Climate reconstructions based on postglacial macrofossil assemblages from four river systems in southwestern Alberta

Figures & data

Figure 1. Map of study area, surrounding region, and drainage area for the downstream-most location sampled on each stream.

Figure 2. Mapped climatic parameters of study watersheds, modelled using geographically weighted regression (GWR). (a) Total annual precipitation (mm of water equivalent); (b) total annual snowfall (cm of fresh snow); (c) mean annual temperature (°C). Data source: Canadian Climate Normals 1981–2010, climate normal and averages (Environment and Climate Change Canada 2016).

Figure 3. Estimated chronological extent of field-determined intervals used in this study. Circles represent the mean values of the upper and lower limits (vertical bars) per class. The tephra chronostratigraphic layer, the Mazama ash, is indicated by the dashed line, dated to ~7600 cal. yr BP (Zdanowicz et al. 1999; Egan et al. 2015).

Table 1. ¹⁴C dates, calibration, and comparative radiocarbon and field-determined age classes. Near-modern samples (denoted by *) were calibrated with the Bomb13NH1 curve (Hua et al. 2013), all others used the IntCal13 curve (Reimer et al. 2013). Samples processed at the André E. Lalonde Accelerator Mass Spectrometry Laboratory (Ottawa, Ontario) and the Keck Carbon Cycle Accelerator Mass Spectrometry facility (Irvine, California).

		Conventional radiocarbon age		Calibration results
Lab number	Sample number	^14C yr BP	±	95.4% probability range	Mean age (cal. yr BP)	Radiocarbon-defined age class	Field-determined age class
UCIAMS-154030	L8*	−70	15	−4 to −6	−5	Modern/late Holocene	Late Holocene
UOC-3440	J17*	72	31	260 to −5	122	Late Holocene	Mid- to late Holocene
UOC-3439	L38	343	31	472 to 317	391	Late Holocene	Late Holocene
UCIAMS-154031	L10	365	15	496 to 327	418	Late Holocene	Late Holocene
UCIAMS-154032	L36	3,925	25	4433 to 4256	4360	Mid- to late Holocene	Late Holocene

Table 2. Number of localities and samples, and maximum stream-course distance between sites per stream.

Stream	Number of sampled localities	Total number of samples	Stream distance between most distant sites (km)
Highwood River	14	24	50.0
Kananaskis River	2	2	9.1
Jumpingpound Creek	2	2	4.1
Tongue Creek	7	8	12.6

Table 3. List of Linnaean and common names, authorities, and organismal groups of indicator taxa used for climate reconstruction.

Taxon	Naming authority	Common name	Organismal group
Discus whitneyi	Newcomb, 1864	Forest disk snail	Terrestrial gastropod
Eleocharis palustris	(Linnaeus) Roemer and Schultes, 1817	Common spikerush	Emergent aquatic/riparian plant
Euconulus fulvus	Muller, 1774	Brown hive snail	Terrestrial gastropod
Galba modicella	Say, 1825	Rock Fossaria snail	Aquatic gastropod
Gyraulus parvus/circumstriatus	Say, 1817/Tryon, 1866	Gyro snail	Aquatic gastropod
Helisoma anceps anceps	Menke, 1830	Two-ridged Rams-horn	Aquatic gastropod
Physa gyrina	Say, 1821	Tadpole snail	Aquatic gastropod
Pisidium valves	Pfeiffer, 1821	Pea clam	Aquatic bivalve
Potamogeton spp.	Linnaeus, 1753	Pondweed	Aquatic plant
Scirpus microcarpus	J. Presl and C. Presl, 1828	Small-fruited bulrush	Emergent aquatic/riparian plant
Stagnicola elodes	Say, 1821	Marsh pondsnail	Aquatic gastropod
Succineidae	Beck, 1837	Amber snail	Terrestrial gastropod
Vallonia gracilicosta	Reinhardt, 1883	Multi-rib Vallonia snail	Terrestrial gastropod
Zannichellia palustris	Linnaeus, 1753	Horned pondweed	Aquatic plant
Zonitoides spp.	Lehmann, 1862	Gloss snail	Terrestrial gastropod

Figure 4. Climate space (annual precipitation and mean annual temperature) diagram of 15 indicator taxa. Discus whitneyi = Dw, Eleocharis palustris = Ep, Euconulus fulvus = Ef, Galba modicella = Gm, Gyraulus parvus/circumstriatus = Gp/c, Helisoma anceps = Ha, Physa gyrina = Pg, Pisidium spp. = Psdm, Potamogeton spp. = Pgtn, Scirpus microcarpus = Sm, Stagnicola elodes = Se, Succineidae = S, Vallonia gracilicosta = Vg, Zannichellia palustris = Zp, and Zonitoides spp. = Za/n. Note: some labels have been slightly moved from their centroids to aid legibility.

Figure 5. Pie chart depicting the number of samples per age class.

Table 4. Average number of indicators (by taxon) per age class and per sample. The initial value is the count of a taxon in all samples of an age class; the value in parentheses is the average value per sample; values with * are maximum values (e.g. AV = 1) for that taxon.

Taxon	Modern	Late Holocene	Mid- to late Holocene	Mid-Holocene	Early to mid- Holocene	Late Pleistocene to early Holocene
Discus whitneyi	5 (1)	38.75 (2.77)	11 (3.67)	0 (0)	13 (3.25)	0 (0)
Eleocharis palustris	9 (1.8)	62 (4.43)	16.5 (5.5)*	0 (0)	0 (0)	0 (0)
Euconulus fulvus	0 (0)	1 (0.07)	6 (2)*	0 (0)	0 (0)	0 (0)
Galba modicella	4 (0.8)	5 (0.36)	23 (7.67)*	2 (0.25)	0 (0)	0 (0)
Gyraulus parvus/circumstriatus	390 (78)	130.5 (9.32)	38.5 (12.83)	54 (6.75)	0 (0)	231 (115.5)*
Helisoma anceps	0 (0)	3 (0.21)	1 (0.33)*	1 (0.13)	0 (0)	0 (0)
Physa gyrina	37.5 (7.5)*	2 (0.14)	1 (0.33)	0 (0)	(0)	0 (0)
Pisidium (valves)	219 (43.8)	68 (4.86)	52 (17.33)	0 (0)	0 (0)	2062 (1031)*
Potamogeton spp.	6.25 (1.25)*	9 (0.64)	0 (0)	0 (0)	1 (0.25)	0 (0)
Scirpus microcarpus	16 (3.2)*	6 (0.43)	0 (0)	0 (0)	0 (0)	0 (0)
Stagnicola elodes	18 (3.6)*	1 (0.07)	0 (0)	2 (0.25)	0 (0)	0 (0)
Succineidae	42 (8.4)	42 (3)	73 (24.33)*	6 (0.75)	26 (6.5)	2 (1)
Vallonia gracilicosta	9 (1.8)*	5 (0.36)	4.25 (1.42)	0 (0)	6 (1.5)	0 (0)
Zannichellia palustris	8.5 (1.7)*	12 (0.86)	0 (0)	0 (0)	0 (0)	0 (0)
Zonitoides spp.	0.5 (0.1)	1 (0.07)	5.5 (1.83)*	0 (0)	0 (0)	0 (0)

Figure 6. Modelled annual precipitation and mean annual temperature for the study region; plotted values represent uncalibrated percent divergence from mean; data labels indicate calibrated values (precipitation is in mm; temperature is in °C).

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