Content uploaded by Juan José Ibánez
Author content
All content in this area was uploaded by Juan José Ibánez
Content may be subject to copyright.
1
Preservation of European Soils. Natural and Cultural Heritage 1
2
Ibáñez, J.J.
(1)
, Sánchez-Díaz, J.
(1)
, Rodríguez-Rodríguez, A.
(2)
, Effland, W.R.
(3)
3
4
(1) Centro de Investigaciones sobre Desertificación, CIDE (CSIC-UV, Valencia, 5
Spain) 6
(2) Departamento de Edafología y Geología. Universidad de la Laguna (Canary 7
Islands, Spain) 8
(3) USDA Natural Resources Conservation Service, G.W. Carver Center, Beltsville, 9
MD 20705 10
11
Abstract 12
13
The terms of soil conservation and conservation biology have not the same meaning. 14
The pedosphere is part of our natural heritage. However, in contrast to most natural 15
resources, soils must be considered as a biological (biodiversity) and geological 16
(geodiversity) resource. The study of both aspects of the pedosphere has been neglected 17
at the date. In this contribution we summarize current progress in pedodiversity 18
analysis, as well as its potentially significant role in conservation biology and the design 19
of an uropean Network of Soil Reserves. The marked resemblance between biodiversity 20
and pedodiversity assemblages in biocenoses as soilscapes respectively was observed 21
when we applied the same mathematical tools, including diversity-area relationships. 22
Additional similarities occur when examining changes in pedodiversity values with time 23
in a given geographic area, reflecting the concepts of ecological succession; niche 24
fragmentation in ecology; and divergent pedogenesis in soil consequences. Similarities 25
between pedodiversity and biodiversity patterns offer a new and unexplored direction to 26
understand the genesis of biological and non-biological assemblages and spatial patterns 27
of soil and living organisms. This new framework, supported by the sciences of 28
Coarse Draft of the final chapter published
in Catena Verlag
2
complexity (non-linear systems), could help to develop a unified theory of all natural 29
diversities. In order to preserve the biological and geological heritage inherent to gthe 30
pedosphere, the authors propose the design of soil reserves networks. The reserves also 31
could function as an efficient way to preserve soil qualities of undisturbed soils that can 32
be used as benchmark sites of soil monitoring programs. 33
34
Key words. Biodiversity, geodiversity, pedodiversity 35
36
1. Introduction 37
The pedosphere is part of our natural heritage. However, in contrast to most natural 38
resources, soils must be considered as a biological (biodiversity) and geological 39
(geodiversity) resource. Furthermore, many soilscapes and soil types are also part of our 40
cultural heritage, when these are the result of ancient or indigenous sustainable farming 41
practices and other human-influenced activities. According to Usher (2005): “Soils have 42
hardly featured in nature conservation thinking. Criteria have been developed for 43
selecting networks of important Earth science sites, but these have not included criteria 44
for soil” In other words, the study of these aspects of the pedosphere has been largely 45
neglected at the global level. In this paper we summarize the state of the art in 46
pedodiversity analysis, as well as its current progress in relation to conservation 47
biology, geology and cultural landscapes. 48
49
Owing to the agronomic bias of classical soil science, the term “soil conservation” has 50
been applied from a utilitarian perspective, in contrast to the term “biological 51
conservation.” Furthermore, as a direct result of the agronomic bias, the potential role of 52
modern soil survey and soil databases in solving environmental deterioration is 53
3
practically unknown to politicians, laypersons and ecologists (Ibáñez et al., 2003; 54
Ibáñez et al., 2005). 55
56
During the “Anthropocene” (Crutzen and Stoermer, 2000), humankind has significantly 57
modified the original pedosphere and thus many natural pedotaxa suffer a serious risk of 58
extinction, whereas human activities have resulted in other new pedotaxa which are 59
distributed worldwide. From the European perspective, the European Environmental 60
Agency recognised seven years ago that the policy for soil conservation is one of the 61
most poorly planned, both at the national and continental levels (EEA, 1999). In 62
addition, the Council of the European Union (Brussels, 18 July 2002) drafted the 63
document entitled “Council Conclusions on Integrated Soil Protection” in response to 64
the Communication from the Commission to the Council, the European Parliament, the 65
Economic and Social Committee and the Committee of the Regions: "Towards a 66
thematic strategy for soil protection" which states that (item 1): 67
68
“THE COUNCIL: recognises the vital role the soil plays as one of the three natural 69
elements essential for life, as the physical support for a great number of human 70
activities and its important functions including its huge richness of biodiversity and 71
genetic variability, its capacity to store, buffer and filter water and other substances as 72
well as its key role for biomass, food and raw materials production; NOTES that soil 73
may not only be affected by climate change but it is also a storehouse for organic matter 74
and that it has an important role in combating climate change; furthermore it has also 75
important cultural and aesthetic values to be properly preserved”. 76
77
This recommendation has been incorporated into the final document on the European 78
“Thematic Strategy for Soil Protection” submitted in September 2006 at the European 79
4
Institutions for its approval. Although it is true that the EU Soil Protection Directive 80
(http://eusoils.jrc.it) does not propose any direct statements to preserve European soils, 81
EU policy makers currently have added this topic to their agendas for consideration. In 82
a parallel effort the study of conservation biology has begun to appreciate the topic of 83
soil biodiversity and incorporate its research into their scientific programs. Thus for 84
example, Usher (2005) state that: “Above ground, nature conservation has focused on 85
communities of plants and the animals that they support, and criteria have been 86
developed for selecting the 'best' sires. There has been scant attention to the soils on 87
which those plant communities depend (…) Both the increasing concentration on 88
biodiversity and 'the ecosystem approach' are shifting thinking in relation to soils. 89
Despite limited taxonomic knowledge (…). The 'ecosystem approach' is forcing a more 90
holistic view, focusing on the function of terrestrial Ecosystems”. 91
92
In fact, Ibáñez et al. (2003) proposed a framework for the design of networks of soil 93
reserves in order to ensure the preservation of soils and the pedosphere as a part of the 94
biological and geological heritage. Furthermore a network of Pan European Soil 95
Reserves also could function as an efficient way to preserve soil qualities of undisturbed 96
soils that can be used as benchmark sites for future EU soil monitoring programs. This 97
strategy will allow directed scientific observation and measurement as the qualities and 98
functions (i.e. ecosystem services) change for “domesticated” or disturbed soils with 99
respect to the natural, undisturbed soils (Amundson, 2003; Ibáñez et al., 2003). 100
Furthermore, current initiatives related to the protection of the geological heritage in 101
Europe are highly detailed, but do not consider soils in their framework (Usher, 2005). 102
Therefore, in view that the functions and processes of the pedosphere are not well 103
understood, the EU should require a novel strategy to preserve pedodiversity, soil 104
5
biodiversity and soil qualities of the most natural (i.e. least disturbed) soils and 105
soilscapes, as well as those under farming practices which have been sustainable for 106
centuries or millennia. 107
108
Measuring biodiversity is a rapidly developing area of scientific inquiry on a global 109
scale (Williams, 1996). However, geodiversity (e.g. geological forms and structure, 110
landforms, sedimentary deposits, minerals, rocks, fossils, soils, etc.) has not been 111
measured to the same degree, even though it is important to assess geodiversity for 112
interpretation of the geological history of the Earth, the processes that modeled it, past 113
and present climates and landscapes, the origin and evolution of life, and other critical 114
areas of scientific inquiry. Earth scientists have only recently become involved with 115
these problems (e.g. Gray, 2004). International and national forums are now being 116
organized, such as, The European Association for the Conservation of the Geological 117
Heritage (ProGEO) (visit www.sgu.se/hotell/progeo) to address these research areas in 118
Europe and other locations. 119
120
Several initiatives join forces to preserve the geological heritage in various context (e.g., 121
natural parks, legislation, environmental impact, geoparks), but quantitative methods 122
have hardly ever been used. Several aspects of geodiversity (e.g. geomorphic diversity, 123
lithodiversity and pedodiversity) should be quantified when estimating a region’s 124
ecological value. These aspects refer to non-renewable natural resources with profound 125
qualitative and quantitative repercussions on the architecture of landscapes, ecosystems 126
and biocenoses (McBratney, Ibáñez et al., 1900, 1995a, b, 2003; 1992, 1995; Amundson, 127
