Composition and spatial structure of dwarf shrub heath in Norway

Figures & data

Table 1. Description, number and percentage of Secondary Statistical Unit (SSU) points in dwarf shrub heath polygons; the subtypes are based on, or generalized from the detailed description system for vegetation in Norway (Fremstad 1997); subtypes defined as dwarf shrub heath in Rekdal & Larsson’s guide for vegetation mapping using the VK50 system (Rekdal & Larsson 2005) are shaded grey

Fremstad subtypes	Number	Per cent	Description
Loiseleuria procumbens – lichen/bryophyte subtype (R1)	35	4.8	Ridge vegetation type found on very exposed areas with little or no snow coverage during wintertime
Betula nana – Empetrum nigrum coll. subtype (R2)	67	9.2	Present in exposed mountainous areas with thin or unstable snow coverage; very low shrub layer (0.1–0.3 m) of Betula nana and a field cover of different heath species
Juniperus communis – Betula nana heath (S2)	149	20.4	Present in snow-rich low alpine mountains, with sloping terrain; the dominating vegetation is low-growing shrubs, grass and plants with low nutrition demand, covered by a 0.5–1 m shrub layer of juniper (Juniperus communis) and Betula nana
Vaccinium myrtillus – Phyllodoce caerulea and Empetrum nigrum coll. heath (S3)	290	39.7	Mostly located in snow-rich low alpine mountains, with sloping terrain, on oligotrophic soil; the dominating vegetation is low-growing shrubs and grass composed of plants with low nutrition demand
Mire	20	2.7	Different subtypes of peat bogs and fens, spanning from poor ombrotrophic bog to extremely rich fen; vegetation formed around springs is also included in this group; includes Fremstad subtypes J2, J3, K1, K2, K3, K4, L2, L4, M2, M3, N1 and N2
Forest	37	5.1	Low alpine areas typically include patches of birch forest with variable understories; includes Fremstad subtypes A2, A3, A4, A5 and C2
Snowbed	46	6.3	Exists in convex terrain and on lee sides with especially thick snow coverage, both with late snow melt; includes Fremstad subtypes T1, T2 and T4
Special heath and meadow vegetation	24	3.3	Different, infrequently occurring subtypes of open heath, moor and grassland; includes Fremstad subtypes S1, S4, S5, S6, S7, G, H3 and X1
Boulder field and exposed bedrock	28	3.8	Sparsely vegetated areas, mainly with mosses or lichens, or not vegetated at all; includes Fremstad subtype R7
Not defined/Water	34	4.7	SSU points located in water or with invalid coding
Total	730	100

Fig. 1. Distribution of the AR18X18 grid throughout Norway; the dominating vegetation type is decided by the highest number of Secondary Statistical Unit (SSU) points in each Primary Statistical Unit (PSU); R2: Betula nana – Empetrum nigrum coll. subtype. S2: Juniperus communis – Betula nana heath; S3: Vaccinium myrtillus – Phyllodoce caerulea heath and Empetrum nigrum coll. heath

Table 2. The F-values and the P-values from the one-way ANOVA test (8 and 441 df) for Sections and Zones, and the coefficient values from the first linear discriminant

Environmental variable	F-value	P-value	LD1*
All subtypes
Sections	13.4120	0.0000	0.5810
Zones	6.0976	0.0000	0.1500
Defined subtypes (R2, S2 and S3)
Sections	30.9160	0.0000	-0.4985
Zones	14.0980	0.0000	0.1139

Note: * Linear discriminant 1

Fig. 2. Box plot with mean and ± SD of the distribution of the different subtypes in dwarf shrub heath according to the environmental gradients; a) Sections; b) Zones (representing principal components PC1 and PC2 in Bakkestuen et al. 2008); R1: Loiseleuria procumbens – lichen/bryophyte subtype; R2: Betula nana – Empetrum nigrum coll. subtype. S2: Juniperus communis – Betula nana heath; S3: Vaccinium myrtillus – Phyllodoce caerulea heath and Empetrum nigrum coll. heath

Appendix 1. Common species found in dwarf shrub heath defined by the VK50 system for vegetation mapping at intermediate scale (1:20,000 – 1:50,000) (Rekdal & Larsson 2005); species common in areas with high precipitation are marked with *

Character and lead species	Other common species
Betula nana	Anthoxanthum odoratum (L.)
Vaccinium myrtillus	Solidago virgaurea
Empetrum nigrum	Pedicularis lapponica
Avenella flexuosa	Pleurozium schreberi
Cornus suecica*	Cladonia ssp.
Hylocomium splendens	Juniperus communis
Cladonia stellaris	Salix glauca var glauca
	Salix lapponum
	Calluna vulgaris
	Vaccinium vitis-idaea
	Vaccinium uliginosum
	Phyllodoce caerulea
	Nardus stricta*
	Melampyrum pratense
	Lysimachia europaea
	Cetraria islandica
	Stereocaulon paschale (L.)

Appendix 2. Results (p-values) from the pairwise t-test for the different environmental variables; P-values < 0.01 are marked with grey shading; R1: Loiseleuria procumbens – lichen/bryophyte subtype; R2: Betula nana – Empetrum nigrum coll. subtype; S2: Juniperus communis – Betula nana heath; S3: Vaccinium myrtillus – Phyllodoce caerulea heath and Empetrum nigrum coll. heath.

(a) Sections	Mire	R1	R2	S2	S3	Forest	Snowbed	Special heath and meadow vegetation
R1	1	-	-	-	-	-	-	-
R2	0.0068	0.1034	-	-	-	-	-	-
S2	0.057	0.7014	1	-	-	-	-	-
S3	1	1	3.20E-08	5.00E-08	-	-	-	-
Forest	1	1	0.0285	0.1653	1	-	-	-
Snowbed	0.3793	0.1238	6.10E-07	4.70E-06	1	1	-	-
Special heath and meadow vegetation	0.5918	0.1844	2.20E-07	1.50E-06	1	1	1	-
Boulder field and exposed bedrock	0.0219	0.0059	1.20E-09	6.70E-09	0.1628	0.8791	1	1
(b) Zones	Mire	R1	R2	S2	S3	Forest	Snowbed	Special heath and meadow vegetation
R1	1	-	-	-	-	-	-	-
R2	0.06637	1	-	-	-	-	-	-
S2	0.1615	1	1	-	-	-	-	-
S3	1	0.47872	0.00153	0.00155	-	-	-	-
Forest	1	0.03398	0.0008	0.00184	1	-	-	-
Snowbed	1	1	0.77837	1	1	1	-	-
Special heath and meadow vegetation	1	0.08542	0.00092	0.00187	1	1	1	-
Boulder field and exposed bedrock	1	1	0.16905	0.41541	1	1	1	1

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