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Using assisted colonisation to conserve biodiversity and restore ecosystem function under climate change


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Assisted colonisation has received considerable attention recently, and the risks and benefits of introducing taxa to sites beyond their historical range have been vigorously debated. The debate has primarily focused on using assisted colonization to enhance the persistence of taxa that would otherwise be stranded in unsuitable habitat as a consequence of anthropogenic climate change and habitat fragmentation. However, a complementary motivation for assisted colonisation could be to relocate taxa to restore declining ecosystem processes that support biodiversity in recipient sites. We compare the benefits and risks of species introductions motivated by either goal, which we respectively term ‘push’ versus ‘pull’ strategies for introductions to preserve single species or for restoration of ecological processes. We highlight that, by focusing on push and neglecting pull options, ecologists have greatly under-estimated potential benefits and risks that may result from assisted colonisation. Assisted colonisation may receive higher priority in climate change adaptation strategies if relocated taxa perform valuable ecological functions (pull) rather than have little collateral benefit (push). Potential roles include enhancing resistance to invasion by undesired species, supporting co-dependent species, performing keystone functions, providing temporally critical resources, replacing taxa of low ecological redundancy, and avoiding time lags in the provisioning of desired functions.
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Using assisted colonisation to conserve biodiversity and restore ecosystem
function under climate change
Ian D. Lunt
, Margaret Byrne
, Jessica J. Hellmann
, Nicola J. Mitchell
, Stephen T. Garnett
Matt W. Hayward
, Tara G. Martin
, Eve McDonald-Maddden
, Stephen E. Williams
, Kerstin K. Zander
Institute for Land, Water & Society, Charles Sturt University, Albury, NSW, Australia
Department of Environment and Conservation, Bentley, WA, Australia
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, WA, Australia
Research Institute for The Environment and Livelihoods, Charles Darwin University, Casuarina, NT, Australia
Australian Wildlife Conservancy, Nichols Point, Victoria, Australia
Climate Adaptation Flagship, CSIRO Ecosystem Sciences, Dutton Park, Qld, Australia
ARC Centre for Excellence in Environmental Decisions, University of Queensland, St. Lucia, Qld, Australia
Centre for Tropical Biodiversity and Climate Change, James Cook University, Townsville, Qld, Australia
article info
Article history:
Received 15 April 2012
Received in revised form 6 August 2012
Accepted 24 August 2012
Ecological replacement
Managed relocation
Climate change adaptation
Ecosystem management
Assisted colonisation has received considerable attention recently, and the risks and benefits of introduc-
ing taxa to sites beyond their historical range have been vigorously debated. The debate has primarily
focused on using assisted colonization to enhance the persistence of taxa that would otherwise be
stranded in unsuitable habitat as a consequence of anthropogenic climate change and habitat fragmen-
tation. However, a complementary motivation for assisted colonisation could be to relocate taxa to
restore declining ecosystem processes that support biodiversity in recipient sites. We compare the ben-
efits and risks of species introductions motivated by either goal, which we respectively term ‘push’ versus
‘pull’ strategies for introductions to preserve single species or for restoration of ecological processes. We
highlight that, by focusing on push and neglecting pull options, ecologists have greatly under-estimated
potential benefits and risks that may result from assisted colonisation. Assisted colonisation may receive
higher priority in climate change adaptation strategies if relocated taxa perform valuable ecological func-
tions (pull) rather than have little collateral benefit (push). Potential roles include enhancing resistance to
invasion by undesired species, supporting co-dependent species, performing keystone functions, provid-
ing temporally critical resources, replacing taxa of low ecological redundancy, and avoiding time lags in
the provisioning of desired functions.
Crown Copyright Ó2012 Published by Elsevier Ltd. All rights reserved.
1. Introduction ......................................................................................................... 172
2. Push versus pull assisted colonisation . . . . . . . . . . . . . . ...................................................................... 173
3. Contrasting risk–benefit profiles ......................................................................................... 173
4. Conclusions. ......................................................................................................... 176
Acknowledgements . . . . . . . . . . ......................................................................................... 176
References . ......................................................................................................... 176
1. Introduction
Assisted colonisation (also known as assisted migration or man-
aged relocation) is one option that has been proposed to conserve
biodiversity under anticipated climate change (McLachlan et al.,
0006-3207/$ - see front matter Crown Copyright Ó2012 Published by Elsevier Ltd. All rights reserved.
Corresponding author. Address: Science Division, Department of Environment
and Conservation, Locked Bag 104, Bentley Delivery Centre, WA 6983, Australia.
Tel.: +61 8 9219 9078; fax: +61 8 9334 0327.
E-mail address: (M. Byrne).
Biological Conservation 157 (2013) 172–177
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2007; Hoegh-Guldberg et al., 2008; Richardson et al., 2009). As-
sisted colonisation involves the planned introduction of a popula-
tion or species beyond its current distribution where the climate is
expected to become unsuitable into new localities where the taxon
is expected to persist under future climatic conditions (Seddon,
2010). Management under climate change will require steps after
colonisation (sensu managed relocation, Richardson et al., 2009),
but introduction is the first step in helping species relocate as
the climate changes.
