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The Xingu Seed Network and mechanized direct seeding

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Abstract

Direct seeding proved to cost less than planting seedlings (approximately US$2000/ha, compared with US$5000/ha) and to be more practical, since seeds are easier to carry and to plant. To plant one hectare, approximately 60 kilos of seeds of native trees (200 000 seeds) are mixed with 100 000 seeds of annual and subperennial legumes and sand, in a mixture called muvuca. The legumes help to create a multilayer vegeta- tion, reducing niches for invasive grasses. Their root systems can contribute to soil aeration and decompaction, enhancing water absorption. Their ability to fix nitrogen and their intense leaf fall contribute to enhancing nutrient cycling and soil fertility. However, if they grow too densely, they can shade out the tree seedlings, slowing tree growth. If this occurs, manual or chemical weeding or thinning will be necessary. Ninety-one of the native tree species planted have germinated and survived droughts of up to six months without irrigation. Tree populations of between 2500 and 32 250 trees/ha have been established on the reseeded areas. The campaign has contributed to the restoration of 2565 ha of riparian forest at 238 sites until 2014.
THE STATE
OF THE WORLD’S
FOREST GENETIC RESOURCES
THEMATIC STUDY
GENETIC
CONSIDERATIONS
IN ECOSYSTEM RESTORATION
USING NATIVE TREE SPECIES
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
GENETIC CONSIDERATIONS IN ECOSYSTEM RESTORATION USING NATIVE TREE SPECIES
There is renewed interest in the use of native tree species in ecosystem restoration
for their biodiversity benefits. Growing native tree species in production systems
(e.g. plantation forests and subsistence agriculture) can also ensure landscape
functionality and support for human livelihoods.
Achieving full benefits, however, requires consideration of genetic aspects that are
often neglected, such as suitability of germplasm to the site, quality and quantity of
the genetic pool used and regeneration potential. Understanding the extent and
nature of gene flow across fragmented agro-ecosystems is also crucial to successful
ecosystem restoration.
This study, prepared within the ambit of
The State of the World’s Forest Genetic Resources
,
reviews the role of genetic considerations in a wide range of ecosystem restoration
activities involving trees. It evaluates how different approaches take, or could take,
genetic aspects into account, thereby leading to the identification and selection of
the most appropriate methods.
The publication includes a review and syntheses of experience and results; an
analysis of successes and failures in various systems; and definitions of best
practices including genetic aspects. It also identifies knowledge gaps and needs for
further research and development efforts. Its findings, drawn from a range of
approaches, help to clarify the role of genetic diversity and will contribute to future
developments.
I3938E/1/07.14
ISBN 978-92-5-108469-4
9789251 0 8 4694
i
THE STATE OF THE WORLD’S
FOREST GENETIC RESOURCES –
THEMATIC STUDY
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 2014
GENETIC CONSIDERATIONS
IN ECOSYSTEM RESTORATION
USING NATIVE TREE SPECIES
Editors
Michele Bozzano,1 Riina Jalonen,1 Evert Thomas,1 David Boshier,1,2
Leonardo Gallo,1,3 Stephen Cavers,4 Sándor Bordács,5 Paul Smith6 and
Judy Loo1
1 Bioversity International, Italy
2 Department of Plant Sciences, University of Oxford, United Kingdom
3 Unidad de Genética Ecológica y Mejoramiento Forestal, INTA Bariloche, Argentina
4 Centre for Ecology and Hydrology, Natural Environment Research Council, United
Kingdom
5 Central Agricultural Office, Department of Forest and Biomass Reproductive
Material, Hungary
6 Seed Conservation Department, Royal Botanic Gardens, Kew, United Kingdom
ii
Recommended citation:
Bozzano, M., Jalonen, R., Thomas, E., Boshier, D., Gallo, L., Cavers, S., Bordács, S., Smith, P. & Loo, J., eds.
2014. Genetic considerations in ecosystem restoration using native tree species. State of the World’s
Forest Genetic Resources – Thematic Study. Rome, FAO and Bioversity International.
Photo credits:
p. 47 A. Borovics
p. 69 Leonardo Gallo, Paula Marchelli
pp. 139-140 Nik Muhamad Majid and team members
p. 154 Mauro E. González
p. 158 Philip Ashmole
p. 162 Dannyel de Sá, Cassiano C. Marmet, Luciana Akemi Deluci
p. 163 Luciano Langmantel Eichholz (top photos), Osvaldo Luis de Sousa, Elin Rømo Grande
p. 170 Wilmer Toirac Arguelle
p. 171 Orlidia Hechavarria Kindelan
p. 197 Lewis Environmental Services Inc.
pp. 217-218, 220 Luis Gonzalo Moscoso Higuita
pp. 231-232 Fulvio Ducci
p. 234 Sándor Bordács, István Bach
p. 238 Jesús Vargas-Hernández
p. 239 Alfonso Aguirre
The designations employed and the presentation of material in this information
product do not imply the expression of any opinion whatsoever on the part of the
Food and Agriculture Organization of the United Nations (FAO) or of Bioversity
International concerning the legal status of any country, territory, city or area or of its
authorities, or concerning the delimitation of its frontiers or boundaries. The mention
of specific companies or products of manufacturers, whether or not these have been
patented, does not imply that these are or have been endorsed or recommended by
FAO or Bioversity International in preference to others of a similar nature that are
not mentioned. All reasonable precautions have been taken by FAO and Bioversity
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reader. In no event shall FAO or Bioversity International be liable for damages arising
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The views expressed herein are those of the authors and do not necessarily represent
those of FAO or Bioversity International.
ISBN 978-92-5-108469-4 (print)
E-ISBN 978-92-5-108470-0 (PDF)
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iii
Foreword
One of the major and growing environmental challenges of the 21st century will be the
rehabilitation and restoration of forests and degraded lands. Notwithstanding the large-
scale restoration projects initiated in Africa and Asia as of the 1970s, the current level
of interest in forest and landscape restoration is more recent. With the adoption of the
strategic plan of the United Nations Convention on Biological Diversity for 2011-2020, a
strong new impetus has been given not only to halt degradation, but to reverse it. The
plan states that, by 2020, 15 percent of all degraded lands should be restored. This target
is consistent with the Bonn Challenge, which calls for restoring 150 million hectares of
degraded land by 2020.
Forests play a crucial part in resilient landscapes at multiple scales. Restoring forest
ecosystems is therefore a key strategy not only for tackling climate change, biodiversity
loss and desertification, but can also yield products and services that support local people’s
livelihoods.
Restoration is not only about planting trees. Its success requires careful planning, as
painfully demonstrated by numerous past restoration projects that have not attained
expected goals. Restoration practices must be based on scientific knowledge, particularly so
in these times of progressive climate change. The trees we plant today and other associated
measures for restoration and rehabilitation of degraded ecosystems must be able to
survive abiotic and biotic pressures, including social ones, in order to be self-sustaining
and generate the products and services vital to supporting the world’s population and
environment for the years to come.
Biodiversity International coordinated this thematic study as an input to FAO’s landmark
report on The State of the World’s Forest Genetic Resources. The report was requested by the
Commission on Genetic Resources for Food and Agriculture, which guided its preparation,
and agreed, in response to its findings, on strategic priorities which the FAO Conference
adopted in June 2013 as the Global Plan of Action for the Conservation, Sustainable Use
and Development of Forest Genetic Resources.
The publication of this study is an important step in the implementation of the Global
Plan of Action. It provides fundamental information for the achievement of knowledge-
based ecosystem restoration using native tree species. It draws attention to the importance
of embedding genetic considerations in restoration activities, an aspect which is often
overlooked both by restoration scientists and practitioners, but is nonetheless crucial to
rebuilding resilient landscapes and ecosystems. We trust that it will contribute to informing
future restoration efforts and help to ensure their success.
Eduardo Rojas-Briales Stephan Weise
Assistant Director-General, Forestry Department Deputy Director General – Research
Food and Agriculture Organization of the United Nations Bioversity International
iv
Acknowledgements
We would like to express our gratitude to the scientists who contributed to the writing
of the scientific overviews presented in Part 2 of this thematic study. We would also like
to thank all of the practitioners who shared the experiences collected in Part 3, and who
completed the survey, which allowed us to undertake the analysis (Part 4) and to derive the
conclusions and recommendations (Part 5) of this study
The text was edited by Paul J.H. Neate, who was very helpful in standardizing and
simplifying the language. Gérard Prosper carried out the layout. We are grateful for their
professional work.
This thematic study was prepared thanks to funding from the CGIAR Research Program
on Forests, Trees and Agroforestry.
v
Contents
Foreword iii
Acknowledgements iv
Part 1 Overview 1
Chapter 1 Introduction 3
Evert Thomas, Riina Jalonen, Leonardo Gallo, David Boshier and Judy Loo
1.1. Objectives and organization of the study 8
Insight 1 Examples illustrating the importance of genetic considerations
in ecosystem restoration 13
David Boshier, Evert Thomas, Riina Jalonen, Leonardo Gallo and Judy Loo
Insight 2 The Great Green Wall for the Sahara and the Sahel Initiative:
building resilient landscapes in African drylands 15
Nora Berrahmouni, François Tapsoba and Charles Jacques Berte
Insight 3 Invasive species and the inappropriate use of exotics 19
Philip Ivey
Part 2 Theoretical and practical issues in ecosystem restoration 23
Chapter 2 Seed provenance for restoration and management: conserving
evolutionary potential and utility 27
Linda Broadhurst and David Boshier
2.1. Local versus non-local seed 28
2.2. Basic concepts and theory 28
2.3. Historical perspective of local adaptation 29
2.4. The scale of local adaptation in trees: how local should
a seed source be? 29
2.5. Are non-local seed sources ever appropriate? 30
2.6. Local seed sources may not produce restoration-quality seed 31
2.7. Adaptation and climate change 32
2.8. Benefits of using larger but more distant seed sources 33
2.9. Conclusions 33
Chapter 3 Continuity of local genetic diversity as an alternative
to importing foreign provenances 39
Kristine Vander Mijnsbrugge
3.1. Why should autochthonous diversity be protected? 39
3.2. Inventory of autochthonous woody plants 40
3.3. Producing autochthonous planting stock 40
3.4. Seed orchards 41
vi
3.5. Promotion of use 43
3.6. Discussion 45
Insight 4 Historical genetic contamination in pedunculate oak
(Quercus robur L.) may favour adaptation 47
Sandor Bordacs
Insight 5 The development of forest tree seed zones in
the Pacific Northwest of the United States 49
Brad St Clair
Chapter 4 Fragmentation, landscape functionalities and connectivity 53
Tonya Lander and David Boshier
4.1. Genetic problems related to fragmentation 53
4.2. Management of fragmented landscapes 55
4.3. The use of native species in ensuring functionality in fragmented
landscapes 57
4.4. Conclusions: policy and practice 59
Chapter 5 Gene flow in the restoration of forest ecosystems 67
Leonardo Gallo and Paula Marchelli
5.1. Genetic effects at different scales 68
5.2. Considerations in restoration and management 68
Chapter 6 The role of hybridization in the restoration of forest
ecosystems 75
Leonardo Gallo
6.1. The impact of restoration 75
6.2. Promoting hybridization 76
6.3. Avoiding hybridization 76
6.4. Seed sources and seed-zone transfer 76
Chapter 7 Collection of propagation material in the absence of genetic
knowledge 79
Gösta Eriksson
7.1. Evolutionary factors 79
7.2. Methods for sampling diversity 80
7.3. Genetic variation 80
7.4. Avoidance of genetic drift 83
7.5. Conclusion 84
Chapter 8 Evaluation of different tree propagation methods in ecological
restoration in the neotropics 85
R.A. Zahawi and K.D. Holl
8.1. Establishing tree seedlings from seed in nurseries 85
8.2. Establishment by vegetative propagation 88
8.3. Direct seeding 90
8.4. Choosing an appropriate restoration strategy 91
vii
Chapter 9 Seed availability for restoration 97
David J. Merritt and Kingsley W. Dixon
9.1. Landscape-scale restoration requires large quantities of seed 97
9.2. Seeding rates necessary to delivery restoration outcomes 98
9.3. Constraints to seed supply for landscape-scale restoration 99
9.4. Approaches to improving seed availability for restoration 100
9.5. Conclusion 102
Insight 6 Seed availability: a case study 105
Paul P. Smith
Insight 7 The role of seed banks in habitat restoration 106
Paul P. Smith
Chapter 10 Traditional ecological knowledge, traditional resource
management and silviculture in ecocultural restoration of
temperate forests 109
Dennis Martinez
Chapter 11 Designing landscape mosaics involving plantations of native
timber trees 121
David Lamb
11.1. How much reforestation? 121
11.2. What kind of reforestation? 122
11.3. Where to undertake reforestation? 122
11.4. How to plan and implement restoration on a landscape scale? 123
11.5. Will forest landscape restoration succeed in conserving
all biodiversity? 124
11.6. Conclusion 124
Insight 8 Identifying and agreeing on reforestation options
among stakeholders in Doi Suthep-Pui National Park,
northern Thailand 126
David Lamb
Part 3 Methods 129
Chapter 12 Ecological restoration approaches 133
