Harvard Forest

Data Archive

HF106

Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003

Related Publications

Data

• hf106-01: species codes (preview)
• hf106-02: o-layer and substrate (preview)
• hf106-03: shrub and herb cover (preview)
• hf106-04: seedling count and cover (preview)
• hf106-05: saplings (preview)
• hf106-06: species list (preview)
• hf106-07: sapling heights (preview)

Overview

• Lead: Aaron Ellison, Audrey Barker Plotkin
• Investigators: David Foster, David Orwig
• Contact: Information Manager
• Start date: 2003
• End date: 2024
• Status: ongoing
• Location: Simes Tract (Harvard Forest)
• Latitude: +42.47 to +42.48 degrees
• Longitude: -72.22 to -72.21 degrees
• Elevation: 200 to 240 meter
• Datum: WGS84
• Taxa: Tsuga canadensis (eastern hemlock)
• Release date: 2024
• Language: English
• EML file: knb-lter-hfr.106.35
• DOI: digital object identifier
• EDI: data package
• DataONE: data package
• Related links:
• Overstory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003
• Study type: long-term measurement
• Research topic: large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
• LTER core area: disturbance patterns
• Keywords: hemlock, hemlock woolly adelgid, timber harvest, tree maps, understory vegetation, vegetation dynamics
• Abstract:

  Hemlock decline in New England is caused by direct and indirect effects of invasion of the hemlock woolly adelgid. Direct damage from the insect is causing gradual mortality of hemlock, and widespread harvesting of hemlock in advance of mortality, in contrast, causes immediate mortality and removal of biomass from the site. Although both processes affect thousands of acres of forest annually we have only a limited understanding of their effects on forest ecosystem function and productivity and the nature of the subsequent forest community. We anticipate that harvesting will yield different consequences than gradual mortality from the insect. Therefore we designed an experiment to simulate these contrasting impacts, by logging or girdling hemlock stands. Results from the experimental treatments are compared to the changes observed in forests that are being infested by the adelgid, and can also be included in integrated analyses of a suite of large experiments that form a core component of the Harvard Forest LTER program.

• Methods:

  Study Design

  The study uses large plots and a Before After Control Impact (BACI) design. Plots were established and most response parameters were monitored for 1-2 growing seasons prior to the manipulations. There are two replicates of four treatments: hemlock reference, hardwood reference, commercial logging and girdling. In 2009, HWA was observed on trees in the experimental plots; the effects of HWA will overlay all treatments. Intensive study plots are 30 x 30 m within 90 x 90 m treatment units - that is, the center (or "core area") is surrounded by approximately one tree height of treatment area (overstory tree heights range from ~25-35m) . Intensive measurements focus on the central plots, but the buffers and outlying areas provide additional area for other studies and manipulations. Treatments include:

  1. Hemlock reference plots are hemlock dominated and received no manipulation other than sampling.

  2. Hardwood Reference plots simulate a likely future forest condition after hemlock woolly adelgid kills all hemlock in a stand and deciduous trees grow into the site. They received no manipulation other than sampling.

  3. Commercial Logging plots simulate an intensive commercial logging operation. Hemlock and other commercially valuable trees were removed, including larger hardwoods and pine for saw logs as well as smaller stems that a logger might take in order to improve future stand quality, facilitate skidding and general operation, or initiate a new cohort of sprouts. Two-thirds to three-fourths of the stand basal area was cut in these two plots, using hand-felling by chainsaw and skidding with a rubber-tired skidder. The intent was to generate an extreme response that is within the range of those seen on real commercial cuts. This treatment took place in Winter 2004-05.

  4. Girdling plots simulate some of the characteristics of hemlock woolly adelgid. All sizes of hemlock were girdled, resulting in gradual mortality and standing dead hemlock. No other species were girdled, and there is no further site disturbance. Important characteristics of hemlock woolly adelgid infestation missing include the very lengthy period of decline during which the plant is undergoing physiological stress and metabolic imbalance that may induce biogeochemical and microbial changes on the site. This treatment took place in late May 2005.

  Understory Vegetation Sampling

  In 2003, we established two transects running north-south through the center 30m x 30m of each plot at the Simes Tract of Harvard Forest for understory vegetation sampling. Five 1 m2 subplots were spaced evenly along each transect. We labeled the NW corner, unless otherwise marked, with an orange flag.

  For each quadrat, we annually estimate percent cover for herbs, shrubs, and seedlings to the nearest one percent. We count the number of seedlings by species. A seedling is a tree less than 1.3m tall. If rocks, stumps, slash, standing tree bases or coarse woody debris cover more than 5% of the plot, their percent cover is recorded to the nearest 5%. In addition, the depth of the organic soil layer is measured to the nearest 0.5 cm at the NW corner of each subplot (2003, 2006 and 2016). Finally, we search each plot and compile a species list for the entire 30m x 30m area.