The concept of assisted colonisation has generated intense de-
bate over the relative benefits and risks of moving taxa beyond
their historical range (Hoegh-Guldberg et al., 2008; Mueller and
Hellmann, 2008; Ricciardi and Simberloff, 2009; Richardson et
al., 2009; Vitt et al., 2009, 2010; Hewitt et al., 2011). The potential
benefit is the retention of biodiversity that is threatened by climate
change, but introduced populations could cause unanticipated
ecological or economic damage (Mueller and Hellmann, 2008;
Ricciardi and Simberloff, 2009; Sandler, 2010). To date, the assisted
colonisation literature has focused primarily on a single rationale:
to enhance the survival prospects of the taxon being moved, or
small numbers of inter-dependent taxa, such as butterflies and
host plants (Hellmann, 2002). However, here we suggest that as-
sisted colonisation could also be undertaken to achieve a very dif-
ferent conservation goal – to maintain declining ecosystem
processes. Adopting the terminology of Seddon (2010), this type
of assisted colonisation would be classified as ecological replace-
ment – the release of ‘a species outside its historic range in order
to fill an ecological niche left vacant by the extirpation of a native
species’, and is akin to the ‘anticipatory restoration’ activities pro-
posed by Manning et al. (2009). This goal may become prominent
in future climate change adaptation programs as the impacts of cli-
mate change become more severe, but the juxtaposition of goals
has not been considered in the assisted colonisation literature
and demands benefit–risk evaluation.
In addition to direct physiological effects on organisms and
associated changes to fitness, climate change will affect many spe-
cies through indirect impacts on ecosystem structure, functions
and processes (Diaz and Cabido, 1997; Petchey et al., 1999; Dale
et al., 2001; Gilman et al., 2010). Changes in the abundance of dom-
inant, foundation and keystone species will alter ecosystem pro-
cesses that will, in turn, affect many associated organisms.
Declines in dominant forest trees, for example, lead to changes in
micro-climatic conditions, nutrient and water cycles, habitat struc-
ture, and disturbances such as fire regimes (Cochrane, 2003; Foley
et al., 2007; Van Mantgem et al., 2009).
Reviews of climate change adaptation strategies include a wide
range of approaches for maintaining ecological processes such as
nutrient cycling, hydrology, species interactions, habitat provision,
dispersal and disturbances (Millar et al., 2007; Bennett et al., 2009;
Mawdsley et al., 2009; Steffen et al., 2009; Lindenmayer et al.,
2010). Additionally, landscape and restoration ecologists have pro-
posed that vegetation be established and restored across local and
regional scales to enhance ecological processes and functions that
may in turn maintain biodiversity (Hobbs and Harris, 2001; Millar
et al., 2007; Manning et al., 2009; Seddon, 2010). Proposals to use
assisted colonisation for ecosystem benefit are not widely encom-
passed by the existing literature and its decision frameworks
(Sandler, 2010). We suggest that acknowledgement of a broader
array of motivations for assisted colonisation will enhance our
ability to contribute to the development of national and regional
climate change adaptation strategies.
Therefore, we contrast two rationales for introductions of species
outside their historical ranges: (1) direct conservation of one or
more species diminished in their native range and (2) restoration
or maintenance of a declining ecosystem function, and consider
how these rationales could be combined. We restrict our attention
to introductions for conservation purposes, but our framework
could also encompass a wider range of goals, including utilitarian
services such as timber production (McKenney et al., 2009).
2. Push versus pull assisted colonisation
For simplicity, we characterize these two contrasting rationales
for assisted colonisation as ‘push’ and ‘pull’ strategies (Fig. 1). Push
strategies that focus on conserving individual taxa or small groups
of inter-dependent taxa are already widely discussed in the as-
sisted colonisation literature. In these cases, issues such as rarity
and threat guide the selection of target taxa, and populations are
‘pushed’ into one or more localities where it is expected that they
will maintain viable populations for an extended period under cli-
mate change (e.g. Willis et al., 2009). Risk assessments are required
to ensure that informed decisions are made to relocate taxa such
that there is minimal impact on other species where they are intro-
duced (Burbidge et al., 2011).
In contrast, assisted colonisation that is also motivated by a de-
sire to restore ecosystem function should expect to have an appre-
ciable impact at the recipient site. In such ‘pull’ scenarios, desired
ecosystem functions and potential recipient sites would first be
identified, and appropriate candidate species would then be
‘pulled’ into recipient sites to maintain or restore the specified
function (Fig. 1). Relocation of taxa may be undertaken to deliver
ecological functions that are directly affected by climate change,
or where climate change exacerbates other causes of decline, such
as fragmentation or salinisation. For example, consider a tree spe-
cies that is declining (directly or indirectly) due to climate change
and provides nest holes to a bird community. Pull assisted coloni-
sation would ask which species of tree might persist regionally in
the future to provide nesting habitat for birds, and could include
the option to introduce multiple species, if a range of species are
capable of performing the desired function. Indeed, bet-hedging
approaches that relocate multiple taxa and genotypes may be pru-
dent given uncertainties about future species performances under
climate change (Beale et al., 2008). Relocation of multiple taxa will
also be important for co-dependent species, such as insects and
their host plants or species and their parasites.
In push + pull assisted colonisation, selection of species would
be guided by the function to be performed in the recipient site,
as well as the conservation status of the relocated species. Oppor-
tunities for push + pull assisted colonisation may be limited where
rare taxa have restricted distributions due to biological constraints
because they are unlikely to have the capacity to influence ecosys-
tem processes strongly in recipient sites. However, there may be
greater opportunities to maximize conservation outcomes using
‘push + pull’ assisted colonisation in landscapes where historical
stochasticity has been a major driver of rarity (Yates et al., 2007).
While further research is required to develop decision support
tools to guide pull assisted colonisation strategies, this approach
may receive high priority where relocated taxa: (1) perform ‘key-
stone’ functions that generate a cascade of ecological services
(e.g. ecosystem engineers); (2) provide ecosystem services that
are unique or have low levels of ecological redundancy; (3) provide
functions that take long periods to become effective, e.g. hollow-
bearing trees; (4) enhance resistance to invasion by undesired
species; (5) fill temporal resource gaps driven by climate-driven
phenological shifts; and (6) maintain valued species that are highly
dependent on other species. Descriptions and examples of these
functions are provided in Table 1.