12.1. Miyawaki method 133
Akira Miyawaki
12.1.1. Tropical rainforest rehabilitation project in Malaysia using the
Miyawaki Method 137
Nik Muhamad Majid
12.1.2. Adapting the Miyawaki method in Mediterranean forest
reforestation practices 140
Bartolomeo Schirone and Federico Vessella
viii
12.2. Framework species method 144
Riina Jalonen and Stephen Elliott
12.3. Assisted natural regeneration 148
Evert Thomas
12.3.1. Assisted natural regeneration in China 149
Jiang Sannai
12.4. Post-fire passive restoration of Andean Araucaria–Nothofagus
forests 151
Mauro E. González
12.5. Carrifran Wildwood: using palaeoecological knowledge
for restoration of original vegetation 157
Philip Ashmole
12.6. The Xingu Seed Network and mechanized direct seeding 161
Eduardo Malta Campos Filho, Rodrigo G. P. Junqueira, Osvaldo L.deSousa,
Luciano L. Eichholz, Cassiano C. Marmet, José Nicola M.N.da Costa, Bruna
D. Ferreira, Heber Q. Alves and André J. A. Villas-Bôas
Chapter 13 Approaches including production objectives 165
13.1. Analogue forestry as an approach for restoration and ecosystem
production 165
Carlos Navarro and Orlidia Hechavarria Kindelan
13.1.1. Restoring forest for food and vanilla production under
Erythrinaand Gliricidia trees in Costa Rica using the analogue
forestry method 168
Carlos Navarro
13.1.2. Restoration of ecosystems on saline soils in Eastern Cuba usingthe
analogue forestry method 169
Orlidia Hechavarria Kindelan
13.2. Post-establishment enrichment of restoration plots with timber
andnon-timber species 173
David Lamb
13.3. Enrichment planting using native species (Dipterocarpaceae)
with local farmers in rubber smallholdings in Sumatra, Indonesia 178
Hesti L. Tata, Ratna Akiefnawati and Meine van Noordwijk
13.4. “Rainforestation”: a paradigm shift in forest restoration 184
Paciencia P. Milan
13.5. The permanent polycyclic plantations: narrowing the gap
between tree farming and forest 188
Enrico Buresti Lattes, Paolo Mori and Serena Ravagni
ix
Chapter 14 Habitat-specific approaches 195
14.1. Mangrove forest restoration and the preservation of mangrove
biodiversity 195
Roy R. Lewis III
14.2. Forest restoration in degraded tropical peat swamp forests 200
Laura L.B. Graham and Susan E. Page
14.3. Support to food security, poverty alleviation and soil-degradation
control in the Sahelian countries through land restoration and
agroforestry 204
David Odee and Meshack Muga
14.4. The use of native species in restoring arid land and biodiversity
in China 207
Lu Qi and Wang Huoran
14.5. Using native shrubs to convert desert to grassland in the northeast
ofthe Tibetan Plateau 212
Yang Hongxiao and Lu Qi
14.6. Reforestation of highly degraded sites in Colombia 214
Luis Gonzalo Moscoso Higuita
Chapter 15 Species restoration approaches 225
15.1. Species restoration through dynamic ex situ conservation:
Abiesnebrodensis as a model 225
Fulvio Ducci
15.2. Restoration and afforestation with Populus nigra in Hungary 233
Sándor Bordács and István Bach
15.3. Restoration of threatened Pinus radiata on Mexico’s Guadalupe
Island 236
J. Jesús Vargas-Hernández, Deborah L. Rogers and Valerie Hipkins
15.4. A genetic assessment of ecological restoration success in
Banksiaattenuata 240
Alison Ritchie
Part 4 Analysis 243
Chapter 16 Analysis of genetic considerations in restoration methods 245
Riina Jalonen, Evert Thomas, Stephen Cavers, Michele Bozzano, David Boshier,
Sándor Bordács, Leonardo Gallo, Paul Smith and Judy Loo
16.1. Appropriate sources of forest reproductive material 245
16.1.1. Needs for research, policy and action 249
16.2. Species selection and availability 249
16.2.1. Needs for research, policy and action 252
16.3. Choice of restoration and propagation methods 253
16.3.1. Needs for research, policy and action 255
x
16.4. Restoring species associations 255
16.4.1. Needs for research, policy and action 257
16.5. Integrating restoration initiatives in human landscapemosaics 258
16.5.1. Needs for research, policy and action 259
16.6. Climate change 260
16.6.1. Needs for research, policy and action 263
16.7. Measuring success 264
16.7.1. Needs for research, policy and action 267
Part 5 Conclusions and recommendations 275
Chapter 17 Conclusions 277
Evert Thomas, Riina Jalonen, Judy Loo, Stephen Cavers, Leonardo Gallo, David
Boshier, Paul Smith, Sándor Bordács and Michele Bozzano
17.1. Recommendations arising from the thematic study 280
17.1.1. Recommendations for research 280
17.1.2. Recommendations for restoration practice 280
17.1.3. Recommendations for policy 281
Part 1
OVERVIEW
3
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
FAO (2010) estimates that 13 million hectares of
natural forests are lost each year worldwide. This
has been accompanied by an increase in the area
reforested and of forested ecosystems restored.
Between 2000 and 2010, almost 5 million hectares
of trees were planted annually, an area equiva-
lent to that of Costa Rica (FAO, 2010). It is esti-
mated that 76 percent of this area was planted
mainly for productive purposes and 24 percent
for protective purposes, although planted forests
in both categories may serve multiple purposes
(FAO, 2006). Presumably, many trees were also
planted in other types of landscape and pro-
duction systems that were not included in these
statistics, such as farmland, and for which little
information is available on a global scale. The
area of planted forests is expected to continue to
increase, reaching 300 million hectares by 2020
(FAO, 2010). Examples of large-scale reforesta-
tion and forest restoration initiatives are listed in
Table 1.1.
The global interest in planting trees holds
significant promise for restoring degraded eco-
systems, mitigating effects of environmental
changes, conserving biodiversity, and yielding
products and services that support local people’s
livelihoods. Globally, it is estimated that 2billion
hectares of land could benefit from restoration;
this is an area larger than South America (WRI,
2011; Laestadius et al., 2012). The ability of for-
est ecosystem restoration to mitigate the impacts
of numerous environmental problems, and to
slow and eventually reverse their negative ef-
fects, is widely recognized in international agree-
ments, including the United Nations Framework
Convention on Climate Change, the Convention
on Biological Diversity, the United Nations
Convention to Combat Desertification, the Aichi
Biodiversity Targets1 and the European Union
Biodiversity Targets for 2020.2 In particular, resto-
ration and reforestation hold vast potential not
only for mitigating the impacts of climate change,
through sequestration of atmospheric carbon di-
oxide in plant biomass (Canadell and Rapauch,
2008; Alexander et al., 2011a), but also for halt-
ing biodiversity loss and countering the encroach-
ment of the arid frontier (see Insight2).
In spite of serious concerns that restoration may
become a new excuse for continued agribusiness
exploitation and expanded industrial plantations
of exotic tree species that are not likely to en-
hance biodiversity and ecosystem services or ben-
efit local communities (Alexander et al., 2011a),
the growing global interest in reforestation and
restoration is accompanied by an increasing in-
terest in using native plant material (Rogers and
Montalvo, 2004; Aronson et al., 2011; Montagini
and Finney, 2011; Newton and Tejedor, 2011;
Lamb, 2012). However, an important concern in
the shift to native species is the selection of ap-
propriate genetic planting stocks for use in resto-
ration activities (Rogers and Montalvo, 2004).
1 http://www.cbd.int/sp/targets/
2 http://www.cbd.int/nbsap/about/targets/eu
Chapter 1
Introduction
Evert Thomas,1 Riina Jalonen,1 Leonardo Gallo,1,2 David Boshier1,3 and Judy Loo1
1 Bioversity International, Italy
2 Unidad de Genética Ecológica y Mejoramiento Forestal, INTA Bariloche, Argentina
3 Department of Plant Sciences, University of Oxford, United Kingdom
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
4
In this thematic study we discuss the use of
native species and genetic considerations in a
selection of current approaches to ecosystem res-
toration, and identify the most important bottle-
necks that currently restrict the generalized use
of native species, and which may put at risk the
long-term success of restoration efforts. Our main
message is that increasing the use of native spe-
cies in restoration activities provides real environ-
mental and livelihood benefits, but also involves
clear risks, mainly related to the selection of the
appropriate genetic source for the target plant
species.
First and foremost, increasing the use of na-
tive species in restoration activities contributes
to conservation of the species themselves and
TABLE 1.1.
Examples of large-scale tree planting and forest landscape restoration initiatives (as of March 2012)
Initiative
(year of initiation) Scale Country or region Leading or coordinating
institution
Green Belt Movement (1977) 45 million trees planted Originating in Kenya, now a
worldwide movement
Established by Professor Wangari
Maathai
Green Wall of China (1978) Planned to be 4500 km long and cover
35 million ha, of which it is estimated
that two-thirds have been achieved
so far
China, bordering the Gobi
desert
Government of China
Great Green Wall
(2005)
Planned to be a tree belt 15 km wide
and 7775 km long, with an area of 11.7
million ha
Sahel across Africa, with
11 countries, from Senegal
to Djibouti, participating
African Union
Billion Tree Campaign (2006) 12 billion trees planted Global United Nations Environment
Programme, Plant for the Planet
Foundation
The Atlantic Forest Restoration
Pact (2009)
Aims to restore 15 million ha of
degraded lands in the Brazilian Atlantic
Forest biome by 2050, and to sustainably
manage the remaining forest fragments
Brazilian Atlantic Forest
biome
Joint effort of non-governmental
organizations, the private sector,
government and research
institutions
The Green Mission
(2010)
Plans to afforest or restore 5 million ha
of degraded and cleared forests, and
improve the quality of another 5 million
ha over the next 10 years
India Ministry of Environment and
Forests
Aichi Nagoya Target 15
(2010)
Restoration of at least 15% of degraded
ecosystems by 2020, as part of the
target to enhance ecosystem resilience
and the contribution of biodiversity to
carbon stocks through conservation and
restoration
Global Parties to the Convention on
Biological Diversity
Rwanda’s Forest Landscape
Restoration Initiative (2011)
Plans to restore forest nationwide “from
border to border”
Rwanda The Government of Rwanda
in collaboration with the
International Union for
Conservation of Nature (IUCN), the
Secretariat of the United Nations
Forum on Forests and the private
sector
The Bonn Challenge (2011) Targets to restore 150 million ha of
deforested and degraded lands
Global Announced at the Bonn Challenge
Ministerial Roundtable in
September 2011; supported
and promoted by IUCN, World
Resources Institute and the Global
Partnership on Forest Landscape
Restoration, among others
5
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
their genetic diversity. Second, if planting ma-
terial represents not only a native species but
originates from seed sources local to the plant-
ing site, it will have evolved together with oth-
er native flora and fauna of the area. It should
therefore be well adapted to cope with the local
environment and should support native biodiver-
sity and ecosystem resilience to a greater extent
than would introduced (exotic) planting material
(Tang et al., 2007). Third, native species may be
less likely either to become invasive or to suc-
cumb to introduced or native pests than exotic
species (Ramanagouda et al., 2010; Hulme, 2012).
Finally, native species may correspond better to
the preferences of local people, and chances are
also higher that local people hold ethnobotani-
cal and ethno-ecological knowledge of native
species, which may facilitate their successful use
in restoration projects (Shono, Cadaweng and
Durst, 2007; Chazdon, 2008; Douterlungne et al.,
2010). In turn, promoting native species that pro-
duce non-timber forest products can contribute
to the conservation of related traditional knowl-
edge as well as the cultures that maintain it.
Use of exotic species in reforestation and forest
restoration can result in negative impacts for con-
servation and the environment (Richardson, 1998;
Pimentel, Zuniga and Morrison, 2005; Stinson
et al., 2006; Tang et al., 2007; see also Insight 3:
Invasive species and the inappropriate use of ex-
otics). However, it must be recognized that the
exotic versus native species debate is not free of
controversy. There may be situations in which the
benefits generated by exotics largely outweigh
the disadvantages, not only in socioeconomic
terms but also in ecological terms (D’Antonio and
Meyerson, 2002; Alexander et al., 2011a). In addi-
tion, it would be unrealistic to think that exotics
can be completely eliminated from the environ-
ments in which they have been introduced and
in some cases have become naturalized. Better
understanding of local people’s preferences can
help promote the use of those exotics already
introduced, with clear benefits for restoration
projects. However, species with known invasive
potential should be avoided.
It is not always easy to establish with certainty
whether a species is native to a particular area
or has been introduced by humans, possibly long
ago (e.g. Vendramin et al., 2008). Some exotic tree
species – most notably Eucalyptus and Pinus spp. –
have been deliberately introduced to various parts
of the world for their perceived greater utility or
production capacity, and because know ledge
about their propagation is generally greater than
that about native alternatives. The global spread
of homogeneous planted forests, centred on eu-
calypts, pines and poplars, was largely driven by
industry that had developed in areas where these
species occurred naturally and had tailored its pro-
duction lines to the wood properties of these spe-
cies. In addition, the distribution of species (and
provenances) by humans is often an outcome of
unplanned events (Finkeldey, 2005).
