Spontaneous Development of Peri-Urban Woodlands in Lignite Mining Areas of Eastern Germany

Abstract

In the eastern German federal states of Saxony, Saxony-Anhalt and Brandenburg, open-cast mining has destroyed vast landscapes of near-natural floodplain ecosystems and forests as well as elements of cultural landscapes or has affected them by lowering of the ground water table. On the one hand, forests have been considerably extended in total area compared to the situation before the open-cast lignite mining by the afforestation of spoil dumps. In Saxony and Saxony-Anhalt, for example, the destroyed forests have been replaced by 163 %. However, afforestation with monocultures of non-native species and low structural diversity has led to a mostly reduced ecological value of these forests (Berkner 1998). On the other hand, some spoil dumps have, more-or-less by chance, been settled by spontaneous succession since the 1930s. The result of this natural colonization is astonishing: on these sites, often called "lunar landscapes," grasslands, heaths and fens as well as varied woodlands have developed. Stages of development, species composition and stand structure of these woodlands are very different. Due to their accessibility for urban residents and their location in postindustrial landscapes, these woodlands can be classified as "peri-urban woodlands." Species composition and stand structure mainly result from natural processes, but the site factors have been changed by the impact of open-cast mining. Therefore, these woodlands represent typical examples of "nature of the fourth kind" (see Kowarik 2005).

Full text

Kowarik I, Körner S (eds) Wild Urban Woodlands.
© Springer-Verlag Berlin Heidelberg 2005, pp 163–180
Spontaneous Development of Peri-Urban
Woodlands in Lignite Mining Areas of Eastern
Germany
Sabine Tischew, Antje Lorenz
Vegetation Science and Landscape Ecology, University of Applied Sci-
ences Anhalt
Introduction
In the eastern German federal states of Saxony, Saxony-Anhalt and Bran-
denburg, open-cast mining has destroyed vast landscapes of near-natural
floodplain ecosystems and forests as well as elements of cultural land-
scapes or has affected them by lowering of the ground water table. On the
one hand, forests have been considerably extended in total area compared
to the situation before the open-cast lignite mining by the afforestation of
spoil dumps. In Saxony and Saxony-Anhalt, for example, the destroyed
forests have been replaced by 163 %. However, afforestation with mono-
cultures of non-native species and low structural diversity has led to a
mostly reduced ecological value of these forests (Berkner 1998). On the
other hand, some spoil dumps have, more-or-less by chance, been settled
by spontaneous succession since the 1930s. The result of this natural colo-
nization is astonishing: on these sites, often called “lunar landscapes,”
grasslands, heaths and fens as well as varied woodlands have developed.
Stages of development, species composition and stand structure of these
woodlands are very different.
Due to their accessibility for urban residents and their location in post-
industrial landscapes, these woodlands can be classified as “peri-urban
woodlands.” Species composition and stand structure mainly result from
natural processes, but the site factors have been changed by the impact of
open-cast mining. Therefore, these woodlands represent typical examples
of “nature of the fourth kind” (see Kowarik 2005).
Thirty-two active surface mines were shut down after the German reuni-
fication in 1990. An area of nearly 1,000 km2 was included in a reclama-
tion process (LMBV 2002). Since the beginning of this process, scientists

