By Yao-Hua Law
No soil? No problem. Some herbaceous shrubs living on rocky mountains in Brazil use roots equipped with fine hairs and acids to dissolve rocks and extract the key nutrient phosphorus. The discovery, published in the May Functional Ecology, helps explain how a variety of plants can survive in impoverished environments.
“While most people tend to view nutrient-poor environments as less diverse, they are actually very diverse because plants use diverse ways to get nutrients,” says coauthor Patricia de Britto Costa, a plant ecologist at the University of Campinas in Brazil.
She and other colleagues in Brazil and Australia investigated how shallow-soil regions called campos rupestres in Portuguese, or rocky grasslands, can sustain more than an estimated 5,000 plant species — 15 percent of Brazil’s vascular plant diversity — despite occupying less than 1 percent of the country’s land area. What soil there is in these regions is poor, with nearly undetectable levels of the nutrients that plants need. And some plants manage to survive on rocky patches with no soil.
Researchers used chisels and hammers to dig up the plants. “We found the roots growing into the rocks,” at least 10 centimeters deep, says coauthor Anna Abrahão, a plant ecologist now at the University of Hohenheim in Stuttgart, Germany. “The roots go deeper, and we always lose some of them.”