ecosystem antifragility: beyond integrity and resilienceevaluate heuristically in real-world...
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A peer-reviewed version of this preprint was published in PeerJ on 11February 2020.
View the peer-reviewed version (peerj.com/articles/8533), which is thepreferred citable publication unless you specifically need to cite this preprint.
Equihua M, Espinosa Aldama M, Gershenson C, López-Corona O, Munguía M,Pérez-Maqueo O, Ramírez-Carrillo E. 2020. Ecosystem antifragility: beyondintegrity and resilience. PeerJ 8:e8533 https://doi.org/10.7717/peerj.8533
Ecosystem antifragility: Beyond integrity and resilienceMiguel Equihua Zamora 1 , Mariana Espinosa 2 , Carlos Gershenson 3, 4, 5 , Oliver López-Corona Corresp., 4, 6, 7 , MarianaMunguia 8 , Octavio Pérez-Maqueo 1 , Elvia Ramírez-Carrillo 9
1 Red ambiente y sostenibilidad, Instituto de Ecología A.C, Xalapa, Veracruz, Mexico2 Doctorado en Ciencias Sociales y Humanidades, UAM-Cuajimalpa., cdmx, cdmx, Mexico3 IIMAS, Universidad Nacional Autónoma de México, cdmx, Mexico4 Centro de Ciencias de la Complejidad (C3), Universidad Nacional Autónoma de México, cdmx, cdmx, Mexico5 ITMO University, St. Petersburg, 199034, Russian Federation, St. Petersburg, Russia6 Cátedras CONACyT, Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO), cdmx, Mexico7 Red ambiente y sostenibilidad, Instituto de Ecología A.C., Xalapa, Veracruz, Mexico8 Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO), CDMX, Mexico9 Facultad de Psicología, Universidad Nacional Autónoma de México, cdmx, Mexico
Corresponding Author: Oliver López-CoronaEmail address: [email protected]
We review the concept of ecosystem resilience in its relation to ecosystem integrity froman information theory approach. We summarize the literature on the subject identifyingthree main narratives: ecosystem properties that enable them to be more resilient;ecosystem response to perturbations; and complexity. We also include original ideas withtheoretical and quantitative developments with application examples. The maincontribution is a new way to rethink resilience, that is mathematically formal and easy toevaluate heuristically in real-world applications: ecosystem antifragility. An ecosystem isantifragile if it benefits from environmental variability. Antifragility therefore goes beyondrobustness or resilience because while resilient/robust systems are merely perturbation-resistant, antifragile structures not only withstand stress but also benefit from it.
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.27813v1 | CC BY 4.0 Open Access | rec: 21 Jun 2019, publ: 21 Jun 2019
Ecosystem Antifragility: Beyond Integrity1
and Resilience.2
M. Equihua2,*, M. Espinosa8,*, C.Gershenson3,5,6,*, O. Lopez-Corona1,2,3,*,3
M. Munguıa7,*, O. Perez-Maqueo2,*, and E. Ramırez-Carrillo4,*4
1Catedras CONACyT, Comision Nacional para el Conocimiento y Uso de la5
Biodiversidad (CONABIO), CDMX, Mexico6
2Red ambiente y sostenibilidad, Instituto de Ecologıa A.C., Xalapa, Mexico7
3Centro de Ciencias de la Complejidad (C3), Universidad Nacional Autonoma de8
Mexico, CDMX, Mexico9
4Facultad de Psicologıa, Universidad Nacional Autonoma de Mexico, CDMX, Mexico10
5IIMAS, Universidad Nacional Autonoma de Mexico, CDMX, Mexico11
6ITMO University, St. Petersburg, 199034, Russian Federation.12
7Comision Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO), CDMX,13
Mexico14
8Doctorado en Ciencias Sociales y Humanidades, UAM-Cuajimalpa.15
Corresponding author:16
Following the Hardy-Littleton rule, all authors will appear in alphabetical order. And all are17
corresponding authors∗18
Email address: [email protected]; [email protected]; [email protected];19
[email protected]; [email protected]; [email protected];20
ABSTRACT22
We review the concept of ecosystem resilience in its relation to ecosystem integrity from an information
theory approach. We summarize the literature on the subject identifying three main narratives: ecosystem
properties that enable them to be more resilient; ecosystem response to perturbations; and complexity.
We also include original ideas with theoretical and quantitative developments with application examples.