2006; Amundson et al., 2003). This approach may also provide a method to quantify the 128
6
complexity of abiotic landscape structures in different areas and environments (Ibáñez et 129
al., 1995a, b; 1998a, 2005a, b). 130
131
In order to preserve living resources, conservation biologists have applied biodiversity 132
tools which are mathematically based. Following this approach, Ibáñez et al. (1990, 133
1994 and 1995) successfully adopted these tools to apply the same mathematical 134
formulas for spatial analysis of the pedosphere. Currently, pedodiversity analysis is a 135
growing area of scientific study with numerous peer-reviewed publications available in 136
highly reputed international journals (Ibáñez et al., 2003; 2008 and references therein). 137
In fact, pedodiversity analysis was recently recognised as a promising research direction 138
in the rapidly growing field of pedometrics (McBratney et al., 2000). 139
140
Although the taxonomic (soil types or pedotaxa) approach has been most frequently 141
studied to understand the preservation of our pedological heritage, it has limitations 142
(e.g., varying scales of data and multiple systems of soil classification) which 143
necessitate the examination of other sources of information for conserving the 144
pedosphere. As we described previously, soils formed from ancient sustainable farming 145
practices are also disappearing at an alarming rate as a direct result of human 146
disturbances associated with modern agriculture, urban sprawl, mineral extraction and 147
other factors. Many of the soils formed under ancient sustainable farming practices also 148
possess impressive soil qualities such as enhanced storage of soil carbon or marked 149
resistance to soil erosion. In this regard, a “European Red Book” of sustainable farming 150
practices might serve as a starting point to complete an inventory of these valuable 151
agroecosystems. 152
153
7
Likewise soils are blocks of memory also, many stratigraphic columns consists in a 154
superposition of paleosols that contain very valuable information of paleoenvironments 155
and past climate conditions and changes. These were termed “multistorey and 156
composite geosols” by Morrison (1967). Therefore it also could be preserved, against 157
at the date have not into account in legal figures for the preservation of the geological 158
heritage (Ibáñez et al., 2003, 2004; Usher, 2005) (Figure 1). 159
PRESERVING PEDODIVERSITY
Natural Biological
Heritage Biodiversity
Pedosphere
Soil Resources
Cultural Heritage
(Past ancient sustainable
farming practices)
Natural Geological Heritage
(Past Block Memory)
Natural Geological
Heritage Geodiversity
PRESERVING PEDODIVERSITY
Natural Biological
Heritage Biodiversity
Pedosphere
Soil Resources
Cultural Heritage
(Past ancient sustainable
farming practices)
Natural Geological Heritage
(Past Block Memory)
Natural Geological
Heritage Geodiversity
160
Figure 1. Four reasons for the preservation of the pedological heritage. 161
162
In this paper, we propose a framework to explain several guidelines and to describe 163
strategies intended to preserve the pedological resources such as natural (minimally-164
disturbed) soils, paleosols, and soils resulting from sustainable farming systems. 165
8
166
2. Pedodiversity analysis 167
In the early 1990s, pedodiversity analysis was introduced in the pedological literature 168
by Ibáñez et al. (1990, 1995). The term “pedodiversity” was introduced simultaneously 169
in Spanish (Ibanez et al., 1992) and English (McBratney, 1992) as a direct result of the 170
widespread visibility and global acceptance associated with “biodiversity” promoted at 171
the Rio de Janeiro Summit. This direction of research has become an evolving area of 172
scientific inquiry (Ibáñez et al., 1990; 1994, 1995a, 1998a, b, 1999, 2000, 2005a,b, 173
2006; Ibáñez and de Alba, 1999, 2000; Ibáñez and Ruiz-Ramos, 2006; McBratney, 174
1992, 1995, 2000; Phillips, 1999, 2001a,b; Phillips and Marion, 2004, 2005 2007; 175
Krasilnikov et al., 2000; Krasilnikov and Fuentes Romero, 2003; Dazzi and 176
Monteleone, 1998, 1999; Chen et al., 2001a,b; Guo et al., 2003a, b; Tan et al., 2003; 177
Constantini et al., 2003, Caniego et al., 2006; García-Calderón et al., 2006; Saldaña and 178
Ibáñez, 2004, 2007; Toomanian et al. 2007, etc.). The study of the similarities and 179
differences of spatial and temporal patterns between biodiversity and pedodiversity is an 180
area of rapidly developing research. Comparative studies are now feasible because of 181
the increased availability of digital soils and other natural resources data at various 182
scales and widespread development of the mathematical tools for conducting diversity 183
analyses. A synthesis of the mathematical tools used in pedodiversity analysis as well as 184
its role for soil conservation purposes has been carried out by Ibáñez et al. (2003), 185
Ibáñez and Saldaña (2008) and Ibáñez et al. (2008, in progress), respectively. 186
187
The marked resemblance between biodiversity and pedodiversity assemblages in 188
biocenoses as soilscapes respectively was observed when we applied the same 189
mathematical tools, including diversity-area relationships (Ibáñez et al., 2003; 2005a, b; 190
9
2008; Saldaña and Ibáñez 2004, 2007). Additional similarities occur when examining 191
changes in pedodiversity values with time in a given geographic area, reflecting the 192
concepts of ecological succession; niche fragmentation in ecology; and divergent 193
pedogenesis in soil chronosequences (Saldaña and Ibáñez 2004, 2007). In the authors’ 194
opinion, the large number of coincidences supports the hypothesis that these 195
observations are not simply a product of chance. We propose that the similarities 196
between pedodiversity and biodiversity patterns offer a new and virtually unexplored 197
direction to understand the genesis of biological and non-biological assemblages and 198
spatial patterns of soils and living organisms (Saldaña and Ibáñez, 2007). This new 199
framework, supported by the sciences of complexity (non-linear systems), could help to 200
develop a unified theory of all natural diversities (Ibáñez et al., 1990, 1994, 1995, 1998; 201
Phillips, 1999; Ibáñez and Saldaña 2007; Saldaña and Ibáñez 2004, 2007). Thus, we 202
conjecture that both biodiversity and pedodiversity patterns result from the non-linear 203
dynamics of their respective systems in nature and are not an artificial consequence of 204
biological and pedological assumptions (Saldaña and Ibáñez, 2007). 205
206
The principal mathematical analyses and procedures associated with pedodiversity 207
analyses include the following: 208
• Pedodiversity of pedological assemblages (soilscapes, soil regions, etc.) 209
• Pedorichness and pedodiversity-area relationships 210
• Pedorichness and pedodiversity-time relationships (Island and Terrace 211
Chronosequences) 212
• Pedorichness and pedodiversity-energy relationships 213
• Complementarity algorithms (selecting areas to design networks of soil reserves) 214
• Nested subset analysis 215
10
• Species-range size distribution 216
• Fractal and multi-fractal analysis. 217
218
Additional analytical procedures and pedodiversity-landscape relationships may be 219
identified in the near future as pedologists and ecologists collaborate in new areas of 220
soil landscape ecology and biogeography research. 221
222
In the previously described studies, it has been demonstrated that a scientifically sound 223
parallelism exists between biodiversity and pedodiversity results. Some time ago 224
biogeographers and ecologists recognised that many biotaxa must be considered as 225
edaphic endemism, and thus soil preservation is vital for its intrinsic biological and 226
geological value (Ibáñez et al., 2003). Ibáñez (2002, 2004) summarised how the analysis 227
of pedotaxa and its genetic soil horizons could be applied in the context of conservation 228
biology to serve as surrogate indicators of aboveground biodiversity, and primarily for 229
indicators of belowground biodiversity. Therefore, the use of soil taxonomies provides a 230
universal classification of habitat heterogeneity which can be applied to study and 231
achieve multiple objectives, in contrast to application of an “ad hoc” classification of 232
the latter, which does not permit the comparison of results among different studies 233
(Ibáñez et al., 2005, Phillips, 2007). In any case, pedodiversity must be protected also, 234
as a part of natural pedological heritage with independence of its value as a reservoir of 235
biological organisms (Ibáñez et al., 2003). However, as we discussed previously, at this 236
time, pedodiversity tools have been applied to the soil cover only, and other distinct 237
pedological entities such as buried paleosols and soils formed under ancient sustainable 238
practices also have unique characteristics and retain valuable information related to 239
climate and other factors which should be preserved. 240
241
11
3. Criteria for the design of Networks of Soil Reserves (Soil Cover) 242
3.1. Area selection methods 243
Basically there are three models or approaches to preserve biological diversity and, by 244
analogy, soil diversity. First we present the models and then discuss their potential roles 245
in soil preservation and the design of soil reserves. The main approaches are the 246
following (Williams et al., 1996) (Figure 2): 247
Hotspots of richness 248
Rarity areas (or territories rich in endemism) 249