  Saplings were censused by species within the central 30m x 30m area of each plot prior to the treatments, and every two years thereafter. A sapling is a tree greater than 1.3m tall but less than 5cm dbh (diameter at breast height, 1.3m). In 2015, we measured sapling heights with a telescoping height pole. We measured all stems for uncommon species, and a random subsample (e.g. every 10th stem encountered) for frequent species. Stems that recruited into the greater than 5cm dbh class were tagged, measured and mapped in the 2009, 2014, 2019, and 2024 tree censuses (see HF126). Starting in 2009, we tracked location of the saplings within the central 30m x 30m area, and therefore could distinguish some of the saplings as inside or outside the 15m x 30m exclosure fence that was constructed in each plot in Autumn 2011. These fences were maintained until 2024. Some saplings’ locations (in or out of the fence) were not recorded unambiguously; therefore, we categorized the saplings as ‘in_fence’, ‘out_fence’, or ‘no_info’. For most analyses, the total column is sufficient.

  In 2021, we reviewed and revised species names to make them consistent with Arthur Haines’ “Flora Novae Angliae: A Manual for the Identification of Native and Naturalized Vascular Plants of New England” (2011). In addition, we attempted to resolve taxa that were typically identified to species but sometimes were only identified to genus (e.g. we typically distinguished Vaccinium corymbosum and V. angustifolium, but for very small plants, we sometimes listed them simply as Vaccinium spp.). This poses a problem when analyzing data for species richness and turnover. We examined the ambiguous cases relative to the species occurring in a quadrat in later years; when a species identity became clear over time, we corrected the prior data to reflect that species identity (e.g. if V. spp was in a quadrat in 2005 and 2006 and then V. corymbosum from 2007 on, we changed the 2005 and 2006 data to V. corymbosum). Cases that remained ambiguous were left at the genus level; we note that these need to be dealt with in analyses of community change. Some taxa were only identified to genus throughout the survey (e.g. Amelanchier), so they may represent an underestimate of true species richness. Finally, some taxa that were incorrectly identified were corrected (e.g. both Goodyera pubescens and G. tesselata were in the species records, but these are all G. tesselata so we re-coded all as G. tesselata). In 2024, we determined that the plant identified as Pyrola minor was much more likely to be Rubus dalibarda, and we changed these entries and removed Pyrola minor from the species list.

• Organization: Harvard Forest. 324 North Main Street, Petersham, MA 01366, USA. Phone (978) 724-3302. Fax (978) 724-3595.

• Project: The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts. (ROR).

• Funding: National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210.

• Use: This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

• License: Creative Commons Zero v1.0 Universal (CC0-1.0)

• Citation: Ellison A, Barker Plotkin A. 2024. Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003. Harvard Forest Data Archive: HF106 (v.35). Environmental Data Initiative: https://doi.org/10.6073/pasta/2c64e2afd4faa2c0b57582d675d9cb51.

Detailed Metadata

hf106-01: species codes

1. type: life-form
   • Tree: tree
   • Shrub: shrub
   • Herb: herb
   • Fern / Lycopod: fern/lycopod
   • Graminoid: graminoid
2. code: species code (first 2 letters of genus and species for trees; first 3 letters of genus and species for other life-forms)
3. name_Haines_2011: species name, based on Arthur Haines’ “Flora Novae Angliae: A Manual for the Identification of Native and Naturalized Vascular Plants of New England” (2011)
4. old_name: species name before updating to Haines (2011)
5. note: notes on whether a taxon is identified to genus only, or other notes
6. invasive: whether species is invasive or native
   • N: native
   • Y: non-native invasive

hf106-02: o-layer and substrate

1. plot: plot number
2. subplot: subplot number
3. year: year of survey
4. o_layer: depth of o-layer (unit: centimeter / missing value: NA)
5. down_wood: percent cover (unit: number / missing value: NA)
6. slash: percent cover (unit: number / missing value: NA)
7. rock: percent cover (unit: number / missing value: NA)
8. tree: standing tree percent cover (unit: number / missing value: NA)
9. stump: percent cover (unit: number / missing value: NA)
10. root: percent cover (unit: number / missing value: NA)