3. Contrasting risk–benefit profiles
Assisted colonisation for goals of conservation introduction
or ecological replacement both share a common mechanism of
I.D. Lunt et al. / Biological Conservation 157 (2013) 172–177 173
relocating taxa (or genotypes) beyond their historical range in or-
der to conserve biodiversity under climate change. Nevertheless,
we recognise that the two approaches have very different risk
and benefit profiles.
Assisted colonisation for species conservation benefits the relo-
cated taxon only, and minimal (if any) collateral benefits are envis-
aged for other taxa or processes in recipient sites. Indeed, the
current assisted colonisation literature emphasizes the need to
avoid relocations that may alter the composition, structure or func-
tion of recipient sites in a major way (Mueller and Hellmann, 2008;
Ricciardi and Simberloff, 2009). Nevertheless, push assisted coloni-
sation may present risks to recipient sites and ecosystems (and
potentially to the broader environment and economy) if relocated
taxa have negative impacts on other species and those impacts
spread to additional locations (Ricciardi and Simberloff, 2009;
Richardson et al., 2009). Thus, the risk–benefit profile for push as-
sisted colonisation is one of localized benefit and potentially wide
risks (akin to private benefits versus public risks in human enter-
prises), depending on the taxa under consideration (Hoegh-Guld-
berg et al., 2008; Ricciardi and Simberloff, 2009; Richardson et
al., 2009; Burbidge et al., 2011).
By focusing on the conservation of threatened species as
motivation for assisted colonization, ecologists may greatly un-
der-estimate potential benefits that may arise from such intro-
ductions in providing ecosystem services. In contrast to push
assisted colonisation, taxa also introduced as ecological replace-
ments for a degraded component of an ecosystem could have
multiple beneficiaries – including all taxa that benefit from the
environmental functions or processes that relocated species
provide. Thus, the potential biodiversity benefits provided by
push + pull assisted colonisation are far greater if their impact
flows broadly across an ecosystem. Because maintenance of eco-
system processes is a key component of climate change adapta-
tion strategies (Millar et al., 2007; Mawdsley et al., 2009; Steffen
et al., 2009; Lindenmayer et al., 2010), assisted colonisations that
maintain ecosystem function may be prioritized above those that
conserve threatened species, if relocation costs are similar, ben-
efits are greater and risks deemed acceptable. Combined strate-
gies that focus on threatened species conservation and
maintenance of ecosystem function may also rate highly under
constrained management budgets, given potential benefits to
both the relocated species and recipient ecosystems.
However, assisted colonisation intended to have a significant
collateral impact also presents far greater risks, since relocated
taxa are intended to have a substantial, as opposed to negligible,
impact on specified ecosystem processes in recipient sites. For
example, a relocated species could be structurally dominant or a
keystone species, which would be unlikely to be relocated under
current decision support frameworks for assisted colonisation
(Hoegh-Guldberg et al., 2008; Richardson et al., 2009). Candidate
taxa for assisted colonisation could now include taxa with high im-
pact but low dispersal capacity, to minimize the potential for relo-
cated taxa to spread to unwanted areas. In some cases, dispersal
risks may be moderated by landscape context (McIntyre, 2011).
For example, assisted colonisations designed to have an apprecia-
ble collateral impact might receive greater attention in degraded
remnants in fragmented landscapes, where risks to existing taxa
are lower and where such introductions would build upon existing
interventions designed to enhance regional biodiversity (Fischer et
al., 2006; Lindenmayer et al., 2010).
Fig. 1. Contrasting types of assisted colonisation. In (a) specific species assisted colonisation – a specified taxon threatened with decline under climate change is moved
(‘pushed’) into one or more optional recipient sites where future persistence is predicted to be high. In (b) ecological replacement assisted colonization – one or more taxa are
relocated (‘pulled’) to a specified recipient site to maintain or restore an ecosystem process and/or function in the recipient site that is declining due to climate change. In (c)
assisted colonisation is used to ‘push’ a threatened taxon into a recipient site, but in so doing restores an ecosystem process and/or function that is declining due to climate
change, thus achieving outcomes from options (a and b). Dark shading in arrows indicates whether the introduction is motivated by concerns about source populations (a;
push), recipient sites (b; pull), or both (c; push + pull).
174 I.D. Lunt et al. / Biological Conservation 157 (2013) 172–177
Existing decision support tools for assisted colonisation may
be relatively easily expanded to accommodate a goal of ecosys-
tem restoration. For example, the decision making framework
developed by Richardson et al. (2009) requires the addition
of diminished ecosystem function as a potential motivation for
undertaking assisted colonisation, plus the expansion of the con-
cept of ‘focal impact’ to include collateral benefits (not just col-
lateral impacts). Populating these frameworks for push + pull
assisted colonization will require a revised approach to the eval-
uation of potential impacts. For example, impacts that are gener-
ally considered as risks in assisted colonisation motivated to
benefit a threatened taxon would be considered as potential
benefits in movement of species to achieve ecosystem function.
In any risk evaluation, the relevant comparison is not of assisted
colonisation against the status quo, but assisted colonisation
against anticipated losses under continuing climate change
(Schwartz et al., 2009). The uncertainties inherent in assessment
of the scale and direction of climate change itself, and the vulner-
ability of species to that change, are key factors in assessment of
push assisted colonisation adaptation strategies. For assisted colo-
nisation designed to have push + pull impacts, additional uncer-
tainties occur in relation to the potential for selected taxa to
establish self-perpetuating populations that contribute to ecologi-
cal function at a site within an appropriate time frame.
