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Harvard Forest Data Archive

HF021

Stand and Community Response to Hemlock Woolly Adelgid in Southern New England since 1995

Related Publications

Data

Overview

  • Lead: David Orwig, David Foster
  • Investigators:
  • Contact: David Orwig
  • Start date: 1995
  • End date: 2008
  • Status: ongoing
  • Location: South Central Connecticut
  • Latitude: +41.28 to +41.56
  • Longitude: -72.33 to -72.73
  • Elevation:
  • Taxa: Adelges tsugae (hemlock woolly adelgid), Betula lenta (black birch), Tsuga canadensis (eastern hemlock)
  • Release date: 2012
  • Revisions:
  • EML file: knb-lter-hfr.21.19
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: invasive plants, pests and pathogens; physiological ecology, population dynamics and species interactions; regional studies
  • LTER core area: disturbance
  • Keywords: hemlock, hemlock woolly adelgid, invasive species, successional dynamics, tree mortality, vegetation dynamics
  • Abstract:

    Hemlock woolly adelgid (HWA), Adelges tsugae, an introduced aphid-like insect from Asia, is expanding its range across the northeastern United States through the range of Tsuga canadensis (eastern hemlock) and can severely reduce or eliminate this important late-successional species. As part of a study investigating stand- and landscape-level forest dynamics resulting from HWA infestation, we examined initial community response of eight T. canadensis stands in south-central Connecticut and then continued to monitor these stands every other year. Our major objectives were to assess mortality patterns in T. canadensis, evaluate subsequent changes in stand microenvironment, and relate these and stand composition to initial patterns of regeneration, understory response, and community reorganization. Tsuga canadensis damage varied broadly across the study area ranging from near zero to greater than 95 % mortality. All size and age classes sampled were attacked by HWA, although smaller trees exhibited higher mortality rates than larger trees. All remaining T. canadensis sampled in seven of the eight stands were infested with HWA and over 90 % suffered at least 50 % foliar loss. Since 1995, overstory and understory mortality has risen 5 to 15 % per year to overall values of 50 to 99%. There has been no sign of tree recovery and the health and vigor of remaining trees deteriorated in all infested stands. Results suggest that trees on some sites can remain alive for over 10 years following initial infestation and remain standing for 6 to 8 years following mortality. Substantial accumulations of downed woody debris have developed in stands with severe HWA damage. Canopy gaps created by HWA damage significantly increased the amount of light reaching the forest floor and resulted in rapid understory vegetation responses. Prolific Betula lenta (black birch) establishment occurred in stands with moderate to severe T. canadensis mortality. In addition, opportunistic herbaceous species (Erechtites hieracifolia, Phytolacca americana) and exotic species (Ailanthus altissima, Microstegium vimineum) have recently invaded these stands. Due to mortality from HWA, T. canadensis seedlings were scarce in sampled stands, suggesting that advance regeneration and seedbanks will not be important mechanisms for T. canadensis reestablishment. Tsuga canadensis cannot sprout following defoliation and has no apparent resistance to HWA. Tree-ring analysis of hardwood and declining hemlock trees, coupled with age-structure analysis of newly established birch saplings was effective in determining the timing of initial HWA impact in stands of unknown infestation date. Over the last 10 years, radial growth of hemlock declined precipitously in most stands, while oak and maple growth exhibited concomitant, large annual increases. Therefore, dramatic reductions in T. canadensis across broad geographical areas appear imminent if HWA dispersal continues unimpeded and no effective natural enemies of HWA are found.

  • Methods:

    In each of 8 stands, five 20 x 20 permanent plots were established. Within each plot, tree dbh, species, crown class and crown vigor (for hemlock) was assessed. Within 10 nested 1m2 subplots, seedling density, and cover of seedlings, shrubs and herbs were estimated. Random trees were cored initially for age determination and subsequent coring in some stands has occurred to examine radial growth patterns associated with long-term HWA infestations.

  • Use:

    This dataset is released to the public under Creative Commons license CC BY (Attribution). Please keep the designated contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement.

  • Citation:

    Orwig D, Foster D. 2012. Stand and Community Response to Hemlock Woolly Adelgid in Southern New England since 1995. Harvard Forest Data Archive: HF021.

