In the cupboards and drawers of the world’s herbaria are nearly 400 million dried plant specimens. These collections have long served as an essential record of what plant species exist on Earth and where they grow. But hidden in the dried up leaves, stems, flowers and roots is much more information about how the plants interacted with their environment during their lives. Knowing about these “functional properties” — aspects such as leaf structure, chemical composition and water content — could help researchers understand how plant communities change over time, and ultimately how we can help ecosystems thrive in the future.
Until now, the only way to learn about these properties from herbarium collections was to destroy pieces of the precious specimens. But recently, researchers from the University of Minnesota and the Université de Montréal in Quebec developed a fast, non-destructive way to estimate the functional properties of herbarium specimens.
The researchers used a technique called reflectance spectroscopy, which measures how much light a material reflects at different wavelengths to obtain spectroscopic “fingerprints,” or spectra, of leaves. On more than 600 plant samples from northern temperate and boreal forest biomes of North America, they measured the spectra of fresh, live leaves; leaves pressed as herbarium specimens; and crushed leaves. They also measured the chemical and structural properties of the leaves by conventional means. They then used the data to develop models that use spectra to estimate functional properties and evaluated how well the models performed on new plant samples from the same biomes in Cedar Creek Ecosystem Science Reserve. Finally, they tested how well the spectra could be used to distinguish species from one another.
- Fresh leaf spectra provided the best predictions for properties related to leaf structure and water content, while soil leaf spectra worked best for properties related to leaf chemistry.
- Pressed leaf spectra yielded very good predictions – mostly between fresh leaf and soil leaf spectra. For example, they predicted more than 75% of the variation in leaf nitrogen content and more than 90% of the variation in leaf mass per area.
- Both pressed leaf and soil leaf spectra yielded near-perfect predictions of species identity.
The study, published this month in Methods in Ecology and Evolution, provides ecologists with a powerful new tool for using biological collections to understand how plant communities change over time, and provides insight into how best to keep ecosystems healthy in the future.
“This study opens the door to using the world’s herbarium specimens to study the evolution of functional traits in the plant tree of life,” said study co-author and professor Jeannine Cavender-Bares of the University of Minnesota. “It’s a very exciting advancement for the integration of ecology and phylogenetics.”
“Far from just dead plants in musty drawers, herbaria are some of the most important tools we have for understanding the amazing diversity of plant life,” added study co-author and former University of Minnesota graduate student Shan Kothari, now a postdoctoral researcher at Université de Montréal. “We hope this method can take its place among the many clever and innovative ways ecologists have repurposed herbarium collections.”
How do functional traits diversify and phylogenetically correlate for co-occurring understory species in boreal forests?
Quote: A new window on plants from the past (2022, September 28) retrieved September 28, 2022 from https://phys.org/news/2022-09-window.html
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