Complementary areas 250
251
252
Figure 2. Hotspots, rarity areas and complementary areas for British breeding birds 253
(after Williams in WorldMap website) 254
255
The most popular, but probably not the best, approach to select priority areas is the 256
criterion of hotspots of diversity (e.g. Vane-Wright et al. 1991). It seems that this 257
approach also works well in the field of the pedology (Ibáñez et al., 1992; Ferrer et al., 258
12
2007). However, this model depends on the map scale (or database) and sampling effort 259
(Figure 2). Therefore, because regions of a given country and the Europe continent were 260
surveyed using various soil mapping protocols, the hotspots strategy is not appropriate 261
because there are many unsampled or poorly sampled areas in addition to the more 262
sampled areas. Figure 3 indicates that intensive sampling in a study area (represented by 263
larger mapping scales) can yield higher pedodiversity values than comparable study 264
areas in which the sampling design was nested and less intensive (Macizo de Ayllón is a 265
small area of the Guadalajara Province). 266
267
0
5
10
15
20
25
R ichn e ss
CEE
1/1000000
España
1/1000000
Guadalajara
1/25000
Ayllón
1/20000
268
Figure 3. Richness of major soil groups (FAO 1971) for soil maps, the areas and scales 269
of which differ by orders of magnitude, and the soil maps were carried out with very 270
disparate sampling efforts (after Ibáñez et al. 1992, 1995) 271
272
However the hot spots approach does not guarantee that all taxa in a given territory can 273
be preserved. One problem with the hot spots approach is the general emphasis on areas 274
of richness as higher values tend to be associated with “rarity areas” that primarily 275
13
select rich endemic territories, but frequently ignores the most representative or typical 276
taxa. However, where identities of taxa or other surrogates (indicators) for diversity are 277
known, “complementary methods” can be applied (e.g. Vane-Wright et al. 1991). For 278
example, in pedological terms, if one area has a pedosphere (soil cover) consisting of 279
Luvisols, Cambisols and Vertisols, while another area has a pedosphere with Luvisols, 280
Cambisols and Andosols, then the second area’s pedosphere complements the first with 281
the Andosols taxa (Figure 4). 282
283
For examples where the hotspots of richness and rarity methods failed to represent all 284
taxa at least once, the complementary areas method represented these at least two or 285
more times in a given percentage of the area studied. Currently, conservation biology 286
literature describes several reserve selection algorithms such as: richness-based 287
heuristic; weighted rarity-based heuristic; progressive rarity-based heuristic; and 288
simulated annealing, linear programming-based branch-and bound algorithms, among 289
others (e.g. Vane-Wright et al. 1991; Vane-Wright 1996; Csuti, et al. 1997). Table 1 290
shows as areas 2 + 3 complement one another to represent all taxa A-H between them. 291
In this particular case, the hotspot of greatest species richness, area 1, is not needed for a 292
minimum set of complementary representative areas (2 + 3). Areas not needed to attain 293
a particular representation goal may often be identified in the “redundancy test” within 294
“area-selection procedures.” The practical advantage of computational speed from 295
heuristic techniques is widely appreciated in other related sciences also (Faith, 1992, 296
1994). 297
298
14
299
Figure 4. Diagram illustrating the complementarity method for pedotaxa which is 300
conceptually independent of spatial scale (after Williams on the WorldMap website) 301
302
The shape of the reserve has also been considered an important aspect, with respect to 303
the design of biological reserves. Although we hypothesize that the shape of soil 304
reserves may not be important, we have insufficient data to determine if shape is 305
important for designing soil reserves. If a large reserve is planned, its shape is probably 306
unimportant. If small reserves are planned, like those in many industrialised countries, 307
then their shape perhaps could be important. The paradox is that the reserve design 308
analyst has little scope for adjusting size or shape in industrialised regions, but far more 309
flexibility in more remote areas of the world where reserve size can be larger and hence 310
shape is probably unimportant. Game (1980) claims that, “soil diversity and other 311
habitat heterogeneities” must be maximised and no a priori shape (i.e. round) is better 312
than another. 313
314
315
316
317
Taxa
A B C D E F G H
15
Areas
1
X
X
X
X
X
2
X
X
X
X
3
X
X
X
X
4
X
X
X
5
X
X
X
Table 1. Minimum complementary set: choosing complementary areas of preservation 318
(after WorldMap website) 319
320
The criterion of “rarity or singularity” gives greater weight to those taxa that are 321
uncommon in the area of study. There are several proposals for quantitative scores for 322
rarity (e.g. Van der Ploeg, 1986). The criterion of “representativeness” or “typicalness” 323
helps to identify and include the broadest possible sample of components that compose 324
the biota (or soil cover) of a given area or region. The criterion of “naturalness” can be 325
used to reduce the weight of species or soil taxa not thought to occur naturally in the 326
study area (e.g., some Anthrosols and Technosols). However Usher (1991) states, that 327
for the long term, the perception of soils formed primarily from human activities may 328
change and increase their value (e.g. certain ancient indigenous manmade soils such as 329
Terra Preta). In our opinion, representativity or typicalness and rarity are also important 330
for designing soil reserves on a regional basis. 331
332
3.2. Applying area selection methods in a case study: soils of the Aegean Islands 333
In order to show how area selection procedures could be applied in order to preserve 334
soils, we present an example using the soilscapes and pedotaxa of the Aegean 335
Archipelago. Notice that we only consider pedotaxa composition, and don’t include if 336
they are or aren’t covered by natural vegetation. For practical reasons, the presence or 337
absence of natural vegetation may be very important. The use of complementarity 338
algorithms is not conducted for this relatively simple analysis of soil taxonomic data. 339
16
340
The Aegean Islands (including the Ionian Islands), located in the eastern Mediterranean 341
basin is an archipelago of two thousand isles and islets with 681 included in the 342
CORINE Land Cover database. Ibáñez et al. (2005a, b) demonstrated that the 343
pedodiversity-area relationships, taxa-range pedotaxa distribution and the nestedness of 344
small islands’ soil types into the larger ones follow the same patterns that occur with 345
biological species. They also describe the GIS procedures used to obtain the soil dataset 346
applied below. Briefly, the 1:1.000.000 EU Soil Map (CEC 1985), digitalised by Platou 347
in 1986 (Platou et al. 1989) and incorporated into the CORINE database of the EU was 348
used for this application. In order to estimate the proportion of all pedotaxa within each 349
mapping unit, arbitrary rules were applied similar to the FAO Digital Soil Map of the 350
World (FAO, 1995). These rules provide estimated percentages for dominant, 351
associated and included units. The percentages were then converted into estimated area 352
by multiplying the area of each island by the estimated percentage for each island 353
analyzed. The digital map was available in vectorial format and GIS processing of the 354
raw data completed with ArcINFO and ArcView software. The resulting soil database 355
was stored in an Excel format. 356
357
Six major types of islands were differentiated based on their lithologies and soilscapes: 358
(i) small calcareous islands: (ii) small and medium islands with dystric parent materials 359
and soils; (iii) islands with volcanic material and Andosols; (iv) medium islands with 360
calcareous parent materials and soils; (v) large islands with calcareous parent materials 361
and developed depositional landforms and their corresponding soils (e.g. Histosols, 362
Gleysols, Fluvisols) and (vi) islands of medium size and a mix of dystric and calcareous 363
parent materials. Each soilscape type for an island can be subdivided into either (i) 364
eroded or (ii) non-eroded. 365
17
366
The twenty two soil types in increasing order of development or evolution order, 367
included in CORINE soil data base are the following (see Ibáñez et al., 2005a, b for 368
further details): Non-soils or surface rocks (RO); Calcaric Lithosols (Ic); Eutric 369
Lithosols (Ie); Dystric Lithosols (Id); Undifferentiated Lithosols mainly associated to 370
volcanic rocks (I); Calcaric Regosols (Rc); Eutric Regosols (Re); Rendzinas (E); 371
Rankers (U); Eutric Cambisols (Be); Chromic Cambisols (Bc); Dystric Cambisols (Bd); 372
Calcic Cambisols (Bk); Humic Cambisols (Bh); Ochric Andosols (To); Calcaric 373
Fluvisols (Jc); Calcaric Gleysols (Gc); Eutric Histosols; (Oe); Chromic Vertisols (Vc); 374
Orthic Luvisols (Lo); Vertic Luvisols (Lv); Chromic Luvisols (Lc). 375
376
Table 2 shows the cumulative soil richness, minimum island size (km
2
) for each of the 377
six types of island. Fluvisols, Gleysols, and Histosols only appear in larger islands of 378
type (v) on very well developed and mature landforms. Furthermore, only the larger 379
island types have sufficient area for the formation of landforms such as deltas, estuaries, 380