Detailed Metadata

hf021-01: overstory

  1. stand: site codes
    • BB: Burnham Brook
    • CP: Chapman Pond
    • FP: Foster's Pond
    • GU: Guilford
    • RH: Ruth Hill
    • SN or SC: Selden Neck Creek
    • SR: Salmon River
    • TRI: Tri-Mountain
  2. plot: 20 x 20 meter plot number
  3. species: species code
    • ACRU: Acer rubrum
    • ACSA: Acer saccharum
    • AMAR: Amelanchier arborea
    • BEAL: Betula alleghaniensis
    • BELE: Betula lenta
    • CACO: Carya cordiformis
    • CAGL: Carya glabra
    • CAOV: Carya ovata
    • FAGR: Fagus grandifolia
    • FRAM: Fraxinus americana
    • HAVI: Hamamelis virginiana
    • LITU: Liriodendron tulipifera
    • PIST: Pinus strobus
    • QUAL: Quercus alba
    • QUCO: Quercus coccinea
    • QUPR: Quercus prinus
    • QURU: Quercus rubra
    • QUVE: Quercus velutina
    • ROPS: Robinia psuedoacacia
    • TSCA: Tsuga canadensis
    • ULRA: Ulmus rubra
  4. dbh: breast height (1.37m) diameter (unit: centimeter / missing value: NA)
  5. crown: tree canopy crown class
    • 1: overtopped tree
    • 2: intermediate canopy position
    • 3: codominant canopy position
    • 4: dominant canopy position
  6. vigor: crown vigor of hemlock trees
    • 1: healthy; no visible foliar loss
    • 2: healthy; 1-25% foliar loss
    • 3: declining; 26 - 50% foliar loss
    • 4: declining; 51 - 75% foliar loss
    • 5: declining; 76 - 99% foliar loss
    • 6: dead

hf021-02: shrub

  1. stand: site codes
    • BB: Burnham Brook
    • CP: Chapman Pond
    • FP: Foster's Pond
    • GU: Guilford
    • RH: Ruth Hill
    • SC: Selden Neck Creek
    • SR: Salmon River
    • TM: Tri-Mountain
  2. plot: 20 x 20 meter plot number
  3. subplot: 1 x 1 meter plot number nested within 20 x 20 plot
  4. species: species codes
    • BETH: Berberis thunbergii
    • CEOB: Celastris orbiculatus
    • CHMA: Chimaphila maculata
    • CHUM: Chimaphila umbellata
    • CLAL: Celastris orbiculatus
    • GAPR: Gaultheria procumbens
    • HAVI: Hamamelis virginiana
    • ILVE: Ilex verticilata
    • KALA: Kalmia latifolia
    • LIBE: Lindera benzoin
    • LOSPP: Lonicera spp.
    • MIRE: Mitchella repens
    • NA: missing data
    • PAQU: Parthenocissus quinquefolia
    • POSI: Potentilla simplex
    • ROMU: Rosa multiflora
    • RUAL: Rubus alleghaniensis
    • RUHI: Rubus hispidus
    • RUID: Rubus ideaus
    • RUOC: Rubus occidentalis
    • RUPH: Rubus phoenicolasius
    • RUSPP: Rubus spp.
    • SARA: Sambucus racemosa
    • SMGL: Smilax glauca
    • TORA: Toxicodendron radicans
    • VAAN: Vaccinium angustifolium
    • VIAC: Viburnum acerifolium
    • VIDE: Viburnum dentatum
    • VIRI: Vitis riparia
    • VISPP: Vitis spp.
    • VITIS: Vitis spp.
  5. cover.95: percent vegetative cover per square meter (as of 1995) (unit: number / missing value: NA)
  6. cover.96: percent vegetative cover per square meter (as of 1996) (unit: number / missing value: NA)
  7. cover.97: percent vegetative cover per square meter (as of 1997) (unit: number / missing value: NA)
  8. cover.99: percent vegetative cover per square meter (as of 1999) (unit: number / missing value: NA)
  9. cover.01: percent vegetative cover per square meter (as of 2001) (unit: number / missing value: NA)
  10. cover.05: percent vegetative cover per square meter (as of 2005) (unit: number / missing value: NA)