164 Sabine Tischew, Antje Lorenz
and conservationists have demanded a stronger integration of natural proc-
esses in the development of woodlands. Gradually, this demand has been
accepted by the reclamation company. About 3,400 ha of reclamation area
are currently developing spontaneously into woodlands. With the designa-
tion of further successional areas, an additional 3,500 ha will develop into
woodlands over different periods of time.
This paper summarizes the results of our studies on spontaneous wood-
land development on more than a hundred sites of eastern German lignite
surface mines. The aim was to determine opportunities for the integration
of spontaneous colonization processes into former mining areas. The pre-
sent summary of results will focus on the following:
• the analysis of migration processes and the impact of isolating effects
• the analysis of site conditions and chronological differentiation of pio-
neer woodlands
• the integration of woodland development into general successional proc-
esses of post-mining landscapes
• opportunities and perspectives for peri-urban woodland development in
post-mining landscapes
Locations and site characteristics
The study was carried out in nearly all eastern German brown-coal districts
in Saxony, Saxony-Anhalt and Brandenburg that show spontaneous suc-
cession at least in some parts (FLB 2003; Tischew et al. 2004). Forty-four
former mines were included in the investigations. Large areas with sponta-
neous succession were divided into smaller sites with relatively homoge-
neous conditions and considered as sample size. The time since abandon-
ment of the investigated mines ranges from 1 to 98 years.
Lignite has been mined in surface mines in eastern Germany since the
beginning of the 20th century. Overburden layers 40–120 m thick above
the lignite seams had to be excavated and dumped, forming spoil dumps.
This process can be compared with the mass turnover of the last glacial
epoch (Müller and Eissmann 1991). The groundwater level had to be low-
ered significantly. Overburden layers consist of Tertiary and Quarternary
substrates that were often mixed during the dumping processes. Quarter-
nary substrates are usually more suitable for plant colonization. They are
composed of boulder clay, sand and loess. Tertiary substrates consisting of
sand, clay and silt often contain fine coal and sulphur. Due to the oxidation
of the sulphuric compounds (iron pyrite, marcasite), Tertiary substrates
tend to acidify over a long period of time as well as to release high levels

Peri-Urban Woodlands in Lignite Mining Areas 165
of phytotoxic Al3+-ions (Pichtel et al. 1988). Tertiary substrates addition-
ally display high bulk density and low macropore volumina. High levels of
finely distributed coal-containing admixtures can also influence substrate
qualities negatively by their hydrophobic characteristics.
In the investigated mining area, the topsoil, which contained humus,
was often not separated when dumped. Dumped substrates, therefore,
show mostly low biological activity and low levels of available plant nutri-
ents at the beginning of their development. Dumps of the early mining
phases (up until the 1920s and 1930s) are exceptional, because they were
turned by hand and topsoil containing humus was selectively put on the
spoil dumps as the uppermost layer.
The area investigated has a mean annual temperature of 8.0–9.5°C and
an annual precipitation of 450–650 mm. Due to industrial mining, vast sur-
face mines have been created where isolating effects relating to coloniza-
tion processes must be expected. Remnants of natural woodland vegetation
(oak–hornbeam forests, beech forests, birch–oak forests, pine–oak forests,
floodplain forests) have only rarely remained around spoil dumps.
Investigation methods
Investigations were carried out on 104 sample sites for the classification
and description of chronologically and spatially differentiated successional
series. Abundance and species-cover percentage of vascular plant species
in all vegetation layers were estimated (modified Braun-Blanquet scale,
Wilmanns 1998). In order to assess stand structure, all trees of 1 cm or
greater diameter were measured in a plot of 400–2,000 m2. Further investi-
gations were carried out with respect to selected site factors, e.g. soil acid-
ity, soil texture, nutrient availability, cation-exchange capacity, coal con-
tent, humus and fly-ash coating (for detailed methods, see Tischew et al.
2004). The classification of seral successional stages in space and time was
carried out using hierarchical and non-hierarchical cluster analysis as well
as multivariate ordination methods. The following bioindicative parame-
ters were included for every plot: (1) percentage of vegetation layers, (2)
weighted percentage of vegetation units (e.g. dry psammophytic grass-
lands, mesophilic grasslands, woodlands), (3) stand density per hectare of
pioneer, intermediate and climax tree species and (4) stand basal area of all
trees per hectare.
Special aspects of colonization processes were analyzed exclusively in
brown-coal districts north and south of Halle: five northern mining areas
from the region around Bitterfeld and five southern mining areas from