flood plains, etc. and their associated soils. Next, we selected the whole of a smallest 381
soilscape which included these pedotaxa. We have not taken into account the pedotaxa 382
Eutric Regosols (Re) because there are indications that it was also included in the Island 383
Type-I (Yassaglou pers. com). Based on these considerations, only 32 km
2
is required to 384
preserve all pedotaxa after the “Re” correction, while the entire area of this archipelago 385
is thousands of square kilometres. This analysis demonstrates that complementarity 386
methods could be considered for the design of a Network of Soil Reserves. 387
388
Island classification
Minimum
island size (km
2
)
Cumulative soil
richness (%)
(II) dystric islands 1 4 (18.2%)
(I+IV) small/medium calcareous islands 6 11 (50%)
18
Pd. Richness = Number of pedotaxa
389
Table 2. Selection of a minimum data set for conservation of all pedotaxa in the Aegean 390
Islands. 391
392
4. Ensuring diversity in relation to viability and threat 393
394
Quantitative methods are necessary to successfully identify efficient sets of areas to 395
represent diversity. However, to ensure the persistence of diversity, a rigorous and 396
scientifically sound approach is also required to analyse viability and in dealing with 397
threats to diversity (Williams 2000a, b). In order to avoid some of the problems of 398
compromising accountability that are apparent with combinatorial scoring methods 399
(Williams et al. 1996), the additional viability and threat criteria might be applied in 400
separate steps within a sequence or hierarchy of decisions. The idea is to maintain 401
accountability by explaining exactly why each taxa or habitat (pedotaxa or soilscape) is 402
included or excluded at each step of the analysis (i.e. transparency, as exemplified by 403
the rigorous application of the scientific method which allows other scientists to 404
examine research methodologies and reproduce the results reported in the original 405
study). 406
407
According to Williams (2000a, b) one sequential structure for an area-selection exercise 408
consists of a series of 'steps' in which a framework of viability and threat could then 409
take into account the next steps, as applied in conservation 410
biology(http://www.nhm.ac.uk/research-curation/projects/worldmap/priority/steps.htm). 411
The sequential structure proposed by William (2000 a, b) consists of the following six 412
(III) volcanic islands 1 + 1 14 (68.6%)
(IV) large islands with calcareous rocks and developed landforms 3 19 (86.4%)
(*)
extra Soilscape of type V 20 21 (99.4%)
Total
(1)
32 21 (99.4%)
19
steps – (1) Prescription, which determines the values and goals of the area-selection 413
process; (2) Preselection, which organizes the data sets with consideration of the 414
established goals and available data; (3) Selection, which applies complementarity-415
based methods (sets of rules applied interatively) to minimum-area and maximum-416
coverage sets and chooses a set of areas based on conservation priorities; (4) 417
Prioritisation, which examines the selected areas and evaluates potential threats for 418
ranking pedotaxa with respect to preservation; (5) Post-selection, which re-evaluates the 419
area-selection results and considers additional or new criteria for modifying the results; 420
and (6) Reiteration, which applies quantitative methods to re-run previous analyses or 421
expand the geographic scale of the area-selection exercise. 422
423
In considering the design of a network of soil reserves at the continental level, such as a 424
PanEuropean project, we must examine that the only single harmonised product at this 425
date is the “European Soil Data Base” (EU-ESB, 2004). It is clear that a soil map 426
product at 1.000.000 scale would not permit a scientifically rigorous analysis to achieve 427
the goals and objectives of soil preservation for the European continent. Therefore, an 428
initiative to implement EUSIS (European Union Soil Information System in charge of 429
the ESB), at least at the scale 1:250.000 (or larger) is required to develop a suitable 430
product in a relatively short period of time. After that effort, a predictive digital soil 431
mapping approach could be recommended to fill the gaps and expand the scale based on 432
the experts in charge of the project. In light of the fact that current detailed soil maps 433
and soil attribute databases in Europe are unevenly distributed on a geographic basis, 434
efforts to select areas for soil preservation will exhibit strong country bias associated 435
with the varying geographic scales, survey methods and supporting data. 436
437
20
5. Resolving conflict through a hierarchical socio-political framework 438
439
Irrespective of area selection methods, human rights, responsibilities and interests, there 440
are a wide spectrum of levels, from the individual to corporate as well as various levels 441
of local, regional and national government, including federal and global agencies. Due 442
to the effects of spatial scale on pedogeographical analyses, and to the differing values 443
and goals apparent at the various levels of human activity, conservation priorities 444
determined by people with different interests are almost invariably in conflict. If the 445
progress made in the area of selection techniques is not to be vitiated, integrative 446
approaches for assessing area-based conservation priorities are required. Thus, it is 447
imperative to assess conservation priorities. Possible methods for conflict resolution 448
associated with conservation biology are discussed by Vane-Wright (1996), among 449
others. As these topics are beyond the scope of this contribution, we refer to the 450
interested reader to the above mentioned publication and references therein. 451
452
6. Relationships among estimates of diversity value: surrogates indicators of 453
diversity 454
455
According to (Williams, 1996) greater biodiversity value is associated with richness in a 456
currency of expressible genes (or the characters of organisms for which they code). In 457
similar manner, pedodiversity value is related with the genetic diversity associated with 458
the number and types of diagnostic horizons and soil properties among and within each 459
pedotaxa (Saldaña and Ibáñez, 2004, 2007). However, since resources for sampling and 460
analysis are limited, higher levels of biological organisation such as ecosystems (or of 461
the environmental factors affecting its distribution) have been employed as practical 462
21
surrogate measures (although it has been debated whether ecosystems can be mapped 463
and counted) (Williams, 2000a, b). At the European Level, the Natura Network could be 464
a starting point to overcome these shortcomings. Pedotaxa can also serve as surrogate 465
indicators if soil mapping of these protected areas could be completed, as was suggested 466
in several documents related to the Thematic Strategy for Soil Protection (2006). 467
468
In conservation biology when resources for sampling are limited, the use of practical 469
surrogate indicators is typically used. Choosing a surrogacy level at a given scale is a 470
compromise between precision of the measure on the one hand, and availability of data 471
and cost of data acquisition on the other (Williams, 1996). In the most cases there is 472
insufficient scientific evidence concerning the relationship between the surrogate 473
indicator and the soil taxa to be preserved. In other words, the latter relationships are 474
poorly understood in soil science, and thus their use must be appproached with caution 475
(Ibáñez, 2004). For example, Morvan et al (2007) examined earthworm diversity as a 476
surrogate indicator of the whole soil diversity (ENVASSO Project). Although 477
earthworm diversity provides some information on soil ecological diversity, there is 478
insufficient scientific evidence to demonstrate the relationship between earthworm’s 479
species richness and soil biodiversity as a whole. Many soilscapes and environments do 480
not have this type of soil organism, but still exhibit high levels of diversity. Therefore 481
we express caution against using data from these types of initiatives if we would obtain 482
poorer values of soil biodiversity. At this time, a complete inventory of soil biodiversity 483
(all soil species) has been not completed at any site of the pedosphere. In contrast, 484
Ibáñez (2004) and Ibáñez et al. (to be published) demonstrated a strong correlation 485
between biota diversity and pedodiversity at the global scale by countries as well as at 486
regional scales. Therefore, we propose that the measurement of pedodiversity (from soil 487
22
mapping or georeferenced soil databases) is, at the present time, at least one of the best 488
surrogates of soil biodiversity. Preserving pedotaxa or soilscapes in their natural state 489
will help us to also protect soil biodiversity which is still not known. 490
491
In general, for conservation biologists, a surrogate approach to estimate biodiversity 492
assumes that the currency of biodiversity are characters (Williams and Humphries, 493
1996), that models of character distribution among organisms allow comparison of 494
character diversity, and that character diversity measures can be calculated using 495
taxonomic and environmental surrogates (Humphries et al., 1995) In pedological terms, 496
pedodiversity and soil forming factors can serve as taxonomic and environmental 497
