Understanding the functioning of drylands is key to predict how they will change in the future and to identify management approaches that will maintain their role of global food and feed provider. In a recent review article, Giulia Vico from the Department of Crop Production Ecology at SLU, and co-authors, break down the complexity of dryland dynamics and provide an in-depth discussion on the dryland debate.
In drylands, precipitation is insufficient to cover demand of water by plants and evaporation. While dryland ecosystems are adapted to water scarcity, increasing aridity risks to undermine their productivity, particularly in conjunction with anthropogenic pressures.
Drylands extend over 40 percent of the land surface, host more than two billion people, and are important for global primary production and carbon budget.
– Despite their importance globally, there is still a lively debate on which drylands are expanding and where vegetation is changing dramatically, and why, explains Giulia Vico, senior lecturer at SLU and one of the co-authors of a review in the journal Nature Climate Change, led by Prof. Lixin Wang at the IUPUI School of Science.
In spite of infrequent and extremely variable rainfall, drylands can be productive and provide food and feed as well as a home to local populations. Cultivated lands in drylands have been increasing to meet local and global demands, at times along with irrigation applications, and currently provide approximately 60 percent of global food production. But will this last into the future?
The difference in potential and actual crop yields in drylands is often high, particularly in rainfed agriculture. Climate change will result in increased temperature extremes and reduced precipitation, lowered groundwater and worsened land degradation. We expect dryland agriculture to be negatively affected by these climatic changes.
– Agricultural intensification will likely require large investments in precipitation conservation and irrigation, and will be possible only in currently semi-arid or sub-humid regions, says Giulia Vico.
Livestock production has also been increasing in drylands. Land degradation and reducing grassland productivity is already threatening grazing systems. Yet, smallholders relying on a mixture of crops and livestock will remain important producers of ruminants.
– Any management approach will need to consider the complexity of these ecosystems and the remaining uncertainties in the monitoring and prediction of their functioning, says Giulia Vico.
Beyond Prof. Lixin Wang, the IUPUI School of Science, Indiana University, USA, and Giulia Vico, SLU, the team included Dr. Wenzhe Jiao (MIT, USA), Dr. Natasha MacBean (Western University, Canada), Prof. Paolo D’Odorico (University of California, Berkeley, USA), Dr. Stefano Manzoni (Stockholm University, Sweden), and Dr. Maria Cristina Rulli (Politecnico di Milano, Italy).