If assessments reveal that the benefits of undertaking either
assisted colonisation option outweigh the risks, then the question
becomes one of timing of implementation and monitoring of im-
pacts. McDonald-Madden et al. (2011) present a quantitative
framework to guide when to move species in push assisted coloni-
sation activities, based on population dynamics in the source hab-
itat, predicted dynamics in recipient sites, the cost of relocation
and species recovery potential. Additional factors need to be con-
sidered to accommodate push + pull assisted colonisation, includ-
ing the predicted dynamics of declining ecosystem processes, the
thresholds at which major change may occur, and the need to bal-
ance the delivery of the ecological function with the climate suit-
ability for the selected species. Development of success criteria
for evaluation of push assisted colonisation is relatively straight-
forward (Burbidge et al., 2011). For push + pull assisted colonisa-
tion there is the added challenge of monitoring for the continued
delivery of an ecological function with the potential complexities
of interdependences among biotic and abiotic components of the
Further consideration needs to be given to the economic costs
and benefits associated with all forms of assisted colonisation. This
paper has emphasized the ecological value of species in sustaining
ecosystem services and supporting species interactions. These ser-
vices have economic value as well. For example, species that pro-
Table 1
Example functions potentially vulnerable to climate change that could be enhanced by assisted colonisation.
Functional issue for ecosystem Description Example(s)
Loss of keystone species Keystone species interact strongly with other
functions and generate a cascade of ecological
Many forests and woodlands in Australia are dominated by long-lived
Eucalyptus trees. These dominant, ‘foundation’ species control functions and
processes including stand structure and micro-climate, water and nutrient
cycling and fire behavior (Manning et al., 2006). Species replace each other
across climatic gradients so readily lend themselves to assisted colonisation
in anticipation of climate change
Five species of prairie dogs Cynomys spp. have a strong influence on the
functioning of grassland ecosystems in North America but have declined by
98% in the last 200 years (Hoogland, 2006). The existence of climate-related
relictual populations (Mead et al., 2010) suggests natural dispersal has been
too slow to keep up with historical climate change. There may be potential
to assist movement of different prairie dog species to retain ecosystem
services as future climates change
Loss of a unique ecosystem service Provision of ecosystem services with low
ecological redundancy that support the
persistence of other species
Larvae of the endangered European longhorn beetle affect a profound
change on the microstructure of the bark of the wild oak, enabling numerous
other endangered insects to flourish in the beetle’s presence (Buse et al.,
2008). Assisted colonisation of the European Longhorn beetle could generate
collateral benefits to invertebrate fauna at the recipient site
Sheep grazing is an essential to conservation of the Chalkhill Blue butterfly
Polyommatus coridon in the UK (Brereton et al., 2008). If conditions become
too warm for existing races of sheep on the downs, there are several others
that could be brought in as replacements (Gibbons and Lindenmayer, 2002)
Loss of a function that has a time
lag to effectiveness
Functions that take decades or longer to establish
and become effective
Tree hollows provide nesting habitat and retreat sites in almost all forest
types, with approximately 10–31% of reptiles, amphibians, birds and
mammals utilizing tree hollows in Australian ecosystems (Gibbons and
Lindenmayer, 2002). Declining tree species could be replaced with warmer-
or drier-adapted species
Biological control agent becoming
increasingly ineffective in a
changing climate
Species whose introduction to a recipient
ecosystem could prevent or reduce the invasion
of undesired species
Lesser St John’s Wort beetles are effective biological control agents in cold
climates but need to be replaced with Great St John’s Wort beetles for
effective St John’s wort (Hypericum perforatum) control in Mediterranean
climates (Schöpsa et al., 1996)
Increasing temporally mismatch of
Functions that fill temporal resource gaps driven
by climate-driven phenological shifts
Plant species flowering at various times of the year provide resources for
pollinators. Banksia baxterii is one of the few plants that flower in autumn in
south western Australia and is major nectar resource for vertebrate
pollinators, particularly honey possums, a distinct lineage of marsupials. It is
vulnerable to increasing temperature (Yates et al., 2009) and may need to be
replaced by other autumn flowering plants
Maintenance of co-dependence
among species
Functions provided by one species that both
maintain and depend on functions provided by
other species
Terrestrial orchids have strong mutualistic dependence on pollinators that
tends to be site specific (unlike the mutualism with fungi; Waterman et al.,
2011) so that neither orchid nor pollinator could be moved without the
other. Similarly many pollinators have a host of other specializations that
would also need to be considered in assisted colonisation (Pemberton, 2010)
I.D. Lunt et al. / Biological Conservation 157 (2013) 172–177 175
mote pollination services might increase agricultural value. To our
knowledge, no one has investigated economic outcomes from as-
sisted colonization, but it may be possible for particular species
and ecosystems.
This conceptual integration of push + pull motivations in as-
sisted colonisation activities may help to reinforce synergies be-
tween the contrasting theoretical frameworks that underlie the
two approaches (Fig. 2). Push assisted colonisation draws heavily
on single-species population biology, invasion ecology, and an
extensive literature on management of threatened species and
small and declining populations (Simberloff, 1998; Parker et al.,
1999; Purvis et al., 2000). By contrast, push + pull assisted coloni-
sation has stronger theoretical foundations in landscape and resto-
ration ecology at ecosystem scales (Noss, 1990; Fischer et al., 2006;
Hobbs and Cramer, 2008; Lindenmayer et al., 2008). From an inva-
sion ecology perspective, introduction of a high impact taxon is
usually seen as inherently undesirable, whereas introduction of a
functional dominant is commonly viewed as a critical component
of a successful restoration strategy. Clearly, a wide range of intel-
lectual traditions will need to be drawn upon to manage assisted
colonisation effectively and safely within climate change adapta-
tion strategies for biodiversity conservation.