166 Sabine Tischew, Antje Lorenz
Geiseltal and its surroundings. Complete species composition was identi-
fied on sample sites (each about 2 km2) by several mappings from 1998–
2002. The investigated sample sites were characterized by open-land and
woodland stages (age: 2–55 years). About 1,100 relevés were included,
which were conducted during several research projects. To determine the
regional species pool, we used the dataset of the flora mapping of the
states Saxony-Anhalt and Saxony, which was done in grid cells
(5.5 x 5.5 = 30.25 km²).
Statistical tests and cluster analysis were carried out using SPSS 10.0
and PCORD 4.0. Multivariate ordination methods were carried out using
CANOCO 4.5 (ter Braak and Šmilauer 1998).
Colonization processes
Contrary to other studies which report delayed colonization processes in
restoration (Bakker et al. 1996; Coulson et al. 2001; Verhagen et al. 2001),
more than 50% of the species found in the surrounding area of 30 km²
were able to colonize the investigated mining sites north and south of
Halle (Table 1). Depending on the landscape structure of the surroundings,
up to 40% of the species already present in the mining sites were found
more than 3 km away (long-distance dispersal). This phenomenon can be
observed mainly at hospitable mining sites within a species-poor surround-
ing landscape (examples “southern mining sites”).
High migration rates from larger distances can be explained by extraor-
dinary events like gales, thermally induced turbulences or zoochory. These
events can be compared to the migration processes after the last ice age
(Clark 1998). Even rare species can accumulate at the mining sites which
act as large “seed traps” in the cultural landscape (Tischew and Kirmer
2003). The availability of large-scale competition-free space in the mining
sites supports the establishment of these species. Most of the species that
migrated from distances greater than 3 km represent species from open
landscapes and only 25% are woodland species. Most of these woodland
species are trees and shrubs, woodland herbs are rather rare. However,
woodland herbs are suitable for assessing successional dynamics in wood-
lands (Wolf 1989). Further analysis, therefore, refers particularly to this.

Peri-Urban Woodlands in Lignite Mining Areas 167
Table 1. Migration processes at ten former mines in Saxony-Anhalt. Comparison
with the regional species pool and analysis of long-distance dispersal. A No. of
species on the mining sites (mean size 1.9 km²), B No. of species in the surround-
ings within a radius of 3 km (mean size 30 km²), C No. of species migrated to the
mining sites (according to the species pool of 3 km radius), D No. of species mi-
grated to the mining sites from distances of more than 3 km, E No. of woodland
species migrated to the mining sites from distances of more than 3 km.
(SD=standard deviation, Mann-Whitney U-Test: ns = not significant; ** 0.01 ≥ p
> 0.001; *** p ≤ 0.001)
ABCDE
Northern mining
sites (n = 5)
298.8 642.2 263.4 35.4 9.0
SD (+/-) 56.5 69.7 56 5.5 2.8
Southern mining
sites (n = 5)
258.4 292.6 154.0 104.4 23.8
SD (+/-) 38.0 34.9 24.7 23.4 8.1
Mann-Whitney-
U-Test
ns *** ** ns ns
The relationship of distance of diaspore sources to the number of herb
species in dump woodlands was analyzed in detail on four spoil dumps of
similar age and similar site conditions (Fig. 1). In the case of the site with
nearby diaspore sources (A), more than twice as many species migrated
into the site than in the sites with more distant diaspore sources (sites B –
D). The average number of species with animal dispersal (epizoochory,
endozoochory) and self-dispersal (autochory) is much higher for the
nearby site, while the average number of wind-dispersed (anemochorous)
woodland herbs is nearly the same.
Fig. 1. Effect of the dis-
tance of diaspore sources on
the species number of
woodland herbs in pioneer
woodlands on mining sites
(plot size 400–525 m²).
A Mining site Goitzsche-
Tagesanlagen, B mining site
Goitzsche Halde 1035, C
mining site Roßbach, D
mining site Kayna-Süd
0 5 10 15
nearby (A)
appr. 1 km
distant (B)
appr. 4 km
distant (C)
appr. 8 km
distant (D)
average species number
epizoo-, endozoo- and autochorous species
anemochorous species

