Soil types of Aosta Valley (NW-Italy)

Figures & data

Figure 1. The Aosta Valley Region, in the NW Italian Alps.

Figure 2. (a) Elevation map derived from the 10 m DEM of the Aosta Valley Region; (b) Mean Annual Precipitation (MAP); (c) slope angle; (d) Absolute Aspect; (e) Parent Material, reclassified from Bonetto et al. (2010); (f) vegetation/land cover maps, simplified from Amedei et al. (2009).

Table 1. Parent material classification based on the 1:100,000 scale geological map; landslide and slope deposits and unclassified sediments have been reclassified according to their lithological composition and then attributed to the other existing categories.

Lithology	Parent material class
Calcschists, flysch, phillitic marbles	100
Mafic rocks (prasinites, amphibolites, metagabbros)	200
Ultramafic rocks (serpentinites)	300
Black Schists (carbon schists)	400
Landslide deposits	Reclassified
Unclassified sediments	Reclassified
Slope deposits	Reclassified
Limestones, dolomites, carnioles, gypsum-rich rocks	500
Mixed glacial till	600
Sialic rocks (Granites, gneisses, mica-schists, metamorphic conglomerates, quartzites)	700
Alluvial deposits	800

Table 2. Land use/vegetation classification used for the production of the soil map.

Class (Amedei et al., 2009)	Description	Vegetation and land cover class
22.1; 24.1; 62.15; 62.21; 63; 86.1; 86.3; 86.41	Non-soil: Lakes, ponds, rivers, streams, barren rocks, glaciers, urban areas, quarries	0
24.221	Riverbeds with herbaceous cover	2000
31.42; 31.43; 31.52	Rhododendron ferrugineum, Vaccinium ssp. and Juniperus ssp. subalpine heaths	3000
61.611; 61.621; 31.81; 44.11; 44.13; 44.21	Alnus ssp. and Salix ssp. formations	4000
34.314; 34.323; 41.731; 42.53; 42.55	Steppic endoalpine prairies, xerophilous grasslands and xerophilous Pinus sylvestris and Quercus pubescens formations.	5000
36.31; 36.34; 36.431	Subalpine Nardus stricta and alpine Carex curvula and Sesleria varia grasslands	6000
36.5; 38.2; 38.3	Fertilized pastures and meadows	8000
41.11; 41.39; 41.41; 44.31; 41.B; 41.D1	Broadleaf mesophilous forests and woodlands	9000
41.9	Castanea sativa formations	10000
42.12; 42.21; 42.221; 42.222; 42.1B	Montane Picea excelsa and Abies alba forests	11000
42.322; 42.331; 42.41; 42.42	Subalpine Larix decidua, Pinus uncinata and Pinus cembra formations, with Ericaceae in the understory.	12000
53.1; 54.2	Swamps	13000
61.11; 61.21; 61.22; 61.23	Talus slopes	14000
82.3; 83.321	Mixed crops	16000
83.21	Vineyards	17000

Table 3. Cartographic Units in the Aosta Valley soil map 1:100,000, and the most important environmental properties in which they can be found.

CU	ST – classification	Profiles n°	Figure	Luse	PM	Climate regime	Area (km^2)
CU1	1.1 Albic Podzol	83	3.1	Subalpine forest with Ericaceae, sometimes alpine grassland	Sialic (gneisses, micaschists, granites), (mafic rocks, serpentinite, glacial till)	Udic; very narrow belt at high altitude in the inneralpine area	168.83
	1.2 Albic Ortsteinic Podzol	36		Particularly stable areas
CU2	2.1 Entic Podzol	63		Subalpine Vaccinium spp. heath, alpine Carex curvula grassland, sometimes pasture.	Serpentinite, Sialic (gneisses, micaschists, granites), mafic rocks, glacial till	Udic; very narrow belt at high altitude in the inneralpine area	293.72
	2.2 Entic Ortsteinic Podzol	15	3.2	Particularly stable areas
CU3	Umbric Entic Podzol	8	3.3	High altitude Festuca varia and Carex curvula grassland	Mainly sialic rocks on steep slopes	Udic, at high elevation	22.39
CU4	Dystric Cambisols (Protospodic, Arenic)	30	3.4	Alpine Carex curvula grassland	Calcschists	Udic, at high elevation	228.34
CU5	Haplic/Cambic Phaeozems	45	3.5	Anthropogenic grassland and pastures	All parent materials, CaCO3 poor materials in the inneralpine area	Udic/Ustic, montane belt	117.76
CU6	6.1 Calcic Kastanozem	22	3.6	All land uses	Calcschists and mixed till, most common in the western area	Ustic, mainly in the western part of the region with winter precipitation maxima	95.70
	6.2 Petrocalcic Kastanozems	6		The same, on stable surfaces
CU7	7.1 Haplic Calcisols (Hypercalcic)	16		All land uses, not under subalpine forest or heath or alpine grassland	Calcschists and mixed till	Ustic, up to ca. 2350 m asl in the driest areas	187.42
	7.2 Haplic Calcisols (Hypocalcic)	31
	7.3 Petric Calcisols	15	3.7		Mostly on mixed till
CU8	Calcaric Regosols	17	3.8	All land uses	Calcschists and mixed till, alluvial fans	Ustic	127.26
CU9	Haplic/Cambic Umbrisols	33	3.9	Alpine prairies and subalpine and montane pastures	Serpentinite, Sialic (gneisses, micaschists, granites), mafic rocks, glacial till	Udic	196.46
CU10	Eutric Cambisols	41	3.10	Montane forests	Serpentinite, sometimes on mafic rocks (Ustic regime)	Mainly Ustic	76.68
CU11	Hypocalcic Cambisols (Rhodic)	3	3.11	Montane forests	Serpentinite and calcschists (Fenis-Pontey)	Ustic, northward aspect	4.98
CU12	Dystric Cambisols	87	3.12	Montane forests and alpine prairie	All parent materials	Udic	262.79
CU13	Skeletic Regosols	93	3.13	Talus slopes, disturbed areas; steppic forests on sialic PM in Ustic climate	All parent materials	All climatic regimes	474.27
CU14	Eutric Regosols (Turbic)	12	3.14	Alpine tundra and deserts	All parent materials	Areas exposed to wind and little snow cover	119.20
CU15	Fluvisols	12	3.15	All land uses	Alluvial deposits	All climatic regimes	26.38
CU16	Leptosols	19	3.16	All land uses	All parent materials on steep slopes with rocky outcrops	All climatic regimes	93.35

