Dissimilar response of plant and soil biota communities to long-term nutrient addition in grasslands

Response of belowground communities to short-term phosphorus addition in a phosphorus-limited woodland

“…This was unexpected given that plants are thought to allocate less carbohydrates to mycorrhizal fungi when nutrients are not limiting (Read 1991). Alternatively, mycorrhizal fungi may respond positively to fertilizer addition if they are nutrient limited (Treseder and Allen 2002) or, more in line with the evidence observed here, if they respond positively to associated changes in soil pH (Kluber et al 2012;Walker et al 2014). Significant indicator OTUs in the unfertilized treatment included fungal genera identified as putative plant pathogens, antagonists of other fungi, and saprotrophs, suggesting that fertilization may have impacted the strength of some biotic interactions, as has been observed for competition in some plant communities (e.g., Coates et al 2013), or may have simply increased the abundance of other fungi relative to those in these functional groups.…”

“…The former is likely as Eucalyptus and Microlaena in the plots showed significantly increased leaf P concentrations (Crous et al 2015). It is not possible to determine whether the significant path connecting the P fertilization variable and fungal abundance represents either of these scenarios but under very low soil P concentrations fungal growth is limited (Treseder and Allen 2002) even though studies suggest that fungi are more limited by the availability of carbon and nitrogen than by phosphorus (Treseder 2004;Ehlers et al 2010). Fungal community composition was also significantly affected by P fertilization, but we observed that this effect was probably mediated by changes in soil pH.…”

“…While only Collembola responded positively to shortterm P-fertilization, and predatory nematodes responded negatively, the longer term trends may be less equivocal. Several studies have found that long-term fertilizer applications generally have positive effects on the abundance of mites, Collembola and nematodes in a broad range of ecosystem types (Altieri 1999;Oliver et al 2005;Sjursen et al 2005;Berch et al 2009;van der Wal et al 2009). This suggests that continued fertilization at our study site may also result in significant increases in mite and nematode abundances more broadly over time albeit likely accompanied by altered community composition as indicated by our results.…”

“…Negative effects have also been observed on microbial diversity (Camenzind et al 2014), and abundances of protozoans (Krashevska et al 2014) and microarthropods (Jandl et al 2003;Schon et al 2011). These may be attributed to direct or indirect effects of fertilizer application (Bünemann et al 2006;van der Wal et al 2009) including alterations in other mineral nutrient cycles and changes in pH (Vilkamaa and Huhta 1986;Epstein and Bloom 2005). However, fertilization studies rarely investigate the relative contribution of direct and indirect effects on the observed responses and broader soil food web effects.…”

Agro-Industrial Waste Management: A Case Study of Soil Fauna Responses to the Use of Biowaste as Meadow Fertiliser in Galiza, Northwestern Spain

“…Generally, the effects of fertiliser application in moderate doses are positive, originating from the modification of microclimatic conditions or from resource availability [4,[30][31][32][33][34][35][36][37][38].…”