168 Sabine Tischew, Antje Lorenz
More detailed investigations with respect to time-dependent coloniza-
tion by woodland herbs were carried out based on data from all woodland
areas investigated in eastern German post-mining landscapes. Table 2
shows a relatively high number of species that can already occur on young
spoil dumps (10–60 years old). The seeds of these species were effectively
dispersed by wind or animals over long distances (long-distance dispersal).
Species with less effective dispersal mechanisms (autochory or dispersal
by ants) mainly occur only on spoil dumps with pioneer woodlands, which
are older than 60 years and characterized by an accumulation of intermedi-
ate and climax tree species in the shrub or tree layer (late-successional
pioneer woodlands).
Indicator species of “ancient woodlands” (Peterken 1994; Wulf 1995)
have a low frequency in general. They only occur in woodlands directly
bordering “ancient woodlands” or on so-called “handmade dumps” (top-
soil containing humus). It will probably take more time for isolated sites to
be colonized by woodland species. Therefore, maintaining “ancient wood-
lands” in the surroundings of spoil dumps is an important basis for devel-
oping species-rich woodlands in post-mining landscapes (Benkwitz et al.
2002). In spontaneously developed woodlands, neophytes have rather a
small share, with three species per plot. They comprise on average 2.8% of
the herbaceous layer and 3.4% of the tree layer. Only the North American
red oak (Quercus rubra) occurs more frequently in some regions. Quercus
rubra was frequently planted in plantation forests, which provide a source
for dispersal by jays.
Table 2. Frequency of selected woodland herbs in early and late successional pio-
neer woodlands with reference to their dispersal capacity and occurrence of indi-
cator species for recent and ancient woodlands. A: number of occurrences (nto-
tal = 104), B: frequency in pioneer woodlands < 60 years (%, ntotal = 86), C:
frequency in woodlands > 60 years (%, ntotal = 18), D: dispersal modes (Müller-
Schneider 1986; Bonn et al. 2000): a – anemochorous, zepi – epizoochorous, zendo –
endozoochorous, m – myrmecochorous, s – autochorous, ? – dispersal mode un-
known, E: Long-distance dispersal capacity (Frey and Lösch 1998; Verheyen et
al. 2003), long – present; no – not present, F: indicator species for r: recent wood-
lands and a: ancient woodlands (Wulf 1995, 2003).
ABCD E F
Aegopodium podagraria 2 1.2 % 5.6 % s no r
Anemone nemorosa 1 0 % 5.6 % s, m no a
Avenella flexuosa 27 26.7 % 22.2 % a, zepi long r
Brachypodium sylvaticum 26 12.8 % 83.3 % a, zepi long a
Calamagrostis arundinacea 1 1.2 % 0 % a, zepi long
Campanula trachelium 2 0 % 11.1 % s no a

Peri-Urban Woodlands in Lignite Mining Areas 169
Table 2. (cont.)
Convallaria majalis 4 1.2 % 16.7 % s, zendo no & long a
Carex brizoides 2 1.2 % 5.6 % a, zepi long
Carex montana 5 3.5 % 11.1 % a, zepi, m no & long
Carex pilulifera 10 10.5 % 5.6 % a, zepi, m no a
Circaea lutetiana 2 0 % 11.1 % zepi long a
Clematis vitalba 5 2.3 % 16.7 % a, zepi long
Dactylis polygama 6 5.8 % 5.6 % a, zepi long
Dryopteris carthusiana 3 2.3 % 5.6 % a long a
Dryopteris filix-mas 4 2.3 % 11.1 % a long
Epilobium montanum 5 4.7 % 5.6 % a long
Epipactis atrorubens 22 18.6 % 33.3 % a long
Festuca gigantea 4 0 % 22.2 % a, zepi long a
Festuca heterophylla 1 0 % 5.6 % a, zepi long
Fragaria vesca 37 29.1 % 66.7 % zendo long
Hedera helix 3 1,2 % 11.1 % zendo long
Hieracium lachenalii 54 55.8 % 33.3 % a long a
Hieracium laevigatum 40 39.5 % 33.3 % a long
Hieracium murorum 20 19.8 % 16.7 % a long
Hieracium sabaudum 76 74.4 % 66.7 % a long
Hieracium umbellatum 1 1.2 % 0 % a long
Holcus mollis 1 1.2 % 0 % a, zepi long
Listera ovata 6 7.0 % 0 % a long
Luzula pilosa 2 0 % 11.1 % m no a
Maianthemum bifolium 3 0 % 16.7 % zdyso no a
Melampyrum pratense 9 8.1 % 11.1 % m no a
Melica nutans 2 0 % 11.1 % m no a
Milium effusum 1 0 % 5.6 % m, zepi no & long a
Moehringia trinervia 4 0 % 22.2 % m no a
Monotropa hypophegea 3 2.3 % 5.6 % ? ?
Orthilia secunda 16 12.8 % 27.8 % a long
Poa nemoralis 27 25.6 % 27.8 % a, zepi long a
Polygonatum multiflorum 1 0 % 5.6 % zepi no a
Pyrola chlorantha 1 1.2 % 0 % a long
Pyrola minor 18 15.1 % 27.8 % a long
Pyrola rotundifolia 1 0 % 5.6 % a long
Scrophularia nodosa 1 0 % 5.6 % s no
Solidago virgaurea 10 10.5 % 5.6 % a, zepi long
Stachys sylvatica 1 0 % 5.6 % zepi long a
Sanicula europaea 2 0 % 11.1 % zepi long a
Stellaria holostea 2 0 % 11.1 % zepi no? a
Vacinium myrtillus 10 5.8 % 27.8 % zendo no & long a
Vacinium vitis-idea 7 3.5 % 22.2 % zendo no & long
Viola riviniana/V. reichenba-
chiana
15 7.0 % 50.0 % s, m no a

