Estonian Alvars and Juniper Shrublands—
Instructions for the Management and
Restoration of Communities
A brief translated summary of the manual compiled by Aveliina Helmi in 2009. The list of
materials used and references can be found in the original manual.
(http://www.keskkonnaamet.ee/public/PLK/Lisa_2_Loopealsete_ja_kadastike_hooldusk
ava_2011.pdf)
Overview of Estonian Alvars
Alvars are semi-natural grasslands with a thin layer of lime-rich soil which is generally less
than 20 (30) cm deep. Alvars are semi-natural ecosystems that are also known as heritage
communities. This means that their formation and persistence is closely connected to human
activity, mainly grazing.
Most Estonian alvars have formed secondarily due to deforestation and subsequent grazing.
The herb layer of alvars that are in a good condition is short, not very productive and diverse,
consisting mainly of stress-tolerant plants that prefer calcareous soils. Junipers mostly grow
on alvars, either separately or in groups; nowadays, there are no completely treeless alvars in
Estonia. Grazed alvars tend not to have a tree layer, or, if they do have one, it consists of
solitary specimens. However, trees will grow easily on non-grazed alvar grasslands with
deeper soil.
Alvars are not widespread in the world, which makes them globally rare, and, therefore, these
communities also need special protection. In addition to Estonia, a considerable number of
alvars can only be found on large Swedish islands, mainly on Öland and Gotland. In Estonia,
alvars are mainly distributed in areas with exposed limestone bedrock in Saaremaa, Muhu,
Läänemaa and Hiiumaa, but also in Harjumaa and Ida- and Lääne-Virumaa (see figure 1 and
2).
Figure 1: Alvars in Europe
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Figure 2: Historical distribution of alvars in Estonia
In 1930s, there were 43,000 hectares of alvar grasslands in Estonia (Figure 2). During the
inventories of 1978 and 1981, approximately 16,000 hectares of alvar communities were
registered, 25% of which were more or less being encroached by forest. Nowadays, there are
less than 12,000 hectars of alvars preserved in Estonia, only 3,000 of which can be deemed
representative (see figure 3).
Figure 3: Current distribution of alvars in Estonia, more representative areas are marked with
red
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Environmental Conditions on Alvars
Alvars’ alkaline soil is very thin, therefore the plants that grow there are suffering from a lack
of nutrients. Thus, the common species that inhabit alvars have restricted growth and require
considerably less nutritious soil. In summer, thin-soiled alvars are characterised by a
completely dried out soil due to the wind and sun.
Figure 4: Polygons formed by frost
heaving in thin-soiled alvar
community
Flora and Fauna on Alvars
Thanks to the extensive fluctuation of microclimatic environmental conditions, alvars are
home to plant species from different geographic regions: South-Siberia and South-East
European steppes (rock wormwood, spring cinquefoil, purple milk-vetch, mountain clover,
carline thistle, dyer’s woodruff, snowdrop anemone), North-European subarctic (Alpine
mouse-ear chickweed, Alpine meadow-grass, Alpine cinquefoil) and North-West European
oceanic climate (rue-leaved saxifrage, white stonecrop, etc.). The number of vascular plant
species in Estonia that are ecologically suitable for alvars is 267 (17% of domestic flora). 16%
of the species are under protection.
Development of Species Richness in Alvars and its Conservation
By the number of vascular plants, alvars are the second most species rich communities in
Estonia after wooded meadows. Behind its current species richness lies the long-time effect of
human activity and the historically extensive coverage of alvars. Human impact and wide
coverage formed the network of connected habitat patches, which facilitates the dispersal of
vascular plants between different alvar patches. However, the smaller the habitat patches
become and the further they remain from each other due to the habitat loss and fragmentation,
the less probable it is for the species to disperse between individual habitat patches and thus
maintain their historical species richness. At the moment, despite the vast loss of habitat area
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and increased isolation, the alvars in Saaremaa are as species rich as they have been
historically. However, this means that our alvars are suffering from the so-called extinction
debt. Extinction debt is imposed on the species that manage to temporarily defy unsuitable
environmental conditions (such as too small area and increased isolation) and stay viable for a
shorter or longer period after the fragmentation of the community. However, as long as
unsuitable conditions persist, these species are doomed to extinction in the future.
Factors Endangering Alvars. Overgrowth
Since 1930s and throughout the Soviet era, grazing on alvars decreased considerably, which
has brought along the encroachment by shrubs (mainly junipers), trees (mainly pines) and the
invasion of tall grazing-sensitive herbaceous plants.
