Plant Diversity Thrives in Harsh Soil Conditions

How plants adapt to thrive in nutrient-poor soils.

Hocedez and colleagues argue that shrubland is an undervalued sources of biodiversity. They examine the floral diversity of New Caledonia’s shrubland, a biodiversity hotspot known for the extent of its ultramafic rocks. These yield soils poor in nutrients but high concentrations of toxic metals. They found a plot rich in species due to plants each occupying a distinct biochemical niche.

The botanists’ study area was a 20m × 20m plot on ultramafic soil, with few nutrients. This might be expected to be sparsely vegetated. However, the team found 475 plants taller than a metre, from 37 different species. This diversity meant that the shrubland was just as diverse as similar sized plots of New Caledonian forests.

Hocedez and colleagues investigated the niches the plants occupied by using ionomics, a measure of the chemical make-up of a plant.  Some plants, like Homalium kanaliense, showed an extraordinary ability to accumulate high levels of nickel – over 1000 micrograms per gram of leaf, which is considered hyperaccumulation. Another species, Polyscias pancheri, displayed a talent for manganese absorption, with one individual containing over 13,000 micrograms per gram.

The nine most abundant species showed limited overlap in their nutrient profiles, indicating distinct approaches to resource use even among common plants. The rarer a species was, the more distinct the niche it tended to occupy with the rarest species in the plot having the most functionally distinct features, occupying unique positions in the community’s “nutrient space”.

The variety of nutrient strategies observed – from special root partnerships to metal hyperaccumulation – demonstrates the adaptability of plants. It also highlights the diversity of shrublands. Far from being a successional habitat colonised by opportunists, it shows they’re a community of interlinked species working in partnership.

Hocedez, J., Gotty, K., Hequet, V., Chay, S., Léopold, A., Dray, S., & Pillon, Y. (2024). Community ionomics reveals a diversity of mineral nutrition in a species-rich shrubland on infertile soil. Journal of Vegetation Science, 35, e13301. https://doi.org/10.1111/jvs.13301 (OA)

Cross-posted to Bluesky, Mastodon & Threads.