surrogates. Fortunately, when dealing with large numbers of taxa (mainly the low 498
categories of a given classification, such as species or soil types), richness is a 499
reasonable surrogate for gene or character richness (Williams 1996, 2000). Therefore, 500
identifying genes or characters as a fundamental currency of biodiversity value provides 501
an additional justification for using taxa richness (Figure 5). This concept is applicable 502
because as more species are added in total, at least some representatives of the more 503
divergent, higher groups of taxa usually co-occur (Williams 2000a, in WorldMap web 504
site). Ibáñez et al., 2005 described this concept in pedology as “taxonomic contrast” 505
for higher groups of taxa which, when combined, have a high degree of richness in 506
various soil characters. 507
508
Another potential problem with using the relationship between surrogate indicators and 509
the studied diversity is that the relationships may not be linear (Williams 2000 in 510
WorldMap web site). 511
23
512
Figure 5. Species as surrogates of character diversity (after Williams 2000: WorldMap 513
website) 514
515
However, Saldaña and Ibáñez (2004, 2007) demonstrated that at fine scales taxonomic 516
diversity and genetic pedodiversity are highly correlated. Furthermore, Ibáñez et al. 517
(2002) and Ibáñez (2002, 2004) provided evidence that in the Mediterranean climate (i) 518
nematodes species are distributed along the whole of soil profiles; (ii) different soil 519
horizons have different communities of soil nematodes, and (iii) some nematode species 520
emigrate along the solum in response to pedoclimate variation during a single annual 521
cycle. Therefore, the following provisional conclusions must be considered: (i) it 522
appears that different genetic horizons could be considered as distinct habitats for soil 523
organisms, (ii) the whole soil profile must be sampled, horizon per horizon to 524
understand soil biodiversity; (iii) pedotaxa can have different genetic horizons 525
assemblages, and as a corollary, preserving a single pedotaxa in a given area does not 526
guarantee conservation of the whole soil diversity and (iv) the usual practice in soil 527
biodiversity inventory studies of sampling exclusively only the 10-20 topsoil 528
24
centimetres is not justified by empirical evidence, at least in seasonally contrasted 529
environments (e.g. Ekschmitt et al., 2001). 530
531
7. What soils resources must be preserved? 532
533
“Soils are intimately involved in many ecosystem processes that contribute to the 534
sustainable use of the planet's land resources.”(Usher, 2005). Although this statement 535
may be an obvious fact to some, the state of the art in the preservation of soil resources 536
is intriguing and surprising in many aspects. It is intriguing because: (i) a major part of 537
the biodiversity of terrestrial ecosystems is housed in soil, either totally (e.g. microbial 538
and fauna soil communities) or partially (e.g. underground biomass of plant 539
communities, house of reptilians and some small mammal); (ii) some soils and/or 540
soilscapes are essential to the conservation of certain biotaxa and plant communities, 541
because if the former disappear, then the latter may disappear too (e.g. the survival of 542
sphagnum and associated plant species in the Mediterranean mountains depends on the 543
preservation of older glacial landforms and the associated Histosols); (iii) the soil 544
system is extremely important in ecosystem and food webs dynamics (e.g. nutrient 545
recycling organisms, symbiotic microorganisms essential for the survival of many 546
vascular plant species); (iv) soils are part of the geological heritage (geodiversity), and 547
(v) soils are a part of the cultural heritage. It is surprising because, despite the fact that 548
many pedologists propose that pedology should be reoriented from its agronomic 549
perspective toward positions and solutions more able to resolve environmental 550
problems, as far as we know, at the present time, except for occasional comments (e.g. 551
Ibáñez et and Boixadera, 2002; Ibáñez et al., 1990, 1995, 2005c; MacBratney, 1992, 552
1995), and the work of Amundson et al., (2003) this topic has hardly awoken their 553
25
interest. The known and unknown attributes of undisturbed (or at least, minimally-554
disturbed) soils suggests the need for an integrated biogeodiversity perspective in 555
landscape preservation efforts (Amundson et al., 2003). 556
557
The conservation of soil resources in themselves can also be deemed important since: (i) 558
we need to determine benchmark soils whose “soil functions” remain as undisturbed as 559
possible to act as references for studies on a European “soil quality” monitoring 560
program; (ii) conserving pedotaxa and, especially, soilscapes as undisturbed as possible, 561
deserves the same interest in conservation as that of any other natural resource; (iii) soil 562
endemism has begun to be a focus of study for pedologists (e.g. Amundson et al., 2003; 563
Bockheim, 2005) and (iv) many pedotaxa are at risk of extinction as a consequence of 564
urban sprawl, mineral extraction, agriculture and other factors, or could be considered 565
as “domesticated soils” (Amundson, 2006; Amundson et al., 2003; Sun et al., 2006; 566
Zhang et al., 2006). To this respect Amundson et al. (2003) distinguished between 567
undisturbed soils and domesticated soils. For these authors, the domesticated soils have 568
been modified by humans, whereas the undisturbed soils did not suffer this type of 569
alteration. It is clear that, at least in Europe, pristine soils disappeared centuries ago. In 570
some regards, all natural ecosystems including soilscapes have been altered by human 571
impacts. Thus, in rigorous terms it is better talk of soils under natural vegetation and 572
domesticated soils. In order to design a PanEuropean network of soil reserves, the best 573
candidate soils to preserve are those that occur under potential natural vegetation or the 574
“climax plant communities,” to distinguish the areas from other phytocenoses that occur 575
along the ecological successions. 576
577
26
The concept of soil endemism is promising for identifying rare, unique, or endangered 578
soils (e.g. Bockheim, 2005). In this manner, Amundson et al. (2003) showed that the 579
4.5% of the soils series in the USA are in danger of substantial loss, or complete 580
extinction. Guo et al. (2003a, b) reported that centers of plant diversity and endemism in 581
North America are associated with geographical zones in areas where a high level of 582
pedodiversity generally occurs (see also Bockheim, 2005, and references therein). 583
Furthermore, paleosols, in a broad sense, are invaluable soil bodies that may serve as 584
blocks of memory of past environments (e.g. Phillips and Marion, 2004) and can be 585
very useful for paleo-environmental and climate change history reconstruction efforts. 586
Ibáñez et al. (2007) proposed another scale-independent concept of soil endemism, 587
which in contrast with the Bockheim (2005), avoids some of the theoretical assumptions 588
and can be quantified with mathematical tools, making it possible to distinguish 589
between several “degrees of endemism”. 590
591
Likewise, it is necessary to re-emphasize those soils formed under ancient sustainable 592
farming practices have sufficient merit to be preserved for the following reasons: (i) 593
they are part of our cultural heritage; (ii) in most cases, pedologists and agronomists do 594
not have a good understanding of their soil qualities, and (iii) knowledge of their 595
formation and characteristics can help us to learn how to develop new agronomic 596
sustainable farming practises both in industrialised and third world countries. 597
598
Therefore, we propose there are at least three types of pedological entities which should 599
be preserved: (i) the natural soil cover; (ii) the cultural sustainable soil cover, and (iii) 600
the soils of the past (Retallack, 2001) also termed (geosols) in stratigraphy studies 601
(Morrison, 1967). In the conclusions section, we provide additional guidelines to 602
achieve this purpose. 603
27
604
8. Soil conservation in Europe 605
606
Because the pedosphere in general and soil ecosystems in particular are not well 607
understood, the EU needs a strategy to preserve soil biodiversity and the qualities and 608
ecosystem services associated with the minimally-disturbed soils. The rationale and 609
reasons for this proposal were discussed previously. As far as we know, this is the first 610
initiative to propose a scientifically-based strategy for the design of a network of natural 611
(and minimally-disturbed) soil reserves at the European level, with the exception of the 612
chapter by Ibáñez et al (2003) that was not distributed commercially. It is clear that 613
preservation of pedodiversity has been neglected and it is important to begin this 614
process before additional soilscapes and pedotaxa are lost forever. 615
616
In 2006 the EU approved the EU Soil Protection Directive. At the end of 2004 several 617
Working Groups elected by the EU DG Environment in 2002 submitted the supporting 618
documents required to write the final document of this Directive (available from 619
http://eusoils.jrc.it). However, this ambitious initiative in its beginnings did not
620
convince the European Union authorities, and in September 2006, a Directive was
621
approved focussing only on contaminated sites, delaying other topics for future actions.
