees that are often subject to felling. Among the 16 species were several endangered species and the tallest tropical tree species in the world (‘Shorea faguetiana’), which can reach more than 100 m in height. The first trees were planted in 2002, and in the following years almost 100,000 in total were planted.
The recovery of the plots was evaluated by applying statistical models to aerial images captured by satellite. After a few years, it was seen that those with 1 species recovered worse than those planted with a mixture of 4 species, and that those enriched with 16 species were the ones that recovered best of all.
Lead author Ryan Veryard, who analyzed the data as part of his PhD at the University of Oxford, said: “Importantly, our results show that logged forests can recover as long as they are not converted to agricultural uses such as planting trees. oil palm. They also highlight the need to conserve biodiversity within undisturbed forests, to be able to recover it in the areas that have already been cut down.
The Sabah Biodiversity Experiment team is now starting a new three-year project funded by the UK Natural Environment Research Council to census all surviving trees from the experiment.
This will be combined with a wider range of remote sensing methods (including helicopter-borne lidar sensors and smaller drone-borne sensors) for a more complete analysis of forest health.
#20year #experiment #supports #repopulating #cleared #tropical #forests