N2 fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO2 enrichment

Abstract

Helen. 2012 N2 fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO2 enrichment. Oecologia, 169 (2). 541-552. 10.1007/s00442-011-2197-4 Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.1 N 2 fixation and cycling in Alnus glutinosa,

Responses of symbiotic N2 fixation in Alnus species to the projected elevated CO2 environment

“…The increase in the total Alnus species plant N mass under elevated CO 2 is smaller than that predicted by the response of the total biomass to elevated CO 2 in phytotron experiments (Temperton et al 2003b;Tobita et al 2011). The same phenomenon was observed in FACE studies, which showed increased N use efficiency in an A. glutinosa monoculture stand under elevated CO 2 (Millett et al 2012;Pourhassan et al 2015). These results suggest that it is necessary to evaluate biomass accumulation as well as total N content and its allocation when considering the N 2 -fixing ability of Alnus species under elevated CO 2 .…”

“…The other was the UK Bangor FACE experiment in which the effects of elevated CO 2 on A. glutinosa performance were compared between monocultures and mixed plantings of Betula pendula, Fagus sylvatica, and Populus tremula 9 tremuloides (Hoosbeek et al 2011;Millett et al 2012;Smith et al 2013aSmith et al , 2013bGodbold et al 2014;Scullion et al 2014). N 2 fixation in A. glutinosa increases under elevated CO 2 despite the absence of significant growth stimulation in a mixedspecies stand after 4 years (Millett et al 2012). However, the fraction of N 2 derived from N 2 fixation, calculated using the 15 N natural abundance method (Chaia and Myrold 2010;Zhang et al 2014), was unaffected by the elevated CO 2 in an A. glutinosa monoculture stand, indicating no increase in N 2 fixation under elevated CO 2 in a monoculture although plant biomass increased significantly (Hoosbeek et al 2011).…”

“…However, because N 2 fixation is influenced by several abiotic and biotic factors, it is predicted that N 2 -fixers, such as Alnus species, do not always enhance their N 2 fixation ability under elevated CO 2 (Tobita et al 2010b). We will discuss the probable responses of Alnus species to elevated CO 2 , considering other factors, such as N, P, and water conditions, by reviewing the results from chamber experiments (Tobita et al 2011) and recent freeair CO 2 enrichment (FACE) experiments (Millett et al 2012). In addition, we will review the understanding of the effects of elevated ozone (O 3 ) (Wittig et al 2009) and leaf chemistry in relation to herbivores (Koike et al 2006), which can decrease the growth of Alnus species.…”

“…One was conducted in Japan (Hokkaido), as introduced in the previous section, on the responses of A. hirsuta to elevated CO 2 in fertile and infertile soils compared to those of non-N 2 -fixing deciduous tree species, including Betula platyphylla, Betula maximowicziana, Quercus mongolica, and Fagus crenata (Agari et al 2007;Eguchi et al 2008aEguchi et al , 2008bWatanabe et al 2010). The other was the UK Bangor FACE experiment in which the effects of elevated CO 2 on A. glutinosa performance were compared between monocultures and mixed plantings of Betula pendula, Fagus sylvatica, and Populus tremula 9 tremuloides (Hoosbeek et al 2011;Millett et al 2012;Smith et al 2013aSmith et al , 2013bGodbold et al 2014;Scullion et al 2014). N 2 fixation in A. glutinosa increases under elevated CO 2 despite the absence of significant growth stimulation in a mixedspecies stand after 4 years (Millett et al 2012).…”

Nitrogen inputs and losses in response to chronic CO<sub>2</sub> exposure in a subtropical oak woodland

“…1). Growth and N 2 fixation in N 2 -fixing plants can respond positively to elevated CO 2 (Cernusak et al, 2011), but in many cases these responses are absent, e.g., N-fixers in temperate grasslands (Garten et al, 2008;Zhang et al, 2011), Alnus (Temperton et al, 2003;Millett et al, 2012), and ocean cyanobacteria (Czerny et al, 2009;Law et al, 2012). Chronic CO 2 exposure was found to reduce cyanobacterial abundance in desert crusts (Steven, 2012).…”