4. Conclusions
We emphasise that we are not promoting the adoption of any
particular assisted colonisation strategy, and we advocate that all
assisted colonisation activities must be subject to comprehensive
risk assessments and ongoing monitoring and management.
However, we encourage ecologists and managers to consider
how assisted colonisation could be adopted to achieve broader
goals than the persistence of a single, or just a few, threatened
The perspective presented in this paper was developed at a
workshop on assisted colonisation supported by the Terrestrial
Biodiversity Adaptation Research Network of the National Climate
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... Although our study was conducted under the expectation that one species would be less affected than the other by temperature increase, both species had similar losses in terms of survival, growth and physiological status. Then, although selecting the less sensitive species for ecosystem restoration projects could improve the overall establishment of individuals from revegetation -and thereby help adapt the future forest to hotter conditions through assisted compositional change (Lunt et al., 2013)-, species considered to be more sensitive can sometimes yield surprisingly positive results, as in our case. Further, selecting different species to create mixed forests increases diversity and may drive resistance to natural disturbances such as mammal herbivory, insect pests, fungal diseases, fires, drought events and windstorms (Jactel et al., 2017;Jactel and Brockerhoff, 2007;Kelty, 2006;Pardos et al., 2021;Stemmelen et al., 2022). ...
Climate change constitutes a major threat to global biodiversity and to the success of natural and assisted tree regeneration. Oaks are among the most emblematic tree species in the Northern Hemisphere, so it is crucial to understand the impact of changing climate on seedling recruitment and early development. In this study, we investigated the effect of air warming on the early development of one deciduous species-Quercus faginea-and one evergreen species-Quercus ilex subsp. ballota. Acorns of both species were seeded in an alluvial valley in southern Spain and subjected to an air warming treatment with Open-Top Chambers (OTC), which increased air temperature by 2 • C. We monitored seedling emergence, growth, chlorophyll concentration, and mortality in the first growing season. The simulated climate change treatment accelerated plant emergence in early spring, reduced spring shoot growth, and increased mortality from ~ 23 % in control plots to ~ 40 % inside OTCs. Although Q. ilex and Q. faginea are sympatric species, Q. faginea showed lower performance under simulated climate change in terms of growth. In addition, acorn fresh weight was positively related with the probability and speed of emergence (only for Q. faginea), seedling size, and relative chlorophyll content, and plants that emerged earlier had a greater likelihood of surviving. In short, larger acorns partly counterbalanced the negative impact of temperature increase on plants. This study highlights the importance of understanding plant response to climate change both to forecast potential changes in species composition and to choose adequate species and traits such as acorn size in restoration projects.
... The frequency of plant translocation has increased dramatically in the past four decades (Armstrong et al. 2019;Brichieri-Colombi and Moehrenschlager 2016;Silcock et al. 2019;Julien et al. 2022a), with further increases forecast (Swan et al. 2018;Zimmer et al. 2019). Translocations have been used to recover plant populations declining due to a diverse array of threats, including climate change (Lunt et al. 2013;Vitt et al. 2010), pollution, and sedimentation (Ferretto et al. 2019;Paoli et al. 2020), restricted gene flow (Weeks et al. 2011) or habitat fragmentation (Dalrymple et al. 2012;Monks and Coates 2002). However, the greatest threat to plant biodiversity is habitat loss or degradation of populations by anthropic developments (Millenium Ecosystem Assessment 2005; Corlett 2016). ...
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Many countries have legislation intended to limit or offset the impact of anthropogenic disturbance and development on threatened plants. Translocations are often integral to those mitigation policies. When translocation is used exclusively to mitigate development impacts, it is often termed a ‘mitigation translocation.’ However, both the terminology and processes vary regarding interpretation and application, resulting in inconsistent standards, often leading to poorly planned and implemented projects. These mitigation projects rarely achieve the intended ‘no net loss’ of protected species due to issues with timelines and procedures that result in the mortality of translocated individuals. Instead, such projects are often process driven, focused on meeting legislative requirements which enable the development to proceed, rather than meaningful attempts to minimise the ecological impact of developments and demonstrate conservation outcomes. Here, we propose to reframe mitigation translocations as conservation driven, ensuring best practice implementation and hence, a quantified no net loss for impacted species. These methods include redefining the term mitigation translocation to include conservation objectives and outlining issues associated with the mitigation translocation processes worldwide. We also nominate global standards of practice to which all proposals should adhere, to ensure each project follows a trajectory towards quantified success, with genuine impact mitigation. These proposed standards focus on building efficient translocation plans and improving governance to facilitate a transition from project centred to ecology-driven translocation. Employment of these standards is relevant to development proponents, government regulators, researchers, and translocation practitioners and will increase the likelihood of conservation gains within the mitigation translocation sector.
... Numerous authors have highlighted the possible ecological and genetic risks associated with assisted migration including negative consequences to the source population/ecosystem, translocated individuals, and recipient ecosystems (Ricciardi and Simberloff, 2009;Seddon et al., 2009;Hewitt et al., 2011;Bucharova, 2017). Indeed, much of the concern over assisted migration (beyond species ranges) stems from the broad literature, and well-grounded understanding of the impacts of invasive species on native ecosystems (Lunt et al., 2013;Loss et al., 2011), as well as the disruption of relationships among species (e.g., symbioses; Gallien and Carboni, 2017). Discussion of genetic risks of assisted migration within range have largely focused on outbreeding depression due to disruption of coadapted gene complexes (Aitken and Whitlock, 2013;Keller et al., 2000;Weeks et al., 2011), or the disruption of adaptation to non-climatic environmental factors (e.g., soil or water characteristics) as well as disruption of coadaptation of populations (e.g., plants and mycorrhizal communities; Bucharova, 2017). ...