Figure 5: overgrown alvar on
Muhu.
Still, not even thin-soiled and almost platy alvars are not safe from overgrowth
Figure 6: Thin soil does not
prevent overgrowth.
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During 1950s, an extensive afforestation programme (on approximately 25,000 hectares) was
carried out in Saaremaa, which succeeded on 6,000 hectares of alvars. Fertilisation is very
dangerous to alvars.
Figure 7: The result of the
afforestation attempt at Lõo
alvar, Saaremaa.
Protection of Alvars
Alvars are a priority habitat type in the framework of NATURA 2000 (Habitats Directive
Annex 1 habitat type *6280 and also *8240). Estonia is home to a considerable number of the
world’s alvars (28%). Inactivity will lead to the complete disappearance of alvars already in
the next decade. The organisation of alvar conservation is not very advanced in Estonia.
Europe’s largest alvar formation Great Alvar (Stora Alvaret; 26,000 hectares) on the island of
Öland, Sweden is in the list of UNESCO World Heritage sites
Figure 8: Restored alvar on the
island of Öland, Sweden.
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Landowners’ initiative in relation to the management of alvars should be supported in all
manners. Alvars are the type of community which could nowadays bring financial profit from
its semi-natural functioning by producing so-called meadow meat and via agri-environmental
subsidies for the management of heritage communities.
Alvar Management
First of all, following aspects should be kept in mind in relation to alvar management.
(1) Alvars are semi-natural communities, which, in order to persist as an open community for
a long period of time, need
moderate
human
influence—
grazing.
Figure 9: Grazing with suitable
intensity ensures the preservation
of an alvar.
(2) It is useful to switch between the types of livestock (sheep/cows/horses/goats) as well as
the grazing intensity in every few years. This allows species with different needs to settle in
the areas, since different animals prefer different forage.
(3) Because of extinction debt, it is very important to ensure the spread of both plant and
animal species between habitat patches or, in other words, to re(create) the network of habitat
patches.
(4) Activities which damage topsoil should not be allowed (driving motor vehicles, self-made
campfires, ploughing, milling, afforestation)! Excessive damage to herb layer makes the
preservation or restoration of the alvar community highly unlikely. Recreational activities—
camping, hiking and walking, field trips—should be promoted.
Grazing as the Most Effective way to Conserve Alvars
In case of suitable grazing intensity, the herd will consume 50% of the biomass available,
which means that at least half of the pasture must be characterized by very low herb layer (ca
5 cm in dry alvar grasslands and 10 cm in temporarily wet alvar grasslands). While
determining the intensity, one should take into account the energy value of meadow grass as
well as the energy needs of the grazing animals.
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Tor-grass is an exceptionally good indicator species of the poor condition of the community
long before the spread of shrubs.
Figure 10: Deep-soiled alvar in
Saaremaa. If this is also grazed,
the intensity is clearly too low.
On deep-soiled alvars, the wide spread of low and light-demanding species and dense herb
layer undamaged by trampling indicate long-term grazing with suitable intensity. Indicator
species of good light conditions are, for instance, pink pussy-toes, rockrose, wild thyme,
milkwort, little mouse-ear, common kidneyvetch, spring cinquefoil, dyer’s woodruff, vernal
sedge (see Table 2). In case of excessive grazing, the more palatable species will be eaten
wholly, topsoil will suffer from trampling, excessive manure will overfertilise the community
and the species richness of vascular plants will reduce.
Figure 11: occasionally
overgrazed area in Läänemaa,
Penijõgi.
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Different Types of Alvars and Their Management
In Estonia, a classification of alvars has been compiled on the basis of mathematical analyses,
where one can distinguish roughly three different types of alvars according to moisture
conditions and soil thickness.
1) Temporarily wet or Molinietum-type alvars. These are mainly distributed along the
temporarily wet areas on Saaremaa and in South-West Estonia. Characteristic vascular plant
species are purple moor grass, blue moor grass, carnation sedge, blue sedge, northern
bedstraw, common tormentil. These alvars are not very rich in species and their productivity
is relatively high. They are well suited for grazing and the management is based on the same
principles as those of the Avenetum-type (see point 2).
Figure 12: Moist Molinietumtype alvar.
