Day and night warming have different effect on root lifespan

Abstract

Abstract.Roots are key components of C cycling in terrestrial ecosystems and play an important role in the regulation of response of terrestrial ecosystems to global climate warming, which is predicted to occur with greater warming magnitudes at night than during daytime across different regions on the Earth. However, there has been no detailed study to investigate the effect of asymmetrical warming on root dynamics at the level of terrestrial ecosystems. To understand the effects of day and night warming on root lifespan in the semiarid temperate steppe in northern China, a field study with a full factorial design including control, day warming, night warming and continuous warming was conducted using modified rhizotron technique during three growing seasons in 2007-2009. Our results show that day, night and continuous warming had different effects on longevity of roots born in spring, summer and autumn, and that day warming significantly prolonged overall lifespan for the roots born in the three growing seasons, while night warning had no effect on overall lifespan. Day and night warming had different effects on root non-structural carbohydrate content, suggesting that allocation of photoassimilate may account for the differential responses of root lifespan to day and night warming. These results differ from other processes associated with ecosystems C cycle such as total ecosystem productivity, net ecosystem productivity and soil respiration. Our findings highlight that it is essential to incorporate the differential effects of day and night warming on root dynamics into simulating and predicting the responses and feedbacks of terrestrial ecosystems C cycling to global warming.

Effects of Warming and Precipitation Manipulation on Fine Root Dynamics of Pinus densiflora Sieb. et Zucc. Seedlings

“…In general, warmer soil temperatures stimulate the rapid death of roots in warming treatment of 1.3 to 1.7 • C [35] and 5.0 • C [36]. However, in some cases, no change in FRM with 2.8 • C warmer treatment [37] or decreases in FRM with relatively weak warmer (0.3 to 1.4 • C) system [12,38] was observed. The contradictory results of previous studies might be explained by the water availability in each ecosystem [39].…”

Arbuscular mycorrhizal symbiosis can mitigate the negative effects of night warming on physiological traits of Medicago truncatula L

“…Different artificial warming scenarios, such as day, night, or diurnal warming, have shown differential effects on plant physiological traits and ecosystem productivity. For example, Bai et al (2012) observed that day warming can, but night warming cannot, prolong root lifespan. Also, Wan et al (2009) reported that day warming significantly decreased, while night warming increased, gross ecosystem productivity in the semiarid temperate steppe in northern China.…”

Positive effects of night warming on physiology of coniferous trees in late growing season: Leaf and root

“…Consequently, a cascade of studies have investigated plants responses to global warming (Lemmens et al, 2006;Vicca et al, 2007;Danby and Hik, 2007;Leppalammi et al, 2013;Zheng et al, 2013), such as structure, physiology and function of leaves (Jin et al, 2011;Zheng et al, 2013), root lifespan and physiology (Bai et al, 2012;Yin et al, 2014), plant phenology (K€ orner and Basler, 2010) and carbon gain (Gimeno et al, 2012) as well as net primary productivity (Hudson and Henry, 2009). It is reported that globally averaged maximum and minimum temperatures have both increased since 1950 (IPCC, 2013), which tends to affect carbon assimilation and consumptions in plants, because photosynthesis in most plants occurs during the daytime and is more sensitive to daily maximum temperature, whereas plants respiration occurs throughout the whole day (Atkin et al, 2013), and is therefore influenced by both daily maximum and minimum temperature (Peng et al, 2013).…”