It is clear that in the short term it will not be
possible to replace the predominant use of exotics
with use of native species for restoration and re-
forestation. Currently, most of the planted forests
in the tropics still comprise exotic tree species se-
lected mainly for their production functions. The
proportion of exotic species in afforestation or re-
forestation initiatives between 2003 and 2007 was
reported to be 82 percent in western and central
Africa, 99 percent in eastern and southern Africa,
28 percent in East Asia, 94 percent in South and
Southeast Asia and 98 percent in South America
(calculated from FAO, 2010: 92). While there are
probably hundreds of native species with growth
performance and wood quality at least compara-
ble to that of the commonly used plantation spe-
cies, lack of knowledge about the biology, propa-
gation and management of such native species
is currently among the main constraints for their
wider use (Newton, 2011; Lamb, 2012), along with
the difficulties of trying to alter industrial systems
tailored to particular production species. The time
seems ripe now for large-scale investments to
overcome these limitations.
Despite the expected benefits of using na-
tive species, increasing the scale of restoration
activities will be associated with elevated risks
of failure if some basic guidelines are not fol-
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
6
lowed. For example, only two out of 98 publicly
funded reforestation projects in Brazil were con-
sidered successful during an evaluation in 2000
(Wuethrich, 2007). Reforestation and restoration
efforts may fail for a variety of reasons, from
wrong species for wrong sites to inappropriate
silvicultural approaches and techniques (Rogers
and Montalvo, 2004; Le et al., 2012). In general,
little information is available about the global
success of tree-planting efforts, especially in areas
where ecosystems may be severely degraded or
initial growing conditions are particularly harsh.
People are often hesitant to share information on
failures in spite of the help it could provide to im-
proving current practices, and global efforts to re-
cord reforestation and forest restoration activities
started only recently (FAO, 2010). However, the
annual average area reported for afforestation
and reforestation activities globally in 2003–07
was more than twice the annual average increase
in the area of planted forests over the ten-year
period 2000–2010 (FAO, 2010). Low success rates
in establishment and survival of seedlings can be
assumed to contribute to the difference.
Although the reasons for frequent failures in
reforestation and restoration activities are not of-
ten known, it is probable that many failures are
related to poor matching of planting material to
the target site, or too narrow a genetic base for
the planting stock (Rogers and Montalvo, 2004).
Indeed, to attain a functional and resilient eco-
system, it is crucial that the genetically adapted
planting material used for establishing a plant
community represents a certain minimum level of
intraspecific diversity to ensure that its progeny
will in turn be viable and able to produce viable
offspring. Aside from the initial quality and ge-
netic diversity of germplasm, and its suitability for
the planting site, the extent of gene flow across
landscapes over subsequent generations is also of
central importance for the successful long-term
restoration of ecosystems and tree populations.
This ensemble of genetic qualities is necessary
not only to provide the desired forest functions,
products and services, but also to enable restored
populations to reproduce and survive on the site.
Genetic diversity has generally been found
to be positively related not only with the fit-
ness of individual plant populations (Reed and
Frankham, 2003; Rogers and Montalvo, 2004), but
also with the stability and resilience of ecosystems
(Gregorius, 1996; Elmqvist et al., 2003; Müller-
Starck, Ziehe and Schubert, 2005; Thompson et
al., 2010; Sgro, Lowe and Hoffmann, 2011). Tree
communities need particularly adaptive genetic
variation to succeed over time on the restored site;
such variation promotes survival and good growth
while at the same time enhancing resilience and
resistance to biotic and abiotic stresses such as en-
vironmental variations (Pautasso, 2009; Dawson
et al., 2011; Schueler et al., 2012) or pests and
pathogens (Schweitzer et al., 2005; Cardinale et
al., 2012). In the long term, adaptive genetic diver-
sity will promote successful reproduction, reduce
the risk of inbreeding and genetic impoverishment
that can result from genetic drift, and increase a
population’s ability to adapt to future site condi-
tions.
Currently little is known about the genetic
diversity of most native species, particularly the
thousands of tropical tree species that could play
an important role in restoring degraded tropical
ecosystems and their functions. Where guidelines
exist, for example on the collection of germplasm,
they appear to be largely unknown or overlooked
by restoration practitioners. Moreover, despite
the high expectations for restored forests to miti-
gate climate change, ensuring the capability of
tree populations to adapt to changing environ-
ment as a precondition for their mitigation func-
tion has received hardly any attention. The fact
that the negative effects of genetic homogeneity
are not necessarily immediately evident but accu-
mulate over time means that resulting problems
are difficult to perceive (Rogers and Montalvo,
2004) and address. Furthermore, by the time the
effects are obvious they may already have af-
fected large areas. For example, low genetic di-
versity in planting material, stemming from col-
lecting seed from single isolated trees, can lead to
increased homozygosity, particularly in the next
generation, and may result in the expression of
7
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
A degraded ecosystem “exhibits loss of biodiversity
and a simplification or disruption in ecosystem
structure, function and composition caused by
activities or disturbances that are too frequent or
severe to allow for natural regeneration or recovery”
(Alexander
et al.
, 2011b).
Ecological restoration is “the process of assisting
the recovery of an ecosystem that has been degraded,
damaged, or destroyed” (SER, 2004). Alexander
et al.
(2011b) define ecological restoration as “an intentional
activity that initiates or facilitates the recovery of
ecosystems by re-establishing a beneficial trajectory
of maturation that persists over time. The science
and practice of ecological restoration is focused
largely on reinstating autogenic ecological processes
by which species populations can self-organize into
functional and resilient communities that adapt to
changing conditions while at the same time delivering
vital ecosystem services. In addition to reinstating
ecosystem function, ecological restoration also fosters
the re-establishment of a healthy relationship between
humans and their natural surroundings by reinforcing
the inextricable link between nature and culture and
emphasizing the important benefits that ecosystems
provide to human communities.”
Forest restoration aims to “restore the forest to
its state before degradation (same function, structure
and composition)” (ITTO, 2002).
Forest landscape restoration is “a planned
process that aims to regain ecological integrity and
enhance human wellbeing in deforested or degraded
forest landscapes” (WWF and IUCN, 2001).
Rehabilitation is “a process to re-establish the
productivity of some, but not necessarily all, of the
plant and animal species thought to be originally
present at a site. For ecological or economic reasons
the new forest might also include species not
originally present at the site. The protective function
and many of the ecological services of the original
forest may be re-established” (Gilmour, San and Xiong
Tsechalicha, 2000).
Reforestation is “the re-establishment of forest
through planting and/or deliberate seeding on land
classified as forest, for instance after a fire, storm or
following clearfelling” (FAO, 2010).
Afforestation is “the act of establishing forests
through planting and/or deliberate seeding on land
that is not classified as forest” (FAO, 2010).
Planted forests are forests “composed of
trees established through planting and/or through
deliberate seeding of native or introduced species”
(FAO, 2010).
Resilience is “the ability of an ecosystem to
recover from, or to resist stresses (e.g. drought, flood,
fire or disease)” (Walker and Salt, 2006).
A native species (also indigenous species) is a
species which is part of the original flora of an area
(IBPGR, now Bioversity International).
An exotic species (also alien or introduced
species) is “a species which is not native to the region
in which it occurs” (FAO, 2002).
Naturalized species are “intentionally or
unintentionally introduced species that have
adapted to and reproduce successfully in their new
environments” (FAO, 2002).
A provenance refers to “the original geographic
source of seed, pollen or propagules” (FAO, 2002).
References
Alexander, S., Aronson, J., Clewell, A., Keenleyside, K.,
Higgs, E., Martinez, D., Murcia, C. & Nelson, C. 2011b.
Re-establishing an ecologically healthy relationship
between nature and culture: the mission and vision of
the Society for Ecological Restoration.
In
Secretariat of
the Convention on Biological Diversity.
Contribution
of ecosystem restoration to the objectives of the CBD
and a healthy planet for all people. Abstracts of posters
presented at the 15th Meeting of the Subsidiary Body
on Scientific, Technical and Technological Advice of the
Convention on Biological Diversity, 7–11 November 2011,
Montreal, Canada.
Technical Series No. 62, pp. 11–14.
Montreal, Canada, SCBD.
FAO (Food and Agriculture Organization of the United
Nations). 2002.
Glossary on forest genetic resources
(English version)
. Forest Genetic Resources Working
Papers, Working Paper FGR/39E. Rome.
FAO (Food and Agriculture Organization of the United
Nations). 2010.
Global forest resources assessment. Main
report.
FAO Forestry Paper 163. Rome.
Box 1.1.
Key concepts in ecosystem restoration
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
8
deleterious recessive alleles, which in turn de-
creases individual fitness (i.e. inbreeding depres-
sion) (White, Adams and Neale, 2007). Inbreeding
can have impacts at any stage of development, for
example through reduced embryo viability, seed-
ling survival, tree vigour or seed production (see
Insight 1: Examples illustrating the importance of
genetic considerations in ecosystem restoration).
Restoration, rehabilitation and reforesta-
tion are all terms commonly used to refer to re-
establishing forest vegetation on deforested are-
as. In this study we use the term “ecosystem resto-
ration.” This largely coincides with “ecological res-
toration,” defined as “the process of assisting the
recovery of an ecosystem that has been degraded,
damaged, or destroyed” (SER, 2004), but also aims
to accommodate rehabilitation and reforesta-
tion activities that do not necessarily comply with
some more conservative definitions of restora-
tion (Lamb, 2012). These and other terms related
to ecosystem restoration are defined in Box1.1.
We acknowledge that restoration is not the most
appropriate term for characterizing some of the
activities described in this and the following chap-
ters because it suggests the aim of re-establishing
a pre-existing ecosystem. In some cases it is almost
impossible to define a previous state to which an
ecosystem can be restored (Hilderbrand, Watts and
Randle, 2005). It may also be impossible to return
ecosystems to historical states because of radical
changes that have already taken place (e.g. severe
aridification, soil degradation or socioeconomic
changes) (Buizer, Kurz and Ruthrof, 2012), or the
objective of a restoration activity may simply be
less ambitious with respect to the plant commu-
nity it aims to establish (Lamb, 2012). In spite of
these shortcomings, we have chosen to use “eco-
system restoration” throughout this study for the
sake of uniformity.
While the systems and approaches discussed in
this study cover a range of objectives and species
assemblages, sometimes including exotic species,
they all emphasize the use of indigenous tree spe-
cies and diversity for their intrinsic relationships
with indigenous flora and fauna and local know-
ledge and cultures.
1.1. Objectives and organization
of the study
The objective of this thematic study is to review
and analyse current practices in ecosystem resto-
ration, with a particular focus on the use of native
tree species and genetic considerations related to
the selection of appropriate planting material.
Based on this analysis we put forward a number
of practical recommendations, including genetic
considerations in ecosystem restoration, that are
intended to help practitioners to avoid genetic
problems and enhance both the short- and long-
term success of future restoration activities. Our
target audience includes researchers, restoration
practitioners and policy-makers.
Gilmour, D.A., San, N.V. & Xiong Tsechalicha. 2000.
Rehabilitation of degraded forest ecosystems in Cambodia,
Lao PDR, Thailand and Vietnam: an overview.
Pathumthani,
Thailand, IUCN, The World Conservation Union, Asia
Regional Office.
ITTO (International Tropical Timber Organization). 2002.
ITTO guidelines for the restoration, management and
rehabilitation of degraded and secondary tropical forests.
ITTO
Policy Development Series No. 13. Yokohama, Japan, ITTO.
SER (Society for Ecological Restoration). 2004.
SER
international primer on ecological restoration
. SER,
Washington, DC (available at: http://www.ser.org/
resources/resources-detail-view/ser-international-primer-
on-ecological-restoration).
Walker, B. & Salt, D. 2006.
Resilience thinking: sustaining
ecosystems and people in a changing world
. Washington,
DC, Island Press.
WWF & IUCN. 2000.
Forests reborn. A workshop on forest
restoration.
WWF/IUCN International Workshop on Forest
Restoration: 3–5 July 2000, Segovia, Spain (available
at: http://cmsdata.iucn.org/downloads/flr_segovia.pdf).
Accessed 21 January 2013.
Box 1.1. (continued)
Key concepts in ecosystem restoration (continued)
9
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
This report is organized in five main parts,
including this introduction. In the second part,
experienced scientists briefly present theoretical
and practical issues relevant to ecosystem resto-
ration, with particular emphasis on genetic as-
pects. This more theoretical series of contributions
serves as a basis for the analysis of the restora-
tion methods and approaches and underpins the
recommendations. The third part is an overview
of various methods and approaches that are cur-
rently used in ecosystem restoration and are based
– at least partially – on the use of native species.
The authors contributing to the presentation of
these methods and approaches were requested to
reply to a set of questions aimed at facilitating an
analysis of the methods they used and their genet-
ic implications; the questionnaire is available on
the Bioversity website.3 The fourth part presents
an analysis of the use of genetic considerations in
current restoration methods, as well a number of
action and research recommendations, building
on the previous chapters of theoretical and gen-
eral considerations, presentation of the methods
and approaches, and the responses to the survey.
The fifth and final part summarizes the main con-
clusions of this thematic study.