2) Dry deeper soil layer or Avenetum-type alvars. Characteristic vascular plant species are
meadow oat-grass, fern-leaf dopwort, mountain clover, common kidneyvetch, quaking-grass
mouse-ear hawkweed, dwarf thistle, lady’s bedstraw, blue moor grass, purple milk vetch,
spring cinquefoil, carline thistle, sheep fescue, lady’s mantle, wild thyme and many others.
Figure 13: Managed
Avenetum-type alvar.
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The Avenetum-type alvar is the most rich in species and it is also the community type which
depends on diligent grazing the most. With suitable grazing intensity, these kinds of
communities will become only richer in species; if grazing is discontinued, they will quickly
be encroached by junipers.
Figure 14: Dense grassland
herb layer characteristic to an
alvar in good condition.
In order to conserve/restore the alvar grassland diversity, the recommended optimum number
of grazing sheep is 1.6–3.5 sheep per one hectare (0.2–0.5 livestock units per hectare), up to 1
livestock unit per hectare (up to 6 sheep on a hectare) on deep-soiled alvars. In NorthEstonian highly productive alvar areas, the grazing intensity could be approximately 1
livestock unit per hectare.
Figure 15: North-Estonian
version of Avenetum-type alvars
(Võle alvar).
Heath alvar grassland subtype—distributed in areas with more sandy soil, often in sand ridges
near the sea. Characteristic species are thyme-leaved sandwort, bulbous buttercup, vernal
sedge, brown bent and ling heather. Shingle alvars subtype—appears in areas where thin soil
and vegetation is not able to cover the limestone scree and shingle.
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Figure 16: Developing
community on scree ridges in
Kassari, Hiiumaa.
3) Dry thin soil layer type or Festucetum-type alvars (also plate-alvar). Community with a
thin soil layer (<5 cm), where there are patches free from vegetation covered with soil that are
caused by frost heaving; these may occur similarly to areas with platy alvar. Festucetum-type
alvar grasslands represent an extremely rare plant community and are home for a number of
phytogeographically rare plants and those that inhabit the border of their natural habitat,
therefore it is of great importance in terms of nature conservation. Characteristic species are
sheep fescue, northern wormwood, rock wormwood, white stonecrop, goldmoss stonecrop,
knotted pearlwort, basil thyme, etc. These areas are suitable for grazing sheep. Thin-soiled
alvar grasslands have sparse vascular plant layer, therefore, these areas are not valued as
pastures for larger animals. However, thin soil layer does not prevent overgrowing with
shrubs and trees and the traditional management via grazing is necessary.
Figure 17: Dry thin-soiled
Festucetum-type alvar in Atla
village, Saaremaa.
Where there are plenty of wild orchids, measures should be taken to conserve them. Most of
the orchids require moderate management and an open community in order to sustain
themselves, but very intense sheep grazing may decrease the populations size of orchids.
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Restoration of Alvars. The Goals of the Restoration of Estonian Alvars
Alvar studies have shown that it is necessary to conserve as many alvars as possible, which
should also involve re-creating a network of alvar areas. Creating solitary representative alvar
conservation sites is not enough, since most grassland species need to exchange genetic
material between the populations of different habitat sites in order to sustain them for a long
period of time. The overgrowth processes are not entirely irreversible and even an alvar that is
visually in a rather bad state can be restored.
A sudden drop in species richness and significant changes in the species that make up the
grass layer will take place once the shrub coverage is more than 75–80%. At this coverage,
the light conditions will quickly change, the dense herb layer characteristic to alvars will
disappear and light-demanding trampling-resistant plant species will at first be replaced by the
shade-tolerant species characteristic to alvar forests.
Most Estonian alvar areas can still be restored, since the regional species pool has been
preserved in its entirety. Alvars with less than 75–80% juniper coverage and well-preserved
herb layer should be the first ones to be restored. Since the alvars in different Estonian regions
are valuable with respect to different aspects, it would be good to find regional centres in
Eastern Harjumaa, Keila, Western Estonia, Pärnumaa, Hiiumaa, Muhu, Eastern Saaremaa and
Western Saaremaa.
Alvar Restoration Activities
Most of the experience in the restoration of alvars comes from Sweden. 1996 saw the start of
European Union LIFE project on the island of Öland, in the course of which more than 7,000
hectares of alvars have been restored. Juniper scrub (also broad-leaved tree scrub, if present)
must be removed from as close to the ground as possible during the restoration process.
Nowadays, the cheapest way to do it is by using a shrub cutter and a saw, or during largescale restoration, specific heavy machinery can be used.
