nordic_indicator_values

CLIMATE ‘INDICATOR VALUES’ FOR THE NATIVE NORDIC
FLORA – A FIRST ATTEMPT
Ingeborg Helvik1, Ildikó Orbán1, Mora Aronsson2, John Birks1
1 Department of Biology, University of Bergen, Bergen, Norway
2 Swedish Species Information Centre, Uppsala, Sweden
Introduction
It has long been recognised since the days of Alexander von Humboldt that plants can be
useful indicators of ecological conditions such as moisture, light, soil reaction (pH),
salinity, soil nitrogen, and climate. The German ecologist Heinz Ellenberg was one of the
first ecologists to assign ordinal indicator values (Zeigerwerte) to vascular plant species
occurring in central Europe (Ellenberg 1948, 1979, 1982). This approach has been
extended to the flora of the European Alps (Landolt et al. 2010), to Britain and Ireland by
Hill et al. (2004), and elsewhere in Europe (see Diekmann 2003 for a review). Hill et al.
(2004) provide indicator values for light, soil moisture, soil reaction (pH), soil nitrogen
(soil fertility), and salt tolerance. They do not, however, provide indicator values for
temperature or continentality (as Ellenberg et al. 1991 do) because such values naturally
correspond closely to the major biome and eastern-limit phytogeographical categories
defined by Preston and Hill (1997) for the British and Irish floras based on their total
European distributions.
We have extended the approach of Preston and Hill (1997) and Hill et al. (2004) to
include the entire native flora of Denmark, Færoes, Norway, Svalbard, Sweden, and
Finland (here called the Nordic flora) and assigned, where possible, all the native
species in Norden that do not occur in Britain and Ireland into the Preston and Hill (1997)
nine phytogeographical elements (E1) based on occurrences in the major European
‘zonobiomes’ (Figure 1 and Table 1) and the seven phytogeographical elements (E2)
based on eastern limits of species in the Northern Hemisphere (Figure 2 and Table 2). In
addition we have assigned, wherever possible, all the native Nordic taxa into 26 broad
habitat types (Table 3) based primarily on Fremstad (1997) and on our own field
observations. For comparison we include the broad habitats according to Hill et al. (2004)
(Table 4) for those taxa that occur in Britain and/or Ireland and the mean values for
January mean temperature (C) (Tjan), July mean temperature (C) (Tjul), and annual
precipitation (mm) for all the 10 km squares in which the taxon occurs in Britain, Ireland,
and the Channel Islands (Hill et al. 2004). We have also included the Red List categories
for species and subspecies occurring in Norway, Svalbard, Sweden, and Finland.
Spreadsheet Details
Details of the entries in the spreadsheet are as follows:
1. Plant nomenclature
This follows, as far as possible, Mossberg and Stenberg (2012) as this is the most recent
source of vascular plant nomenclature for the Nordic countries. Some of the subspecies
are derived from the various national Red Lists.
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2. Native status
Inevitably, deciding whether a taxon is native or not is difficult and partially subjective.
We have followed, as far as possible, Mossberg and Stenberg (2012), Lid and Lid (2005),
and other national authorities, and in some cases tried to reach a consensus about
whether a taxon is native or not. Naturalised taxa that occur commonly in semi-natural
vegetation (e.g. Acer pseudoplatanus) are not included. Our compilation includes 1869
presumed native taxa consisting of 1636 presumed native species, 172 presumed native
subspecies, 14 presumed native taxon aggregates, 28 presumed native genus sections
(14 Taraxacum, 14 Hieracium), and 14 presumed native varieties. This contrasts with
1606 native species in Britain and Ireland (Hill et al. 2004) (including 151 archaeophytes
(species introduced before 1500) and 46 species of doubtful native status).
3. Phytogeographical elements based on major biomes (E1)
We follow Preston and Hill (1997) and Hill et al. (2004) with their nine phytogeographical
elements based on major biomes. We used the same sources of distributional data as
Preston and Hill (1997) to assign Nordic taxa not included in Hill et al. (2004) into the
nine elements (1–9) of the major biome category (E1). There are no Mediterranean
species (element 0 within E1 in Hill et al. 2004) in the native Nordic flora.