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Assisted migration entails the human assisted movement of individuals to more climatically-suitable areas within or outside of their current species range to help species respond to climate change. To better understand the potential for assisted migration to benefit species threatened by climate change, we conducted an evidence synthesis to map examples where assisted migration has been implemented around the world. With this mapping exercise, we collate and describe the quantity and key characteristics of the available evidence base, including the taxa, species conservation status, locations, and contexts relating to the use of this conservation tactic. Findings from this exercise highlight that assisted migration has been implemented very few times as a conservation tactic, though assisted migration has been conducted experimentally (for research purposes) and inadvertently (e.g., for reforestation) much more frequently. Assisted migration was most common for plants (particularly trees), followed by birds, and was rarely implemented for other taxa. Our review highlights the need for more research on assisted migration, with particular emphasis on understanding the population- and community-level outcomes of these actions. Our discussion focuses on the potential for assisted migration of Canadian species but will be informative to those considering assisted migration in other jurisdictions.
... Examples include the assisted colonisation by moving individuals of a species to new habitat sites (Lunt et al. 2013, Casazza et al. 2021, "Targeted Gene Flow" in which more adapted individuals of a species which already inhabits a site are relocated (Reside et al. 2018), the control or eradication of invasive species (Srivastava et al. 2019), adaptation of restoration activities (e.g. by selecting new, climate change-robust seed mixtures (Reside et al. 2018)), adaptations in the rewetting of wetlands (Dorau et al. 2015), and adaptations to fire management (Stephens et al. 2020). ...
Climate change is a major threat to biodiversity and ecologists have identified necessary adaptation strategies. However, little research has been conducted so far on the economics of climate adaptation for biodiversity conservation. Three challenges arise from an economic perspective: How to (1) assess the impact of climate change on the cost-effectiveness of conservation, (2) consider the increasing uncertainty, and (3) evaluate conservation policy instruments under climate change. Addressing these challenges provides a thus far largely unexplored perspective on the economics of biodiversity conservation. This perspective relies on novel methodologies and provides policy-relevant insights. In this thesis, these challenges are addressed in eight articles. Chapter 2 presents a novel economic evaluation framework to assess policy instruments for climate adaptation. Specific criteria are developed, their relevance for different strategies is assessed and suitable instruments identified. Chapters 3 and 4 have a methodological focus as two climate-ecological-economic (CEE) models are developed. Chapter 3 presents an applied model integrating detailed sub-models able to assess the cost-effective spatio-temporal allocation of conservation measures. In chapter 4, methods from operations research are developed further to identify optimal time series of reserve networks. In both chapters, cost-effective conservation plans are identified in case study applications. In chapter 5, CEE modelling is applied to examine the role of uncertainties regarding future climatic conditions. It is found that a trade-off between expected performance and robustness emerges in the case study in the future. In chapters 6 to 8, CEE modelling is used to assess policy instruments under climate change. Chapter 6 examines an agri-environment scheme: cost-effectiveness requires flexibility in adapting the timing of conservation measures due to species’ adaptations and changes in costs. Chapter 7 examines two versions of land purchase: a “no sale” policy which prohibits sales for ecological reasons and a “sale” policy to enhance spatial flexibility for adaptation. A new trade-off is identified: while “no sale” mainly increases habitat permanence of expanding habitat types, “sale” improves the outcome for increasingly threatened habitat types. Chapter 8 is novel in its comparative analysis of two policy instruments considering spatial and management flexibility in a case study. It is found that in the case study, conservation contracts are more cost-effective than land purchase, but that the relative suitability switches when the conservation agency is able to capture producer rents. Finally, chapter 9 uses the results of chapters 3 and 5 to develop an innovative teaching tool for students to learn about cost-effective biodiversity conservation under climate change.
... There are many strategies to conserve threatened animal species, some more drastic (e.g. assisted colonisation; Lunt et al., 2013) or more costly (e.g. ecosystem restoration; Strassburg et al., 2019) than others. ...
While the imminent extinction of many species is predicted, prevention is expensive, and decision-makers often have to prioritise funding. In democracies, it can be argued that conservation using public funds should be influenced by the values placed on threatened species by the public, and that community views should also affect the conservation management approaches adopted. We conducted on online survey with 2400 respondents from the general Australian public to determine 1) the relative values placed on a diverse set of 12 threatened Australian animal species and 2) whether those values changed with the approach proposed to conserve them. The survey included a contingent valuation and a choice experiment. Three notable findings emerged: 1) respondents were willing to pay $60/year on average for a species (95% confidence interval: $23 to $105) to avoid extinction in the next 20 years based on the contingent valuation, and $29 to $100 based on the choice experiment, 2) respondents were willing to pay to reduce the impact of feral animals on almost all presented threatened species, 3) for few species and respondents, WTP was lower when genetic modification to reduce inbreeding in the remaining population was proposed.
