Moderate phosphorus additions consistently affect community composition of arbuscular mycorrhizal fungi in tropical montane forests in southern Ecuador

Abstract

Anthropogenic atmospheric deposition can increase nutrient supply in the most remote ecosystems, potentially affecting soil biodiversity. Arbuscular mycorrhizal fungal (AMF) communities rapidly respond to simulated soil eutrophication in tropical forests. Yet the limited spatio-temporal extent of such manipulations, together with the often unrealistically high fertilization rates employed, impedes generalization of such responses. We sequenced mixed root AMF communities within a seven year-long fully factorial nitrogen (N) and phosphorus (P) addition experiment, replicated at three tropical montane forests in southern Ecuador with differing environmental characteristics. We hypothesized: strong shifts in community composition and species richness after long-term fertilization, site-and clade-specific responses to N vs P additions depending on local soil fertility and clade life history traits respectively. Fertilization consistently shifted AMF community composition across sites, but only reduced richness of Glomeraceae. Compositional changes were mainly driven by increases in P supply while richness reductions were observed only after combined N and P additions. We conclude that moderate increases of N and P exert a mild but consistent effect on tropical AMF communities. To predict the consequences of these shifts, current results need to be supplemented with experiments that characterize local species-specific AMF functionality.

Influence of 37 Years of Nitrogen and Phosphorus Fertilization on Composition of Rhizosphere Arbuscular Mycorrhizal Fungi Communities in Black Soil of Northeast China

“…In our study, N fertilizer did not significantly changed AMF diversity in the wheat rhizosphere, consistent with previous reports (Mueller and Bohannan, 2015;Dueñas et al, 2020). This may reflect the influence of interaction between fertilization and plant on rhizosphere AMF, as the relocation of C to AMF increased with N fertilization.…”

“…The NMDS analysis demonstrated that AMF communities differed significantly among different fertilization regimes, suggesting that different N and P additions induced a shift in AMF community composition. These results agree with former findings that the abundance of soil nutrients plays a crucial role in shaping the rhizosphere AMF community (Qin et al, 2015;Dueñas et al, 2020). It was reported that nutrients accumulation caused markedly changes in soil chemical properties, species that are insensitive to the disturbances or efficient in acquiring plant C will increase in relative abundance (Koch et al, 2017;Wang et al, 2018).…”

“…The available nutrients were higher in N 2 and N 2 P 2 than other fertilizer treatments and CK ( Table 1). The relative abundances of Glomus and Claroideoglomus were significantly positively correlated with soil C:N values, consistent with other reports that soil C:N was also an important factor affecting the soil AMF community (Shi et al, 2014;Treseder et al, 2018;Dueñas et al, 2020).…”

“…The longterm fertilization experiment has a completely randomized block design with three replicated plots (9 m × 4 m). As previous studies shown that AMF composition and diversity was most affected by N and P fertilizers, but not K fertilizer (Lin et al, 2012;Dueñas et al, 2020), we selected the following treatments: no added fertilizer (CK) and low N (N 1 , 150 kg urea ha −1 y −1 ), low N plus low P (N 1 P 1 , 150 kg urea plus 75 kg P 2 O 5 ha −1 y −1 ), high N (N 2 , 300 kg urea ha −1 y −1 ) and high N plus high P (N 2 P 2 , 300 kg urea plus 150 kg P 2 O 5 ha −1 y −1 ) fertilizer. The N fertilizer was applied as in the form of urea, while the P fertilizer was ammonium hydrogen phosphate and calcium super phosphate.…”

“…In this scenario, rhizosphere AMF diversity levels might be maintained. When N and P fertilization increases N and P supply, the benefit provided by this symbiosis is reduced (Dueñas et al, 2020). This may intensify competition among AMF taxa for plant derived C. In this case, a reduction in rhizosphere AMF diversity can be expected.…”