Preston and Hill (1997) define four major zonobiomes and
combinations used in their classification as follows (see Figure 1).
five
zonobiome
“Arctic-montane. Species with their main distribution north of or (on mountains)
above the tree line.
Boreal-montane. Species with their main distribution in the coniferous forest
zone. They may occur in the Boreal zonobiome, and/or in the coniferous forest
zone on mountains to the south.
Temperate. Species with their main distribution in the cool-temperate,
broadleaved deciduous forest zone, often called the nemoral zone by European
authors. These species may occur in cool steppes in continental interiors.
Southern. Species with their main distribution in the warm-temperate zone south
of the broadleaved deciduous forest zone. In Europe the warm-temperate zone is
characterized by a Mediterranean climate with summer drought. These species
may also occur in warm steppes in continental interiors.
Many species are confined to one of these zones. The zones contain numerous
different habitats and a species of the Boreal zone does not necessarily grow in
coniferous woodland: it may grow, for example, in bogs or fens, on rock
outcrops, as a submerged aquatic or as a weed. Species may be classified as
belonging to a single zone if their main range lies in that zone even though they
extend to a limited extent into the neighbouring zone to the north or to the
south, or both. Species are classified as belonging to two zones if they occur
widely in both zones, or narrowly but to an equal extent in each. The following
categories are recognised for species occurring in more than one biome.
Boreo-arctic Montane. Species occurring in the Arctic-montane and Borealmontane zones.
Wide-boreal. Species with a distribution which is centred on the Boreal zone but
which also occur widely in the Arctic and Temperate zones
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Boreo-temperate. Species which occur more or less equally in the Boreal and
Temperate zones or, if absent from the Boreal zonobiome, ascend to the
subalpine zone on mountains.
Wide-temperate. Species with a distribution which is centred on the Temperate
zone but which also occur widely in the Boreal and the Southern (Mediterranean)
zones.
Southern-temperate. Species which are found more or less equally in the
Temperate and the Southern (Mediterranean) zones.” (from Preston and Hill
1997).
Arctic
Temperate
Boreal
Southern
Figure 1. Map showing the approximate southern limits of the Arctic (A) and Boreal (C)
zonobiomes, and the approximate northern limits of the Temperate (B) and Southern (D)
zonobiomes, in Europe and western Asia. The distribution of land over 1000 m is shown by shaded
0.5 x 0.5 grid-cells (from Preston and Hill 1997)
3
The E1 codes in the Nordic spreadsheet are defined in Table 1 (Hill et al. 2004):
Code
1
N
153
2
3
4
5
6
7
8
9
150
24
170
346
41
583
186
17
Biogeographical element, major zonobiomes and combinations
Arctic-montane (main distribution in tundra or above tree-line in temperate
mountains)
Boreo-arctic montane (in tundra and coniferous forest zones)
Wide-boreal (from temperate zone to tundra)
Boreal-montane (main distribution in coniferous zone)
Boreo-temperate (in conifer and broadleaf zones)
Wide-temperate (from Mediterranean region to coniferous forest zone)
Temperate (in broadleaf forest zone)
Southern-temperate (in Mediterranean region and broadleaf forest zones)
Mediterranean-atlantic (in Mediterranean region, and extending north in Atlantic
zone of temperate Europe)
Table 1. E1 codes of the major zonobiomes. N = number of taxa
4. Phytogeographical elements based on eastern-range limits (E2)
We follow Preston and Hill (1997) and Hill et al. (2004) in their E2 elements. We used the
same sources of distributional data as Preston and Hill (1997) to assign Nordic taxa not
included in Hill et al. (2004) into the seven elements (0–6) in the eastern limit category
(E2).
Preston and Hill (1997) define six major elements within their eastern-limit category as
follows (see Figure 2).
“(1) Oceanic. Species which are restricted to the Atlantic zone. Oceanic species
do not (or only just) extend eastwards in Europe to Germany; they are western
in Scandinavia. They may occur in the Boreal, Temperate or Southern biomes. In
the Temperate biome the Oceanic zone is exemplified by the distribution of Erica
cinerea. We use the term Oceanic to apply to a defined area of western Europe,
not to describe species with coastal affinities.
