The role of vegetation in methane flux to the atmosphere: should vegetation be included as a distinct category in the global methane budget?

A novel pathway of direct methane production and emission by eukaryotes including plants, animals and fungi: An overview

“…By assuming UV radiation-induced CH 4 emissions from pectin as representing foliar CH 4 emissions, Bloom et al (2010) suggested a global contribution of 0.2e1.0 Tg plantderived CH 4 yr À1 . However, clear evidence shows that pectin is not the only precursor (Carmichael et al, 2014;Lenhart et al, 2014;Vigano et al, 2009), and several environmental stresses in addition to UV radiation have been observed to induce CH 4 production. Thus, whether Bloom et al (2010) underestimated the magnitude of this plant source of CH 4 has been a subject of debate (Bruhn et al, 2012;Fraser et al, 2015).…”

“…3). Recently, Carmichael et al (2014) suggested that plant-based CH 4 emissions represent about 5e22% of the global total CH 4 budget by summing direct and indirect CH 4 emissions by vegetation (indirect pathways including plant cisterns, heartwood rot, litter and transport processes through plants). Their estimate of direct CH 4 emissions by vegetation, which is 8e60 Tg CH 4 yr À1 , is only based on the existing upscaling methods including above-ground NPP, but our estimate is based on all existing reasonable upscaling results.…”

“…Their estimate of direct CH 4 emissions by vegetation, which is 8e60 Tg CH 4 yr À1 , is only based on the existing upscaling methods including above-ground NPP, but our estimate is based on all existing reasonable upscaling results. Another difference between our calculations is that Carmichael et al (2014) used the figure of 645 Tg yr À1 to present the current global CH 4 budget (Schlesinger and Bernhardt, 2013) while we used the figure of 548 Tg CH 4 a À1 that is proposed by the IPCC (2013) .…”

“…However, Keppler et al (2006) reported a startling discovery that terrestrial plants can produce and emit CH 4 directly under aerobic conditions. This finding has sparked an interest in determining whether a direct source of unrecognised CH 4 generation exists in different structural/architectural hierarchies of plants (Bruhn et al, 2012;Carmichael et al, 2014), because before this discovery, different forms of combustion were the only processes known to form CH 4 in the presence of oxygen. Although the observation of plants acting as direct emitters of CH 4 is a paradigm shift and has received substantial criticism, it has indeed challenged the traditional view on the CH 4 biosynthetic pathway and opened another avenue to account for the fluctuation of the global CH 4 concentration and the recent satellite-observed discrepancy in CH 4 over tropical forests (Frankenberg et al, 2008(Frankenberg et al, , 2005.…”

Regime shift in the littoral ecosystem of volcanic Lake Atitlán in Central America: combined role of stochastic event and invasive plant species

“…Invasive macrophytes are typically faster growing and produce more biomass than native species (Herb & Stefan, 2006;Kennedy, Horth, & Carr, 2009). Macrophyte productivity impacts carbon (C) budgets of freshwater lakes directly via photosynthesis and autotrophic respiration and indirectly due to the degradation of plant litter (Carmichael, Bernhardt, Brauer, & Smith, 2014;Grasset, Abril, Guillard, Delolme, & Bornette, 2016). Therefore, significant changes in life forms of primary producers, such as those resulting from plant invasions, have the potential to change the net C flux of a lake (Attermeyer et al, 2016).…”