Conservation and effective management of marine ecosystems and biodiversity requires accurate species identification. This study classifies sea bamboo (Isis hippuris) specimens using DNA barcoding, a technique widely recognized for its speed, accuracy, and objectivity. This study examines the cytochrome c oxidase subunit I (COI) gene analysis for species identification. Isis hippuris was collected from two stations (coral and seagrass areas) of Tanjung Tiram Waters, South Konawe, Southeast Sulawesi. Genomic DNA was extracted from the base, main, and lateral stem of I. hippuris. Polymerase chain reaction (PCR) was used to amplify the mtDNA of I. hippuris with HCO2198 and LCO1490 primers. The highest quality PCR product based on the COI gene was chosen for sequencing analysis. The study revealed that COI gene analysis could only be performed on the base and main stem of the I. hippuris. Samples from coral and seagrass-coral areas on lateral stems were not further analyzed due to low concentration and purity values, which could potentially fail DNA sequencing. Each part of I. hippuris may have unique genetic differences. This study highlights the advantages of DNA sequencing in providing a unique genetic fingerprint for each species, enabling accurate species identification. This research provides insight into using DNA barcoding for sea bamboo species identification.
Australia's biota is species rich, with high rates of endemism. This natural legacy has rapidly diminished since European colonization. The impacts of invasive species, habitat loss, altered fire regimes, and changed water flows are now compounded by climate change, particularly through extreme drought, heat, wildfire, and flooding. Extinction rates, already far exceeding the global average for mammals, are predicted to escalate across all taxa, and ecosystems are collapsing. These losses are symptomatic of shortcomings in resourcing, law, policy, and management. Informed by examples of advances in conservation practice from invasive species control, Indigenous land management, and citizen science, we describe interventions needed to enhance future resilience. Many characteristics of Australian biodiversity loss are globally relevant, with recovery requiring society to reframe its relationship with the environment.
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Temperature and precipitation changes are among the vital climatic driving forces of global vegetation change. However, the strategy to separate the relative contributions of these two critical climatic factors is still lacking. Here, we propose an index CRTP (contribution ratio of temperature and precipitation) to quantify their impacts on vegetation and then construct the CRTP classification prediction models based on climatic, geographic, and environmental factors using the Random Forest classifier. We find that precipitation predominates more than 70% of the significant vegetation change, mainly located in the low and middle latitudes during 2000–2021. Precipitation will remain the dominant climatic factor affecting global vegetation change in the coming six decades, whereas areas with temperature-dominated vegetation change will expand under higher radiative forcings. Hopefully, the promising index CRTP will be applied in the research about climatic attribution for regional vegetation degradation, monitoring drought-type conversion, and alarming the potential ecological risk.
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The implementation of French mitigation bank requires an approval (agrément SNC) delivered by state services through an instruction phase. However, the ecological expectations of state services need to be clarified. To assist stakeholders, we developed an assessment framework whose aim is to specify the useful criteria to justify/determine whether or not a mitigation bank project is ecologically relevant. In this context, we intended to answer the following question: regarding its ecological gains strategy and the site location, is the project suitable to achieve its ecological gains objectives? We define as ecologically relevant a mitigation bank project whose (1) ecological gains strategy is based on acceptable objectives, realistic and operational restauration, management and monitoring measures. This strategy must be (2) consistent with the intrinsic characteristics of the host site(s) and the (3) landscape context in which the project takes place. (4) The respect of the offset principles is ultimately the guiding line of any mitigation project. The different criteria identified through those four assessment components were organized under the form of a project reading grid on which we give more details.
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Translocations are an important conservation tool that enable the restoration of species and their ecological functions. They are particularly important during the current environmental crisis. We used a combination of text-analysis tools to track the history and evolution of the peer-reviewed scientific literature on animal translocation science. We compared this corpus with research showcased in the IUCNs Global Conservation Translocation Perspectives, a curated collection of non-peer-reviewed reintroduction case studies. We show that the peer-reviewed literature, in its infancy, was dominated by charismatic species. It then grew in two classical threads: management of the species of concern and management of the environment of the species. The peer-reviewed literature exhibits a bias towards large charismatic mammals, and while these data are invaluable, expansion to under-represented groups such as insects and reptiles will be critical to combating biodiversity loss across taxonomic groups. These biases were similar in the Translocation Perspectives, but with some subtle differences. To ensure translocation science can address global issues, we need to overcome barriers that restrict this research to a limited number of countries.
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More than 300 species of Australian native animals — mammals, birds, reptiles and amphibians — use tree hollows, but there has never been a complete inventory of them. Many of these species are threatened, or are in decline, because of land-use practices such as grazing, timber production and firewood collection. All forest management agencies in Australia attempt to reduce the impact of logging on hollow-dependent fauna, but the nature of our eucalypt forests presents a considerable challenge. In some cases, tree hollows suitable for vertebrate fauna may take up to 250 years to develop, which makes recruiting and perpetuating this resource very difficult within the typical cycle of human-induced disturbance regimes. Tree Hollows and Wildlife Conservation in Australia is the first comprehensive account of the hollow-dependent fauna of Australia and introduces a considerable amount of new data on this subject. It not only presents a review and analysis of the literature, but also provides practical approaches for land management.
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Species composition of prey consumed by spotted hyaenas Crocuta crocuta in three divergent areas in southern Africa was determined by scat analyses. The larger abundant antelopes predominated in the diet and their occurrence in the diet was apparently directly related to the availability of the prey within the hyaena foraging areas. In Mkuzi' Game Reserve and the Namib Naukluft National Park, hyaenas coexist with only one other large predator. In Umfolozi Game Reserve, where hyaenas coexist with four other large predators, a greater variety of prey was taken. Scat weight in desert-dwelling hyaenas was twice that of those from more mesic areas, which may be an adaptation to restricted water intake. The incidence of domestic livestock in the diet was meagre, probably the result of collecting scats only from latrines within the game reserves. Die spesies-samestelling van prooi verbruik deur gevlekte hienas Crocuta crocuta in drie verskillende gebiede in Suidelike Afrika is bepaal deur faeces-analise. Die groter meer volop wildsbokke het die dieet gedomineer en die voorkoms in dieet toon 'n direkte verwantskap met beskik­ baarheid van prooi in hiena-jaggebiede. Hienas deel Mkuzi Wildtuin en die Namib Naukluft Nasionale Park met slegs een ander groot roofdier terwyl vier ander groot roofdiere Umfolozi Wildtuin met hienas deel, wat lei tot groter variasie in prooi-items. Faeces-massa van woestynlewende hienas ..,as twee keer meer as die van hienas in meer mesiese gebiede wat waarskynlik 'n aanpassing is vir beperkte water inname. Die voorkoms van plaasdiere in die dieet was baie laag, maar dit is heel waarskynlik as gevolg van faeces­ versameling slegs binne die wildtuine.
