These methods, instrumentation and/or protocols apply to all data in this dataset:| Methods and protocols used in the collection of this data package |
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| Description: | Site: The Dukes Research Natural Area RNA, within the Hiawatha National Forest, Marquette Co., MI, amounts to ca. 100 ha of minimally disturbed original forests. No extensive logging is recorded, though a few high-value trees may have been removed from more accessible parts of the stand in the early 20th century. The area is roughly equally divided between mesic upland forest (hemlock-northern hardwood dominated) and peaty swamp forest (dominated by conifers and black ash). The RNA has very little topographic relief, with total elevation varyiation of about 5 m. Soils are developed in deep glacial till over Paleozoic sedimentary formations, and vary in texture from sandy to silty loam. Soils are generally relatively high in CEC. Some areas have well-developed hard-pan restricting rooting depth. In 2002, a severe localized thunderstorm with high winds caused extensive blow-downs in some parts of the stand.
Publications cited in this package include more site and historical information.
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| | Description: | Initial (1935 and 1948) measurements: In 1935, shortly after creation of the RNA, U.S. Forest Service researchers established a regular grid of 246 0.2-acre (~809 m^2) "continuous forest inventory" (CFI) plots. Plots are circular (radius approx 16.05 m), with centers located on a 2-chain (=40.24 m) (N-S) by 5-chain (=100.58 m) (E-W) grid. Plot centers are marked by sections of steel pipe. In 1935, woody stems >5 inches (12.7 cm) Diameter at Breast Height (DBH) were tallied by 1-inch DBH classes (assumed to have been rounded to nearest inch) in 226 CFI plots. Plots judged to be 'transitional' between mapped forest 'types' at the time were not sampled (most of these were plots that included areas of mesic forest and swamp forest). Remeasurements were conducted in 1948, using the same methods, for half (123) of the CFI plots, alternating along N-S lines; in 1948 'transitional' plots were not skipped, so some plots measured in 1948 were not measured in 1935. No information is available on personnel involved in the 1935-48 measurements.
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| | Description: | 1974-1980 remeasurements: CFI plots were remeasured in 1974-1980 by U.S. Forest Service personnel under the direction of Dr. Frederick T. Metzger. All woody stems > 0.5 inch DBH were identified to species and listed by DBH to nearest 0.1 inch. Some standing dead trees >10 in DBH are recorded, but it is unclear whether this protocol was followed consistently. Data-entry from original fieldsheets was conducted by U.S. Forest Service under direction of Dr. Thomas Crow ca. 1990. Data from this period include information for 243 of the original CFI plots.
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| | Description: | Recensuses 1989-2019 - mesic stands: Beginning in 1989, CFI plots in upland/mesic stands were recensused with mapping of stems. allowing tracking of individual trees over multiple measurements. Protocols varied somewhat: in 1989 all stems >2cm DBH were measured and mapped; in 1992, all stems >5 cm were mapped throughout the CFI Plot, and stems >2 cm mapped within 8 m of plot center; from 1993 onward, stems >1 cm DBH were mapped within the 8-m radius central sub-plot, and stems >5 cm DBH for the entire CFI plot. From 1994-2019, upland CFI plots were recensused on a five-year cycle in two cohorts (beginning in 1994 and 1997) with one exception: funding delays caused a delay of recensusin of the 2017 'cohort' until 2018. A total of 133 plots were remeasured at least once using this mapping protocol, but only126 of these were remeasured for all relevant five-year censuses.
Stems were mapped using polar coordinates with origin at plot center (marked by steel and PVC pipes). Azimuth was measured throughout in degrees east of north using Suunto 'site-through' compasses. In 1989-92, distance from plot center was measured using tapes; from 1993-2004, distances were measured using Sonin ultrasonic range-finders; in 2007-2019, distances were measured using laser range-finders.
All stems measured in mapped CFI plots were assigned unique stem numbers.
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| | Description: | Recensus of swamp forest CFI plots, 1993-2012: 95 additional plots in peaty, swamp forests were remeasured at least once since 1993 (most in 2001, 2004, 2009, and 2012). These were censused without stem-mapping. All woody stems > 1 cm DBH were tallied by DBH (to nearest 0.1 cm) within 8.0 m of plot center, and all stems > 5.0 cm DBH within the entire plot.
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