Climate change alters pasture productivity and quality: Impact on fatty acids and amino acids in Mediterranean silvopastoral ecosystems

Abstract

Climate change is threatening ecosystem functioning and sustainability worldwide. In silvopastoral systems, ongoing warmer and drier conditions could impact productivity and quality of pastures (in terms of protein content and digestibility), with important economic consequences. However, the extent to which climate change could alter other nutritional traits with a potential role in livestock nutrition and production, such as essential fatty acids and amino acids, is a question that remains poorly known. We designed a field manipulative experiment of increased temperature (+2–3 °C) and rainfall exclusion (−30%) aimed to evaluate the influence of forecasted climate variations on the yield and nutritional composition of pastures (i.e. proteins, lipids, fibers, amino acids, fatty acids and digestibility) in a Mediterranean silvopastoral system. To test whether scattered trees typical of these ecosystems could buffer the effects of higher aridity, experimental plots were installed under trees and in open grasslands. First, we found that plant communities under tree canopies were less productive but exhibited higher quality than those located in open grasslands, likely due to the shade and higher soil fertility provided by trees. Both climatic stressors had a significant influence on pasture productivity and nutritional composition. Thus, pastures subjected to rainfall reduction produced less biomass with higher content in nitrogen, proteins, essential amino acids and lipids, likely as a mechanism of plant tolerance to water stress. In contrast, warming increased plant productivity and enhanced the proportion of unsaturated fatty acids, likely mediated by alterations in plant community composition. Finally, our results suggest that trees might slow the impact of climate change on productivity and specific amino acids in pasture. These results could be also applied for the design of management strategies to ensure the ecologic and economic value of silvopastoral ecosystems under future climate scenarios.