The main contribution is a new way to rethink resilience, that is mathematically formal and easy to
evaluate heuristically in real-world applications: ecosystem antifragility. An ecosystem is antifragile if
it benefits from environmental variability. Antifragility therefore goes beyond robustness or resilience
because while resilient/robust systems are merely perturbation-resistant, antifragile structures not only
withstand stress but also benefit from it.
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1 INTRODUCTION32
Sustainable development needs to preserve the structure and functioning of natural ecosystems, i.e. their33
integrity, as a Sine qua non condition. In previous work [25] an operational framework has been34
developed to quantify ecosystem integrity as well as viable standards useful for managing the way people35
intervene ecosystems, promoting development along sustainable avenues.36
Humans are starting to be recognized as an overwhelming forcing factor modulating biosphere37
dynamics. In this view, the Earth system can be interpreted as entering in a geological era that can38
be called the Anthropocene [99] the Technocene [62] or even Capitalocene [41], depending on the39
conceptual stance adopted. Because of this driving influence of human decisions, there has been long40
interest in understanding and measure the way ecosystems recover (or not) from human perturbations. To41
operationalize sustainability, we require working definitions of this ecosystem ability and metrics to asses42
it, in addition to ecosystem integrity (as a component of a likely state variable accounting for the amount43
of natural capital assets: condition× extension). The recovery property has already been encapsulated44
into the ecosystem resilience concept. Here, we propose that information theory is a suitable framework45
to encompass both ecosystem integrity and resilience.46
According to [25], numerous studies have aimed to find a suitable and inclusive definition of ecological47
integrity; however, no general consensus has been achieved to date. In their work, Equihua and co-48
workers embrace a complex systems approach in which ecosystems are considered as self-organized49
entities constrained in their structure (including biological composition or biodiversity), and function by50
thermodynamic dissipative system properties [52, 87, 67, 72] and evolutionary processes [61].51
The concept of ecosystem resilience was first introduced by Holling [46] to portray the persistence of52
natural structures in the presence of environmental stressors due to natural or anthropogenic triggers. In53
his seminal work, Holling follows a system dynamics analysis. There, resilience concept is defined as:54
“the capacity of a system to absorb disturbance and reorganize while undergoing a change so as to still55
retain essentially the same function, structure, identity, and feedbacks” [109]. Nevertheless, resilience56
or stability, which is commonly used as synonym, have at least 163 different definitions (grouped in at57
least 70 concepts of stability/resilience) [37]. For example, Saint-Beat and co-workers [91] summarize58
resilience and others related concepts often used interchangeably as follows:59
• Resilience is the rate at which a system returns after a disturbance to the equilibrium state [20,60
Pimm]. Long return time is equivalent to low resilience. A community’s resilience relies on the61
least resilient species (the slowest to return to equilibrium). This definition of resilience corresponds62
to the ‘engineering resilience’ defined by [47] And assumes that there is only one balance or a63
stable state [38].64
• Persistence is the time for a variable to remain in the same state before changing to a different one65
[Pimm]. Persistence is a measure of a system’s capacity to preserve itself over time. [63]66
• Resistance is described as the capacity of an ecosystem in the presence of external disturbance to67
preserve its initial state. [43]. Only small changes (in amount and intensity) within an ecosystem68
correspond to high resistance. This concept is similar to the ‘ecological resilience’ defined by [47]69
and Suggests that various stable states exist.70
• Robustness relates to the durability of the stability of the environment. Robustness is then a measure71
of the amount of disturbance an ecosystem can endure before it changes to a different state. [63].The72
more robust the food web is, the more stable it is.73
In this paper, we ascertain that both integrity and resilience frameworks can be formalized using74
information theory. The second law of thermodynamics is probabilistic by its very nature, because its75
formulation involves a probabilistic description of the state of a system [78]. It is customary in information76
theory to relate the Shannon information of a random variable X (microscopic state of a physical system)77
with the thermodynamic entropy of the system. This relation can be expressed as78
H(X) =−k∑x
[p(x) log p(x)], (1)
where p(x) is the probability density and assuming k as the Boltzmann’s constant. Even more, once79
the connection between entropy (thermodynamics) and Shannon information (information theory) is80
