Hemlock woolly adelgid alters fine root bacterial abundance and mycorrhizal associations in eastern hemlock

Vendettuoli, Justin F.; Orwig, David A.; Krumins, Jennifer Adams; Waterhouse, Matthew D.; Preisser, Evan L.

doi:10.1016/j.foreco.2014.12.010

Cited by 12 publications

(8 citation statements)

References 49 publications

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“…Surveys of hemlock roots in infested stands in Connecticut found that ectomycorrhizal colonization, bacterial abundance in the adjacent rhizosphere, and root C:N all declined (Vendettuoli et al. ). While we cannot exclude the possibility that hemlock has naturally low C investment to roots or that the three‐year trend is due to chance, our direct observations of crown thinning in the area surrounding the minirhizotron tubes and measurements would seem to suggest otherwise (A. Finzi, personal observations ).…”

Section: Discussionmentioning

confidence: 99%

Seasonality and partitioning of root allocation to rhizosphere soils in a midlatitude forest

Abramoff

Finzi

2016

Ecosphere

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Citation: Abramoff, R. Z., and A. C. Finzi. 2016. Seasonality and partitioning of root allocation to rhizosphere soils in a midlatitude forest. Ecosphere 7(11):e01547. 10.1002/ecs2.1547Abstract. Root growth, respiration, and exudation are important components of biogeochemical cycles, yet data on the timing and partitioning of C to these processes are rare. As a result, it is unclear how the seasonal timing, or phenology, of root C allocation is affected by the phenology of its component processes: growth of root tissue, respiration, mycorrhizal allocation, and exudation of labile C. The objective of this study was to estimate the phenology and partitioning of C belowground across the growing season in a midlatitude forest located in central Massachusetts. Fine and coarse root production, respiration, and exudation were summed to estimate a monthly total belowground C flux (TBCF) in two hardwood stands dominated by Quercus rubra and Fraxinus americana, respectively, and one conifer stand dominated by Tsuga canadensis. We observed significant stand-level differences in belowground C flux and the partitioning of C to root growth, mycorrhizal fungi, exudation, and respiration. The deciduous hardwood stands allocated C belowground earlier in the season compared to the conifer-dominated stand. The deciduous stands also allocated a greater proportion of TBCF to root growth compared to the conifer-dominated hemlock (T. canadensis) stand. Of the three stands, red oak partitioned the greatest proportion of TBCF (~50%) to root growth, and hemlock the least. Low root growth rates in hemlock may be related to the arrival and spread of the invasive pest, hemlock wooly adelgid (Adelges tsugae), during the study period. Ongoing research in the eastern hemlock stand may yet determine how whole tree allocation and partitioning change as a result of this infestation.

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Section: Discussionmentioning

confidence: 99%

Seasonality and partitioning of root allocation to rhizosphere soils in a midlatitude forest

Abramoff

Finzi

2016

Ecosphere

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“…Our results confirm previous findings indicating a strong effect of HWA on EMF colonisation. Both Lewis et al (2008) and Vendettuoli, Orwig, Krumins, Waterhouse, and Preisser (2015) observed drastic reductions in rates of EMF colonisation for mature hemlocks growing within HWA-infested stands. Gehring and Whitham (2002) found a similar result, that above-ground herbivory of a pine can compromise its ability to maintain EM.…”

Section: Discussionmentioning

confidence: 97%

Individual and non‐additive effects of exotic sap‐feeders on root functional and mycorrhizal traits of a shared conifer host

et al. 2017

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Forest pests drive tree mortality through disruption of functional traits linked to nutrient acquisition, growth and reproduction. The impacts of attack by individual or multiple above‐ground herbivores on root functional traits critical to tree health have received little attention. This is especially true for exotic herbivores, organisms often found in disturbed forests. We excavated whole‐root systems from eastern hemlock (Tsuga canadensis) individuals experimentally infested with hemlock woolly adelgid (HWA: Adelges tsugae) and elongate hemlock scale (EHS: Fiorina externa) individually, or in combination, for periods of 2 and 4 years. Below‐ground root biomass, functional traits and storage nutrients were measured to assess impacts of herbivory. We also quantified ectomycorrhizal fungal (EMF) colonisation of fine roots and used culture‐independent methods to examine EMF diversity. Trees infested with HWA had a greater root mass fraction (root to total biomass ratio), although feeding had no observable effects on root functional traits (e.g. specific root length) or on resource allocation to roots. HWA feeding did significantly reduce EMF colonisation of hemlock fine roots, though surprisingly, EMF diversity and that of other fungal associates were unaffected. In contrast to HWA, EHS (alone or in conjunction with HWA) feeding had no observable effect on below‐ground traits or EMF colonisation alone; however, its presence mediated HWA effects when trees were co‐infested. Simultaneous infestation within the same year yielded significant reductions in EMF colonisation, whereas prior EHS attack weakened HWA effects. Our results collectively suggest that prior EHS attack dampens the impact of HWA on below‐ground functional traits. This highlights how the timing and sequence of herbivore arrival can alter plant‐mediated interactions between herbivores and their effects on above–below‐ground linkages and associated tree health. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12910/suppinfo is available for this article.

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“…in North America caused by outbreaks of the invasive gypsy moth (Lymantria dispar) results in a large pulse of nutrients to the soil in the form of frass, dead caterpillars and unconsumed fallen foliage, which can in turn be utilized by soil microbes and transformed to organic matter (Lovett and Ruesink 1995). Sublethal effects of invertebrate and pathogen outbreaks also lead to physiological changes in host plants that alter their inputs to the soil (Cobb and Rizzo 2016), which may impair associated soil biota (Vendettuoli et al 2015) and alter nutrient cycling rates (Rubino et al 2015). Whether and how the effects of invasive herbivorous invertebrates and pathogens on the belowground subsystem feedback aboveground remains unexplored, but such feedbacks may be important in perpetuating their impacts over the longer term.…”

Section: Invasive Aboveground Consumersmentioning

confidence: 99%

Impacts of invasive biota in forest ecosystems in an aboveground–belowground context

Wardle

Peltzer

2017

Biol Invasions

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Forest ecosystems world-wide are being subjected to invasion by organisms representing all domains of life. Here we use a combined aboveground-belowground approach to provide a conceptual framework for assessing how forests respond to biological invasions. We first address mechanisms by which invasive plants and aboveground and belowground consumers impact on forests, and highlight that although we have a growing understanding of the determinants of the effects of invasive plants, for invasive consumers we have yet to move from a series of iconic case studies to the development of general principles. We also address the effects of invasive biota in the context of the drivers of invasion, coinvasion and invasional meltdown, the issue of simultaneous species gains and losses, and forest restoration and recovery post-invasion. We then highlight areas that would benefit from further work, particularly regarding underlying mechanisms, determinants of context-dependency of invader effects, and linkages between causes and consequences of invasion. In concluding, we emphasize that biological invaders have the potential for largescale and long-term impacts on forest processes, and consideration of these impacts in an abovegroundbelowground context will enable better prediction of future responses of forests to invaders and their management as well as of restoration efforts.

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Hemlock woolly adelgid alters fine root bacterial abundance and mycorrhizal associations in eastern hemlock

Cited by 12 publications

References 49 publications

Seasonality and partitioning of root allocation to rhizosphere soils in a midlatitude forest

Seasonality and partitioning of root allocation to rhizosphere soils in a midlatitude forest

Individual and non‐additive effects of exotic sap‐feeders on root functional and mycorrhizal traits of a shared conifer host

Impacts of invasive biota in forest ecosystems in an aboveground–belowground context

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