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Endophytic fungi are ubiquitous in nature and can play important roles in regulating plant– herbivore interactions. While some aboveground obligate symbionts are considered defensive mutualists of host plants, the importance of root endophytes in plant defense, especially against root-feeding insects, remains unclear. This study aimed to investigate the effects of root fungal endophytes on plant resistance against belowground herbivores and the recovery of host plants from damage. We grew the common grass Festuca arundinacea (tall fescue) semi-aeroponically in the laboratory and inoculated roots with one of five fungal endophytes isolated from field-collected tall fescue or meadow soil. Endophyte-inoculated and uninoculated control plants were subjected to feeding by larvae of the generalist root herbivore Rhizotrogus majalis (European chafer). Herbivory intensity was quantified after eight days, and regrowth of roots and shoots following root herbivory and mechanical shoot damage was measured thereafter for each treatment. Fungal identifications by DNA sequence analysis were conducted after completion of the herbivory experiments and revealed that the five endophytes included the decomposer fungi Trametes versicolor and Mortierella alpina, the entomopathogenic fungi Isaria fumosorosea and Beauveria bassiana, and a potential plant pathogen/entomopathogen Fusarium cf. equiseti. The effects of these root endophytes on plant defense against root-feeding insects were species-specific. While four endophytes had few effects on plant resistance, endophytic B. bassiana significantly reduced herbivore damage to roots. In comparison, plant tolerance to damage was impaired after colonization by all endophyte species except T. versicolor and M. alpina. The contrasting effects of endophytes on plant resistance and plant tolerance suggest that research solely evaluating plant resistance is likely to overestimate the benefits conferred by endophytes without accounting for potential negative effects on plant tolerance. We propose a conceptual framework to include both plant resistance and tolerance as two dimensions of a defensive strategy and show that plant associations with different root endophytes may shift the relative importance of resistance and tolerance for plant defense. [ABSTRACT FROM AUTHOR]

A common finding in multiple CO2 enrichment experiments in forests is the lack of soil carbon ( C) accumulation owing to microbial priming of 'old' soil organic matter ( SOM). However, soil C losses may also result from the accelerated turnover of 'young' microbial tissues that are rich in nitrogen ( N) relative to bulk SOM. We measured root-induced changes in soil C dynamics in a pine forest exposed to elevated CO2 and N enrichment by combining stable isotope analyses, molecular characterisations of SOM and microbial assays. We find strong evidence that the accelerated turnover of root-derived C under elevated CO2 is sufficient in magnitude to offset increased belowground inputs. In addition, the C losses were associated with accelerated N cycling, suggesting that trees exposed to elevated CO2 not only enhance N availability by stimulating microbial decomposition of SOM via priming but also increase the rate at which N cycles through microbial pools. [ABSTRACT FROM AUTHOR]

A common finding in multiple CO2 enrichment experiments in forests is the lack of soil carbon ( C) accumulation owing to microbial priming of 'old' soil organic matter ( SOM). However, soil C losses may also result from the accelerated turnover of 'young' microbial tissues that are rich in nitrogen ( N) relative to bulk SOM. We measured root-induced changes in soil C dynamics in a pine forest exposed to elevated CO2 and N enrichment by combining stable isotope analyses, molecular characterisations of SOM and microbial assays. We find strong evidence that the accelerated turnover of root-derived C under elevated CO2 is sufficient in magnitude to offset increased belowground inputs. In addition, the C losses were associated with accelerated N cycling, suggesting that trees exposed to elevated CO2 not only enhance N availability by stimulating microbial decomposition of SOM via priming but also increase the rate at which N cycles through microbial pools. [ABSTRACT FROM AUTHOR]

Urbanization profoundly impacts biodiversity and ecosystem function, exerting an immense ecological filter on the flora and fauna that inhabit it, oftentimes leading to simplistic and homogenous ecological communities. However, the response of soil animal communities to urbanization remains underexplored, and it is unknown whether their response to urbanization is like that of aboveground organisms. This study investigated the influence of urbanization on soil animal communities in 40 public parks along an urbanization gradient. We evaluated soil animal abundance, diversity, and community composition and related these measures to urban and soil characteristics at each park. The most urbanized parks exhibited reduced animal abundance, richness, and Shannon diversity. These changes were influenced by many variables underscoring the multifaceted influence of urbanization on ecological communities. Notably, contrary to our expectation, urbanization did not lead to community homogenization; instead, it acted stochastically, creating unique soil animal assemblages. This suggests that urban soil animal communities are concomitantly shaped by deterministic and stochastic ecological processes in urban areas. Our study highlights the intricate interplay between urbanization and soil animal ecology, challenging the notion of urban homogenization in belowground ecosystems and providing insight for managing and preserving belowground communities in urban areas., (© 2024 The Author(s). Ecological Applications published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)