hf106-03: shrub and herb cover

1. plot: plot number (1-8)
2. subplot: subplot number (1-10)
3. trt: experimental treatment
   • girdled: girdled
   • hardwood: hardwood reference
   • hemlock: hemlock reference
   • logged: logged
4. block: block
   • valley: valley
   • ridge: ridge
5. year: year of survey, completed June – August
6. species: species code, see HF106-01 for species codes. In addition, for each quadrat, the sum of the total cover of all species is listed as ‘ztot.cover’
7. cover: percent cover; values represent percent cover to the nearest 1%. Values less than 1% are listed as 0.5% (unit: dimensionless / missing value: NA)

hf106-04: seedling count and cover

1. plot: plot number
2. subplot: subplot number
3. trt: experimental treatment
   • girdled: girdled
   • hardwood: hardwood reference
   • hemlock: hemlock reference
   • logged: logged
4. block: block
   • valley: valley
   • ridge: ridge
5. year: year of survey, completed June – August
6. species: species code, see HF106-01 for species codes. In addition, the total cover and number of seedlings are listed as ‘total’
7. number: the number of seedlings in the quadrat (unit: number / missing value: NA)
8. cover: percent cover; values represent percent cover to the nearest 1%. Values less than 1% are listed as 0.1% (unit: dimensionless / missing value: NA)

hf106-05: saplings

1. plot: plot number (1-8)
2. year: year (2004=Winter 2004/2005; 2007=Winter 2007/2008; 2009=Winter 2009/2010; 2017=Winter 2017/2018; 2019=Winter 2019/2020; 2021=Winter 2021/2022; 2023=Winter 2023/2024)
3. species: species code (see hf106-01 for species codes)
4. in_fence: number of live stems within the exclosure fence area (fence constructed Autumn 2011) of the core 30m x 30m portion of the plot (unit: number / missing value: NA)
5. out_fence: number of live stems outside of the exclosure fence area (fence constructed Autumn 2011) of the core 30m x 30m portion of the plot (unit: number / missing value: NA)
6. no_info: number of live stems in the core 30m x 30m portion of the plot that were not identified as being inside or outside of the fence (unit: number / missing value: NA)
7. total: number of live stems in the core 30m x 30m portion of the plot (unit: number / missing value: NA)
8. note: note

