JurnalPost.com - Forests harbor biodiversity not only on the forest floor but also high up in the trees, within the forest canopy. This region serves as a habitat for various organisms, ranging from insects to other animals. However, observing life in the canopy is no easy task. The height of the trees and the difficulty of reaching branches and foliage present significant challenges for researchers.
To overcome these obstacles, researchers from ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) have developed a technology called eProbe. This technology was introduced through research by Steffen Kirchgeorg and his colleagues, published in 2024.
eProbe is a sampling technology that utilizes drones to collect traces of genetic material from plant surfaces. This genetic material is known as environmental DNA (eDNA), which is DNA left behind by organisms in their surrounding environment.
DNA traces can adhere to the surfaces of leaves and tree branches. By analyzing these traces, researchers can identify groups of organisms that have left genetic material in an environment without needing to capture or observe the organisms directly.
How Does eProbe Work?
Based on the illustration in the research article, the sampling process begins by attaching a specialized device to a drone. Once airborne, the drone is flown to the canopy area designated for observation.
Next, the sampling tool is lowered using a winch system until it touches the vegetation. As it moves up and down, the tool brushes against the surfaces of leaves and tree branches to collect the adhering DNA traces.
After the sampling process is complete, the drone returns to the landing point. The sampling device is then detached for further examination in the laboratory.
In the laboratory, researchers extract DNA from the collected samples. The target DNA segments are then amplified before being read through a process of DNA sequencing or DNA sequencing.
The resulting sequencing data is then analyzed using a computer to find matches with specific groups of organisms.
Through this process, eProbe combines the drone's ability to reach inaccessible parts of the forest with molecular analysis technology to study biodiversity.
From DNA Traces to Biodiversity Information
One of the key stages in the research by Kirchgeorg and his colleagues is the use of the DNA metabarcodingmethod.
Simply put, this method allows researchers to analyze a mixture of DNA in a single sample to help identify various groups of organisms that have left genetic traces.
In the eProbe study, the researchers used the cytochrome c oxidase subunit I (COI) gene segment as a DNA marker to analyze animal organisms.
The analysis results were then grouped into molecular operational taxonomic units (MOTU). This term refers to groups of DNA sequences used as units in taxonomic analysis.
MOTUs help researchers distinguish groups of organisms based on DNA characteristics. However, one MOTU does not always equate to a single, definitively identified species.
In tests conducted in Singapore in June 2023, the research team successfully collected 10 samples using eProbe.
From these samples, the analysis identified 152 MOTUs from animal groups or Metazoa. Most belonged to the Arthropoda, Rotifera, and Nematoda groups.
Additionally, researchers found DNA traces of several organisms, including long-tailed macaques (Macaca fascicularis), ants, and termites.
These findings demonstrate the potential of collecting environmental DNA samples from vegetation surfaces to help reveal the diversity of organisms in forest canopy areas.
What Can Be Learned from eProbe Analysis Results?
Data generated by eProbe can help researchers obtain an overview of organism diversity based on DNA traces found on plant surfaces.
Through samples collected from several observation points, researchers can also compare the DNA groups detected at each location.
This information can be used to study the relationship between sampling processes, environmental characteristics, and the number of DNA groups successfully identified.
Thus, the benefits of eProbe are not limited to its ability to take samples from hard-to-reach locations. This technology also serves as a bridge between environmental observation in the field and molecular analysis in the laboratory.
However, DNA detection results must still be interpreted with caution.
The presence of an organism's DNA on a leaf or branch does not always prove that the organism is alive or located exactly at the sampling point.
DNA traces can be transported through various environmental processes. Therefore, the presence of DNA is better understood as a clue regarding the possible presence of an organism, rather than as definitive proof to determine the exact location of that organism.
Furthermore, identification capability depends on sample quality, analysis methods, and the availability of reference DNA data used by researchers.
Opportunities for eProbe Development in Forest Research
The development of eProbe demonstrates how drone technology and DNA analysis can be integrated to support biodiversity research.
With the help of drones, researchers can collect samples from canopy sections that were previously difficult to access through conventional observation methods.
These samples are then analyzed to obtain information about the groups of organisms that have left genetic traces on vegetation surfaces.
This approach opens opportunities for developing more flexible research methods, especially in forest areas with complex vegetation structures.
However, its application still requires further testing and development so that the results obtained can be interpreted accurately.
Ultimately, eProbe serves as an example of utilizing technology in modern ecological research. Through the combination of drones, environmental DNA sampling, and molecular analysis, researchers have an additional way to study life that has historically been difficult to observe directly in the forest canopy.
References
Kirchgeorg, S., Chang, J. J. M., Ip, Y. C. A., Jucker, M., Geckeler, C., Lüthi, M., van der Loo, E., Mächler, E., Franco-Sierra, N. D., Gonzalez Herrera, M. A., Pellissier, L., Deiner, K., Desiderato, A., & Mintchev, S. (2024). eProbe: Sampling of Environmental DNA within Tree Canopies with Drones. Environmental Science & Technology. https://doi.org/10.1021/acs.est.4c05595
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