170 Sabine Tischew, Antje Lorenz
Site-dependent and chronological woodland
differentiation
Based on multivariate analysis, three successional series (A, B, C) could
be derived for woodland development on different site conditions (Fig. 2).
Only woodlands not directly influenced by groundwater were included in
the analysis.
Woodland development proceeds very slowly on sites with a high pro-
portion of Tertiary substrates (A). These are characterized by extremely
acid pH-values (minimum 3,0), high to very high coal contents (25 % on
average in the 60–100 years old stages) and hydrophobic features. The
carbon-to-nitrogen ratio as one parameter for nutrient availability was ex-
tremely high, even on the older dumps (1:55 in a soil depth of 0–10 cm in
the 60–100 years old stages). These substrates are hardly suitable for colo-
nization. Several pioneer woodland stages have to be passed through fre-
quently until the development to later woodland stages is possible.
Considerably faster development compared to species-rich woodlands
was recorded on more hospitable substrates depending on diaspore sources
in the surroundings (B, C). Sites of series B are characterized by Tertiary
and Quarternary mixed substrates. They have low to moderate pH-values
(3,9–5,9; all data relate to the upper soil layers (0–10 cm depth) in the 60–
100 years old woodland stages) and low to moderate nutrient availability
(C/N ratio 1:23 to 1:40). An initial accumulation of intermediate and cli-
max tree species in the tree and shrub layer as well as first woodland herbs
in the herbaceous layer can be observed in the age-class 60 - 100 years.
The quickest successional progress was recorded in the woodlands of the
mesophilic to nutrient rich sites of series C. The Tertiary and Quarternary
mixed substrates show moderate to high pH-values (4.7 to 6.3) and mod-
erate to high nutrient availability (C/N ratio 1:17 to 1:29). Compared to se-
ries B, an even greater accumulation of particular woodland herbs in the
herbaceous layer as well as intermediate and climax tree species in the tree
and shrub layer may be recorded after a 60–100 years development.
Fig. 2 (next page) Successional series (A, B, C) in lignite mining areas of eastern
Germany

Peri-Urban Woodlands in Lignite Mining Areas 171

172 Sabine Tischew, Antje Lorenz
In addition to site conditions, successional rate depends on availability
of diaspore sources in the surroundings and substrate-modifying influences
(e.g. fly-ash coating). Non-linear developments, related to general individ-
ual conditions are possible, i.e. successional stages can be passed through
more quickly or slowly.
Fig. 3. Development of stand structure (bare soil, herbaceous, shrub and tree lay-
ers) of the successional series A, B and C
As shown in Fig. 3, bare soils and open woodland structures persist on
the less hospitable sites of series A over a considerably longer period, in
contrast to series B and C. This development is not necessarily negative
with respect to biodiversity as these woodlands remain as refuges for the
less competitive, rare species which prefer open woodland structures. This
differentiated development also leads to a varied and aesthetically attrac-
tive landscape.
series B
pioneer shrubs climax shrubs
series C
pioneer trees climax trees
years years years
Fig. 4. Development of species number in herbaceous, shrub and tree layers of the
successional series A, B and C