hf106-06: species list

1. year: year (2003, then annually since 2005, sampled July)
2. plot: plot number (1-8)
3. acpe: presence or absence of acpe; see hf106-01 for species codes
   • 1: present
   • 0: absent
4. acru: presence or absence of acru; see hf106-01 for species codes
   • 1: present
   • 0: absent
5. acsa: presence or absence of acsa; see hf106-01 for species codes
   • 1: present
   • 0: absent
6. beal: presence or absence of beal; see hf106-01 for species codes
   • 1: present
   • 0: absent
7. bele: presence or absence of bele; see hf106-01 for species codes
   • 1: present
   • 0: absent
8. bepa: presence or absence of bepa; see hf106-01 for species codes
   • 1: present
   • 0: absent
9. bepo: presence or absence of bepo; see hf106-01 for species codes
   • 1: present
   • 0: absent
10. besp: presence or absence of besp; see hf106-01 for species codes
    • 1: present
    • 0: absent
11. caca: presence or absence of caca; see hf106-01 for species codes
    • 1: present
    • 0: absent
12. casp: presence or absence of casp; see hf106-01 for species codes
    • 1: present
    • 0: absent
13. fagr: presence or absence of fagr; see hf106-01 for species codes
    • 1: present
    • 0: absent
14. fram: presence or absence of fram; see hf106-01 for species codes
    • 1: present
    • 0: absent
15. nysy: presence or absence of nysy; see hf106-01 for species codes
    • 1: present
    • 0: absent
16. osvi: presence or absence of osvi; see hf106-01 for species codes
    • 1: present
    • 0: absent
17. pisp: presence or absence of pisp; see hf106-01 for species codes
    • 1: present
    • 0: absent
18. pist: presence or absence of pist; see hf106-01 for species codes
    • 1: present
    • 0: absent
19. potr: presence or absence of potr; see hf106-01 for species codes
    • 1: present
    • 0: absent
20. prpe: presence or absence of prpe; see hf106-01 for species codes
    • 1: present
    • 0: absent
21. prse: presence or absence of prse; see hf106-01 for species codes
    • 1: present
    • 0: absent
22. qual: presence or absence of qual; see hf106-01 for species codes
    • 1: present
    • 0: absent
23. quru: presence or absence of quru; see hf106-01 for species codes
    • 1: present
    • 0: absent
24. quve: presence or absence of quve; see hf106-01 for species codes
    • 1: present
    • 0: absent
25. tsca: presence or absence of tsca; see hf106-01 for species codes
    • 1: present
    • 0: absent
26. amesp: presence or absence of amesp; see hf106-01 for species codes
    • 1: present
    • 0: absent
27. berthu: presence or absence of berthu; see hf106-01 for species codes
    • 1: present
    • 0: absent
28. celorb: presence or absence of celorb; see hf106-01 for species codes
    • 1: present
    • 0: absent
29. swialt: presence or absence of swialt; see hf106-01 for species codes
    • 1: present
    • 0: absent
30. corcor: presence or absence of corcor; see hf106-01 for species codes
    • 1: present
    • 0: absent
31. crasp: presence or absence of crasp; see hf106-01 for species codes
    • 1: present
    • 0: absent
32. dielon: presence or absence of dielon; see hf106-01 for species codes
    • 1: present
    • 0: absent
33. gaupro: presence or absence of gaupro; see hf106-01 for species codes
    • 1: present
    • 0: absent
34. hamvir: presence or absence of hamvir; see hf106-01 for species codes
    • 1: present
    • 0: absent
35. ilemuc: presence or absence of ilemuc; see hf106-01 for species codes
    • 1: present
    • 0: absent
36. ilever: presence or absence of ilever; see hf106-01 for species codes
    • 1: present
    • 0: absent
37. loncan: presence or absence of loncan; see hf106-01 for species codes
    • 1: present
    • 0: absent
38. lonsp2: presence or absence of lonsp2; see hf106-01 for species codes
    • 1: present
    • 0: absent
39. mitrep: presence or absence of mitrep; see hf106-01 for species codes
    • 1: present
    • 0: absent
40. comper: presence or absence of comper; see hf106-01 for species codes
    • 1: present
    • 0: absent
41. parqui: presence or absence of parqui; see hf106-01 for species codes
    • 1: present
    • 0: absent
42. rhopri: presence or absence of rhopri; see hf106-01 for species codes
    • 1: present
    • 0: absent
43. fraang: presence or absence of fraang; see hf106-01 for species codes
    • 1: present
    • 0: absent
44. rhucop: presence or absence of rhucop; see hf106-01 for species codes
    • 1: present
    • 0: absent
45. toxrad: presence or absence of toxrad; see hf106-01 for species codes
    • 1: present
    • 0: absent
46. ruball: presence or absence of ruball; see hf106-01 for species codes
    • 1: present
    • 0: absent
47. rubdal: presence or absence of rubdal; see hf106-01 for species codes
    • 1: present
    • 0: absent
48. rubhis: presence or absence of rubhis; see hf106-01 for species codes
    • 1: present
    • 0: absent
49. rubida: presence or absence of rubida; see hf106-01 for species codes
    • 1: present
    • 0: absent
50. samrac: presence or absence of samrac; see hf106-01 for species codes
    • 1: present
    • 0: absent
51. sasalb: presence or absence of sasalb; see hf106-01 for species codes
    • 1: present
    • 0: absent
52. sorame: presence or absence of sorame; see hf106-01 for species codes
    • 1: present
    • 0: absent
53. spispe: presence or absence of spispe; see hf106-01 for species codes
    • 1: present
    • 0: absent
54. toxver: presence or absence of toxver; see hf106-01 for species codes
    • 1: present
    • 0: absent
55. vacang: presence or absence of vacang; see hf106-01 for species codes
    • 1: present
    • 0: absent
56. vaccor: presence or absence of vaccor; see hf106-01 for species codes