(2) Suboceanic. Species with a main distribution which extends beyond the
Oceanic zone to the western Mediterranean, western Central Europe or Sweden.
(3) European. Species with a mainly European distribution; they may extend
eastwards to the Caucasus, Pontic Asia and the Middle East but do not occur east
of 60 E. As Perring (1985) pointed out, relatively few species are strictly
confined to Europe as defined, for example, by Flora Europaea; he therefore
amalgamated Matthews' European and Eurasian floristic elements whereas we
have chosen to define Europe rather more widely to incorporate those areas in
western Asia to which primarily European species characteristically extend.
(4) Eurosiberian. Species with a main distribution which reaches its easterly limit
between 60 E and 120 E. Species with a southerly distribution qualify for this
category only if they extend east of Iran, Iraq and the Arabian peninsula to
reach their eastern limit in or beyond Afghanistan.
(5) Eurasian. Species with a distribution which extends across Asia to an eastern
limit east of 120 E.
(6) Circumpolar. Species which are found in Europe, Asia and North America.
Species qualify as circumpolar even if they are absent from part of one of these
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continents (e.g. absent from eastern North America); in this case they are
described as disjunctly circumpolar.” (from Preston and Hill 1997).
Figure 2. The approximate eastern limits of the Oceanic (A) and Suboceanic (B) categories. (from
Preston and Hill 1997)
In addition we have followed Hill et al. (2004) in using an extra element, Hyperoceanic
(code 0) for plants such as Hymenophyllum wilsonii that have a strongly western
distribution within the Oceanic element.
The E2 codes in the Nordic spreadsheet are defined in Table 2 (Hill et al. 2004):
Code
N
Biogeographic element, eastern limit category
0
1
Hyperoceanic with a western distribution in Atlantic zone
1
40
Oceanic (in Atlantic zone of Europe, not or scarcely reaching east to Sweden,
Germany or S Spain)
2
88
Suboceanic (extending east to Sweden, C Europe or Italy)
3
622
European (extending to more continental parts of Europe but not to Siberia)
4
341
Eurosiberian (eastern limit between 60 E and 120 E)
5
151
Eurasian (extending across Asia to east of 120 E)
6
426
Circumpolar (in Europe, Asia and N America)
Table 2. E2 codes of the eastern-limit elements. N = number of taxa
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Preston and Hill (1997) combined the E1 (major zonobiome) and E2 (eastern limit)
elements to create floristic elements for the British and Irish flora. These elements (not
used here for the Nordic flora) are defined on the basis of the major zonobiome and the
eastern-limit categories and areas as follows: the first digit refers to the major
zonobiome element (Table 1) and the second digit refers to the eastern-limit element
(Table 2).
13
14
15
16
European Arctic-montane
Eurosiberian Arctic-montane
Eurasian Arctic-montane
Circumpolar Arctic-montane
21
23
24
26
Oceanic Boreo-arctic Montane
European Boreo-arctic Montane
Eurosiberian Boreo-arctic Montane
Circumpolar Boreo-arctic Montane
61
63
64
65
66
Oceanic Wide-temperate
European Wide-temperate
Eurosiberian Wide-temperate
Eurasian Wide-temperate
Circumpolar Wide-temperate
34 Eurosiberian Wide-boreal
35 Eurasian Wide-boreal
36 Circumpolar Wide-boreal
71
72
73
74
75
76
Oceanic Temperate
Suboceanic Temperate
European Temperate
Eurosiberian Temperate
Eurasian Temperate
Circumpolar temperate
41
42
43
44
45
46
Oceanic Boreal-montane
Suboceanic Boreal-montane
European Boreal-montane
Eurosiberian Boreal-montane
Eurasian Boreal-montane
Circumpolar Boreal-montane
81
82
83
84
85
86
Oceanic Southern-temperate
Suboceanic Southern-temperate
European Southern-temperate
Eurosiberian Southern-temperate
Eurasian Southern-temperate
Circumpolar Southern-temperate
51
52
53
54
55
56
Oceanic Boreo-temperate
Suboceanic Boreo-temperate
European Boreo-temperate
Eurosiberian Boreo-temperate
Eurasian Boreo-temperate
Circumpolar Boreo-temperate
91 Mediterranean-Atlantic
92 Submediterranean-Subatlantic
93 Mediterranean-montane
The one Hyperoceanic species in Norden, Hymenophyllum wilsonii, is according to Hill et
al. (2004) E1-5 and E2-0, namely 50 Hyperoceanic Boreo-temperate
5. Broad habitats within Norden
In the spreadsheet under Nordic habitats, we have assigned as many taxa as possible to
26 broad habitat types. These correspond closely to Fremstad’s (1997) major habitat
types A–X. We have combined her habitat types A (lichen/bryophyte and dwarf-shrub
woodland) and B (low-herb woodland). Our assignments are based on Fremstad (1997),
Mossberg and Stenberg (2012), Lid and Lid (2005), Rønning (1996), and our own field
observations. The 26 habitat types are summarised in Table 3.
