Invasive insect effects on nitrogen cycling and host physiology are not tightly linked

Lucy Rubino, Sherley Charles, Abby G. Sirulnik, Amy Tuininga, James D. Lewis

Research output: Contribution to journalArticleResearchpeer-review

12 Citations (Scopus)

Abstract

Invasive insects may dramatically alter resource cycling and productivity in forest ecosystems. Yet, although responses of individual trees should both reflect and affect ecosystem-scale responses, relationships between physiological-and ecosystem-scale responses to invasive insects have not been extensively studied. To address this issue, we examined changes in soil nitrogen (N) cycling, N uptake and allocation, and needle biochemistry and physiology in eastern hemlock (Tsuga canadensis (L) Carr) saplings, associated with infestation by the hemlock woolly adelgid (HWA) (Adelges tsugae Annand), an invasive insect causing widespread decline of eastern hemlock in the eastern USA. Compared with uninfested saplings, infested saplings had soils that exhibited faster nitrification rates, and more needle 15N uptake, N and total protein concentrations. However, these variables did not clearly covary. Further, within infested saplings, needle N concentration did not vary with HWA density. Light-saturated net photosynthetic rates (Asat) declined by 42% as HWA density increased from 0 to 3 adelgids per needle, but did not vary with needle N concentration. Rather, Asat varied with stomatal conductance, which was highest at the lowest HWA density and accounted for 79% of the variation in Asat. Photosynthetic light response did not differ among HWA densities. Our results suggest that the effects of HWA infestation on soil N pools and fluxes, 15N uptake, needle N and protein concentrations, and needle physiology may not be tightly coupled under at least some conditions. This pattern may reflect direct effects of the HWA on N uptake by host trees, as well as effects of other scale-dependent factors, such as tree hydrology, affected by HWA activity.

Original languageEnglish
Pages (from-to)124-133
Number of pages10
JournalTree Physiology
Volume35
Issue number2
DOIs
StatePublished - 1 Jan 2015

Fingerprint

Hemlock
Adelges tsugae
Insects
Nitrogen
physiology
Needles
insects
nitrogen
saplings
Tsuga canadensis
Tsuga
uptake mechanisms
Ecosystem
Soil
Adelgidae
Hydrology
soil
Nitrification
Light
ecosystems

Keywords

  • Adelges tsugae
  • Eastern hemlock
  • Hemlock woolly adelgid
  • Invasive species
  • N allocation
  • N cycling
  • Photosynthesis
  • Tsuga canadensis

Cite this

Rubino, Lucy ; Charles, Sherley ; Sirulnik, Abby G. ; Tuininga, Amy ; Lewis, James D. / Invasive insect effects on nitrogen cycling and host physiology are not tightly linked. In: Tree Physiology. 2015 ; Vol. 35, No. 2. pp. 124-133.
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abstract = "Invasive insects may dramatically alter resource cycling and productivity in forest ecosystems. Yet, although responses of individual trees should both reflect and affect ecosystem-scale responses, relationships between physiological-and ecosystem-scale responses to invasive insects have not been extensively studied. To address this issue, we examined changes in soil nitrogen (N) cycling, N uptake and allocation, and needle biochemistry and physiology in eastern hemlock (Tsuga canadensis (L) Carr) saplings, associated with infestation by the hemlock woolly adelgid (HWA) (Adelges tsugae Annand), an invasive insect causing widespread decline of eastern hemlock in the eastern USA. Compared with uninfested saplings, infested saplings had soils that exhibited faster nitrification rates, and more needle 15N uptake, N and total protein concentrations. However, these variables did not clearly covary. Further, within infested saplings, needle N concentration did not vary with HWA density. Light-saturated net photosynthetic rates (Asat) declined by 42{\%} as HWA density increased from 0 to 3 adelgids per needle, but did not vary with needle N concentration. Rather, Asat varied with stomatal conductance, which was highest at the lowest HWA density and accounted for 79{\%} of the variation in Asat. Photosynthetic light response did not differ among HWA densities. Our results suggest that the effects of HWA infestation on soil N pools and fluxes, 15N uptake, needle N and protein concentrations, and needle physiology may not be tightly coupled under at least some conditions. This pattern may reflect direct effects of the HWA on N uptake by host trees, as well as effects of other scale-dependent factors, such as tree hydrology, affected by HWA activity.",
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Invasive insect effects on nitrogen cycling and host physiology are not tightly linked. / Rubino, Lucy; Charles, Sherley; Sirulnik, Abby G.; Tuininga, Amy; Lewis, James D.

