Strong pulse effects of precipitation events on soil microbial respiration in temperate forests

Abstract

Precipitation is a critical factor triggering soil biogeochemical processes in arid and semi-arid regions. In this study, we selected soils from two temperate forests-a mature natural forest and a degraded secondary forest-in a semi-arid region. We investigated the pulse effects of simulated precipitation (to reach 55% soil water-holding capacity) on the soil microbial respiration rate (R S ). We performed high-intensity measurements (at 5-min intervals for 48 h) to determine the maximum value of R S (R S-max ), the time to reach R S-max (T R S-max ), and the duration of the pulse effect (from the start to the end of ½R S-max ). The responses of R S to simulated precipitation were rapid and strong. R S-max was significantly higher in degraded secondary forest (18.69 μg C g soil) than in mature natural forest (7.94 μg C g soil). In contrast, the duration of the pulse effect and T R S-max were significantly lower in degraded secondary forest than in mature natural forest. Furthermore, the accumulative microbial respiration per gram of soil (A R S-soil ) did not differ significantly between degraded secondary forest and mature natural forest, but the accumulative microbial respiration per gram of soil organic C (A R S-soc ) was significantly higher in degraded secondary forest than in mature natural forest. Soil microbial biomass, soil nutrient, and litter nitrogen content were strongly correlated with the duration of the pulse effect and T R S-max . Soil physical structure, pH, and litter nitrogen content were strongly correlated with R S-max and A R S-soc . Our results indicate that the responses of soil microbial respiration to simulated precipitation are rapid and strong and that microbial respiration rate per gram C can be used to precisely determine the precipitation pulse of different soil samples as well as the effects of changing precipitation patterns on soil C content under various scenarios of global climate change.

Interactive effects of forest die-off and drying-rewetting cycles on C and N mineralization

“…Independently of the mechanisms behind the observed CO pulses, our results corroborated the rapid and strong response of semiarid soils to even small rainfall pulses after a drought event (e.g. Rey et al, 2017;Song et al, 2017;Wang et al, 2016). This rapid CO 2 pulse after a dry soil is rewetted (Birch effect) is of great interest due to its important implications for soil C stocks (Blazewicz et al, 2014;Borken and Matzner, 2009), ecosystem C balances (Ma et al, 2012) and global warming (Jarvis et al, 2007).…”

“…This microbial activity pulse, named the Birch effect after one of its first observers (Birch, 1958), can be a major contribution to ecosystem C release into the atmosphere (Jenerette et al, 2008). The size of the pulse depends on the intensity and duration of the rainfall and the previous drought event, as well as on the vegetation and soil organic matter content and quality (Huxman et al, 2004;Meisner et al, 2015;Morillas et al, 2017;Song et al, 2017;Wang et al, 2016). Global warming circulation models predict changes in precipitation regimes including more frequent and intense droughts as well as increased extreme rainfall events (IPCC, 2013).…”

“…These changes will be particularly critical in the Mediterranean region, characterized by a large intra-annual variation in soil water content, which largely regulates ecosystem functioning (Gallardo et al, 2009). Whilst recent studies have suggested that small rainfall pulses and drying-rewetting processes may be the main driver of soil C and N cycling in Mediterranean environments (Rey et al, 2017;Song et al, 2017;Wang et al, 2016), the effects of multiple drying-rewetting cycles on both C and N mineralization rates of Mediterranean forest soils…”

“…have not yet been well elucidated (Wang et al, 2016). Mediterranean forests are representative of one of the most widely distributed semiarid areas throughout the world (Jarvis et al, 2007) and are considered biodiversity hotspots.…”

Responses of soil respiration with biocrust cover to water and temperature in the southeastern edge of Tengger Desert, Northwest China

“…Key words respiration; biocrust; precipitation patterns; stimulated warming (Maestre et al, 2013;Shen et al, 2015;Wang et al, 2016) 的影响 (Conant et al, 2004;Sharkhuu et al, 2016)。 另 外, 荒漠生态系统有机质贫乏 (Zhang et al, 2012), …”