The Secret Lives of Roots: Dataset Reveals How Plants Persist, Spread and Rebuild After Disturbance

A major new plant database is bringing the hidden half of vegetation into clearer view by gathering information about roots, underground stems, bud banks and other structures that help plants find resources, survive disturbance and regenerate after damage. The study, 'A global dataset of key traits for plant belowground functioning,' published in Nature in Scientific Data, introduces UNDERPLOT- the UNDERground PLant Organ Trait dataset, which combines information for 10,453 vascular plant species and 19 belowground traits while adding two new indices designed to describe persistence and clonal spreading strategies.

Plant ecology has traditionally gathered belowground information through separate research areas, with scientists studying fine-root economics, maximum rooting depth and horizontal root spread, or clonal organs and bud banks without always being able to connect those findings. UNDERPLOT brings these pieces into one harmonised resource, giving researchers a broader picture of what plants are doing beneath the soil and how those hidden traits could influence ecosystem stability under climate change and disturbance.

One Dataset Brings Previously Separated Underground Plant Traits Together

The research team assembled information from 14 different sources, including established databases such as GRooT, RSIP and CLO-PLA3, alongside published studies and previously unpublished datasets. Species names coming from different sources were standardised through the sPlot 4.1 taxonomic backbone, which is linked to the TRY plant trait database and based on World Flora Online, allowing records collected under different naming systems to be brought together more consistently.

The resulting database covers far more than the fine roots commonly used to describe plant resource strategies. It records root nitrogen concentration, root diameter, root tissue density and specific root length, along with maximum rooting depth, horizontal root-system extent and the ratio of coarse-root to fine-root mass. Clonal traits include bud-bank depth and size, the number of offspring shoots produced each year, annual lateral expansion, persistence of physical connections between clonal shoots and an estimate of how far connected parts of a single genetic individual can extend.

These traits tell different parts of a plant's underground story. Fine roots reveal how plants acquire and conserve nutrients; rooting depth and lateral spread describe how widely plants explore soil for water and resources, while bud banks and clonal organs show how vegetation can regenerate or maintain itself after fire, drought, grazing or other severe disruption.

A New Persistence Index Shows Which Plants May Be Better Equipped to Survive Disturbance

UNDERPLOT's most important addition is the Belowground Persistence Type, or BPT, which could be assigned to 7,323 of the 10,453 species. The classification combines three characteristics: whether a plant has woody belowground structures, whether it reproduces clonally and whether it can resprout after all aboveground biomass has been lost.

The researchers arranged plants along BPT categories running from 1 to 6, with increasing numbers representing stronger belowground persistence. Annual plants sit toward the lowest end because their individual lifespan is short, while woody and clonal species can maintain persistent underground structures capable of producing new shoots or replacing ageing parts. Some clonal woody plants can maintain a genetic individual for extremely long periods because old shoots may die while new connected shoots continue to form.

Resprouting is particularly important under severe disturbance because a plant that loses all visible aboveground growth needs underground buds and stored resources to rebuild shoots. Root crowns, xylopodia and lignotubers are among the structures capable of supporting this kind of regeneration, while clonal plants already possess mechanisms that allow new shoots to develop from connected underground organs.

Clonal Spread Adds Another Dimension to How Plants Occupy and Recover Space

The researchers also created a Clonal Spread Index, or CSI, to describe how strongly a plant can expand sideways through vegetative growth. CSI 0 represents non-clonal plants, CSI 1 describes clonal species with relatively limited horizontal expansion, and CSI 2 represents species capable of wider spread. The researchers used 5 centimetres as the dividing point between short-distance and wider-spreading clonal growth, drawing mainly on measurements from CLO-PLA3 and supplementing missing information with growth-form characteristics.

This distinction matters because survival after disturbance is only one part of vegetation resilience. Plants that can remain alive underground may recover in place, while species able to spread through rhizomes, roots or other clonal organs can also recolonise surrounding ground, connect resources across several shoots and rebuild vegetation structure without depending entirely on seeds.

The full UNDERPLOT resource contains 47 fields, including the aggregated species name, 21 fields covering traits, indices, growth forms and clonal organs, 14 fields recording replicate numbers and 11 fields preserving different stages of taxonomic naming. Trait coverage varies greatly: the coarse-root-to-fine-root ratio is available for only 134 species, while information on belowground woodiness reaches 10,132 species.

Hidden Plant Traits Could Improve Climate Research, Restoration and Ecosystem Predictions

The value of UNDERPLOT goes beyond creating a large catalogue of roots. Researchers can combine it with aboveground plant information from databases such as TRY, opening the door to more complete studies of whole-plant strategies instead of treating leaves, stems and underground organs as separate ecological worlds. The dataset could support research into drought resistance, carbon storage, decomposition, nutrient cycling, soil microbial activity, water storage, soil anchorage, post-disturbance recovery and vegetation productivity. It may also help restoration teams identify species with belowground traits suited to ecosystems where survival and recovery after disturbance are especially important.

The researchers are clear that the database is not yet geographically balanced. Distribution information was available for 10,298 species, around 99% of the dataset, yet coverage remains heavily weighted toward temperate regions because several of the major contributing databases were developed there. Tropical regions and parts of the Global South remain less well represented.

Missing combinations of traits remain another challenge, and some BPT and CSI values could not be assigned with the available evidence. Even with those gaps, at least one UNDERPLOT species occurs in about 2.2 million of the 2.5 million vegetation plots in sPlot 4.1, or roughly 88%, giving the dataset broad relevance for studying plant communities around the world. The authors encourage researchers to contribute new measurements as the resource develops.

UNDERPLOT shifts attention toward structures that are easy to overlook because they remain hidden beneath the soil. Roots, buds, rhizomes and other underground organs can determine whether a plant reaches water during drought, returns after fire, survives the loss of its shoots or slowly spreads through a landscape, making these traits increasingly valuable for understanding how vegetation may respond to a rapidly changing world.