Traits mediate drought effects on wood carbon fluxes

Abstract

CO 2 fluxes from wood decomposition represent an important source of carbon from forest ecosystems to the atmosphere, which are determined by both wood traits and climate influencing the metabolic rates of decomposers. Previous studies have quantified the effects of moisture and temperature on wood decomposition, but these effects were not separated from the potential influence of wood traits. Indeed, it is not well understood how traits and climate interact to influence wood CO 2 fluxes.Here, we examined the responses of CO 2 fluxes from dead wood with different traits (angiosperm and gymnosperm) to 0%, 35%, and 70% rainfall reduction across seasonal temperature gradients. Our results showed that drought significantly decreased wood CO 2 fluxes, but its effects varied with both taxonomical group and drought intensity. Drought-induced reduction in wood CO 2 fluxes was larger in angiosperms than gymnosperms for the 35% rainfall reduction treatment, but there was no significant difference between these groups for the 70% reduction treatment. This is because wood nitrogen density and carbon quality were significantly higher in angiosperms than gymnosperms, yielding a higher moisture sensitivity of wood decomposition. These findings were demonstrated by a significant positive interaction effect between wood nitrogen and moisture on CO 2 fluxes in a structural equation model. Additionally, we ascertained that a constant temperature sensitivity of CO 2 fluxes was independent of wood traits and consistent with previous estimates for extracellular enzyme kinetics. Our results highlight the key role of wood traits in regulating drought responses of wood carbon fluxes. Given that both climate and S U PP O RTI N G I N FO R M ATI O NAdditional supporting information may be found online in the Supporting Information section.

Emission of CO2 and CH4 From 13 Deadwood Tree Species Is Linked to Tree Species Identity and Management Intensity in Forest and Grassland Habitats

“…Organic extractives, as the sum of diverse compounds involved in plant defense mechanisms, can inhibit fungal decomposition activity (Gierlinger et al., 2004; Kahl et al., 2017), which would explain the observed negative effect on CO 2 emission rates. In contrast, the natural abundance of nitrogen and magnesium promoted deadwood decomposing microorganisms and enzyme activities (Bebber et al., 2011; Hu et al., 2020; Rosenstock et al., 2016; Zak et al., 2019), which consequently increased CO 2 emission rates.…”

“…For CO 2 emission rates, the importance of temperature was shown to increase in the mid‐stage of decomposition (Gough et al., 2007; Ohtsuka et al., 2014; Russell et al., 2014). In addition, higher deadwood moisture and rainfall led to increased CO 2 emission rates (Herrmann & Bauhus, 2013; Hu et al., 2020) and decomposition rates as long as the wood moisture content was between 20% and 80% (vol./vol. ; Cornelissen et al., 2012).…”

Wood species identity alters dominant factors driving fine wood decomposition along a tree diversity gradient in subtropical plantation forests

“…This innate difference explains their affinity for some wood species over others (softwoods vs. hardwoods). As tree species identity and traits can even modify local microclimate and soil conditions (Eviner & Chapin, 2003; Gottschall et al., 2019; Vivanco & Austin, 2008), considering how multiple wood traits interact with exogenous factors helps to understand species identity effects on wood decomposition (Cornwell et al., 2009; Hu et al., 2020; Zanne et al., 2015).…”

Relative importance of climatic variables, soil properties and plant traits to spatial variability in net CO2 exchange across global forests and grasslands

“…If the vegetation type shifts under future climate change (Svenning and Sandel, 2013;Franklin et al, 2020), plant traits may have independent effects on carbon fluxes, the importance of which may be further amplified by the potential interactions among plants traits, climatic variables and soil properties (Fig. 8, Hu et al, 2020;Reichstein et al, 2014).…”