1. Ecological factors influencing prey selection by tiger Panthera tigris, leopard Panthera pardus and dhole Cuon alpinus were investigated in an intact assemblage of large mammals in the tropical forests of Nagarahole, southern India, between 1986 and 1990. 2. Densities of large herbivores were estimated using line transects, and population structures from area counts. Carnivore diets were determined from analyses of scats (faeces) and kills. Selectivity for prey species was inferred from likelihood ratio tests comparing observed counts of scats to hypothesized scat frequencies generated from prey density estimates using parametric bootstrap simulations. Predator selectivity for size, age, sex and physical condition of prey was estimated using selection indices. 3. Ungulate and primate prey attained a density of 91 animals km-2 and comprised 89-98% of the biomass killed. Predators showed significant (P
Canada regenerates more than 400 000 ha of forest land annually through planting and seeding operations. Much of the stock for this effort is selected to be climatically suited to the planting site-a match that is often facilitated through the development of seed zones. However, if climate change proceeds as predicted, stock that is well matched under current climate will be growing in sub-optimal conditions within the next 20 to 50 years-in some parts of the country, trees may already be growing outside their optimal climates. To provide a sense of the magnitude of these changes, we present past and predicted future climate trends for Ontario and British Columbia seed zones. For Ontario, over the period 1950 to 2005, minimum temperature of the coldest month has already increased by up to 4.3°C, growing season has lengthened by up to 6 days, and precipitation during the growing season has increased by up to 26%. Changes were more pronounced across British Columbia's Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) seed zones, with minimum temperature increasing by up to 8°C, a growing season extension of up to 30 days, and growing season precipitation increases of up to 40%. Projections for the end of the current century include: minimum temperature increase of 5°C to 10°C, growing season extension of 31 to 60 days, and growing season precipitation increases of 3% to 42% across the seed zones in both provinces. These changes are certain to have extensive impacts on forest ecosystems. We briefly discuss 3 forest management adaptation strategies intended to mitigate the negative impacts of climate change in Canada.
The predator-prey aspects of four cheetah (Acinonyx jubatus) groups were studied in Nairobi National Park, Kenya, from October, 1966, through February, 1967. Hunt:kill ratios were applied to direct observation data of 157 hunts and 30 kills. Hunting success apparently varied with habitat-type, prey species, sex and age-classes of prey, herd size, cheetah group size, and the cheetah's or group's hunting experience. Cheetah kills appeared to be other than a random sample of prey populations. There was differential selection in prey of females and juveniles.
African wild dog (Lycaon pictus) predation was observed in Ngorongoro Crater, Tanzania, between September, 1964, and July, 1965, when packs were in residence. The original pack of 21 dogs remained only 4 months, but 7 and then 6 members of the group reappeared in the Crater at irregular intervals. The ratio of males:females was disproportionately high, and the single bitch in the small pack had a litter of 9 in which there was only one female. The pack functions primarily as a hunting unit, cooperating closely in killing and mutual defense, subordinating individual to group activity, with strong discipline during the chase and unusually amicable relations between members. A regular leader selected and ran down the prey, but there was no other sign of a rank hierarchy. Fights are very rare. A Greeting ceremony based on infantile begging functions to promote pack harmony, and appeasement behavior substitutes for aggression when dogs are competing over meat. Wild dogs hunt primarily by sight and by daylight. The pack often approaches herds of prey within several hundred yards, but the particular quarry is selected only after the chase begins. They do not run in relays as commonly supposed. The leader can overtake the fleetest game usually within 2 miles. While the others lag behind, one or two dogs maintain intervals of 100 yards or more behind the leader, in positions to intercept the quarry if it circles or begins to dodge. As soon as small prey is caught, the pack pulls it apart; large game is worried from the rear until it falls from exhaustion and shock. Of 50 kills observed, Thomson's gazelles (Gazella thomsonii) made up 54 percent, newborn and juvenile wildebeest (Connochaetes taurinus) 36 percent, Grant's gazelles (Gazella granti) 8 percent, and kongoni (Alcelaphus buselaphus cokei) 2 percent. The dogs hunted regularly in early morning and late afternoon, with a success rate per chase of over 85 percent and a mean time of only 25 minutes between starting an activity cycle to capturing prey. Both large and small packs generally killed in each hunting cycle, so large packs make more efficient use of their prey resource. Reactions of prey species depend on the behavior of the wild dogs, and disturbance to game was far less than has been represented. Adult wildebeest and zebra (Equus burchelli) showed little fear of the dogs. Territorial male Thomson's gazelles, which made up 67 percent of the kills of this species, and females with concealed fawns, were most vulnerable. The spotted hyena (Crocuta crocuta) is a serious competitor capable of driving small packs from their kills. A minimum of 4-6 dogs is needed to function effectively as a pack. It is concluded that the wild dog is not the most wantonly destructive and disruptive African predator, that it is an interesting, valuable species now possibly endangered, and should be strictly protected, particularly where the small and medium-sized antelopes have increased at an alarming rate.