Figure 3. Examples of soil types belonging to the 16 CUs (Table 3). (a) CU1 – Albic Ortsteinic Podzol; (b) CU2 – Entic Ortsteinic Podzol; (c) CU3 – Umbric Entic Podzol; (d) CU4 – Protospodic Dystric Cambisol; (e) CU5 – Haplic Phaeozem; (f) CU6 – Calcic Kastanozem; (g) CU7 – Petric Calcisol; (h) CU8 – Calcaric Regosol; (i) CU9 – Cambic Umbrisol; (j) CU10 – Eutric Skeletic Cambisol; (k) CU11 – Hypocalcic Cambisol (Rhodic); (l) CU12 – Dystric Cambisol; (m) CU13 – Eutric Regosol; (n) CU14 – Turbic Regosol; (o) CU15 – Haplic Fluvisol (Arenic); (p) CU16 – Dystric Leptosol.

Table 4. Confusion matrix for the training data set, showing the number of profiles included in polygons attributed to different CUs in the produced soil map.

CU	N. Profiles in CU polygons*	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	% User’s accuracy	% broadly correct	% wrong	RG + FL
Training data set
1	128	78	26			2		1		3	2		9	4			4	60.9	81.3	13.3	5.5
2	80	23	38	4		1				3	1		7	1		2		47.5	81.3	15.0	3.8
3	18	1	7	5						4			1					27.8	94.4	5.6	0.0
4	53	2	2		27	5	2			4			2	3	2	3	1	50.9	69.8	13.2	17.00
5	38					23		2	1	2	4		3	3				60.5	71.1	21.1	7.9
6	31				1	2	19	5	1				1	1			1	61.3	80.7	12.9	6.5
7	59						6	45	3		2			1		1	1	76.3	91.5	3.4	5.1
8	28	1	1				1	7	11		3		1			3		39.3	67.9	21.4	10.7
9	23	2	2			1				5	2		6	3	1		1	21.7	56.5	21.7	21.7
10	32				1	2	1	1			17		4	5		1		53.1	59.4	21.9	18.8
11	5					1		1				3						60.0	80.0	20.0	0.0
12	74	4	5		1	1				7	6		39	8			3	52.7	70.3	14.9	14.9
13	75	2	1		2	5				1	2		3	55			4	73.3	80.0	20.0	0.0
14	35	1				1				3	1		5	9	11	1	3	31.4	57.1	31.4	11.4
15	4								1				1			2		50.0	50.0	50.0	0.0
16	7										1		1	2			4	50.0	50.0	25.0	25.0
Producer’s accuracy		68.4	46.3	81.8	84.4	52.3	65.5	72.6	64.7	15.6	41.5	100.0	47.0	58.5	78.6	15.4	18.2
Control data set Lys Valley
1	5	5																100.0	0.0	0.0	0.0
2	7		7															100.0	0.0	0.0	0.0
9	1									1								100.0	0.0	0.0	0.0
12	5												5					100.0	0.0	0.0	0.0
Control data set – Val di Rhemes and Valsavarenche
1	4	3															1	75.0	75.0	0.0	25.0
2	6		5										1					83.3	100.0	0.0	0.0
3	2									1				1				0.0	50.0	0.0	50.0
4	2				1			1										50.0	50.0	50.0	0.0
6	6						2				3			1				33.3	33.3	50.0	16.7
7	3			1				1	1									33.3	66.7	33.3	0.0
8	1								1									100.0	100.0	0.0	0.0
9	6									3			1	1			1	50.0	66.7	0.0	33.3
10	5										3			2				60.0	60.0	0.0	40.0
12	5			1						1				1		2		0.0	40.0	0.0	60.0
13	5									1				4				80.0	80.0	20.0	80.0
15	1															1		100.0	100.0	0.0	100.0
Producer’s accuracy		100.0	92.3	0.0	100.0		100.0	50.0	50.0	57.1	27.3		0.0	40.0	100.0	0.0

User’s and Producer’s Accuracies, broadly correct attribution, wrong attributions are shown. ‘% broadly correct' refers to the amount of profiles which were included in mapping units with associated soil types (e.g. Albic Podzols in areas dominated by Entic Podzols). RG + FL are Regosols and Fluvisols (azonal soils) included in other CU polygons, mainly because of localized morphological processes such as eroded areas, landslides, or small flatlands. Below, the control data sets divided by area: Lys Valley and Val di Rhemes and Valsavarenche.

Bonetto, F. , Dal Piaz, G. V. , De Giusti, F. , Massironi, M. , Monopoli, B. , & Schiavo, A. (2010). Carta geologica della Valle d’Aosta al 1:100000 con note illustrative. Regione Aut. Valle d’Aosta, Ass. Territorio Ambiente OOPP. http://geologiavda.partout.it/GeologiaVDA/default/GeoCartaGeo

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