Higher species richness enhances yield stability in intensively managed grasslands with experimental disturbance

Abstract

Climate models predict increased frequency and severity of drought events. At an Irish and Swiss site, experimental summer droughts were applied over two successive years to grassland plots sown with one, two or four grassland species with contrasting functional traits. Mean yield and plot-to-plot variance of yield were measured across harvests during drought and after a subsequent post-drought recovery period. At both sites, there was a positive relationship between species richness and yield. Under rainfed control conditions, mean yields of four-species communities were 32% (Wexford, Ireland) and 51% (Zürich, Switzerland) higher than in monocultures. This positive relationship was also evident under drought, despite significant average yield reductions (−27% at Wexford; −21% at Zürich). Four-species communities had lower plot-to-plot variance of yield compared to monoculture or two-species communities under both rainfed and drought conditions, which demonstrates higher yield stability in four-species communities. At the Swiss but not the Irish site, a high degree of species asynchrony could be identified as a mechanism underlying increased temporal stability in four-species communities. These results indicate the high potential of multi-species grasslands as an adaptation strategy against drought events and help achieve sustainable intensification under both unperturbed and perturbed environmental conditions.

Effect of species identity and diversity on biomass production and its stability in cover crop mixtures

“…Overall, mixtures were slightly more productive than sole crops but no difference was observed on yield stability. While most studies investigating the influence of species diversity showed a positive correlation between diversity and biomass production or stability (Haughey et al, 2018;Hector et al, 2010;Isbell et al, 2009;Nyfeler et al, 2009), we did not observe that increasing species diversity in mixtures results in higher and more stable biomass yield. Two plausible explanations could be the varied influence of species identity according to diversity level, and the influence of the growing conditions.…”

“…Several studies conducted in natural ecosystems (Hooper et al, 2005) and intercropping (e.g. Andersen et al, 2004;Bedoussac and Justes, 2010;Hauggaard-Nielsen et al, 2006) showed that the performance of a mixture can exceed the average of the individual to higher stability in biomass production (Haughey et al, 2018;Tilman et al, 2006;Yachi and Loreau, 1999). It has been shown for example that, for a broad range of extreme climate events, high-diversity communities (16-32 species) had higher productivity stability, i.e.…”

“…To face the lack of information of the CV, several studies have considered both the mean and the variation of the response (e.g. Haughey et al, 2018). Another option would be to assess stability in its dynamic view (as opposed to the static view with the CV), using linear regression method as described by Finlay and Wilkinson (1963).…”

Plant diversity effects on forage quality, yield and revenues of semi-natural grasslands

“…Here, pathways to exploit the positive plant diversity effects over longer periods could include increasing livestock diversity to promote plant diversity 60 , maintaining and promoting species-diverse hay meadows, e.g., Arrhenatheretum elatioris, with two to three cuts and low to moderate fertilization levels 61 , and seeding of plant diverse mixtures containing complementary species and legumes. Such plant diverse mixtures can also be helpful in dealing with droughts [62][63][64] , which are becoming more severe and frequent under changing climatic conditions 65 . Maintaining and reestablishing plant diverse grasslands could provide a win-win situation as it enables a sustainable increase in quality-adjusted yield and revenues, while at the same time it supports other important ecosystem services and functions.…”

Diverse approaches to crop diversification in agricultural research. A review

“…It can be one measure to develop more sustainable production systems, develop value-chains for minor crops (Meynard et al 2018) and contribute to socio-economic benefits (Feliciano 2019). Crop diversification practices can include higher crop diversity (Renard and Tilman 2019), more diverse crop rotations (Reckling et al 2016), mixed cropping (Bedoussac et al 2015;Malézieux et al 2009), cultivation of grain legumes in otherwise cereal dominated systems (Watson et al 2017), perennial leys or grassland (Haughey et al 2018;Phelan et al 2015;Weißhuhn et al 2017) and regionally adapted varieties or variety mixtures (Yang et al 2019;Vijaya et al 2019). Crop diversification and/or additional diversification measures like variation of seeding time or changing cropping patterns have the potential to lead to higher and more stable yields, increase profitability and lead to greater resilience of agro-ecosystems in the long term (Rosa-Schleich et al 2019;Meynard et al 2018;Liu et al 2019;Raseduzzaman and Jensen 2017;Renard and Tilman 2019;Urruty et al 2016).…”