622
This directive was published with another document termed the “Thematic Strategy for
623
Soil Protection.” The latter defended the idea of a pedosphere that must be preserved as 624
any other natural resource. However, no further action was officially launched with 625
respect to this proposal. At the end of the 5th Congress of the European Society for Soil 626
Conservation (ESSC) held in Palermo from 25-30 June 2007, the ESSC General 627
Assembly published a document with the purpose of informing the EU Commission of 628
28
their concern about the substantially diminished scope and goals of the previous 2002 629
communication as part of the content of the approved Soil Protection Directive (ESSC, 630
2007). However it is also true that none of the EU DG Working Groups presented 631
documents proposing the design of a PanEuropean Network of Soil Reserves. Therefore 632
the main question that must be approved by consensus is: “What and how the European 633
soil resources must be preserved?” As we stated above, during the Anthropocene 634
(Crutzen and Stoermer 2000), the European soilscapes have deteriorated, and at this 635
time, we can not speak of continental “pristine” soils. Thus it is the moment to move 636
beyond current simplistic documents and carry on a scientifically-sound framework for 637
a future design of a PanEuropean Network of Soil Reserves. This document is a critical 638
step toward achieving that goal. 639
640
Likewise, in order to carry on a European soil monitoring program, benchmark soils or 641
soilscapes with undisturbed pedotaxa are required in order to compare the results 642
obtained by predictive soil modelling using raster-based approaches (grid cells). By 643
means of this procedure, it is possible to compare the soil qualities of disturbed and 644
non-disturbed soils. Sampling soils periodically by grid cells without information on 645
reference benchmark sites for each pedological soil region will not assure either soil 646
preservation, or help increase our knowledge of soil quality changes with time and 647
space (i.e. soil region). 648
649
9. Conclusions 650
651
Preserving soils is currently one of the major gaps of the environmental policies in 652
many countries (Gentile et al., 1999). As with other natural resources, the soil is part of 653
29
the Earth’s natural heritage, containing both biological and non-biological components. 654
In a similar manner, soils formed under ancient sustainable practices are also a part of 655
the human cultural heritage. Because the later has not created any interest from the 656
conservationist community, an initiative to carry on a “Red Book” of soils under this 657
type of agronomic practise is also required, before many of them are lost forever. 658
Humans are dramatically altering the global pedosphere; therefore, we should initiate 659
efforts to describe and classify materials, processes and structures that previously did 660
not occur in nature, both in national and international soil classifications (Ibáñez et al., 661
2008). Areas such as urban sprawls and waste disposal facilities can reset the time zero 662
for soil formation and result in new pedotaxa (e.g., manmade soils such as Anthrosols, 663
Urbisols, Technosols) as the new WRB recognized (IUSS, ISRIC, FAO, 2006) (see also 664
Ibáñez et al., 2008 and Effland and Pouyat, 1997). At the same time, some natural 665
pedotaxa are being dramatically reduced or they are at risk of extinction (Amundson et 666
al., 2003). Therefore, as a result of soil erosion (Dazzi and Monteleone, 1998), urban 667
sprawl and other factors, global and regional pedodiversity is decreasing at alarming 668
rates (Amundson et al., 2003; Zhang et al., 2006). 669
670
With the consideration that several pedological entities should be preserved, a simple 671
strategy is not possible. The proliferation of different values and goals for soil 672
protection will require difficult decisions for policy makers to preserve soil resources. 673
Many areas have different conservation purposes which require a large expenditure of 674
funds and numerous supporting technicians , as well as conflicts with land uses. In order 675
to reduce these circumstances, the following framework is proposed: 676
677
30
1. Preservation of the soil cover or pedosphere (taxonomic pedodiversity and soil 678
biodiversity): In order to preserve taxonomic pedodiversity and biodiversity of 679
undisturbed soils, a soil inventory of currently protected areas (Nature Network 680
and related activities) will permit a first selection of areas that could be 681
preserved without additional expenses. However, this procedure will not 682
guarantee complete protection of European pedodiversity and soil diversity, 683
therefore, a PanEuropean soil inventory program at the scale 1:250.000 with 684
representative soilscapes surveyed at the scale 1:25.000 (or larger) must be 685
conducted. We must also consider that this initiative is imperative for other 686
purposes such as detecting the state of deterioration of soil qualities, 687
identification of contaminated sites and soils at risk to be contaminated, etc. This 688
program will be implemented by the European Union Soil Information System 689
(EUSIS) that is presently conducted by the European Soil Bureau (ESB, IES, 690
JRC, Italy). Similarly, because at this date it is not possible to have a complete 691
inventory of soil biodiversity and candidate surrogates of soil biodiversity have 692
not been tested at European level, this strategy will permit the preservation of 693
soil diversity that will be inventoried at a later date. Complementarity methods 694
will permit the area selection among the already protected areas (Natura 695
Networks) and the non protected soilscapes that must be preserved in the future. 696
2. Preserving soils under ancient or traditional sustainable farming practices: 697
These farms or cultural landscapes are a European heritage that must be 698
preserved. A strategy is proposed in three parts. First, an initiative to conduct a 699
geographical inventory of all systems to be included in this category must be 700
completed. After that a “Red Book” indicating farming types and procedures 701
used by owners must be published. Second, guidelines in order to include these 702
31
pedological entities in the framework of the Nature Network must be developed 703
by a Working Group. Third, using complementarity methods as tools, the areas 704
to be preserved could be selected. 705
3. Preserving paleosols as part of the geological heritage. Paleosols or soils 706
formed in the past, which serve as blocks of memory of the European past, must 707
be included in a future network of legal figures carry on to preserving the 708
European Geological heritage. To achieve this purpose, a working group of 709
experts in paleopedology must be included when the EU discusses a thematic 710
strategy of this topic. 711
712
10. References 713
714
Amundson, R., 2006. Soils in the Anthropocene. 1.2A Spatial, Societal and 715
Environmental Aspects of Pedodiversity - Oral. The 18th World Congress of Soil 716
Science (July 9-15, 2006, Philadelphia) 717
718
Amundson, R., Guo, Y., Gong, P., 2003. Soil diversity and land use in the United 719
States. Ecosystems 6, 470-482. 720
721
Bockheim, J. G., 2005. Soil endemism and its relation to soil formation theory, 722
Geoderma 129, 109-124. 723
724
Caniego, J., Ibáñez, J. J., San-José, F., 2006. Selfsimilarity of pedotaxa distributions at 725
planetary level: a multifractal approach. Geoderma 134, 306-317. 726
727
32
CEC, 1985. Soil Map of the European Communities at 1:1.000.000. CEC DG VI. 728
Luxembourg. 729
730
CEC, 2006., Communication from the Commission to the Council, the European 731
parliament, the European Economic and Social Committee and the Committee of the 732
Regions: Thematic Strategy for Soil Protection. Brussels 733
734
Chen, J., Zhang, X. L., Gong, Z. T., Wang, J., 2001a. Pedodiversity: A controversial 735
concept. J. Geographical Sci. 11, 101-136. 736
737
Chen, J., Zhang, X. L., Zhao, W. J., Ahang, G. L., Luo, G. H., Zao, Y. G., 2001b. 738
Pedodiversity and its management. A case study from Hainan Province focused on 739
parent rock-dependent variability. J. Geographical Sci. (in Chinese) 21, 145-151. 740
741
