Differential responses of arbuscular mycorrhizal fungi to nitrogen addition in a near pristine Tibetan alpine meadow

Abstract

Elucidating the responses of soil microbial abundance and community composition to nitrogen (N) addition is important for predicting ecosystem function under increased atmospheric N deposition. We examined the arbuscular mycorrhizal (AM) fungal community under three N forms (NH4(+)-N, NO3(-)-N, and NH4NO3-N) and two N rates (1.5 and 7.5 g N m(-2) year(-1)) in an alpine meadow of the Qinghai-Tibetan Plateau. AM fungal extraradical hyphal density was significantly decreased by NH4(+)-N in May, but was not affected by N form nor N rate in August. N rate, but not N form, significantly affected AM fungal spore density; high N rate decreased spore density. No direct N addition effect was observed on AM fungal community; however, soil available phosphorus, pH, and NO3(-)-N were considered as important factors that influenced AM fungal community composition. Structural equation model results showed that N rate, not N form, strongly affected soil characteristics, which directly influenced community compositions of plants and AM fungi, as well as spore density. Therefore, AM fungal community was influenced by N addition, primarily because of altered soil characteristics, and partially by a modified plant community, but not or just slightly by direct N addition effects in this alpine meadow ecosystem.

Arbuscular Mycorrhizal Fungi Improve the Antioxidative Response and the Seed Production of Suaedoideae Species Suaeda physophora Pall Under Salt Stress

“…These species structures can form mutualistic associations with most land plant species and obtain carbon (C) from their plant partners in exchange for mineral nutrients (Zheng et al, 2014). AMF can not only improve plant growth but also protect their host plants from drought stress, salt stress and nutrient depletions (Morte et al, 2001;Alqarawi et al, 2014).…”

Arbuscular mycorrhizal fungal communities and Rhizophagus irregularis populations shift in response to short-term ploughing and fertilisation in a buffer strip

“…The effect of two common agricultural practices used in conventional and intensive farming, namely physical soil disturbance and the application of fertilisers, has been studied separately in long-term experiments in agroecosystems (e.g. Jansa et al 2002Jansa et al , 2003Oehl et al 2003;Lin et al 2012;Liu et al 2012;Thian et al 2013;Stockinger et al 2014).…”

Response of Soil Fungal Diversity to Nitrogen Deposition in a Deyeuxia augustifolia Wetland of Sanjiang Plain, Northeast, China

“…Thus, nitrogen deposition plays a complex role in the composition change of soil fungal communities. If the observed trends can be generalized to other ecosystems, high nitrogen deposition in some regions of China is likely to affect local soil fungal communities (Zhou and Yan, 2001;Zheng et al, 2014;He et al, 2016).…”