In: Tree Physiology, Vol. 35, No. 2, 01.01.2015, p. 124-133.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Invasive insect effects on nitrogen cycling and host physiology are not tightly linked

AU - Rubino, Lucy

AU - Charles, Sherley

AU - Sirulnik, Abby G.

AU - Tuininga, Amy

AU - Lewis, James D.

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N2 - Invasive insects may dramatically alter resource cycling and productivity in forest ecosystems. Yet, although responses of individual trees should both reflect and affect ecosystem-scale responses, relationships between physiological-and ecosystem-scale responses to invasive insects have not been extensively studied. To address this issue, we examined changes in soil nitrogen (N) cycling, N uptake and allocation, and needle biochemistry and physiology in eastern hemlock (Tsuga canadensis (L) Carr) saplings, associated with infestation by the hemlock woolly adelgid (HWA) (Adelges tsugae Annand), an invasive insect causing widespread decline of eastern hemlock in the eastern USA. Compared with uninfested saplings, infested saplings had soils that exhibited faster nitrification rates, and more needle 15N uptake, N and total protein concentrations. However, these variables did not clearly covary. Further, within infested saplings, needle N concentration did not vary with HWA density. Light-saturated net photosynthetic rates (Asat) declined by 42% as HWA density increased from 0 to 3 adelgids per needle, but did not vary with needle N concentration. Rather, Asat varied with stomatal conductance, which was highest at the lowest HWA density and accounted for 79% of the variation in Asat. Photosynthetic light response did not differ among HWA densities. Our results suggest that the effects of HWA infestation on soil N pools and fluxes, 15N uptake, needle N and protein concentrations, and needle physiology may not be tightly coupled under at least some conditions. This pattern may reflect direct effects of the HWA on N uptake by host trees, as well as effects of other scale-dependent factors, such as tree hydrology, affected by HWA activity.

AB - Invasive insects may dramatically alter resource cycling and productivity in forest ecosystems. Yet, although responses of individual trees should both reflect and affect ecosystem-scale responses, relationships between physiological-and ecosystem-scale responses to invasive insects have not been extensively studied. To address this issue, we examined changes in soil nitrogen (N) cycling, N uptake and allocation, and needle biochemistry and physiology in eastern hemlock (Tsuga canadensis (L) Carr) saplings, associated with infestation by the hemlock woolly adelgid (HWA) (Adelges tsugae Annand), an invasive insect causing widespread decline of eastern hemlock in the eastern USA. Compared with uninfested saplings, infested saplings had soils that exhibited faster nitrification rates, and more needle 15N uptake, N and total protein concentrations. However, these variables did not clearly covary. Further, within infested saplings, needle N concentration did not vary with HWA density. Light-saturated net photosynthetic rates (Asat) declined by 42% as HWA density increased from 0 to 3 adelgids per needle, but did not vary with needle N concentration. Rather, Asat varied with stomatal conductance, which was highest at the lowest HWA density and accounted for 79% of the variation in Asat. Photosynthetic light response did not differ among HWA densities. Our results suggest that the effects of HWA infestation on soil N pools and fluxes, 15N uptake, needle N and protein concentrations, and needle physiology may not be tightly coupled under at least some conditions. This pattern may reflect direct effects of the HWA on N uptake by host trees, as well as effects of other scale-dependent factors, such as tree hydrology, affected by HWA activity.

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KW - Hemlock woolly adelgid

KW - Invasive species

KW - N allocation

KW - N cycling

KW - Photosynthesis

KW - Tsuga canadensis

UR - http://www.scopus.com/inward/record.url?scp=84937556302&partnerID=8YFLogxK

U2 - 10.1093/treephys/tpv004

DO - 10.1093/treephys/tpv004

M3 - Article

VL - 35

SP - 124

EP - 133

JO - Tree Physiology

JF - Tree Physiology

SN - 0829-318X

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