Potassium: a neglected nutrient in global change

• Published in: Global ecology and biogeography Vol. 24; no. 3; pp. 261 - 275
• Main Authors: Sardans, Jordi, Peñuelas, Josep
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.03.2015; John Wiley & Sons Ltd; Wiley Subscription Services, Inc
• Subjects: abiotic stress; anthropogenic activities; carbon sequestration; Climate change; drought; dry environmental conditions; ecological stoichiometry; environmental impact; eutrophication; global change; humans; invasive species; invasiveness; land use change; metabolic studies; N:K; nitrogen; phosphorus; plant growth; Potassium; RESEARCH REVIEW; soil; stoichiometry; Terrestrial ecosystems; tissues; water use efficiency
• ISSN: 1466-822X; 1466-8238
• DOI: 10.1111/geb.12259

Aim: Potassium (K) is the second most abundant nutrient in plant photosynthetic tissues after nitrogen (N). Thousands of physiological and metabolic studies in recent decades have established the fundamental role of K in plant function, especially in water-use efficiency and economy, and yet macroecological studies have mostly overlooked this nutrient. Methods: We have reviewed available studies on the content, stoichiometry and roles of in the soil–plant system and in terrestrial ecosystems. We have also reviewed the impacts of global change drivers on K content, stoichiometry and roles. Conclusions: The current literature indicates that K, at a global level, is as limiting as N and phosphorus (P) for plant productivity in terrestrial ecosystems. Some degree of K limitation has been seen in up to 70% of all studied terrestrial ecosystems. However, in some areas atmospheric K deposition from human activities is greater than that from natural sources. We are far from understanding the K fluxes between the atmosphere and land, and the role of anthropogenic activities in these fluxes. The increasing aridity expected in wide areas of the world makes K more critical through its role in water-use efficiency. N deposition exerts a strong impact on the ecosystem K cycle, decreasing K availability and increasing K limitation. Plant invasive success is enhanced by higher soil K availability, especially in environments without strong abiotic stresses. The impacts of other drivers of global change, such as increasing atmospheric CO₂ or changes in land use, remain to be elucidated. Current models of the responses of ecosystems and carbon storage to projected global climatic and atmospheric changes are now starting to consider N and P, but they should also consider K, mostly in arid and semi-arid ecosystems.