Costantini, E. A. C., Barbetti, R., Righini, G., 2003. Managing the Uncertainty in Soil 742
Mapping and Land Evaluation in Areas of High Pedodiversity. Methods and Strategies 743
Applied in the Province of Siena (Central Italy). Acts of the Int Sym. On Soils with 744
Med type of Climate, CIHEAM-IAMB, Bari, p. 45-56. 745
746
Crutzen, P. J., and E. F. Stoermer. 2000. The "Anthropocene". Global Change 747
Newsletter. 41: 12-13. 748
749
Csuti, B., Polasky, S., Williams, P. H., Pressey, R. L., Camm, J. D., Kershaw, M., 750
Kiester, A. R., Dwons, B., Hamilton, R., Huso, M., Shar, K., 1997. A comparison of 751
33
reserve selection algorithms using data on terrestrial vertebrates in Oregon. Biological 752
Conservation 80, 83-97. 753
754
Dazzi, C. and Monteleone, S., 1998. Consequences of human activities on pedodiversity 755
of soils: a case study in a vineyard area in south-east Sicily. Proceedings 16th ISSS 756
Congress, Montpellier, France. 757
758
Dazzi, C., Monteleone, S., 1999. Consequences of human activities on pedodiversity of 759
soils: a case study in a vineyard area in South-East Sicily (Italy). Procecedings of the 760
ESSC International Conference on "Soil Conservation in Large Scale Land Use", 761
Bratislava, Slovak Republic, May 1999, pp. 99-108. 762
763
EEA, 1998. Environment in the European Union at the Turn of the Century. European 764
Environmental Agency. Copenhagen, Denmark, 447 pp. 765
766
Effland, W. R., Pouyat, R.V., 1997. The genesis, classification and mapping of soils 767
in urban areas. Urban Ecosystems special issue entitled “Baltimore-Washington 768
Integrated Regional Framework and Research” 1(4): 217-228. 769
770
Ekschmitt, K., Bakonyi, G., Bongers, M., Bongers, T., Boström, S., Dogan, H., 771
Harrison, A., Nagy, P., O’Donnell, A. G., Papatheodorou, E. M., Sohlenius, B., 772
Stamou, G., Wolters, V., 2001. Nematode community structure as indicator of soil 773
functioning in European grassland soils. European Journal of Soil Biology 37, 263-268. 774
775
34
ESSC, 2007., ESSC Statement in Support of the EU Soil Framework Directive. 776
Palermo, 27 June 2007 777
778
EU., Europesn Soil Buro Network (2004)., The European Soil Database Version 2.0. 779
CD-ROM IES, JRC, Ispra, Italy. 780
781
Faith, D. P., 1992., Conservation evaluation and phylogenetic diversity. Biol. Conserv. 782
61, 1-10. 783
784
Faith, D.P., 1994., Phylogenetic patterns and the quantification of organismal 785
biodiversity Phil. Trans. Roy. Soc. Lond. B 345, 45-58. 786
787
FAO, 1995. Digital Soil Map of the World and Derived Soil Properties (CD-ROM). 788
FAO, Rome. 789
790
Ferrer, F., Flores, V., Goberna, M., Jiménez, M.G., Sánchez, J. 2007. Pedodiversity as 791
abiotic factor to asses soil quality in Mediterranean environments. 5
th
International 792
Congress of the European Society of Soil Conservation (Palermo, June 2-30, 2007) 793
Book of Abstracts, pp. 50. 794
795
Game, M., 1980. Best shape of nature reserves. Nature 287, 630-631. 796
797
García-Calderón, N. E., Ibáñez-Huerta,
A., Álvarez-Arteaga, G, Krasilnikov, P. V., 798
Hernández-Jiménez., 2006. Soil diversity and properties in mountainous subtropical 799
areas, in Sierra Sur de Oaxaca, Mexico. Can. J. Soil Sci. 86, 61-76. 800
35
801
Gentile, A. R., Koprok, G., Blum, W. H., Pollack, M., Loveland, P., Van der Born, G.J., 802
Syed, B., De la Rosa, D., Ibáñez, J. J., Kristensen, P., 1999. Soil degradation. 803
Environment in the European Union at the Turn of the Century. European 804
Environmental Agency, Copenhagen, Denmark, pp. 183-201. 805
806
Gray, M., 2004. Geodiversity: Valuating and Conserving Abiotic Nature. Willey, 807
Norfolk. 808
809
Guo, Y., Gong, P., Amundson, R., 2003a. Pedodiversity in the United States of 810
America. Geoderma 117, 99–115. 811
812
Guo, Y., Amundson, R., Gong, P., Ahrens, R., 2003b. Taxonomic structure, 813
distribution, and abundance of soils in the USA. Soil Sci. Soc. Am. J. 67, 1507-1516. 814
815
Humphries, C.J., Williams, P.H., Wright, R.I.V. , 1995. Measuring Biodiversity Value 816
for Conservation. Annual Review of Ecology and Systematics 26, 93-111. 817
818
Ibáñez, J.J. 2002. Nematodes and Soil Biodiversity, Challenges and Uncertainties. 819
Symposium of Nematodes Diversity in Soils. Open Conference. Fourth International 820
Congress of Nematology. (8-13 June 2002). Tenerife, Spain. 821
822
Ibáñez, J. J., 2004b. Decline in soil biodiversity. In: In Micheli E., Dobos E., Huskova 823
B., Filippi N., Montanarella L., Jones R.(Eds), European Summer School on Soil 824
36
Survey. European Commission, Joint Research Center, Italy. EUR 21196 EN pp. 335-825
349. 826
827
Ibáñez, J. J., 1995. Pedodiversity: pedometrics and ecological research. Pedometron. 4: 828
2-5 829
830
Ibáñez, J. J., Boixadera, J., 2002. The search for a new paradigm in pedology: a driving 831
force for new approaches to soil classification. In: Micheli, E. Nachtergaele, F. Jones, R. 832
J. A. and Montanarella, L. (Eds.). Soil Classification 2001, EU-JRC, Hungarian Soil. 833
Sci. Soc. & FAO, Italy, pp. 93-110. 834
835
Ibáñez, J. J., De Alba, S., 1999. On pedodiversity concept and its measurement. A 836
Reply. Geoderma 93, 339-344 (Discussion Paper). 837
838
Ibáñez, J. J., De Alba, S., 2000. Pedodiversity and scaling laws: sharing Martín and 839
Rey's opinion on the role of the Shannon index as a measure of diversity. Geoderma 98, 840
5-9 (Discussion Paper). 841
842
Ibáñez, J. J., García-Álvarez, A., 2002. Diversidad: biodiversidad edáfica y 843
geodiversidad. Edafología 9, 329-385. 844
845
Ibáñez, J. J., Ruiz-Ramos, M., 2006. Biological and Pedological Classifications: a 846
Mathematical Comparison. Eurasian Soil Sci. 39, 712-719. 847
848
37
Ibáñez, J. J. and Saldaña, A. 2008. Continuum versus discrete spatial soil pattern 849
analysis. Russian Academy of Sciences. In: Krasilnikov, P. V. (Ed.) pp. 109-120, 850
Geostatistics and soil geography.. (publicación lengua rusa) Moscow : Nauka, 2007. 851
176 p. (Academia Rusa de las Ciencias). 852
853
Ibáñez, J. J., Perez, P., 2007. The fractal distribution of Pedotaxa in Europe. 854
International Workshop on Scale Dependences in Soils and Hydrologic Systems 855
(Pedofract2007), (July 3-6, 2007, El Barco de Ávila, Spain), UCM pp 21. 856
857
Ibáñez, J.J., Jiménez-Ballesta, R. and García-Álvarez, A., 1990. Soil landscapes and 858
drainage basins in Mediterranean mountain areas. Catena, 17: 573-583. 859
860
Ibáñez,J.J., López Lafuente,A., Saldaña,A. y de Alba, S. 1992. La diversidad de los 861
suelos en las áreas de montaña bajo clima mediterráneo. Mem. III Congr. Nac. Cien. 862
Suelo, (p. 508-513); Pamplona, Septiembre 1992). 863
864
Ibáñez, J.J., Pérez, A., Jiménez-Ballesta, R., Saldaña, A. and Gallardo, J. 1994. Evolution 865
of fluvial dissection landscapes in Mediterranean environments. Quantitative estimates and 866
geomorphological, pedological and phytocenotic repercussions. Z. Geomorph. N.F., 38: 867
105-119. 868
869
Ibáñez, J.J., De-Alba, S., Bermúdez, F.F. and García-Álvarez, A., 1995. Pedodiversity 870
concepts and tools. Catena, 24: 215-232. 871
872
38
Ibáñez, J.J., De-Alba,S., Lobo, A. and Zucarello,V., 1998a. Pedodiversity and global 873
soil patterns at coarser scales (with Discussion). Geoderma, 83: 171-192. 874
875
Ibáñez, J. J., Saldaña, A., De-Alba, S., 1998b. In Yaalon D. H., Pedodiversity and 876
global soil patterns at coarser scales. Geoderma 83, 206-214 (Discussion Paper). 877
878
Ibáñez, J. J., García-Álvarez, A., Arias, M. 2002. Current Uncertainties in the 879
estimation of soil nematode diversity and its use in soil quality. Fourth International 880
Congress of Nematology. (8-13 June 2002). Tenerife, Spain Nematology: Volume 4(2): 881
253 p. 882
883
Ibáñez, J. J., García-Álvarez, A., Saldaña, A., Recatalá, L., 2003. Scientific rationality, 884
quantitative criteria and practical implications in the design of soil reserves networks: 885
their role in soil biodiversity and soil quality studies. In: Lobo, M . C., Ibáñez, J. J. 886
(Eds.) Preserving Soil Quality and Soil Biodiversity; The Role of Surrogate Indicators. 887
IMIA-CSIC, Zaragoza, pp. 191-274. 888
889
Ibáñez, J. J., Bello, A., García-Álvarez, A., 2004. La Conservación de los Suelos 890
Europeos. Un Análisis Crítico de la Actual Estrategia de la Unión Europea. En: 891
Protección del Suelo y el Desarrollo Sostenible, Publicaciones del IGME, Serie Medio 892
Ambiente nº 6: MEC, Madrid, 133-161. 893