Code Fremstad
habitat type
N
Description (and sub-type codes)
1
A+B
281
Lichen/bryophyte and dwarf-shrub
woodland (B) (A1–A7, B1, B2)
2
C
159
Tall-herb and tall fern woodland (C1–C3)
3
D
232
Deciduous broadleaf and mixed woodland (D1–D2)
4
E
158
Swamp woodland and scrub (E1–E6)
5
F in part
426
Scree and rock vegetation (F1–F3, F6)
6
F in part
173
Woodland border (F4, F5)
6
woodland
(A)
and
low-herb
7
G
708
Anthropogenic grasslands (G1–G14)
8
H
137
Coastal heaths (H1–H5)
9
I
565
Vegetation on strongly disturbed ground (I1–I7)
10
J
39
Ombrotrophic bog (J1–J4)
11
K
68
Poor fen (K1–K4)
12
L
94
Intermediate fen (L1–L4)
13
M
159
Rich fen (M1–M4)
14
N
126
Spring and flush vegetation (N1–N3)
15
O
150
Lake-shore vegetation (O1–O5)
16
P
125
Aquatic vegetation (P1–P6)
17
Q
209
Alluvial (river-bank) vegetation (Q1–Q4)
18
R
133
Alpine ridge vegetation (R1—R8)
19
S
142
Early snow-patch vegetation (S1–S7)
20
T
128
Late snow-patch vegetation (T1–T0)
21
U
199
Sub-littoral, salt-marsh, and brackish swamp (U1–U9)
22
V
159
Coastal shingle and sand (V1–V7)
23
W
187
Established sand-dunes (W1–W4)
24
X
74
Rocky shores and coastal bird cliffs (X1, X2)
25
156
Middle arctic tundra heath and grassland
26
68
Northern arctic tundra and polar desert
Table 3. Broad habitat types for Norden used in the spreadsheet (1–26) primarily based on
Fremstad (1997). The sub-types recognised by Fremstad (1997) are listed for each of the broad
types. N = number of Nordic species in the habitat type.
6. Broad habitats within Britain and Ireland
Hill et al. (2004) recognise 22 broad habitat types (Table 4) based in part on the UK
Biodiversity Action Plan. Hill et al. (2004 pp. 65–68) discuss how their broad habitat
types relate to National Vegetation Classification communities in Britain.