References
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Cliquet, A., Erwin, K.L., Finlayson, C.M., de
Groot, R.S., Harris, J.A., Higgs, E.S., Hobbs, R.J.,
Robin Lewis, R.R., Martinez, D. & Murcia, C.
2011a. Opportunities and challenges for eco-
logical restoration within REDD+. Restor. Ecol., 19:
683–689.
Alexander, S., Aronson, J., Clewell, A., Keenleyside,
K., Higgs, E., Martinez, D., Murcia, C. & Nelson,
C. 2011b. Re-establishing an ecologically healthy
relationship between nature and culture: the mission
and vision of the Society for Ecological Restoration.
In Secretariat of the Convention on Biological
Diversity. Contribution of ecosystem restoration
to the objectives of the CBD and a healthy planet
for all people. Abstracts of posters presented at
the 15th Meeting of the Subsidiary Body on
Scientific, Technical and Technological Advice of the
Convention on Biological Diversity, 7–11 November
2011, Montreal, Canada. Technical Series No. 62,
pp. 11–14. Montreal, Canada, SCBD.
Aronson, J., Brancalion, P.H.S., Durigan, G.,
Rodrigues, R.R., Engel, V.L., Tabarelli, M.,
Torezan, J.M.D., Gandolfi, S., de Melo, A.C.G.,
Kageyama, P.Y., Marques, M.C.M., Nave, A.G.,
Martins, S.V., Gandara, F.B., Reis, A., Barbosa,
L.M. & Scarano, F.R. 2011. What role should gov-
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3 See https://www.bioversityinternational.org/fileadmin/user_
upload/SoW_FGR_RestorationSurvey.pdf.
While the emphasis here has been on sourcing seed
for restoration, it is important to recognise that
many species have intimate associations with a
range of organisms and that these too may require
restoration. The “If you build it, they will come”
paradigm does not always apply and ill-considered
placement of restoration projects can lead to poor
utilization by the very organisms they are expected
to attract to recreate interactions and processes at
the population and community level. In addition,
there can be considerable benefits for simultaneously
restoring plants and associated organisms. For
example, the survival and growth of acacias is
significantly improved if seed is simultaneously
planted with nitrogen-fixing bacterial symbionts, with
excess nitrogen benefiting other co-planted species,
resulting in a better and more rapid restoration
outcome (Thrall
et al.,
2005).
Reference
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revegetation success.
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42: 740–751.
Box 1.2.
It’s not just about restoring plants
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Thrall, P.H., Millsom, D.A., Jeavons, A.C., Waayers,
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13
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
Poor genetic matching of planting material to
the target site may result in reduced viability
of restoration projects
The widespread and severe dieback in three pon-
derosa pine plantations planted south of Pagosa
Springs, Colorado, United States, in the late
1960s to mid-1970s has been related to the use
of inappropriate genetic seed source. A pathogen
(Cenangium ferruginosum) has been identified
in the plantations, but observations are consist-
ent with this being a secondary impact and not
the primary cause of failure (Worral, 2000; Rogers
and Montalvo, 2004).
Use of provenance trials to guide genetic
matching
The natural range of black walnut (Juglans
nigra L.) extends from the eastern United States
west to Kansas, South Dakota and eastern Texas.
A subset of 15 to 25 sources from 66 sampled
provenances was planted in each of seven geo-
graphically disparate common-garden field trials.
After 22 years, survival was much higher for local
trees (71 percent) than for the other provenances
(zero survival at some sites) (Bresnan et al., 1994;
Rogers and Montalvo, 2004). This allowed the
authors to make informed decisions about where
best to use what germplasm.
Selfing (self-pollination) can considerably
affect survival and size of offspring
In a study in which offspring of Pseudotsuga
menziesii selfed and outcrossed crosses were
compared 33 years after establishment of seed-
lings, the average survival of selfed offspring was
only 39 percent that of the outcrossed individuals.
Moreover, the average diameter at breast height
(DBH) of the surviving selfed trees was 59 percent
that of the surviving outcrossed siblings (White,
Adams and Neale, 2007).
Low levels of genetic diversity can
compromise successful mating between plant
individuals
Attempts to restore the endangered daisy Ruti-
dosis leptorrhynchoides were constrained by the
limi ted reproductive potential of small popu-
lations (fewer than 200 plants) where the low
number of self-incompatibility alleles prevented
successful mating between many of the remnant
plants (Young et al., 2000). Among trees, several
Prunus species are known to have self-incompat-
ibility alleles, so the same considerations could
apply.
Insight 1
Examples illustrating the importance
of genetic considerations in
ecosystem restoration
David Boshier,1,3 Evert Thomas,1 Riina Jalonen,1 Leonardo Gallo1,2 and Judy Loo1
1 Bioversity International, Italy
2 Unidad de Genética Ecológica y Mejoramiento Forestal, INTA Bariloche, Argentina
3 Department of Plant Sciences, University of Oxford, United Kingdom
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
14
Negative consequences of low genetic
diversity of the source material usually
accumulate in the subsequent generations
Acacia mangium was first introduced to Sabah
(Malaysia) from Australia in 1967 in two small
stands of 34 and approximately 300 trees of the
“maternal half-sib family.” This material formed
the basis for more than 15 000 hectares of planta-
tions. A simple nursery trial comparing seedlings
from the first to third generation showed a re-
duced height growth in seedlings harvested from
the second and third generation, as compared
with the first generation (20.7 cm and 18.1 cm,
compared with 32.5 cm) (Sim, 1984).
Selection for favourable characteristics
can considerably improve the quality of
individuals where specific objectives have
been set for the planted forests
Tree improvement programmes have been suc-
cessful in dramatically increasing growth and
quality in commercially valuable and widely
planted species. For example, a study compared
the performance of Acacia auriculiformis trees
grown from seedlots obtained from: (1) a seed-
ling seed orchard (SSO), (2) a seed production
area (SPA), (3) a natural-provenance site (NPS)
and (4) a commercial seedlot from the same
provenance (CS) from Viet Nam. Four-year old
trees grown from the SSO and SPA seedlots scored
significantly higher than trees from the NPS for
a number of traits including height, DBH, conical
stem volume, stem straightness and axis persis-
tence. In contrast, trees grown from commercial
seedlots scored consistently lower for these traits
(Hai et al., 2008). Inbreeding may have contri-
buted to the poor growth and quality of trees
originating from the commercial seedlots.
References
Bresnan, D.R., Rink, G., Diesel, K.E. & Geyer, W.A.
1994. Black walnut provenance performance in
seven 22-year-old plantations. Silvae Genet., 43:
246–252.
Hai, P.H., Harwood, C., Kha, L.D., Pinyopusarerk, K. &
Thinh, H. 2008. Genetic gain from breeding Acacia
auriculiformis in Vietnam. J. Trop. Forest Sci., 20:
313–327.
Rogers, D.L. & Montalvo, A.M. 2004. Genetically
appropriate choices for plant materials to main-
tain biological diversity. Report to the USDA Forest
Service, Rocky Mountain Region, Lakewood, CO,
USA. University of California (available at: http://
www.fs.fed.us/r2/publications/botany/plantgenetics.
pdf). Accessed 21 January 2013.
Sim, B.L. 1984. The genetic base of Acacia mangium
Willd. in Sabah. In R.D. Barnes, & G.L. Gibson, eds.
Provenance and genetic improvement strategies in
tropical forest trees, pp. 597-603. Mutare, Zimbabwe,
April, 1984. Oxford, UK, Commonwealth Forestry
Institute; Harare, Zimbabwe, Forest Research Centre.
Young, A., Miller, C., Gregory, E. & Langston, A.
2000. Sporophytic self-incompatibility in diploid
and tetraploid races of Rutidosis leptorrhynchoides
(Asteraceae). Aust. J. Bot., 48: 667–672.
White, T.W., Adams, W.T. & Neale, D.B. 2007. Forest
genetics. Wallingford, UK, CABI Publishing.
Worrall, J. 2000. Dieback of ponderosa pine in planta-
tions established ca. 1970. Internal Forest Service
Report. Gunnison, CO, USA, USDA Forest Service,
Gunnison Service Center.
15
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
Desertification,4 land degradation and drought,
combined with climate change, have a strong
negative impact on the food security and liveli-
hoods of local communities in Africa’s drylands,
home to some of the world’s poorest populations.
The Great Green Wall for the Sahara and the
Sahel Initiative (GGWSSI) was launched by African
heads of state and government “to improve the
resilience of human and natural systems in the
Sahel–Saharan zone to Climate Change through
a sound ecosystems’ management, sustainable
development of land resources, protection of ru-
ral heritage and improvement of the living con-
ditions and livelihoods of populations living in
these areas.” This African Union initiative, based
on a proposal of former President of Nigeria, H.E.
Olusegun Obasanjo, involves over 20 countries
bordering the Sahara.
The Food and Agriculture Organization of the
United Nations (FAO), the European Union and
the Global Mechanism of the UNCCD are support-
ing the African Union Commission and 13 partner
countries (Algeria, Burkina Faso, Chad, Djibouti,
Egypt, Ethiopia, the Gambia, Mauritania, Mali,
Niger, Nigeria, Senegal and the Sudan) in their
efforts to implement the GGWSSI. This support
4 Desertification refers to land degradation in arid, semi-arid and
subhumid areas resulting from factors such as human pressure on
fragile ecosystems, deforestation and climate change.
involves: (i) the development and validation of
a harmonized regional strategy for effective im-
plementation and resource mobilization of the
GGWSSI; (ii) the preparation of detailed imple-
mentation plans and project portfolios in the 13
countries, identifying priorities and intervention
areas and at least three cross-border projects;
(iii) the development of a partnership and re-
source mobilization platform and a learn ing and
networking platform for enhancing knowledge
sharing, technology transfer and promotion
of best practices across GGWSSI countries and
among partners; (iv) the preparation of a capaci-
ty-building strategy and programme; and (v)the
preparation of a communication strategy and ac-
tion plan for engaging key target audiences and
stakeholders in supporting implementation of
the GGWSSI.
Among the priority interventions identified
with in the GGWSSI action plans developed to date
is the restoration of forest landscapes and de-
graded lands in the GGWSSI priority intervention
areas. Achieving this will depend on developing
the capacity of the partners in the following areas:
• use of native species adapted to the local
environmental, socioeconomic and cultural
conditions;
• selection, production and use of a wide
range of site-adapted planting material
(genotypes) from native tree, shrub and
Insight 2
The Great Green Wall for the Sahara
and the Sahel Initiative: building
resilient landscapes in African drylands
Nora Berrahmouni, François Tapsoba and Charles Jacques Berte
Forest Assessment, Management and Conservation Division, Forestry Department,
Food and Agriculture Organization of the United Nations, Rome, Italy
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
16
grass species, including production sufficient
quantities of seeds and seedlings of
adequate quality;
• application of the principles of forest
landscape restoration planning to
restore ecological integrity and enhance
human well-being in the degraded forest
landscapes and lands;
• promoting effective stakeholder
participation and governance to ensure
effective planning, design, implementation
and sharing of benefits from afforestation
and restoration;
• promotion of sustainable management of
forests and rangelands to assist and enhance
natural regeneration;
• promotion of multipurpose agrosilvipastoral
systems and economically valuable native
plant species to improve rural livelihoods;
• combined use of traditional knowledge
and innovative forestation and restoration
techniques, with particular focus on soil and
This project, developed and implemented between
2003 and 2010, was funded by Italian Cooperation.
It aimed at strengthening the capacity of six pilot
countries (Burkina Faso, Chad, Kenya, Niger, Senegal
and the Sudan) to address food security and
desertification problems through the improvement
and restoration of the acacia-based agrosilvipastoral
systems, and at sustainably developing the resins
and gums sectors. The project benefited local
communities engaged in harvesting and processing
gums and resins. The project tested a microcatchment
water-harvesting system (the Vallerani system)1 and
restored a total of 13 240 hectares. Local people
were empowered though an intensive programme of
capacity building on the use and application of the
Vallerani system, nursery establishment and plant
production, agricultural production, and harvesting
and processing of gums and resins. Native tree
species, including
Acacia senegal, Acacia seyal, Acacia
nilotica, Acacia mellifera, Bauhinia rufescens and
Ziziphus mauritiana
, were established by planting
seedlings and by direct sowing. Herbaceous plants,
such as
Cassia tora, Andropogon gayanus
and
Cymbopogon
sp., were established by direct sowing.
The project also focused on strengthening the
Network for Natural Gums and Resins in Africa, which
involves 15 member countries, through resource
assessment, training programmes and information
sharing.
The project published a working paper, “Guidelines
on sustainable forest management in drylands in sub-
Saharan Africa,” in both English and French.
A regional meeting held in Addis Ababa,
Ethiopia, on 3–4 March 2009 identified the need
for a strategy to develop the outcomes of the pilot
project into a programme large enough to address
the magnitude of food insecurity, poverty, land
degradation and desertification in the region, and
to mitigate and adapt to climate change. The future
programme must first focus on improving livelihoods
through broadening the sources of income for local
populations, while restoring degraded lands and
increasing the productivity of agriculture, range and
forest systems. These are cross-sectoral activities and
the programme must adopt an integrated approach.