Peri-Urban Woodlands in Lignite Mining Areas 173
Fig. 4 presents differences in the development of species diversity in
separated vegetation layers. High numbers of woodland species in shrub
and tree layers, as well as herbaceous layers, mainly occur on the oldest
sites of series C. Many of these spoil dumps represent “handmade dumps.”
Here, woodland species can establish themselves faster on account of the
topsoil coverings, which accelerate soil formative processes and provide a
diaspore source of the woodland species. Therefore, slower development
processes are expected on isolated younger (non-handmade) sites of this
successional series in the future. However, the younger and less developed
age-classes of succession are also of high value for nature conservation
and for experiencing nature. For example, a total of 245 species are found
on a 20 ha, 30-year-old dump with different stages of birch and pine pio-
neer woodlands on the Goitzsche mining site. Fourteen species alone are to
be found on Red Lists of Saxony-Anhalt (Frank et al. 1992) and Germany
(Korneck et al. 1996). Therefore, young woodland stages in post-mining
landscapes contribute substantially to the maintenance of biological diver-
sity in post-industrial landscapes.
Gradual migration of woody species onto spoil dumps was evaluated in
detail for successional series C (Fig. 5). Young stages are characterized by
the pioneer tree-species silver birch (Betula pendula) and Scots pine
(Pinus sylvestris). Common oak (Quercus robur) can migrate onto young
sites, whereas most intermediate and climax tree species become estab-
lished only slowly in the shrub and tree layer in the second or third stage.
Rejuvenation of pioneer tree species is already considerably restricted on
the oldest sites. Here, a general change in stand structure is beginning as
pioneer tree species are also dying off.
Woodland development during succession on spoil
dumps – an overview
Further data (FLB 2003; Tischew et al. 2004) were included to integrate
woodland development into general colonization processes on soil dumps.
Ordination methods or results from permanent plots were used to deter-
mine site factors (e.g. pH values, soil textures, diaspore sources) that could
work as “switch points” within successional dynamics (Fig. 6). Based on
these results and on the development of complex successional networks, it
is possible to predict general developmental tendencies in eastern German
post-mining landscapes. Depending on the diaspore sources in the direct

174 Sabine Tischew, Antje Lorenz
SERIES C
OVERSTORY CANOPY
UNDERSTORY CANOPY
SHRUB LAYER
10 - 30 years 30 - 60 years 60 - 100 years
Betula pendula
Populus tremula
Quercus robur
1)
Betula pendula
Populus tremula
Quercus robur
Salix caprea
Sorbus aucuparia
Betula pendula
Populus tremula
Ligustrum vulgare
Salix caprea
Sorbus aucuparia
Prunus avium
Crataegus monogyna
Cornus sanguinea
Frangula alnus
Rosa canina
Quercus robur
Pinus sylvestris
Fraxinus excelsior
Pinus sylvestris
Acer pseudoplatanus
Tilia cordata
Fagus sylvatica
Pinus sylvestris
Quercus petraea
Fraxinus excelsior
Acer pseudoplatanus
Ulmus minor
Carpinus betulus
Fagus sylvatica
Tilia cordata
Carpinus betulus
Fagus sylvatica
Tilia cordata
Rhamnus cathartica
Rubus caesius
early successional tree species
late successional tree species
70 - 100 %
> 50 - 70 %
> 30 - 50 %
> 15 - 30 %
> 0 - 15 %
dispersal mode
(Bonn et al ,
Frank et al. 1990)
. 2000
a - anemochorous
s - autochorous
z - zoochorous
light requirements
(Burschel and Huss 1997,
partly changed)
young aged
middle to old aged
left:
right:
+
high
(
less
[a][ ]
+)
[a]
[]
))
[a][ ]
+)
[z][ ]
-+
[a][ ]
-+
[a][ ]
(-
[a][ ]
--
[s,z][ ]
((
[a][ ]
+)
[a]
[]
))
[a][ ]
+)
[a][ ]
+)
[a][ ]
-+
[a][ ]
-+
[a][ ]
(-
[a][ ]
(-
[s,z][ ]
((
[a][ ]
+)
[a][ ]
+)
[z][ ]
-+
[z][ ]
++
[z][ ]
+)
[z][ ]
-+
[z][ ]
++
[z]
[]
))
[z][ ]
++
[z][ ]
+)
[z][ ]
+)
[a]
[]
))
[a][ ]
+)
[z][ ]
-+
[z][ ]
-+
[a][ ]
-+
[a][ ]
(-
[a][ ]
(-
[a][ ]
-+
[a][ ]
--
[s,z][ ]
((
Fig. 5. Frequency of selected pioneer, intermediate and climax tree species in
shrub as well as upper and lower tree layers in three age-classes (10–30 years, 30–
60 years, 60–100 years) of the successional series C, with information about dis-
persal modes and light requirements in different life stages
Fig. 6 (next page) Successional scheme for primary succession in eastern German
post-lignite mining landscapes on sites distant from groundwater (groundwater
depth > 2 m)

