Does greater night‐time, rather than constant, warming alter growth of managed pasture under under ambient and elevated atmospheric CO₂?

Abstract

Summary• This study examined the effects of warming, elevated atmospheric CO 2 and cutting regimen on the growth of Phalaris aquatica cv. Holdfast swards.• Six temperature gradient tunnels ( TGT ) were used to manipulate both air temperature and atmospheric CO 2 concentrations (ambient and 750 ppm). Within each tunnel, there were three temperature treatments: no warming, constant warming of +3.0 ° C and a daytime warming of 2.2 ° C combined with a night-time warming of 4.0 ° C and two defoliation frequencies.• Averaged across 20 months of growth, there was a positive effect of elevated atmospheric CO 2 (+11%), no effect of either warming treatment and a negative effect of frequent cutting ( − 19%) on total above ground biomass production. The responses to all treatments, however, were strongly seasonal.• Positive responses to CO 2 were statistically significant only in the spring, when plant growth was strongest. No evidence was found that high night-time warming had different effects on plant growth and plant responses to elevated atmospheric CO 2 , than constant warming.

Plant Physiological, Morphological and Yield-Related Responses to Night Temperature Changes across Different Species and Plant Functional Types

“…In fact, the effects of night temperature are different from that of day temperature (Xia et al, 2014) and produced a relatively greater challenge in estimating global change impact on crop yield and ecosystem functions (Jagadish et al, 2015). Previous studies on night temperatures have focused either on the effects of HNT and LNT alone (Friend, 1981; Seddigh and Jolliff, 1984a,b,c; Koscielniak, 1993; Bertamini et al, 2005) or the mixed effects of night temperatures and CO 2 concentration (Mortensen and Moe, 1992; Volder et al, 2004; Cheng et al, 2008, 2009, 2010), light period (Gimenez and Rumi, 1988; Turner and Ewing, 1988; Lee et al, 1991; Verheul et al, 2007), intensity (Bunce, 1985; Mortensen, 1994; Rapacz, 1998; Flexas and Osmond, 1999; Davies et al, 2002) as well as other environmental factors (Schoppach and Sadok, 2013) and growth regulators (Shah et al, 2011; Mohammed et al, 2013; Zhang et al, 2014). These experiments had been conducted on pineapple (Neales et al, 1980), peanut (Bagnall et al, 1988; Wang, 2007; Lin et al, 2011) and shrub-grass ecosystems (Beier et al, 2004).…”

Day and night warming have different effect on root lifespan

“…Numerous studies have reported that terrestrial ecosystems are highly sensitive to night warming (Alward et al, 1999;Peng et al, 2004;Volder et al, 2004;Lobell, 2007;Beier et al, 2008). Root growth is closely dependent on soil temperature (Pregitzer et al, 2000).…”

Effects of diurnal warming on soil respiration are not equal to the summed effects of day and night warming in a temperate steppe

“…However, most of the manipulative experiments (Rustad, 2008) were conducted with diurnal or constant warming so far. To the best our knowledge, only a few experiments have been designed to examine the effect of night warming on ecosystem C processes, and day warming was not included in these studies (Volder et al, 2004;Beier et al, 2008). In order to better understand the mechanisms controlling ecosystem C processes and to convincingly project climate change-carbon feedback under the diurnally asymmetric climate warming, it is essential to examine the effects of day and night warming separately and to compare their summed effects with the effects of diurnal warming.…”