The programme will have to be of sufficient scale to
be seen as a major actor in regional initiatives, such
as the GGWSSI. Such a programme would contribute
to combating desertification, to the success of the
GGWSSI and, above all, to improving the well-being
of the whole population in the region.
Source: For further information, see http://www.fao.org/forestry/
aridzone/62998/en/.
1 See http://www.lk.iwmi.org/africa/West/projects/
Adoption%20Technology/RainWaterHarvesting/26-
ValleranisSystem.htm.
Box I2-1.
Acacia operation project – Support to food security, poverty alleviation and soil
degradation control in the gums and resins producer countries
17
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
water conservation and management;
• promoting awareness of the contribution
of forestation and drylands restoration
to climate change adaptation and
mitigation within the framework of carbon
market schemes (e.g. Clean Development
Mechanism, Reduced Emissions from
Deforestation and Forest Degradation
(REDD) and REDD+) and adaptation schemes;
• sustainable financing and investments
(e.g. through payments for environmental
services) and related policy issues;
• monitoring and evaluation of the
performance of restoration initiatives,
and the assessment of their long-
term sustainability and economic and
environmental impacts;
• considering restoration along the whole
market chain value, from the seed to the
final product.
To support the effective planning and implemen-
tation of restoration work in the priority GGWSSI
areas, FAO launched a process for developing
guidelines on dryland restoration based on a
compilation of lessons learned from past and
current forestation and restoration projects and
programmes. As a first step, the Turkish Ministry
of Forestry and Water Affairs, FAO, the Turkish
International Cooperation and Coordination
Agency (TIKA) and the German Agency for In-
ternational Cooperation (GIZ) convened an in-
ternational workshop in Konya, Turkey, in May
2012. This workshop, entitled “Building forest
landscapes resilient to global changes in drylands
This project was implemented between 2000 and
2007 by FAO and the Ministry of Environment
and Sustainable Development of Mauritania, with
financing from the Walloon Region of Belgium. The
project objective was to foster conservation and
development of agrosilvipastoral systems around
Nouakchott, while at the same time combating
encroachment of sand on the green belt around
the city. The project engaged the local community
and national authorities in planning and delivering
activities and in selecting appropriate local plant and
tree species. A total of 400 000 plants were grown in
nurseries and used to fix 857 hectares of threatened
land (inland and costal dunes).
The project employed both mechanical and
biological fixation methods. Partners and beneficiaries
were trained on field techniques and management
of tree nurseries through a participatory approach
involving the local community and the support and
supervision of technical experts from the project.
The project gave priority to the production and
use of indigenous woody and grassy species. For
example,
Aristida pungens
was planted on very
mobile strip dunes in accumulation zones. Deflation
zones were planted with
Leptadenia pyrotechnica,
Aristida pungens
and
Panicum turgidum
, while
other slow-growing woody species, such as
Acacia
raddiana
and
A. senegal
,
were planted in more stable
intermediate zones. Local grassy species were sown
using broadcast seed, while
Colocynthus vulgaris
, a
cucurbit, was sown in pouches. Establishment rate
depended on rainfall. Plantings on coastal dunes
concentrated on halophytic species, including
Nitraria
retusa, Tamarix aphylla
and
T. senegalensis
.
The techniques used and the lessons learned are
presented in detail in an FAO forestry paper published
in 2010, which is available in English, French and
Arabic. The best practices identified are now being
replicated in other regions of Mauritania and will
be promoted for adaptation and implementation in
Mauritania and other countries of the GGWSSI.
Source: FAO (Food and Agriculture Organization of the United
Nations). 2010.
Fighting sand encroachment: lessons from
Mauritania
, by C.J. Berte, with the collaboration of M. Ould
Mohamed & M. Ould Saleck. FAO Forestry Paper 158. Rome.
Box I2-2.
Support to the rehabilitation and extension of the Nouakchott green belt,
Mauritania
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
18
– Analysis, evaluation and documentation of les-
sons learned from afforestation and forest resto-
ration,” aimed at:
• gathering lessons learned from past and
ongoing forest restoration efforts in the
countries involved in the GGWSSI;
• identifying key elements determining
the success or failure of forest restoration
projects and;
• discussing the comprehensive Forest
Restoration Monitoring Tool, recently
developed by FAO to guide planning,
implementation and evaluation of field
projects and programmes.
A number of successful forestation and forest
restoration projects exist in the GGWSSI countries
and these can be quickly upscaled to support the
effective implementation of the initiative. These
include the two projects implemented by FAO
and its partners: the Acacia operation project –
Support to food security, poverty alleviation and
soil degradation control in the gums and resins
producer countries (Box I2-1), implemented in six
sub-Saharan African countries; and the Support
to the rehabilitation and extension of the
Nouakchott green belt, funded by the Walloon
region (Belgium), and implemented in Mauritania
(Box I2-2).
For more information on the Great Green Wall
for the Sahara and Sahel Initiative, please visit
www.fao.org/partnerships/great-green-wall
19
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
Sometimes the choice of plant used in restoration
can have unexpected and dramatic consequences
both at the site of restoration and beyond. This
Insight highlights some examples in which plants
introduced from elsewhere in the world to help
restore disturbed environments resulted in inva-
sion and great environmental damage.
Exotic or non-native trees, shrubs, creepers,
succulents and grasses have all been used to reha-
bilitate sites after human or natural perturbation
has removed indigenous vegetation cover. Many
introductions of exotic plants happened late in
the nineteenth century or early in the twentieth
century, when understanding of the likely impacts
of these species was limited and not considered.
• Pueraria montana (kudzu), indigenous
to China, eastern India and Japan, was
introduced in the United States of America
as a forage and ornamental plant, but was
also extensively used in soil stabilization and
erosion control.5 It is estimated that about
120 000 hectares had been planted with
kudzu by 1946, and the species has since
spread beyond the planted range. By 2004
it was reported to be present and invasive
in 22 states of the southeastern United
States, where it causes extensive damage
by smothering indigenous vegetation. It is
not surprising that this species has a local
common name of “vine that ate the South.”
• Acacia cyclops and Acacia saligna were
5 http://www.na.fs.fed.us/fhp/invasive_plants.
both introduced in the 1830s into South
Africa from Australia to stabilize dunes and
protect roads from sand storms (Carruthers
et al., 2011) but they became invasive
species in the Western Cape of South Africa.
Successful implementation of biological
control measures to reduce seed production
of these species will reduce the long-term
threats they pose.
• Ailanthus altissima (Tree of Heaven), native
to China and northern Viet Nam, has
been used for a wide variety of purposes,
including erosion control, afforestation,
shelterbelts and to line promenades
in Europe and elsewhere in the world.
Consequently, the species has established
and become invasive in suitable, lower-
altitude environments across all of Europe.
For a comprehensive review, see Kowerik
and Säumel (2007).
• Carpobrotus edulis is known by the
descriptive local common name of
“highway iceplant” in California. The
common name refers to the species’
extensive use as a landscape plant to secure
disturbed environments along roads.
Since its introduction it has spread into
natural environments where it threatens
natural vegetation in several different
environments, from dune systems to
scrublands. Carpobrotus edulis is also a
significant problem in Mediterranean
countries, particularly Portugal.
Insight 3
Invasive species and
the inappropriate use of exotics
Philip Ivey
South African National Biodiversity Institute and Working for Water Programme
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 1
20
It is important that we learn from the mistakes
of the past and if possible do not repeat them.
There are several international protocols in place
to encourage better practices to reduce the likeli-
hood of invasions. Article 8(h) of the Convention
on Biological Diversity (CBD) calls on parties to
“prevent the introduction of, control or eradi-
cate those alien species which threaten ecosys-
tems, habitats or species.” The Aichi Biodiversity
Targets6 agreed under the CBD similarly address
invasive species: “By 2020, invasive alien species
and pathways are identified and prioritized, pri-
ority species are controlled or eradicated and
measures are in place to manage pathways to
prevent their introduction and establishment”
(Aichi Target 9).
The International Standards for Phytosanitary
Measures, prepared by the Secretariat of the
International Plant Protection Convention (IPPC)
deals with “environmental risks,” including “in-
vasive plants.” The IPPC encourages each of its
regions to set regional standards. In response
to this, the European and Mediterranean Plant
Protection Organization (EPPO) has set standards
to provide support to members dealing with both
quarantine pests and more recently invasive alien
species, and members are encouraged to manage
these through national phytosanitary regulations.
Hulme (2007) estimates that 80 percent of in-
vasive alien plants in Europe were voluntarily in-
troduced for ornamental purposes. In an effort
to curb the influx of new invasive plant species
to Europe, the EPPO, in collaboration with the
Council of Europe, developed a Code of con-
duct on horticulture and invasive alien plants
(Heywood and Brunel, 2011) aimed at the horti-
cultural industry. To an extent the European code
of conduct has been based around the St Louis
Declaration of 2002,7 which calls on horticultural-
ists and the nursery industry to ensure that unin-
tended harm (risk of invasion) is kept to a mini-
mum when new plant species are considered for
introduction.
6 http://www.cbd.int/sp/targets/
7 http://www.fleppc.org/FNGA/St.Louis.htm
One of the key indicators used to assess wheth-
er a species is likely to be invasive in a particular
environment is whether it has been invasive else-
where in the world. There are numerous reference
lists of invasive and weedy plant species, including
Randall (2002), the Invasive species compendium8
and the DAISIE (Delivering Alien Invasive Species
Inventories for Europe) database.9
In order to achieve the targets set by the CBD
and to reduce the likelihood of new invasive
species being used by the horticultural industry
for landscape rehabilitation, it is important that
governments control imports of new plant spe-
cies. Horticultural interests also should regulate
their own businesses by adhering to the volun-
tary protocols to control invasive species. With
adequate control and self-regulation, the errors
of the past need not be repeated by environmen-
tal managers of today. With better knowledge of
the risks posed by certain species, the goodwill of
all stakeholders and much hard work, there is no
reason why further potentially invasive species
should be introduced for the purposes of environ-
mental rehabilitation.
8 http://www.cabi.org/isc
9 http://www.europe-aliens.org/
21
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
References
Carruthers, J., Robin, L., Hattingh, J.P., Kull, C.A.,
Rangan, H. & van Wilgen, B.W. 2011. A native at
home and abroad: the history, politics, ethics and
aesthetics of acacias. Divers. Distrib., 17: 810–821.
Heywood, V. & Brunel, S. 2011. Code of conduct on
horticulture and invasive alien plants. Convention
on the Conservation of European Wildlife and
Natural Habitats (Bern Convention). Nature and
environment, no. 162. Strasbourg, France, Council
of Europe Publishing (available at: http://www.coe.
int/t/dg4/cultureheritage/nature/bern/ias/Documents/
Publication_Code_en.pdf). Accessed 22 January
2013.
Hulme, P.E. 2007. Biological invasions in Europe: drivers,
pressures, states, impacts and responses. In R.E.
Hester & R.M. Harrison, eds. Biodiversity under
threat, pp. 55-79. Issues in Environmental Science
and Technology 25. Cambridge, UK, Royal Society of
Chemistry.
Kowarik, I. & Säumel, I. 2007. Biological flora of
Central Europe: Ailanthus altissima (Mill.) Swingle.
Perspect. Plant Ecol. Evol. Syst., 8: 207–237.
Randal, R.P. 2002. A global compendium of weeds.
Meredith, Victoria, Australia, R.G. and F.J.
Richardson.
Part 2
THEORETICAL AND
PRACTICAL ISSUES
IN ECOSYSTEM
RESTORATION
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
25
Part 2 presents issues that should be considered
in all restoration efforts, irrespective of the local
context and the specific methods used. Building
on theoretical understanding of genetic pro-
cesses, the authors discuss how selection, ge-
netic drift and gene flow can affect outcomes
of restoration efforts. Local forest remnants are
widely considered to be ideal sources of propa-
gation material because they are assumed to be
well adapted to local conditions as a result of mil-
lennia of natural selection. However, it is often
overlooked that the remnant forests may be too
small to sustain viable populations, and may suf-
fer from genetic drift that results in random loss
of diversity (Chapter 2, Insight 4: Historical ge-
netic contamination in pedunculate oak (Quercus
robur L.) may favour adaptation and Chapter 4).
Gene flow through pollen and seed dispersal can
counteract negative implications of small popu-
lations (Chapter 5). Transferring genetic material
over longer distances may, however, threaten
indigenous genetic diversity and result in a loss
of local adaptations (Chapter 6 and Chapter 3).
However, such long distance transfers may be
beneficial in certain circumstances (see Insight 4:
Historical genetic contamination in pedunculate
oak (Quercus robur L.) may favour adaptation). In
most cases, little is known about the extent and
distribution of genetic diversity of tree species
used in restoration. Rules of thumb may exist for
collecting and transferring propagation material
in such cases, although those remain little studied
in practice (Chapter 7).
The introduction to the theoretical concepts
is followed by presentation of examples of their
practical application and constraints faced in res-
toration efforts. Various types of propagation
materials are discussed and guidance is provid-
ed on choosing suitable types for local contexts
(Chapter8). Considering the current proliferation
of restoration efforts and the simultaneous deg-
radation of natural tree populations of many spe-
cies, little attention is usually given to the sustain-
able sourcing of massive amounts of propagation
material (see Chapter8 and Insight6: Seed avail-
ability: a case study). Seed banks are effective and
often-overlooked sources of material for those
species that can easily be stored as seed (Insight7:
The role of seed banks in habitat restoration).