Code N
Explanation
1
310
Broadleaved, mixed and yew woodlands
2
32
Coniferous woodland
3
543
Boundary and linear features (e.g. hedges, roadsides, walls)
4
198
Arable and horticultural (includes orchards, excludes domestic gardens)
5
22
Improved grassland
6
163
Neutral grassland (includes coarse Arrhenatherum grassland)
7
218
Calcareous grasslands (includes lowland and montane types)
8
89
Acid grassland (includes non-calcareous sandy grassland)
9
10
Bracken (Pteridium aquilinum)
10
83
Dwarf-shrub heath (cover of dwarf shrubs at least 25%)
11
254
Fen, marsh, and swamp (not wooded: includes flushes, rush-pastures, springs, and
mud communities)
12
41
Bog (on deep peat: includes bog pools as well as acid lowland valley mires on slightly
shallower peat)
13
174
Standing water and canals
14
149
Rivers and streams
15
103
Montane habitats (acid grassland and heath with montane species)
16
292
Inland rock (heterogeneous – includes quarries, limestone pavement, cliffs, screes,
and skeletal soils over rock)
7
17
231
Built-up areas and gardens
18
74
Supralittoral rock (does not include maritime grassland)
19
135
Supralittoral sediment (strandlines, shingle, coastal dunes)
21
65
Littoral sediment (includes saltmarsh and saltmarsh pools)
23
1
Inshore sublittoral sediment (only Zostera marina)
Table 4. Explanation of the 22 broad habitat types used by Hill et al. (2004) for the British and
Irish flora. The same codes for British habitats are used in our spreadsheet. N = number of British
and Irish species in the habitat type.
7. Red List taxa
We have used the current Red Lists for Norway, Svalbard, Sweden, and Finland to assign
the species to the following categories
CR – critically endangered
EN – endangered
VU – vulnerable
NT – near threatened.
As many of the Red List taxa are subspecies whose habitat preferences and distributions
are not known by us, we have an additional category
DD – data deficient.
For the Red List species (but not subspecies) the highest category in the Norway Red List
is NT, with the highest number of NT species having an E1 value of 7 and an E2 value of
3, and occurring in habitat types 5, 7, and 9. In the Swedish Red List, there are about
equal numbers of EN and NT species centred on an E1 value of 7 and an E2 value of 3,
and habitats 5 and 9. In the Finnish Red List NT species predominate with an E1 of 5 and
an E2 of 3 and habitat types of 7 and 9.
Preliminary results
An analysis of the data in the spreadsheet will be published elsewhere but some
preliminary observations can be made at this stage.
1. The highest proportion of the Nordic taxa is in element 7 (temperate) followed by 5
(boreo-temperate) within E1 (major biome) and 3 (European) within E2 (eastern limit)
followed by 6 (circumpolar).
2. The highest proportion of taxa in E1–7 occur in habitat types 7 (anthropogenic
grasslands) and 9 (vegetation on strongly disturbed ground) and 6 (scree and rock
vegetation).
3. The highest proportion of taxa in E2–3 occur in habitat types 5 (scree and rock
vegetation), 7 (anthropogenic grasslands), and 9 (vegetation on strongly disturbed
ground).
4. The bulk of the native Nordic flora belongs to the European Temperate element (E1:
7 and E2: 3) of Preston and Hill (1997) as does the British and Irish flora.
Potential uses
The E1 major biome classes 1–9 can be viewed as simple summer growing-season
temperature indicator values with 1 being the coldest (arctic-montane) and 9 being the
warmest (Mediterranean-atlantic). They can be used either as simple averages for an
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assemblage of species using species presences or as weighted averages where the
weights are the relative abundance of the species in the assemblage (Ellenberg 1948; ter
Braak 1987; Diekmann 2003). However, as Hill et al. (2004) point out E1 and E2 should
be used with caution in an oceanic climate such as that of western Norway.
Final comments
This is very much a first attempt at compiling a list of presumed native species for the
Nordic countries (done primarily by Mora Aronsson). It inevitably will contain errors,
especially about species not being native or species that are native but which have been
omitted. The assignment of these Nordic species to the nine elements within E1 and the
seven elements within E2 are likely to be consistent as they are all based on the same
sources of distributional data. This assumes that the distributional data are reliable and
our decisions about native status are valid. There is likely to be different opinions about
what is native in the Nordic flora. Comments and corrections will therefore be
appreciated. Please email john.birks@bio.uib.no with your comments.
Acknowledgements
This compilation was initiated as part of the NorFa Stay or Go network co-ordinated by
Bente Graae. It has been funded as part of the NFR AVIT project Research Infrastructure
for High-Precision Palaeoecological Analyses (195332). We are grateful to Hilary Birks,
Arild Breistøl, John-Arvid Grytnes, Cathy Jenks, Jonathan Lenoir, and Chris Preston for
help, discussion, and advice.
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