Plant diversity promotes healthier land: study

Maintaining a mix of species boosts a crucial soil nutrient, according to the first global study of its kind.

Xinli Chen

Post-doc Xinli Chen led a study showing that conserving plant diversity boosts phosphorus in soil and benefits ecosystems worldwide, from forests and grasslands to farm fields. (Photo: Supplied)

A new study by University of Alberta researchers is the first to show on a global scale that conserving plant diversity boosts a nutrient crucial for healthy land, including productive croplands.

An analysis of 180 studies done worldwide on farm fields, grasslands, forests and pot-grown experiments showed that overall, mixtures of diverse plant species increased the availability of phosphorus in the soil, compared with systems with single species.

Soil phosphorus is needed for plant growth and reproduction.

Another benefit of biodiversity

The findings, published in Nature Ecology and Evolution, highlight an additional benefit to preserving plant biodiversity around the globe, says lead author Xinli Chen, a Banting postdoctoral fellow in the Faculty of Agricultural, Life & Environmental Sciences.

“Maintaining biodiversity has already been shown to have many benefits — more diverse ecosystems are considered to be more stable and have a greater capacity to sequester carbon, for example,” Chen says. 

“Now we've established that improving soil phosphorus availability is an additional benefit that helps sustain our current and future productivity of croplands, forests and other types of terrestrial ecosystems.”

The study found that compared with ecosystems with a single plant species or crop type, land with plant mixtures showed more benefits of phosphorus. The total amount of the nutrient in the surface soil, where most of the roots grow, was 6.8 per cent higher, the enzyme activity that makes phosphorus available to plants was 8.5 per cent higher and the amount of phosphorus plants could take up was 4.6 per cent higher.

“Win-win situation” for crop producers

The findings are also important to agricultural practices, Chen says.

Phosphorus is difficult for plants to access naturally, and while large amounts of it have been mined to produce fertilizers, easily mineable deposits could be depleted in the next 50 to 100 years, he notes.

“Sustainable management strategies to better use and increase soil phosphorus are urgently needed to reduce the dependence on fertilizer, and maintaining plant diversity is one way to do that.”

Encouraging plant diversity can also provide economic benefits to crop producers, Chen adds. Preserving shelterbelts and windrows around their fields, and growing more than one crop at the same time on the same piece of land, can increase soil phosphorus and consequently reduce the amount of phosphorus fertilizer they need to buy.

“It’s a win-win situation.”

The findings could help guide policy to protect plant biodiversity in the face of its rapid global loss due to changes in land use, adds soil scientist Scott Chang, who was a co-author on the study.

“We hope this research helps show the need for policy makers and the general public alike to promote the maintenance of biodiversity in all of our ecosystems.”

The study was funded by the Natural Sciences and Engineering Research Council of Canada and by Chen’s Banting Postdoctoral Fellowship.