Traditional ecological knowledge held by local
and indigenous communities can be a valuable
source of information on suitable tree propa-
gation and management practices, not least be-
cause it has played an important role in shaping
tree diversity for hundreds or thousands of years
in many areas (Chapter10). Finally, restoration ef-
forts should not be planned in isolation but must
carefully consider the local landscape context,
recognizing and appreciating the needs and pri-
orities of the various interest groups (Chapter11).
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
27
Diverse biological, cultural, environmental and
socioeconomic conditions across the world de-
mand diverse approaches to forest or habitat
restoration and sustainable farming. Trees are a
vital component of many farming systems, while
a range of agroforestry systems have the poten-
tial to conserve native species as well as to diver-
sify and improve the production and income of
resource-poor farmers. Although native species
are usually favoured in tree planting for for-
est or habitat restoration or by local people on
farms, often only a limited range of management
options and tree species (often exotics) are pro-
moted.
Tree planting depends on a ready supply of
germplasm (seeds or vegetative material) of the
chosen species, which in turn requires consid-
eration of what is the best or most appropriate
source of seed. Inevitably the choice of seed source
should be influenced by the objective of planting
(e.g. for restoration or production, future adapt-
ability or past adaptation) and the risks associated
with particular seed sources (e.g. loss of adapta-
tion, outbreeding depression, loss of diversity, ge-
netic bottlenecks or contamination of native gene
pools). Choice of seed source, both in terms of its
location and its composition, can have important
consequences for the immediate success and for
the long-term viability of plantings.
Many tree species are outbreeding and gener-
ally carry a heavy genetic load of deleterious reces-
sive alleles. This means that inbreeding, in particu-
lar selfing, can have negative impacts, including
reduced seed set and survival resulting in poorer
regeneration, progeny with slower growth rates
and lower productivity, limited environmental tol-
erance and increased susceptibility to pests or dis-
eases. Consequently, the use of genetically diverse
germplasm is vital if plantings are to be productive,
viable and resilient. Intraspecific genetic diversity
may, however, be limited by several factors relat-
ed to the sourcing of seed. For example, farmers,
nursery managers and commercial collectors may
collect seed from only a few trees as this requires
less effort than collecting from many trees; how-
ever, this captures only a small amount of the vari-
ability present. In addition, variability in fertility
between trees can contribute to a rapid accumula-
tion of relatedness and inbreeding in subsequent
generations. Genetic issues can also be of particular
concern for nursery material, where inbred mate-
rial may survive benign nursery conditions but be
genetically compromised for survival and growth
when planted out in the wider environment.
Chapter 2
Seed provenance for restoration
and management: conserving
evolutionary potential and utility
Linda Broadhurst1 and David Boshier2,3
1 CSIRO Plant Industry, Australia
2 Department of Plant Sciences, University of Oxford, United Kingdom
3 Bioversity International, Italy
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2.1. Local versus non-local seed
Many guidelines for sourcing seed to restore
plant populations and communities advocate the
use of local seed under the premise that this will
be better adapted to local conditions and deliver
superior outcomes through improved survival
and growth (Broadhurst et al., 2008 and refer-
ences therein). Apart from the possibility of non-
local seed being maladapted to local conditions,
using seed collected close to a restoration site
is also predicted to prevent negative outcomes,
such as intraspecific hybridization (potentially)
resulting in outbreeding depression, superior in-
troduced genotypes becoming invasive and im-
pacts on associated organisms such as bud burst
occurring prior to herbivore emergence, and to
help maintain a range of biotic interactions with
pollinators and pathogens (Linhart and Grant,
1996; Jones, Hayes and Sackville Hamilton, 2001;
Cunningham et al., 2005; Vander Mijnsbrugge,
Bischoff and Smith, 2010). Although the impor-
tance of local provenance in habitat conserva-
tion and restoration remains contentious (e.g.
Sackville Hamilton, 2001; Wilkinson, 2001), the
concept is easy to understand and the message
is therefore attractive and easy to “sell” (see, for
example, www.floralocale.org). Hence the Gen-
eral guidelines for the sustainable management
of forests in Europe (MCPFE, 1993) state that
“native species and local provenances should be
preferred where appropriate.” Forest certifica-
tion and timber labelling standards also require
action to conserve genetic diversity and to use lo-
cal provenances (e.g. PEFC, 2010; UKWAS, 2007).
Grants for tree planting often require the use of
local material, although this may depend on the
purpose of planting (e.g. Forestry Commission,
2003).
Despite such requirements to source seed lo-
cally, many guidelines provide little direction
as to how this should be evaluated (Broadhurst
et al., 2008), with practitioners often interpret-
ing guidelines in a spatial context at a range of
scales (e.g. as small as a particular farm or wood
to as large as a country). To fully evaluate the
superiority of local seed requires complex experi-
ments and long-term monitoring that go beyond
early effects on germination and growth, and
that are beyond the scope of most restoration
projects. Consequently, there is often little empir-
ical evidence for deciding how local a seed source
should be. Should seed come from the same
wood, the same watershed, the same county or
the same country? Is geographical or ecologi-
cal distance more important (e.g. Montalvo and
Ellstrand, 2000)? With limited information about
the extent and scale of adaptive variation in na-
tive trees, discussion about suitable seed sources
often emphasizes “local” in a very narrow sense
or within political boundaries, rather than being
based on sound evidence of the scale over which
adaptation occurs.
The requirement to use locally collected seed
has been given such precedence that restoration
projects have occasionally been abandoned be-
cause of a lack of appropriate local seed sources
(Wilkinson, 2001). Use of native species in both
restoration and on farms has also been limited by
a lack of basic information on seed storage and
germination and establishment methods; a reflec-
tion of the historical emphasis on plantation for-
estry with a limited range of exotic species.
2.2. Basic concepts and theory
It is worth considering some basic concepts to ap-
preciate to what extent and at what scale local
adaptation may apply. The forces of natural se-
lection may vary in space, resulting in genotype
× environment interactions for fitness. In the ab-
sence of other forces and constraints, such diver-
gent selection should cause each local population
to evolve traits that provide an advantage under
its local environmental conditions (i.e. its habitat),
regardless of the consequences of these traits for
fitness in other habitats. What should result, in
the absence of other forces and constraints, is
a pattern in which genotypes of a population
would have on average a higher relative fitness
in their local habitat than genotypes from other
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
29
habitats. This pattern and process leading to it is
local adaptation (Williams, 1966).
However, local adaptation may be hindered by
gene flow, confounded by genetic drift, opposed
by natural selection as a result of temporal envi-
ronmental variability and constrained by a lack of
genetic variation or by the genetic architecture of
underlying traits. Thus, although divergent natu-
ral selection is the driving force, these other forc-
es, in particular gene flow, are integral aspects of
the process of local adaptation. Owing to such
forces, local adaptation is not a necessary out-
come of evolution under spatially divergent se-
lection (Kawecki and Ebert, 2004). Environmental
heterogeneity also favours the evolution of adap-
tive phenotypic plasticity. Where there are no
costs of and constraints on plasticity, a genotype
that produces a locally optimal phenotype in each
habitat would become fixed in all populations.
Adaptive phenotypic plasticity would lead to
adaptive phenotypic differentiation, but without
underlying genetic differentiation. Lack of plas-
ticity is thus a prerequisite for local adaptation.
In summary, factors predicted to promote local
adaptation include: low gene flow (i.e. restricted
pollen or seed dispersal, or strong habitat fidel-
ity), strong selection against genotypes optimally
adapted to other habitats but moderate selection
against intermediate genotypes (most likely un-
der moderate differences between habitats with
respect to traits under selection), little temporal
variation in the forces of selection, small differ-
ences between habitats in size and quality (e.g.
the amount of resources) and costs of or con-
straints on adaptive plasticity.
2.3. Historical perspective of local
adaptation
The extent to which observed morphological and
growth differences in plants are under genetic
control and related to the environment in which
a population occurs, has formed fertile ground for
research. Linnaeus reported as early as 1759 that
yew trees brought to Scandinavia from France
were less winter hardy than indigenous Swed-
ish yews. In his classical research, Turesson (1922)
studied populations of several herbaceous species
in transplant common garden experiments, dem-
onstrating the widespread occurrence of intraspe-
cific, habitat-related genetic variation and intro-
ducing the term “genecology.” Clausen, Keck and
Hiesey (1940) extended study of the expression of
population adaptation to environmental differ-
ences by using climatically different sites over a
range of altitudes. Subsequent research has shown
that such genetically related adaptive variation is
widespread in herbaceous species with low levels
of gene flow under strong selection pressures (see
summary in Briggs and Walters, 1997). There are
many key differences between herbaceous plants
and trees, where long life cycles, wide distribu-
tions and extensive gene flow (pollen and seed
dispersal) would tend to suggest more extensive
scales and patterns of adaptation, with differ-
ences most likely to occur at the geographic and
altitudinal extremes of species ranges.
2.4. The scale of local adaptation
in trees: how local should a
seed source be?
Evidence for strong local adaptation effects, es-
pecially in trees, remains mixed and such adap-
tation is very difficult to predict (Ennos, Worrell
and Malcolm, 1998; Montalvo and Ellstrand, 2000;
Joshi et al., 2001; Hufford and Mazer, 2003; Bis-
choff et al., 2006; Leimu and Fischer, 2008). Prov-
enance and progeny field trials have shown that
while genotype × environment interaction occurs
in many tree species, this may not be expressed
as a home-site advantage (i.e. provenance perfor-
mance is unstable across sites, but not as a result
of greater fitness of local seed source). Geograph-
ical proximity may be a poor indicator of adaptive
fitness (e.g. Betula spp.; Blackburn and Brown,
1988) and also stability, with some provenances
that show stable performance across sites origi-
nating from sites adjacent to unstable performers
(e.g. Kleinschmit et al., 1996).
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The northern hemisphere forestry literature
suggests that latitudinal or altitudinal gradi-
ents, or both, can be important for detecting the
scale of local adaptation, but that other factors
such as habitat, rainfall and topographical dif-
ferences can also be significant (Ennos, Worrell
and Malcolm, 1998). There is evidence for adap-
tive variation over reasonably short distances in a
number of conifer tree species in western North
America, owing to features such as aspect and al-
titude (e.g. Adams and Campbell, 1981; Sorensen,
1994). This is particularly marked in areas with
oceanic climates, where environmental gradients
are much steeper than in more continental sites.
Field, greenhouse and laboratory studies on co-
nifer species in the northwestern United States
show that a significant proportion (typically 25–
45 percent) of the genetic variation within popu-
lations is accounted for by climatic (e.g. rainfall
and temperature) or location (e.g. latitude, alti-
tude, slope aspect, distance from ocean) variables
that reflect environmental factors specific to each
location. There are often differences between
provenances from warmer and colder climates,
the former showing adaptation to the longer
growing season in lower latitudes but suffering
from early or late frosts when moved too far into
higher latitudes. The degree of risk in transplant-
ing across a species’ distribution is correlated
more with environmental changes than with
the geographical distance moved (Adams and
Campbell, 1981; see Insight 5). This suggests that
habitat matching may be a more useful means of
determining where seed should be sourced than
would be an arbitrary distance from the site to be
restored. Provenance trials of a number of tropi-
cal tree species show that most morphological ge-
netic variation occurs within rather than between
provenances. In most of the species studied, rank-
ing reversals (adaptation) or significant geno-
type × environment interactions only occur with
large environmental site differences (e.g. dry vs
wet zones, alkaline vs acidic soils). Unfortunately,
almost nothing is currently known about local
adaptation in temperate southern hemisphere
species.
Currently there are too few studies from too
few regions of the world to allow for predictions
regarding the scale and importance of local ad-
aptation for the myriad of life-history traits and
evolutionary histories of tree species that re-
quire restoration. For example, Leimu and Fischer
(2008) used only 32 species in their local adapta-
tion meta-analysis, none of which were tree spe-
cies. There is also a need for reciprocal transplant
experiments (RTEs), which test the fitness of
“home” and “away” genotypes within the sites
from which the genotypes originate (Primack and
Kang, 1989) and can mimic natural regeneration
by establishing seedlings in a forest at close spac-
ings to encourage early competition and with
minimal intervention (e.g. little or no weeding).
Germplasm selected and tested in forestry trials
or plantations for growth, form and other com-
mercial criteria may be less suited to the more
competitive environment of semi-natural forests
and restoration.
The scale over which species show adaptation
to their environment depends on the degree of
habitat heterogeneity, in particular the specific
habitat characteristics that affect a species, and
the interaction with gene flow. Dispersal levels
may be a useful high-level predictor of the im-
portance of local adaptation, under the premise
that species with long-range gene flow are less
likely to generate strong local adaptation, where-
as restricted gene flow is more likely to generate
genotypes adapted to their local environment.
Extensive gene flow in widely distributed tree
species suggests that local adaptation over a small
geographic scale is unlikely unless selection forces
are very strong.