Restoration work can be done from the late summer until the beginning of spring. The nesting
season in spring and early summer is not suitable for restoration work. In case of dry thin soil
layer type alvars (trampling sensitive), the restoration work should take place at a more wet
time, in autumn and winter.
It is very necessary to start grazing after the restoration. It is particularly necessary on
excessively overgrown areas where the local species pool characteristic to alvars has already
reduced or disappeared, otherwise the area cleared of junipers will be encroached by weeds
and plants from more fertile habitats.
Currently (2011), a great number of Estonian alvars are in a state where the local species pool
is still preserved, but the cover of junipers is already too extensive. Clearing the area from
junipers is the only way to save a great part of alvar areas from further overgrowth and to gain
extra time to organise the suitable management.
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Figure 18: Here we can see an
alvar restored from a juniper
scrub, which has not been
grazed after the clearing of
junipers. As a result, it has been
colonized by pioneer weed
species.
Aim of the restoration is to create open habitat with ca 30% coverage of shrubs, located
sparsely on the site. Sparse shrub cover will allow light conditions to be suitable for lightdemanding grassland plants, while offering wind- and sun-shade for both invertebrates and
grazing animals. If the area has patches of older ‘juniper forest’, then these could definitely
be preserved as they are. However, it should be kept in mind that a managed/restored alvar
that is seen as one area should not include dense shrub or tree patches larger than 1,000 m².
Juniper communis shrublands in Estonia
Estonian juniper shrublands can be divided roughly in two: juniper scrubs that are situated on
former alvars (alvar shrublands) and juniper scrubs which have been formed as the result of
overgrowing of other types of grasslands (boreal, boreal heath, and dry and fresh grasslands),
but also clearings or fallow fields becoming encroached by juniper. Primarily formed juniper
shrublands can be found in small numbers on scree ridges near the sea. It is possible that none
of the Estonian juniper shrublands are climax communities; instead they are successional
(unstable) communities before the formation of a forest community. The distribution of
juniper shrublands has not been mapped. Henceforth, a loose classification has been used:
‘alvar juniper shrublands’ and ‘other type of shrublands’, since the juniper coverage limits
and management manuals assigned to those areas differ.
Alvar Juniper Shrublands
Alvar shrubland is a successional stage between an open alvar (Natura 2000 habitat type
*5130) which is being managed by grazing and a coniferous alvar forest which is a climax
community (Natura 2000 code *9010). Alvar juniper shrublands differ from the other
shrublands formed from grasslands by calcareous soil that is thinner than 30 cm. Juniper
scrublands that have formed in previously open alvars, have been assigned to the Natura 2000
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habitat type 5130 (Juniperus communis formations on heaths or calcareous grasslands)
according to the Habitats Directive manual.
Still, it is important to stress that the area in the danger of overgrowing should be considered
an alvar (habitat type *6280) and not a shrubland (5130) if it meets all of the following
requirements:
(1) the previous condition of the area has been an open alvar
(2) soil thickness (without needle-fall) is less than 30 cm
(3) patches of preserved grassland herb layer consists of species characteristic to open alvars
(4) juniper coverage is less than 75–80% and the light conditions are still good at some spots
(see also Table 1).
If the juniper coverage is 30–50%, it can be considered a relatively open alvar with all
features characteristic to alvars. In this case, the first thing to do is to start grazing and
removing excessive junipers. Secondly, if we consider 50–70% of juniper coverage also as
habitat type *6280, we reserve the opportunity to restore the valuable open alvar grasslands
and manage them in the future. The percentage of light-demanding grassland species in the
community will quickly drop if the juniper coverage (or pine canopy cover) is 75–80%; this is
why this area can be justly considered as an alvar before that coverage percentage is reached.
Restoration of shrublands with less than 80% juniper cover to a more open community is
fruitful and advisable at any given opportunity. In order not to risk the destruction of alvars
and the extinction of the species that inhabit them, we must firstly restore and manage as
many alvar grasslands (habitat type *6280) as possible.
Other Type of Juniper Shrublands
Juniper shrublands do not always originate of alvars. In addition to alvars, other semi-natural
grasslands may become encroached by junipers: dry boreo-nemoral grasslands and sandysoiled dry boreal heath and boreal grasslands. Juniper thickets can also form on abandoned
farmlands, clearings, etc. In Western Estonia, cleared alvar forests often become shrublands.
The juniper scrubs on scree ridges risen from the sea as primary communities (for instance on
Hiiumaa, the island of Suur-Pakri) have formed entirely naturally.