Peri-Urban Woodlands in Lignite Mining Areas 175
5 - 30
y
ears30 - 60 years60 - 150 years> 150 years
dumped bare soil
pH-value
soil texture
pH < 3,0 and/or coal content > 10 %
> 70 % sand and/or
coal content > 10 %
pH 3,0 - 4,0 (4,5) and/
or coal content > 10 %
> 50 - 70 % clay
pH > 3,3 - 4,0 (4,5)
pH-value
pH > 3,0 - 3,3
diaspore sources / water supply
extremely dry very dry
mean to long
persisting
bare soil
stages
mean to long
term persis-
ting club awn
grass
pioneer
stages
dry psammo-
phytic grass-
lands
(
)
Coryne-
phorus canes-
cens
club awn grass
pio-
neer stages &
other pioneer
stages
dry psammo-
phytic grass-
lands
(
)
Corynephorus
canescens
initial open-
land-shrub
stages with
birch/pine
heaths
initial pioneer
birch woodlands
by skipping or
quickly passing
the stage of
herbaceous
layer
initial pioneer
birch wood-
lands with
simultaneous
development
of herbaceous
layer
grasslands/
tall herb
stands
chee reed
grass (
)
dominated
stands
Cala-
magrostis
epigejos
diaspore sources
pH > 4,0 (4,5)
pH-value / sand content pH-value / nutrient availability
chee reed
grass (
)
dominated
stands
Cala-
magrostis
epigejos
initial pioneer
birch woodlands
very thin pioneer woodlands
on extreme sites with birch
and/or pine
pioneer birch woodlands on mesophilic
sites without accumulation of interme-
diate/climax tree species
pioneer birch woodlands on mesophilic to
nutrient rich sites with initial accumulation of
woodland herbs and intermediate/climax
tree species in shrub layer
diaspore sources / nutrient availability
water supply coal content
pioneer birch woodlands on mesophilic
sites with some woodland herbs and initial
accumulation of intermediate/climax tree
species in the shrub/tree layer
pioneer birch woodlands on mesophilic to
nutrient rich sites with accumulation of wood-
land herbs and intermediate/climax tree
species in the shrub/tree layer
serveral
pioneer woodland
cycles
coal content
oak-rich or beech-rich woodlands
with small-leaved lime and hornbeam
birch-oak woodlands and
birch-pine-oak woodlands
birch woodlands and
birch-pine woodlands
prognosis