    • 1: present
    • 0: absent
57. vacsp: presence or absence of vacsp; see hf106-01 for species codes
    • 1: present
    • 0: absent
58. vibace: presence or absence of vibace; see hf106-01 for species codes
    • 1: present
    • 0: absent
59. vibden: presence or absence of vibden; see hf106-01 for species codes
    • 1: present
    • 0: absent
60. vibnud: presence or absence of vibnud; see hf106-01 for species codes
    • 1: present
    • 0: absent
61. vitsp: presence or absence of vitsp; see hf106-01 for species codes
    • 1: present
    • 0: absent
62. anequi: presence or absence of anequi; see hf106-01 for species codes
    • 1: present
    • 0: absent
63. arahis: presence or absence of arahis; see hf106-01 for species codes
    • 1: present
    • 0: absent
64. aranud: presence or absence of aranud; see hf106-01 for species codes
    • 1: present
    • 0: absent
65. araspi: presence or absence of araspi; see hf106-01 for species codes
    • 1: present
    • 0: absent
66. aritri: presence or absence of aritri; see hf106-01 for species codes
    • 1: present
    • 0: absent
67. oclacu: presence or absence of oclacu; see hf106-01 for species codes
    • 1: present
    • 0: absent
68. eurdiv: presence or absence of eurdiv; see hf106-01 for species codes
    • 1: present
    • 0: absent
69. chimac: presence or absence of chimac; see hf106-01 for species codes
    • 1: present
    • 0: absent
70. clibor: presence or absence of clibor; see hf106-01 for species codes
    • 1: present
    • 0: absent
71. coptri: presence or absence of coptri; see hf106-01 for species codes
    • 1: present
    • 0: absent
72. cypacu: presence or absence of cypacu; see hf106-01 for species codes
    • 1: present
    • 0: absent
73. epihel: presence or absence of epihel; see hf106-01 for species codes
    • 1: present
    • 0: absent
74. epirep: presence or absence of epirep; see hf106-01 for species codes
    • 1: present
    • 0: absent
75. erehie: presence or absence of erehie; see hf106-01 for species codes
    • 1: present
    • 0: absent
76. gootes: presence or absence of gootes; see hf106-01 for species codes
    • 1: present
    • 0: absent
77. lacspe: presence or absence of lacspe; see hf106-01 for species codes
    • 1: present
    • 0: absent
78. lysqua: presence or absence of lysqua; see hf106-01 for species codes
    • 1: present
    • 0: absent
79. maican: presence or absence of maican; see hf106-01 for species codes
    • 1: present
    • 0: absent
80. medvir: presence or absence of medvir; see hf106-01 for species codes
    • 1: present
    • 0: absent
81. monuni: presence or absence of monuni; see hf106-01 for species codes
    • 1: present
    • 0: absent
82. phyame: presence or absence of phyame; see hf106-01 for species codes
    • 1: present
    • 0: absent
83. prespe: presence or absence of prespe; see hf106-01 for species codes
    • 1: present
    • 0: absent
84. pyrame: presence or absence of pyrame; see hf106-01 for species codes
    • 1: present
    • 0: absent
85. mairac: presence or absence of mairac; see hf106-01 for species codes
    • 1: present
    • 0: absent
86. solsp: presence or absence of solsp; see hf106-01 for species codes
    • 1: present
    • 0: absent
87. lysbor: presence or absence of lysbor; see hf106-01 for species codes
    • 1: present
    • 0: absent
88. trilsp: presence or absence of trilsp; see hf106-01 for species codes
    • 1: present
    • 0: absent
89. uvuses: presence or absence of uvuses; see hf106-01 for species codes
    • 1: present
    • 0: absent
90. viosp: presence or absence of viosp; see hf106-01 for species codes
    • 1: present
    • 0: absent
91. denpun: presence or absence of denpun; see hf106-01 for species codes
    • 1: present
    • 0: absent
92. dryspe: presence or absence of dryspe; see hf106-01 for species codes
    • 1: present
    • 0: absent
93. dipdig: presence or absence of dipdig; see hf106-01 for species codes
    • 1: present
    • 0: absent
94. hupluc: presence or absence of hupluc; see hf106-01 for species codes
    • 1: present
    • 0: absent
95. denobs: presence or absence of denobs; see hf106-01 for species codes
    • 1: present
    • 0: absent
96. lyccla: presence or absence of lyccla; see hf106-01 for species codes
    • 1: present
    • 0: absent
97. osmcin: presence or absence of osmcin; see hf106-01 for species codes
    • 1: present
    • 0: absent
98. osmcla: presence or absence of osmcla; see hf106-01 for species codes
    • 1: present
    • 0: absent
99. polvir: presence or absence of polvir; see hf106-01 for species codes
    • 1: present
    • 0: absent
100. polacr: presence or absence of polacr; see hf106-01 for species codes
     • 1: present
     • 0: absent
101. pteaqu: presence or absence of pteaqu; see hf106-01 for species codes
     • 1: present
     • 0: absent
102. parnov: presence or absence of parnov; see hf106-01 for species codes
     • 1: present
     • 0: absent
103. braari: presence or absence of braari; see hf106-01 for species codes
     • 1: present
     • 0: absent
104. carpen: presence or absence of carpen; see hf106-01 for species codes
     • 1: present
     • 0: absent
105. carsp: presence or absence of carsp; see hf106-01 for species codes
     • 1: present
     • 0: absent
106. pansp: presence or absence of pansp; see hf106-01 for species codes
     • 1: present
     • 0: absent
107. gram: presence or absence of gram; see hf106-01 for species codes
     • 1: present
     • 0: absent

hf106-07: sapling heights

1. year: year of survey (2015=Winter 2015/2016)
2. plot: plot number
3. species: species code (see hf106-01 for species codes)
4. height_m: sapling height in meters (unit: meter / missing value: NA)
5. note: note