Restoring Grasslands from Juniper Shrublands
In case of dire need it is possible to restore the previous community type also in areas with
more than 80% of juniper coverage. This should be done especially if the grassland
characteristic herb layer is preserved, the juniper coverage has not yet reached 100% and
grassland species can still be found in the vicinity. In case of restoring these areas, juniper
removal during several years is justified. Juniper cover should be reduced to ca 50%. The
establishment of corridors and widening of grassland patches helps to restore the vegetation,
and animals can spread the species over the restored area. The period between the restoration
years should be inversely proportional to the amount of preserved grassland characteristic
herb layer.
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Management of Juniper Shrublands
The general Natura 2000 Habitats Directive manual does not include any instructions on the
management of Juniper communis formations (5130). The juniper shrubland habitat type may
be of natural origin in several cases, but if the juniper coverage has reached 80% it is not
reasonable to manage the community anymore and one must decide whether to leave the area
to develop naturally or to restore it as grassland. Juniper shrubland with dense juniper cover
and small number of other plant species is not a climax community, on the event of the death
of the first generation junipers; the progeny is not able to compete with fast-growing broadleaved trees or pines. Succession will inevitably lead to the formation of a more species rich
alvar forest, while grazing and/or tree removal will only postpone this a little.
Management of Juniper Shrublands Formed on Alvar Grasslands
One must assume the viewpoint that the management (tree removal, grazing) of an alvar
shrubland is no longer reasonable if the community type has been determined correctly with
regard to such areas. If one wishes to manage this kind of area (by grazing), one must restore
the area as an open alvar first and assess the successfulness of the restoration beforehand.
Management of the Other Type of Juniper Shrublands
The classification and management instructions for the other type of shrublands differ from
those imposed on alvar shrublands. Alvar shrublands are former alvar grasslands and if the
juniper coverage is less than 80%, the areas should be classified as alvars in need of
restoration. Juniper covered communities which have developed from dry and fresh
grasslands, boreal heath grasslands or boreal grasslands can be classified as shrublands even
at 30–80% coverage and preserved as a (possibly open) managed shrubland (5130). In short,
one must consult with the landowner in the case of the other type of shrublands and decide
together whether to
- preserve the area as a non-managed continuous shrubland (code 5130), juniper
coverage >80%, no management subsidy)
- preserve the area as a managed shrubland, remove junipers every now and then in order to
maintain a suitable coverage (5130, coverage 30–75%, management subsidy)
- restore the area according to its former condition, either to a managed dry and fresh
grassland, boreal heath grassland or boreal grassland (coverage <30%, restoration subsidy,
management subsidy).
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Table 1. Classifying areas as alvars or Juniper shrublands.
Habitat
Open alvar
Area covered by
junipers
10-30 (40)%
Herb layer
Necessary
activity
Alver in danger
of overgrowing
Overgrown alvar
with a urgent
restoration need
40-50%
50-75% (80% in the
conditions where
the grass layer is
present)
80-100%
species rich herb
species rich herb layer present,
layer present,
grassland
consists of
species
grassland
dominant in the
species
herb layer
grazing
grassland
characteristic herb
layer present in
patches, some
areas are covered
by moss or sparse
vegetation
restoration
grazing, removal (removal of
of trees/shrubs trees/shrubs) and
when necessary then grazing
Juniper shrub
Alvar forest
less juniper
shrub, more
pine trees (also
spruce, birch)
herbaceous
vegetation
species-poor
and sparse, no
dense herb
layer, topsoil is
covered by
needle-fall and
moss
herb layer
consists of forest
species
can be restored
if reasonable,
conservation of
juniper shrub is
not sustainable
in long term
no human
activity is
necessary for
alvar forest
conservation
>>>>>>>>>Succession proceeds in this direction if the management stops>>>>>>>>>>
Table 2. A selection of light-demanding grassland species, which are rarely or not at all found
on overgrown alvars. The list is informative and incomplete.
Acinos arvensis
Anthemis tinctoria
Artemisia campestris
Artemisia rupestris
Carex ornithopoda
Carex caryophyllea
Crepis tectorum
Helianthemum nummularium
Leontodon autumnalis
Libanotis montana
Linum catharticum
Ophrys insectifera
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Orchis militaris
Phleum phleoides
Polygala comosa
Polygala vulgaris
Ranunculus bulbosus
Sagina nodosa
Saxifraga tridactylites
Sedum acre
Sedum album
Thymus serpyllum
Veronica spicata
Vincetoxicum hirundinaria
Viola hirta
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