hf021-03: seedling

  1. stand: site codes
    • BB: BB Burnham Brook
    • CP: Chapman Pond
    • FP: Foster's Pond
    • GU: Guilford
    • RH: Ruth Hill
    • SC: Selden Neck Creek
    • SR: Salmon River
    • TM: Tri-Mountain
  2. plot: 20 x 20 meter plot number
  3. subplot: 1 x 1 meter plot number nested within 20 x 20 plot
  4. species: species code
    • ACRU: Acer rubrum
    • ACSA: Acer saccharum
    • AIAL: Ailanthus altissima
    • AMAR: Amelanchier arborea
    • BELE: Betula lenta
    • CACO: Carya cordiformis
    • CAGL: Carya glabra
    • CATO: Carya tomentosa
    • COFL: Cornus florida
    • FAGR: Fagus grandifolia
    • FRAM: Fraxinus americana
    • FRPE: Fraxinus pennsylvanica
    • HAVI: Hamamelis virginiana
    • JUVI: Juniperus virginiana
    • LITU: Liriodendron tulipifera
    • NYSY: Nyssa sylvatica
    • OSVI: Ostrya virginiana
    • PIST: Pinus strobus
    • PRSE: Prunus serotina
    • QUAL: Quercus alba
    • QUCO: Quercus coccinea
    • QUPR: Quercus prinus
    • QURU: Quercus rubra
    • QUVE: Quercus velutina
    • ROPS: Robinia psuedoacacia
    • SAAL: Sassafras albidum
    • TSCA: Tsuga canadensis
  5. density.95: percent vegetative cover/square meter (as of 1995) (unit: numberPerMeterSquared / missing value: NA)
  6. cover.95: percent vegetative cover/square meter (as of 1995) (unit: number / missing value: NA)
  7. density.96: seedling density per square meter (as of 1996) (unit: numberPerMeterSquared / missing value: NA)
  8. cover.96: percent vegetative cover/square meter (as of 1996) (unit: number / missing value: NA)
  9. density.97: seedling density per square meter (as of 1997) (unit: numberPerMeterSquared / missing value: NA)
  10. cover.97: percent vegetative cover/square meter (as of 1997) (unit: number / missing value: NA)
  11. density.99: seedling density per square meter (as of 1999) (unit: numberPerMeterSquared / missing value: NA)
  12. cover.99: percent vegetative cover/square meter (as of 1999) (unit: number / missing value: NA)
  13. density.01: seedling density per square meter (as of 2001) (unit: numberPerMeterSquared / missing value: NA)
  14. cover.01: percent vegetative cover/square meter (as of 2001) (unit: number / missing value: NA)
  15. density.05: seedling density per square meter (as of 2005) (unit: numberPerMeterSquared / missing value: NA)
  16. cover.05: percent vegetative cover/square meter (as of 2005) (unit: number / missing value: NA)

hf021-04: herb

  1. stand: site code
    • BB: Burnham Brook
    • CP: Chapman Pond
    • FP: Foster's Pond
    • GU: Guilford
    • RH: Ruth Hill
    • SC: Selden Neck Creek
    • SR: Salmon River
    • TM: Tri-Mountain
  2. plot: 20 x 20 meter plot number
  3. subplot: 1 x 1 meter plot number nested within 20 x 20 plot
  4. species: species code
    • ARHI: Aralia hispida
    • ARNU: Aralia nudicaulis
    • ARTR: Arisaema triphyllum
    • ASDI: Aster divaricatus
    • CASPP: Carex spp.
    • CASW: Carex swanii
    • CAVI: Carex virescens
    • CISPP: Cirsium spp.
    • CYAC: Cypripedium acaule
    • DARE: Dalibarda repens
    • DEPU: Dennstaedia punctilobula
    • DRMA: Dryopteris marginalis
    • DRSP: Dryopteris spinulosa
    • ERHI: Erechtites hieracifolia
    • GERO: Geranium robertianum
    • GOPU: Goodyera pubescens
    • HEAM: Hepatica americana
    • HISPP: Hieracium species
    • LOIN: Lobelia inflata
    • LOSPP: Lonicera spp.
    • LYQU: Lysimachia quadifolia
    • MIVI: Microstegium vimineum
    • MOHY: Monotropa hypopithys
    • MOUN: Monotropa uniflora
    • MACA: Maianthemum canadense
    • OXEU: Oxalis europea
    • OXSPP: Oxalis spp.
    • OXST: Oxalis stricta
    • PASPP: Panicum spp.
    • PHAM: Phytolacca americana
    • PHSPP: Phytolacca spp.
    • POAC: Polystichum acrostichoides
    • POBI: Polygonatum biflorum
    • POPE: Polygonum persicaria
    • POPU: Polygonatum pubescens
    • POSI: Potentilla simplex
    • POVU: Polypodium vulgare
    • SOCA: Solidago caesia
    • SODU: Solanum dulcamara
    • SORU: Solidago rugosa
    • SOSPP: Solidago species
    • THNO: Thelypteris noveboracensis
    • TRBO: Trientalis borealis
    • UVSE: Uvularia sessifolia
    • VEOF: Veronica officinalis
    • VETH: Verbascum thapsus
    • VIOLA: Viola spp.
    • VISPP: Vitis spp.
  5. cover.95: percent vegetative cover/square meter (as of 1995) (unit: number / missing value: NA)
  6. cover.96: percent vegetative cover/square meter (as of 1996) (unit: number / missing value: NA)
  7. cover.97: percent vegetative cover/square meter (as of 1997) (unit: number / missing value: NA)
  8. cover.99: percent vegetative cover/square meter (as of 1999) (unit: number / missing value: NA)
  9. cover.01: percent vegetative cover/square meter (as of 2001) (unit: number / missing value: NA)
  10. cover.05: percent vegetative cover/square meter (as of 2005) (unit: number / missing value: NA)
  11. cover.08: percent vegetative cover/square meter (as of 2008) (unit: number / missing value: NA)