2.5. Are non-local seed sources
ever appropriate?
In highly modified or degraded landscapes, us-
ing non-local seed may be entirely appropriate
or indeed the only option for restoration. Miti-
gating the negative physical effects associated
with vegetation removal, such as loss of topsoil,
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
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altered hydrological flows or increased nutrient
loads, may require specific germplasm that is able
to cope with these conditions. For example, sa-
line scalds in southern Australia that developed
following the removal of deep-rooted perennials
are not generally amenable to restoration using
local species, let alone local seed. In these cases,
planting saline-tolerant varieties of other species
may be the only option to prevent further degra-
dation of valuable agricultural land. The loss of
diversity at genes of major effect may also require
sourcing of seed from non-local populations. For
example, small populations of self-incompatible
plants can be mate-limited if diversity in the in-
compatibility locus is low, requiring seed from
beyond the local area to introduce new mating
types. However, impacts on local species and
communities that may arise from using non-local
seed need to be considered carefully, preferably
prior to restoration and using an appropriate risk
management framework (Byrne, Stone and Mil-
lar, 2011). This should also include analysis of the
risk of not undertaking restoration and allowing
landscape degradation and biodiversity loss to
continue.
2.6. Local seed sources may not
produce restoration-quality
seed
Habitat fragmentation remains a major threat
to biodiversity worldwide through the loss of
populations and consequent altered biotic and
abiotic processes (Bakker and Berendse, 1999;
Eriksson and Ehrlen, 2001; Hobbs and Yates,
2003; Lienert, 2004). Unfortunately, some re-
gions of the world have now reached a tipping
point, such that whole biomes may be in danger
of collapse (Hoekstra et al., 2005). The most im-
mediate consequence of fragmentation for use
of native species in restoration and farm systems
is limitations to seed supply following the loss of
individuals and populations. But several nega-
tive genetic and demographic effects associated
with fragmentation can also have an impact on
the quantity and quality of seed available. The re-
moval of trees and populations from landscapes
directly reduces genetic diversity, most of which
is irreplaceable since genetic mutations accumu-
late slowly over long evolutionary periods (i.e.
tens of thousands to millions of generations).
Diversity is further eroded in small populations
by drift resulting from random sampling within
populations, as well as inbreeding as a result of
trees in remnant populations often being more
highly related than those in larger populations
(Barrett and Kohn, 1991; Ellstrand and Elam,
1993). Reduced fitness and productivity are com-
monly documented effects associated with ge-
netic erosion and inbreeding, both of which can
have an impact on a population’s ability to persist
in stressful situations or changing environments
(Frankham, Ballou and Briscoe, 2002; Hughes et
al., 2008). Other negative outcomes include poor
reproductive success, smaller, poor-quality plants
and increased susceptibility to pests and patho-
gens (Lienert, 2004 and references therein). Over
time, this exposes small populations to decline
through recruitment failure (Figure 2.1) and lim-
its their utility as appropriate seed sources for
restoration. Limited seed supply and poor-quality
seed are two major impediments to the successful
planting of native species and restoration of na-
tive vegetation, especially at the landscape level.
Worldwide analyses of fragmentation impacts
on plant reproduction indicate that some spe-
cies are shifting towards selfing (Aguilar et al.,
2006; Aguilar et al., 2008; Eckert et al., 2010), but
how this translates to seed production depends
largely on reproductive strategy. For example,
species that cannot self or mate with close rela-
tives (self-incompatible) will not produce seed
unless pollinated by distantly- or non-related
trees and small, self-incompatible populations
are often characterized by reduced seed produc-
tion, severely limiting quantities available for
restoration. In contrast, species that can self and
mate with close relatives (self-compatible) con-
tinue to produce seed but this is often less fit, be-
ing smaller, slower to germinate and with poorer
survival (Buza, Young and Thrall, 2000; Young
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
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et al., 2000; Mathiasen, Rovere and Premoli,
2007). Restoration using this seed is therefore
likely to produce poorer results than expected
and over the long term is less likely to develop
into a self-sustaining population. A requirement
that only local seed be used for restoration can
drive practitioners to use seed from small, inbred
populations that are unlikely to produce posi-
tive long-term restoration outcomes, but rather
create more small, inbred populations, with lim-
ited long-term persistence. One consideration is
that populations restored with a narrow genetic
base may be limited in their ability to respond
to the rapid predicted shifts in climatic variables
(Helenurm, 1998).
2.7. Adaptation and climate
change
There are theoretical reasons that underlie ob-
served patterns of adaptive variation; these also
suggest that many tree species over large areas
may fail to show local adaptation at a very narrow
scale. The prevalence of extensive gene flow may
counteract selection, while the temporal varia-
tion in selective forces that trees experience (e.g.
yearly variation in temperature, frosts or rainfall)
is likely to have a stabilizing effect rather than the
directional selection that would lead to highly lo-
calized adaptation. Given the long life of trees,
the environment is also likely to have altered over
the lifespan of a tree or only a few generations,
such that a particular site no longer experiences
the same conditions under which the trees origi-
nally evolved. These factors explain the relative
lack of adaptation over short distances in many
tree species. Temporal variation in environment
is particularly important for trees, not only with
respect to past adaptation but also in the context
of predicted climate change (e.g. Broadmeadow,
Ray and Samuel, 2005), and thus undue emphasis
on local seed sources may also cause problems.
Figure 2.1.
Simplified representation of how low genetic
diversity and inbreeding can impact on plant
population persistence and seed production in
small populations of plants
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
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2.8. Benefits of using larger but
more distant seed sources
Using large populations as primary seed sources
for restoration not only ensures that seed quality
will be higher but also that larger quantities are
available. In many cases a population of 100–200
plants would be large enough to provide good-
quality seed, but more than 400 plants may be
needed for some species. A good restoration out-
come is also more likely if the habitat of the site to
be restored is matched as closely as possible with
that of the nearest large population. Seed from
these large populations could be augmented
with that collected from small populations closer
to the restoration site to capture any useful ge-
netic diversity they may contain (Broadhurst et
al., 2008). To capture as much genetic diversity as
possible from large populations, as many plants
as practically possible should be sampled broadly
across the site, collecting from a range of cohorts,
from various sides of plant canopies without dis-
rupting biotic associations that also rely on this
seed. Breed et al. (2012) reviewed such strate-
gies for sourcing restoration seed (Box 2.1) and
summarized their suitability for mitigating cli-
mate change and habitat fragmentation impacts
(Table 2.1).
The mixing of introduced and native germplasm
raises the issue of outbreeding depression; the
potential problem of reduced vigour as adapted
gene complexes are broken up or the proportion
of locally adapted alleles is reduced. As with local
adaptation, evidence for outbreeding depression
comes from herbaceous species that show highly
localized adaptation (see Hufford and Mazer,
2003) and there is little evidence for its occur-
rence in trees at distances of less than hundreds
of kilometres (e.g. Hardner et al., 1998, Boshier
and Billingham, 2000). For example large-scale
importation of cheap seed from Eastern Europe
has shown problems of maladaptation in Britain.
But it seems unlikely that use of material from
maritime France that matches future climate pre-
dictions (Broadmeadow et al., 2005) and of similar
phylogeographic origins will face such problems,
nor lead to outbreeding depression problems on
introgression with British material.
2.9. Conclusions
Any genetic conservation policy for native trees
should aim at conserving the evolutionary po-
tential of their populations, rather than at pre-
serving a particular genetic structure and status.
The extent and scale of local adaptation in many
tree populations, and thus its practical impor-
tance to restoration efforts, remain in doubt.
While there is a need for more field trials, both
of the traditional provenance or progeny and
RTE types, to provide more information on the
scale of adaptation, planting of native trees con-
tinues apace and demand for seed from certified
sources increases. There is good evidence to sug-
gest that emphasis on a very restricted view of
what is “local” will not lead to better-adapted
tree populations and is more likely to lead to use
of stock of limited genetic diversity than would a
broader approach.
It has been argued that, given the lack of ex-
tensive trials investigating adaptive variation
in native tree populations, the precautionary
principle should be adopted in sourcing germ-
plasm for planting trees (e.g. Flora Locale, 1999;
UKWAS, 2007). This is expressed as the use of lo-
cal seed, although the subsequent view of what
constitutes the local population varies from a
particular forest to large seed zones. However,
given current evidence for trees, i.e. clear dan-
gers from inbreeding and loss of genetic diver-
sity, with extensive gene flow and adaptation at
a broad scale, it seems more logical to apply the
precautionary principle in terms of ensuring the
use of genetically diverse material with the ca-
pacity to adapt to current and future conditions.
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Strict local provenancing: collecting seeds
from plants that are located physically very close
to the revegetation site (e.g. Natural England,
United Kingdom: 5 miles; Western Australian Forest
Management Plan 2004–2014: 15 km).
Relaxed local provenancing: collecting seeds
with a bias towards certain ecological criteria, and
avoiding small population fragments (e.g. Australian
FloraBank: soil type, altitude and climate).
Predictive provenancing (Sgrò, Lowe and
Hoffmann, 2011): use of naturally occurring
genotypes experimentally determined to be adapted
to projected conditions. This technique requires
data on local adaptation of target species (e.g. by
reciprocal transplant experiments), as well as climate
projections for these species at a revegetation site
(e.g. by bioclimatic modelling).
Composite provenancing (Broadhurst
et al.
,
2008): collecting a mixture of seed that attempts
to mimic natural gene-flow dynamics. For example,
recommended proportions of seed collected from
local, intermediate and distant distance-classes could
be determined by estimating the pollen dispersal
kernel for target species.
Admixture provenancing (Breed
et al.
, 2012):
collecting seed only from large populations, focusing
on capturing a wide selection of genotypes from a
diversity of environments with no spatial bias towards
the revegetation site. These seeds are then admixed
for sowing or planting, generating a population
with a mixture of genotypes from a wide array of
provenances.
References
Breed, M.F., Stead, M.G., Ottewell, K.M., Gardner,
M.G. & Lowe, A.J. 2012. Which provenance and where?
Seed sourcing strategies for revegetation in a changing
environment.
Conserv. Genet.
, November 2012. doi:
10.1007/s10592-012-0425-z.
Broadhurst, L.M., Lowe, A., Coates, D.J., Cunningham,
S.A., McDonald, M., Vesk, P.A. & Yates, C. 2008. Seed
supply for broadscale restoration: maximising evolutionary
potential.
Evol. Appl.
, 1: 587–597.
Sgrò, CM, Lowe, A.J. & Hoffmann, A.A. 2011. Building
evolutionary resilience for conserving biodiversity under
climate change.
Evol. Appl.
, 4: 326–337.
Source: Breed, M.F., Stead, M.G., Ottewell, K.M., Gardner, M.G.
& Lowe, A.J. 2012. Which provenance and where? Seed sourcing
strategies for revegetation in a changing environment.
Conserv.
Genet.
, November 2012. doi: 10.1007/s10592-012-0425-z.
Box 2.1.
Summary of alternative strategies for sourcing seed for restoration
TABLE 2.1.
Suitability of provenancing techniques under climate change with habitat fragmentation
Provenancing
technique Adaptive
potential
benefits
Genetic rescue
benefits Low genetic
load Suitable
with high
uncertainty
Economically
efficient Likely
population
success
Strict local x*
Relaxed local x*
Predictive x x x
Composite x x x x
Admixture x x x x x
* May experience high failure rates, negating the economic benefit.
Benefit rests on successfully matching genotype fitness with future conditions.
Source: Breed
et al.
(2012).
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
35
Current threats to the maintenance of genetic
diversity come principally from poor practice in
seed collection; undue emphasis on restricting
the area of collection or poor instruction of col-
lectors can limit the number of trees and hence
genetic diversity sampled, leading to the estab-
lishment of trees with restricted genetic diversity
and limited future adaptive potential. A study
of the few remnant ash and rowan trees in the
denuded Carrifran valley in southern Scotland
showed that large amounts of genetic diversity
are maintained, making them suitable for use in
restoration despite their highly fragmented na-
ture (Bacles, Lowe and Ennos, 2004). In contrast,
some of the locally sourced material planted as
part of the Carrifran wildwood restoration pro-
ject was shown to be low in genetic diversity
(Kettle, 2001), presumably because of poor col-
lection practices, which impose limitations on the
future potential of the population.
It is disturbing to contemplate that some of
the poorest seed sources exist in the very regions
where restoration is most needed and that con-
tinued requirements for using local seed simply
perpetuate the problem. In many regions of the
world with fragmented forest populations, being
able to reliably source large volumes of quality
seed of native species can be challenging. Not
only are there fewer populations from which seed
can be collected, but fragmentation has split con-
tinuous populations into much smaller and more
isolated remnants, which can impact the quality
and quantity of seed (e.g. Lowe et al., 2005). The
implications from this are that (i) remnant vegeta-
tion contains all of the diversity that is left that
is extremely valuable, and (ii) it is important that
most of the diversity that does remain is used
for restoration (i.e. avoid over-collection from a
few populations). In regions where fragmenta-
tion is high, should the rules for using local seed
change? Can we afford the luxury of being too
restrictive about seed sources? Are small, frag-
mented and probably inbred populations so pre-
cious that we cannot source seed from beyond
our comfort zone?