894
Ibáñez, J. J., Caniego, J., San-José, F., Carrera, C., 2005a. Pedodiversity-area 895
relationships for islands. Ecological Modelling, Vol 182, 257-269. 896
897
39
Ibáñez, J. J., Caniego, J., García-Álvarez, A., 2005b. Nested subset analysis and taxa-898
range size distributions of pedological assemblages: implications for biodiversity 899
studies. Ecological Modeling, 182, 239-256. 900
901
Ibáñez, J. J., Ruiz-Ramos, M., Zinck, J. A. Brú, A., 2005c. Classical pedology 902
questioned and defended. Eurasian Soil Sci., 38. Suppl. 1, S75-S80 903
904
Ibáñez, J.J. Effland, W.R. and Krasilnikov, P.V. (2008). Pedodiversity Analysis and 905
Soil Preservation. Appl. Soil Ecol., (submitted) 906
907
Ibáñez, J. J., Ruiz-Ramos, M. and Tarquis, A. 2006. The Mathematical Structures of 908
Biological and Pedological Taxonomies. Geoderma, 134: 360-372. 909
910
Ibáñez, J. J. and Saldaña, A. 2008. Continuum versus discrete spatial soil pattern 911
analysis. Russian Academy of Sciences. In: Krasilnikov, P. V. (Ed.) pp. 109-120, 912
Geostatistics and soil geography.. (Publisher in Russain and English versión) Moscow : 913
Nauka, 2007. 176 p. (Academia Rusa de las Ciencias). 914
915
IUSS., ISRIC., FAO., 2006. World reference base for soil resources 2006: A framework 916
for international classification, correlation and communication. World Soil Resources 917
Reports Nº 103. FAO, Rome Italy. 103 pp. 918
919
Krasilnikov P. V., Starr, M., Lantratova, I. M., 2000. Quantitative evaluation of soil 920
diversity of Fennoscandia. In: T. S. Zvereva (ed.), Ecological Functions of Soils of 921
Eastern Fennoscandia. Petrozavodsk, pp. 108-123. (in Russian) 922
40
923
Krasilnikov P. V., Fuentes Romero E., 2003 Soil diversity: theory, practice, and 924
methods of the study. Materials on the Study of Russian Soils. V. 4(31), 37-42 (in 925
Russian) 926
927
McBratney, A. B., 1992. On variation, uncertainity and informatics in environmental 928
soil management. Australian J. Soil Res. 30, 913-935. 929
930
McBratney, A., Minasny, B. 2007. On measuring pedodiversity. Geoderma 141, 149-931
154. 932
933
McBratney, A. B., 1995. Pedodiversity. Pedometron 3, 1-3. 934
935
McBratney, A. B., Odeh, I. O. A., Bishop, T. F. A., Dumbar, M. S., Shatar, T. M., 2000. 936
An overview of pedometric techniques for use in soil survey. Geoderma 97, 293-307. 937
938
Morrison, R. B. 1967. Principles of quaternary soil stratigraphy. In: Quaternary Soils, 939
In: (pp. 77-108), W. C. Mahaney (ed.). Geo Abstracts, Norwich. 940
941
Morvan X., Arrouays D., Saby N., Richer de Forges A., Le Bas C., 2007. Soil 942
monitoring networks in Europe: a representativeness study. 5
Th
International Congress 943
of the European Society of Soil Conservation. Book of Abstracts. P. 473. (Palermo June 944
25-30, 2007) 945
946
Phillips, J. D. 1999. Earth Surface Systems. Blackwell, 180 pp. 947
41
948
Phillips, J. D., 2001a. The relative importance of intrinsic and extrinsic factors in 949
pedodiversity. Annals of the Association of American Geographers 91, 609-621. 950
951
Phillips, J. D., 2001b. Divergent evolution and spatial structure of soil landscape 952
variability. Catena 43, 101-113. 953
954
Phillips, J. D., 2006. Deterministic chaos and historical geomorphology: A review and 955
look forward. Geomorphology 76, 109-121 956
957
Phillips, J. D., Marion, D. A., 2004. Pedological memory in forest soil development. 958
For. Ecol. Manag. 188, 363-380 959
960
Phillips, J. D., Marion, D. A., 2005. Biomechanical effects, lithological variations, and 961
local pedodiversity in some forest soils of Arkansas. Geoderma 124, 73-89. 962
963
Phillips, J. D., Marion, D. A. 2007. Soil geomorphic classification, soil taxonomy, and 964
effects on soil richness assessments. Geoderma 141, 89-97 965
966
Platou, S.W., Norr, A.M. and Madsen, H.B. 1989. Digitizing of the EU Soil Map. In: 967
R.J.A. Jones and B. Biagi (eds.), (pp.12-24), In: Agriculture: Computerization of Land 968
Use Data, EUR 11151 EN, CEC, Luxembourg. 969
970
Retallack, G. J. 2001 (2
nd
ed.). Soils of the past: An Introduction of the Paleopedology. 971
Blackwell Science. Oxford, Uk., 404 pp. 972
42
973
Saldaña, A., Ibáñez, J. J., 2004. Pedodiversity analysis at large scales: an example of 974
three fluvial terraces of the Henares River (central Spain), Geomorphology 62, 123–138 975
976
Saldaña,A., & Ibáñez, J.J. 2007. Pedodiversity and soil variability; What is the 977
relationship?. (Ecological Modelling, en prensa). 978
979
Scull, P., Franklin, J., Chadwick, O.A., McArthur, D., 2003. "Predictive soil mapping - 980
a review". Progress in Physical Geography 27, 171-197. 981
982
Sun, Y., Zhang, X. L., Cheng, X., 2006. Gray Correlative Analysis of the Impact from 983
Growing Urbanization Process on Pedodiversity in Nanjing Area. Acta Geographica 984
Sinica 61, 318-325. 985
986
Tan, M., Zhang, X. L., Chen, J., Yan, W., Yan, Y., 2003. Pedodiversity: A case study 987
based on 1:1 million scale SOTER of Shandong Province, China. Pedosphere 13, 119-988
226. 989
990
Toomanian, N., Jalalian, A., Khademi, H. 2006. Pedodiversity and pedogenesis in 991
Zayandeh-rud Valley, Central Iran Geomorphology 81 (2006) 376–393. 992
Geomorphology 81 (2006) 376–393. 993
994
Usher, M. B., 1985. Implications of species-area relationships for wildlife conservation. J. 995
Environ. Mgmt. 21, 181-191. 996
997
43
Usher, M. B., 1991. Habitat structure and the design of nature reserves. In: Bell, S. S., 998
McCoy, E.D., Mushinsky, H. R., (Eds.), Habitat structure; The Physical Arrangement of 999
Objects in Space. Chapman and Hall, London, pp. 374-391. 1000
1001
Usher, M. B. 2005. Soil biodiversity, nature conservation and sustainability. In: Richard 1002
D. Bardgett, Michael B. Usher and David W. Hopkins (eds.), Biological Diversity and 1003
Function in Soils, Cambridge University Press, 428 pp. 1004
1005
Van der Ploeg, S. W. F., 1986. Wildlife conservation evaluation in the Netherlands: a 1006
controversial issue in a small country. In: Usher, M.B. (Ed.), Wildlife Conservation 1007
Evaluation. Chapman and Hall, London, pp. 161-180. 1008
1009
Vane-Wright, R. I., Humphries, C .J., Williams, P. H., 1991. What to protect? –1010
Systematics and the agony of choice. Biological Conservation 55, 235-254. 1011
1012
Vane-Wright, R. I., 1996. Identifying priorities for the conservation of diversity: 1013
systematic biological criteria within a socio-political framework. In: Gaston, K. J. (Ed.), 1014
Biodiversity: A Biology of Numbers and Difference. Blakewell, pp. 309-344 1015
1016
Williams, P. H., 1996. Measuring biodiversity value. World Conservation 1, 12-14 1017
(previously termed IUCN Bulletin). 1018
1019
Williams, P.H. 2000a. World Map http://www.nhm.ac.uk/science/projects/ 1020
worldmap/key.htm 1021
1022
44
Williams, P.H. 2000b. Key sites for conservation: area-selection methods for 1023
biodiversity. In Mance, G. M., Balmford, A., and Ginsberg, J. R. (eds.), Conservation in 1024
a Changing World: Integrating Processes Into Priorities for Action. Cambridge Univ. 1025
Press (Symposia of the Zoological Society of London nº 72), UK. 1026
1027
Williams, P.H. and Humphries, C.J. 1996. Comparing character diversity among biota. 1028
Spatial Patterns in taxonomic diversity. In: K. J. Gaston (ed.) (pp. 54-76), Biodiversity: 1029
A Biology of Numbers and Difference. Blakwell, 396 pp. 1030
1031
Williams, P.H., Gaston, K.J. and Humphries, C.J. 1994. Do conservationists and 1032
molecular biologists value differences between organisms in the same way?. 1033
Biodiversity Letters. 2: 67-78. 1034
1035
Williams, P.H., Gibbons, D., Margules, C., Rebelo, A., Humphries, C.J. and Pressey, R. 1036
1996. A comparison of richness hotspots, rarity hotspots and complementary areas for 1037
conserving diversity of British birds. Conservation Biology, 10: 155-174. 1038
1039
Williams, P.H., Prance,, G.T., Humphries, C.J. and Edwards, K. S. 1996. Promise and 1040
problems in applying quantitative complementary areas for representing the diversity of 1041
some Neotropical plants (families Dichapetalaceae, Lecythidaceae, Caryocaraceae, 1042
Chrysobalanaceae and Proteaceae). Biol. J. Linnean Soc., 58, 125-157. 1043
1044
Zhang, X. L., Chen, J., Tan, M., Sun, Y., 2006. Assessing the impact of urban sprawl on 1045
soil resources of Nanjing city using satellite images and digital soil databases. Catena 1046
(in press). 1047