made, we are able to calculate self-organization as the complement (1−H(X)) of Shannon information81
[26]. Following [25, 15], an ecosystem that is in a high level of integrity is at full capacity to develop as82
a natural consequence of the continued operation of the processes of self-organization to dynamically83
incorporate the original species set at its location, which can be interpreted as the mechanistic basis of84
what is known as ecosystem resilience.85
It is clear then that in order to construct a unified narrative for ecosystem integrity and resilience,86
information theory is a suitable framework candidate. With that aim, we present in this paper a critical87
review of the literature and then develop a novel proposal related to what we consider a suitable concept88
not incorporated in dynamic ecosystem understanding so far: antifragility, which is the non linear (convex)89
response of a system to profit from variability in the payoffs space, or in simple words the ability of a90
system to benefit from surrounding randomness.91
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Figure 1. Ecosystem Integrity three-tier model. Ecological integrity is understood to
be an underlying attribute in the constitution of ecosystems that produce specific
manifestations in their structural characteristics, development processes, and acquired
composition. In short, ecological integrity arises from processes of self-organization
derived from thermodynamic mechanisms that operate through the locally existing
biota, as well as the energy and materials at their disposition, until attaining “optimal”
operational points which are not fixed, but rather vary according to variations in the
physical conditions or changes produced in the biota or the environment. In the figure
we show the three-tier model of ecosystem integrity (3TEI), the inner tier is hidden to
the observer, but its status can be inferred by the information available at the
instrumental or observational tier where measurements on structure (including
composition or other biodiversity features) and function are obtained, of course
considering the context where the ecosystem is developing. Arrow tips indicate the
direction of assumed mechanistic influence, although information can go either way.
2 SURVEY METHODOLOGY92
It has recently been shown that Web of Science and Scopus is invisible to a big proportion of highly-cited93
papers in the social sciences and humanities. And even when the percentage of missing highly cited94
papers in Web of Science (WOS) and Scopus is in the natural, lives and social sciences. The Spearman95
quotation correlation coefficients in Google Scholar are more powerful in all fields compared to Web of96
Science and Scopus. The researchers conclude that highly cited papers available in the inclusive Google97
Scholar database actually show important deficiencies in the coverage of the Web of Science and Scopus98
in certain study fields. Consequently, using these selective databases to calculate bibliometric indices99
based on the number of highly cited papers could generate partial evaluations in poorly covered fields100
[68].101
For these reasons we choose Google Scholar as the search engine in which we use the term: “Ecosys-102
tem Resilience” AND “Information theory” AND “ “Ecosystem Integrity”. After excluding patents and103
citations we end up with 20 items. Of those 20 co-occurrences, books and patents were discarded, leaving104
10 entries that where fully read. Finally, only 7 items were selected to be analyzed and included in the105
present review. However, Google Scholar, does not provide easy access to cited references, which indicate106
the knowledge background of the selected items. For that reason, the analysis was completed with data107
from the Web of Science and the Astrophysics Data System to visualise their cited references network108
using Science of Science (Sci2) Tool and Gephi. To further analyze the literature set, a text corpus was109
assembled taking the text of the title and abstract of target documents as a bag of words. This small corpus110
was then processed with latent Dirichlet allocation (LDA) and latent semantic analysis (LSA) techniques.111
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FINDINGS112
Basic scientometrics i.e word clouds113
In Table 1 we show basic metrics for papers selected and in Fig. 2 the results of applying LDA analysis114
to this corpus, based on [95] with an interactive viz that can be opened in any browser. A video explaining115
the use of this kind of viz could be found in here. According with LDA, papers can be allocated to the116
topics as indicated in Table 2; although, topics can be concurrently present in any paper.117
Source Google Scholar
Papers 7
Citations 454
Years 23
Cites Year 19.74
Cites Paper 64.86
Cites Author 149.78
Papers Author 1.95
Authors Paper 4
h index 7
g index 7
hc index 6
hI index 1.75
hI norm 6
AWCR 71.34
AW index 8.45
AWCRpA 17.93
e index 20.12
hm index 1.95
QueryDate 2019-02-04
Cites Author Year 6.51
hI annual 0.26
h coverage 100
g coverage 100
star count 3
year first 1996
year last 2018
ECC 454
Table 1. Table shows basic metrics for the Google Scholar search.