References
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Laboratory, Oregon State University.
Aguilar, R., Ashworth, L., Galetto, L. & Aizen, M.A.
2006. Plant reproduction susceptibility to habitat
fragmentation: review and synthesis through a meta-
analysis. Ecol. Lett., 9: 968–980.
Aguilar, R., Quesada, M., Ashworth, L., Herrerias-Diego,
Y. & Lobo J. 2008. Genetic consequences of habitat
fragmentation in plant populations: susceptible signals
in plant traits and methodological approaches. Mol.
Ecol., 17: 5177–5188.
Bacles, C.F.E, Lowe, A.J. & Ennos, R.A. 2004. Genetic ef-
fects of chronic habitat fragmentation on tree species:
the case of Sorbus aucuparia remnants in a deforested
Scottish landscape. Mol. Ecol., 13: 574–583.
Bakker, J.P. & Berendse F. 1999. Constraints in the restora-
tion of ecological diversity in grassland and heathland
communities. Trends Ecol. Evol., 14: 63–68.
Barrett, S.C.H. & Kohn, J.R. 1991. Genetic and evolution-
ary consequences of small population size in plants:
implications for conservation. In D.A. Falk & K.E.
Holsinger, eds. Genetics and conservation of rare
plants, pp. 3–30. New York, USA, Oxford University
Press.
Bischoff, A., Cremieux, L., Smilauerova, M., Lawson,
C.S., Mortimer, S.R., Dolezal, J., Lanta, V., Edwards,
A.R., Brook, A.J., Macel, M., Leps, J., Steinger, T. &
Müller-Schärer, H. 2006. Detecting local adaptation in
widespread grassland species – the importance of scale
and local plant community. J. Ecol., 94: 1130–1142.
Blackburn, P. & Brown, I.R. 1988. Some effects of expo-
sure and frost on selected birch progenies. Forestry, 61:
219–234.
Breed, M.F., Stead, M.G., Ottewell, K.M., Gardner, M.G.
& Lowe, A.J. 2012. Which provenance and where?
Seed sourcing strategies for revegetation in a changing
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environment. Conserv. Genet., November 2012. doi:
10.1007/s10592-012-0425-z.
Briggs, D. & Walters, S.M. 1997. Plant variation and evolu-
tion (3rd ed.). Cambridge, UK, Cambridge University
Press.
Broadhurst, L.M., Lowe, A., Coates, D.J., Cunningham,
S.A., McDonald, M., Vesk, P.A. & Yates, C. 2008.
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A population of trees or shrubs is autochthonous
if it has regenerated naturally since its arrival af-
ter the last glaciation; any human intervention in
breeding should have occurred with strictly local
material only. For long-lived species such as trees,
autochthony assumes a continuous presence at a
given site since post-glacial immigration (Klein-
schmit, Kownatzki and Gegorius, 2004). This im-
plies a continuity of local genetic diversity after
thousands of years of natural selection. Trees and
shrubs that belong to native species but are im-
ported from other climatic zones or geographic
regions are not autochthonous.
After many years of neglect, the use of na-
tive species in afforestation and landscape pro-
grammes is gaining importance all over the
world, based on the basic underlying ecological
principle that native species and genotypes will
be well adapted to local conditions and will have
co-evolved with other components of local forest
ecosystems. This has led to massive plantations
of indigenous tree and shrub species in Western
Europe, not only in forestry but also for native
woodland restoration and other landscape plant-
ings, such as thickets, wooded banks and hedge-
rows. A major challenge is to ensure that plant-
ing material used represents the genetic variation
and diversity within native species. Several initia-
tives have been developed in various European
countries to promote the use of locally sourced
seeds for the production of planting stock (e.g.
Belgium: Vander Mijnsbrugge, Cox and Van
Slycken, 2005; Germany: Kleinschmit, Leinemann
and Hosius, 2008; Denmark: Kjaer et al., 2009).
Here we describe in detail the programme on the
production of autochthonous planting stock in
Flanders, Belgium.
3.1. Why should autochthonous
diversity be protected?
There is a high demand for “native” planting
stock in Flanders, Belgium, and to a broader ex-
tent in many Western European countries. The
use of native planting material is promoted by
a wide range of public organizations. However,
planting stock of native material in commercial
nurseries is largely not autochthonous. Seeds of
native species are often imported, originating
from foreign provenances, often in Eastern Eu-
ropean countries. This is especially true for shrub
species. For trees, in the European Union, Coun-
cil Directive 1999/105/EC of 22 December 1999
(Council of the European Union, 2000) regulates
the marketing and transport of forest reproduc-
tive material through an obligatory certification
system indicating the origin of the material (al-
though control in practice is not perfect). How-
ever, certification is not obligatory for shrubs, and
Chapter 3
Continuity of local genetic diversity
as an alternative to importing
foreign provenances
Kristine Vander Mijnsbrugge1,2
1 Research Institute for Nature and Forest, Belgium
2 Agency for Nature and Forest, Belgium
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 2
40
shrub germplasm is commonly imported from
Eastern and Southern Europe where cheaper
seed is available. Nursery managers often do not
know or are not interested in the exact origin of
the seed they obtain. Tree seed may also be im-
ported when seed is not available from officially
approved sources or supplies are too limited to
meet requirements.
Introduction of non-local material can
have numerous negative consequences. Non-
autochthonous planting stock may be poorly
adapted to local growing conditions, which can
lead to negative consequences such as lower
fitness (e.g. McKay et al., 2005; Krauss and He,
2006; Edmands, 2007; Laikre et al., 2010; Vander
Mijnsbrugge, Bischoff and Smith, 2010). Problems
may only become evident many years after seem-
ingly successful establishment. Intraspecific hy-
bridization of local and introduced genotypes
may result in outbreeding depression, i.e. re-
duced fitness in subsequent generations, loss
of genetic diversity and loss of adaptation, and
less adapted characteristics can introgress into
the autochthonous populations. The introduc-
tion of non-local material may also have negative
effects on associated plant and animal species.
Imported hawthorn (Crataegus monogyna) has
been shown to flower several weeks earlier than
native hawthorn, potentially threatening the in-
sects and birds whose reproductive cycles are syn-
chronized with this event (Hubert and Cottrell,
2007). In addition, purity of the species can be
problematic in commercial planting stock. A ge-
netic study on commercially available hawthorn
in Flanders, grown from seeds imported from
Hungary, showed that it comprised a mixture of
C. monogyna and C. monogyna × C. rhipidophylla
(Debeer, 2006).
3.2. Inventory of autochthonous
woody plants
A simple way to ensure the continuity of local ge-
netic diversity is the production of autochthonous
planting stock. For this an overview is needed of
the remnant autochthonous populations still pre-
sent. A survey was conducted to locate remaining
autochthonous populations in Flanders, Belgium,
from 1997 to 2008. The evaluation of autoch-
thony in the field was conducted following the
methodology presented by Maes (1993). In short,
areas of woody vegetation that are indicated as
forest on historical maps are identified. Informa-
tion on flora, soil conditions and geomorphology
further refine the selection of potentially rel-
evant sites. In the field, the woody vegetation is
evaluated according to a set of criteria. The tree
or shrub must be a wild variety and old. No evi-
dence must be seen of plantation (e.g. trees in
lines). The site must be located within the natural
geographic range of the species, and the growth
conditions correspond to the ecological require-
ments of the species. The tree or shrub must be
present on similar sites in the surrounding area. A
variety of plants in the tree, shrub or herb layer is
indicative of undisturbed woodland and ancient
forests. If hedges or wooded banks have been
planted with locally sourced material the plants
can be considered autochthonous.
The findings show that autochthonous woody
plants have become seriously endangered in
Flanders, with only about 6 percent of the cur-
rent forest cover holding autochthonous woody
plants. Several causes for this loss of autoch-
thonous material are evident. Only 11 percent
of Flanders is now forested and what there is is
highly fragmented as a result of centuries of in-
tensive forest use. Small fields have been replaced
by large, open expanses of farmland, with the
consequent disappearance of wooded banks, old
hedges and small forests on farmland.
The inventory data (in Flemish) are accessible
on the internet (www.natuurenbos.be).
3.3. Producing autochthonous
planting stock
The Agency for Nature and Forest (ANB), under
the Flemish Forest Administration, has been col-
lecting seed from inventoried sites since 1998 to
GENET IC CONS IDERATI ONS IN ECO SYSTEM RE STORATI ON USING N ATIVE TRE E SPECIE S
41
produce autochthonous planting stock. Seed is
collected from natural populations present on
inventoried sites (so-called in situ collecting) fol-
lowing general guidelines for appropriate col-
lection methods. Sites adjacent to plantations of
the same species are omitted because of the risk
of cross-pollination from unknown provenances.
Seed is collected from at least 30 seed-bearing
plants per species within each region of prove-
nance. Region of provenance, a term commonly
used in forestry, is an area within which move-
ment of plant material will not negatively affect
the fitness of the populations in the long run.
In Flanders, the surveyed sites are mostly frag-
mented, small and are not managed for seed
production. Therefore, several sites must be vis-
ited to find 30 seed-bearing trees or shrubs for
every species. This implies a time-consuming and
costly effort. The Flemish legislation (Anony-
mous, 2003a), which follows Council Directive
1999/105/EC, allows mixing seed lots within a re-
gion of provenance. This practice guarantees a
good genetic variability in the derived planting
stock. A genetic study on sloe (Prunus spinosa) in
Flanders showed that old autochthonous hedges
dominated by sloe may show low within-popula-
tion genetic diversity. In this case, mixing of seed
lots from different autochthonous locations is
specifically advised (Vander Mijnsbrugge et al.,
in press.
Until now, the planting stock has been grown
in two government nurseries located in Koekelare
and in Brasschaat. However, the decision has been
taken to close them, mainly for financial reasons.
Future planting stock will be grown increasingly
in private nurseries under contract. The autoch-
thonous planting stock is used only in forests
owned by or managed by ANB. As seed collection,
growth and planting are all performed within the
forest administrative boundaries, no certification
or control system is involved.
Since 1998 seeds have been collected also by
public organizations called Regional Landscapes
(“Regionale Landschappen”) that are working to
protect and enhance the local authenticity of ru-
ral landscapes (Table 3.1). Here, all planting stock
is grown in private nurseries under a sales con-
tract. The seeds and derived planting stock are
not certified, and the work of the nursery is not
controlled by any official agency, necessitating a
relationship of trust between the client and the
nursery. Again, this autochthonous planting stock
is used in the Regional Landscapes’ own projects,
mainly landscape plantings such as hedgerows,
wooded banks, on farms, etc., and can also be
sold to local people.
Since 2004 seeds can be collected on invento-
ried sites that are officially approved as a seed
source, primarily under the category “source
identified” (as defined by the Council Directive
on the marketing of forest reproductive mate-
rial). At least 30 seed-bearing trees or shrubs of
the same species must be present on such sites,
with a good score for autochthony. There must
be no non-autochthonous plantations in the vi-
cinity. Autochthonous stands showing traits of sil-
vicultural value are approved under the category
“selected.” Five stands of Alnus glutinosa have
been given this designation. Private nurseries can
collect seeds from these officially approved seed
sources and obtain a certificate from an independ-
ent governmental control agency that proves the
origin of the seeds. The landowner of the col-
lection site can charge those wanting to collect
seeds, although in general private nurseries are
not willing to pay large sums. Major problems
faced by certified in situ collections are the reluc-
tance of landowners to agree to the designation
of a woody population on their property as an
official seed source, the laborious process of ap-
proval of the sites, the small number of sites that
meet the requirements for approval, and lack of
management for high seed production. A major
advantage of the system is that certified planting
stock becomes available to a broader public.
3.4. Seed orchards
Seed orchards hold many advantages over in situ
collecting. They produce large amounts of seed
and at the same time preserve the gene pool of
THE STATE OF THE WORLD’S FOREST GENETIC RESOURCES – THEMATIC STUDY
PART 2
42
TABLE 3.1.
Seeds and berries collected between 2006 and 2010 by Regional Landscapes (public organizations)
from autochthonous populations in Flanders
Species Fresh weight (kg)*
2006 2007 2008 2009 2010
Acer campestre
70.5 60.0 70.5 66.3 56.7
Alnus glutinosa
35.5 64.3 41.4 28.0 61.2
Carpinus betulus
116.3 159.3 11.5 141.4 88.0
Cornus sanguineum
26.0 39.8 26.0 11.3 6.4
Corylus avellana
10.2 229.3 26.5 56.7 71.9
Crataegus laevigata
4.7 11.6 4.0 2.8 0.9
Crataegus monogyna
111.8 44.1 59.8 107.6 103.8
Crataegus spp.
397.1 465.1 398.9 458.5 309.6
Euonymus europaeus
10.1 11.2 28.6 24.6 21.7
Fraxinus excelsior
105.3 2.5 62.4 5.6 226.4
Ilex aquifolium
18.1 5.0 5.5 6.0 5.9
Malus sylvestris
– 1.8 – 0.3
Mespilus germanica
1.5 42.8 5.1 2.5 9.4
Prunus padus
2.4 0.1 0.7 7.0 6.0
Prunus spinosa
218.3 121.1 2