176 Sabine Tischew, Antje Lorenz
surroundings, species that arrive first on hospitable sites determine the
vegetation structures on these sites (right-hand side of the diagram). Initial
colonization patterns are also influenced by the availability of so-called
safe sites (e.g. small depressions accumulating water and a little organic
material). These initial patterns lead to secondary patterns by the mecha-
nisms of “facilitation” or “inhibition” among the already established spe-
cies and the newly immigrated species, and can vary a lot (patch-dynamics
concept, Wiegleb and Felinks 2001; Prach 1987). Differentiation processes
of species based on site factors become clear in older successional stages.
On extreme sites, the influence of stochastic effects is, in principle, smaller
due to selection for species that can tolerate these site factors (e.g. ex-
tremely low pH values, very wet or very dry soils). Vegetation develop-
ment is impeded mainly on dry and extremely acidic sites (left-hand side
of the diagram), where successional stages free of trees are expected over
longer periods.
Opportunities and perspectives for woodland
development in post-mining landscapes
As a result of the closure of many mines at the beginning of the 1990s after
the German Reunification, there are still large areas of bare soil dumps as
well as older open-cast areas. Based on the analysis of site conditions,
spontaneous development of large woodlands is to be predicted for many
parts of surface mines. These woodlands will show high chronological and
spatial differentiation in their development due to site heterogeneity and
different site advantages. This is related to different land-use potentials.
Varied and continuously changing landscape structures offer ideal condi-
tions for recreational activities in the sense of “nature tourism.” The
mainly regional population uses this wilderness for walking, cycling or
mushrooming. The unique potential of these sites in terms of process con-
servation must also be maintained for nature conservation. In general,
greater proportions of abandoned lignite mining areas reserved for sponta-
neous succession will increase the floristic diversity in intensively used
landscapes (Hadacova and Prach 2003; Tischew and Kirmer 2003). Con-
servation organizations and foundations are taking this chance and cur-
rently buying up large successional areas. Conservation authorities in the
federal states support them. As scientists see it, these sites can be used as
unique specimens for the observation of regeneration processes in large,
disturbed areas. Spontaneous woodland development on these sites should
also be encouraged for financial reasons: afforestation costs about

Peri-Urban Woodlands in Lignite Mining Areas 177
€ 20,000/ha and mostly can not be sold or cultivated profitably, whereas
succession sites require only about € 1,400/ha (Abresch et al. 2000). Suit-
able methods for near-natural acceleration of vegetation development have
been developed for problem areas, where vegetation development has to be
accelerated because of erosion or to avoid dust emissions (Tischew et al.
2004).
Summary
We studied the spontaneous development of peri-urban woodlands on
more than a hundred sample sites in eastern German open-cast lignite min-
ing areas. The regeneration ability of the sites and the variety of develop-
mental paths are remarkable. On hospitable substrates, pioneer birch for-
ests can spontaneously develop within a few years if diaspore sources are
available. Intermediate and climax tree species (e.g. common oak, small-
leaved lime, sycamore) take root on these substrates on 30-year-old sites.
They slowly displace birch after 60–80 years. Due to the variety of sub-
strates and topography, spoil-dump woodlands are mostly of high struc-
tural diversity and aesthetically enrich post-mining landscapes. Thin birch
and pine woodlands, including grasslands or heaths on less hospitable
sites, are interesting examples of colonization processes after a massive
turnover which was previously found to this extent only during the last ice
age. Less competitive species can find refuges on these sites for longer pe-
riods. Therefore, woodlands in post-mining landscapes contribute to the
maintenance of biological diversity and dynamic processes in post-
industrial landscapes. Though far-reaching disturbance is the starting point
of its development, a unique “nature of the fourth kind” can develop by
natural colonization processes and offer various options for recreational
activities for the public to experience a natural wilderness as well as poten-
tial for nature conservation.
Economical points of view are also good reasons for including sponta-
neous colonization processes in the design of former surface-mining areas.
Spontaneous succession in surface mines therefore represents a great chal-
lenge and requires a rethinking of reclamation strategies by all people and
institutions involved. More than 10,000 ha of eastern German post-mining
landscapes are currently designated as sites for succession.

178 Sabine Tischew, Antje Lorenz
Acknowledgements
Investigations were funded by the German Federal Ministry for Education,
Science, Research and Technology (BMBF) as well as the Lusatian and
Central German Mining Management Company (LMBV).
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