In Fig. 3 we present a main axes plot based in a latent semantic analysis (LSA). Both LDA and LSA118
suggest it is possible to recognize four groups in the corpus, which are further discussed in the section119
analyzing perceived literature narratives below. In addition, the analysis of the citation network reveals120
several unconnected sub-groups, while the cited references in general are very poorly connected. We121
interpret this findings as evidence of poor interdisciplinary crossover on the conceptual development of122
ecological resilience and integrity, which prompted our interest in the issues we discuss in this paper.123
LDA Topic Paper
1 Cabezas 2005
1 Sidle 2013
2 Aronson 1996
2 Gustavson 2002
3 Saint-Beat 2015
4 Filotas 2014
4 Schmeller 2018
Table 2. Allocation of paper to dominant topic found by LDA.
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Figure 2. Latent Dirichlet Allocation (LDA) analysis based on [95] with an interactive
viz to be opened in any browser. In short, the interface has two main panels. Topic
pattern on the left and terms frequencies on the right. The left panel shows a general
perspective of the discovered subjects indicating how common each is in the corpus (the
set of papers) and how they relate to each other ; the subjects are plotted as circles
whose centers are characterized by the computed range between the subjects (projected
into 2 dimensions). The prevalence in the corpus of each topic is proportional to the
circle size. The right panel has a bar chart showing the meaning of terms, informative of
the possibly interpretation of the topics essence. You can pick any subject interactively
and find out the function of terms in it. Two overlaid bars are shown at each place when
pointing to a subject, displaying the topic-specific frequency of each word (in red) and
the corpus-wide frequency (in blue gray). When no topic is selected, the right panel
displays the top 30 most salient terms for the dataset. A video explaining the use of this
kind of viz could be found in here
In Fig.5 we show a TreeMap for the type of documents that cite the set of reviewed ones; in Fig6 The124
organizations of origin for the documents that cite the set of reviewed ones; in Fig.7 we show the number125
of documents that cite the set of reviewed ones; and in Fig.8 the distribution of documents that cite the set126
of reviewed ones in terms of research field.127
2.1 Literature narratives128
We consider that in the context of the relation of resilience with ecological integrity under the lens of129
information theory, narratives has gone from trying to identify (with information theory tools) ecosystem130
features that allow them to be more resilient and hence maintain their integrity, to a more technical131
approach using times series or network analysis in addition to new mathematical concepts (see fig. 9).132
The importance of interactions and a complex system approach is highlighted. Finally, the field completes133
a circle getting again back into ecology and refining resilience feature and properties of ecosystems.134
2.2 Resilience features and properties I135
Noble and Slayter [? ] have described several categories of essential life history characteristics that are136
helpful in determining a species ’ reaction to recurrent disturbances. In the revised paper by Aronson137
and co-workers [4], the authors make reference to a previous work [3] where they modified the Noble138
and Slayter’s concept [77], defining Vital Ecosystem Attributes (VEAs). The VEAs attempt to capture139
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Figure 3. Latent semantic analysis of papers
those features or attributes that are correlated with and that can serve as ecosystem structure and function140
indicators, the same attributes in the Ecosystem Integrity Model (3TEI) instrument layer from Equihua141
and colleagues [25]. In that way, one may interpret that a resilient ecosystem is one for which VEAs fall142
into an optimal range, represented as ecosystem integrity. But unlike the 3TEI model, VEAs requires143
intense (often cost and not scalable) fieldwork that most likely make VEAs not such a good option for a144
national assessment of ecosystem condition trends.145
Structure Function
Perennial species richness Biomas productivity
Annual species richness Soil organic matter
Total plant cover Maximum available water reserves
Aboveground phytomass Coefficient of rain off efficacy
Beta diversity Rain use efficacy
Life form spectrum Length of water availability period
Keystone species Nitrogen use efficacy
Microbial biomass Microsymbiont effectiveness
Soil biota diversity Cyclic indexes
Table 3. Vital Ecosystem Attributes according to [3]
6/25
Figure 4. The citation network for the selected paper including them
Figure 5. TreeMap for the type of documents that cite the set of reviewed ones
From the idea of VEAs (see Table3) Aronson and his colleagues [4] extracted the insight into146
considering 16 quantifiable characteristics for use on a more particular spatial scale: the landscape as a147
multifunctional environment. The writers intend to use the fresh Vital Landscape Attributes (VLAs) to148
evaluate the outcomes of ecological restoration or rehabilitation conducted from the view of the landscape.149
Most interesting is the chance that as VEAs relate to the integrity of the ecosystem, VLAs (see Table??150
could give way to a 3TLI model.151
In a different line of thought, the reviewed paper by Gustavson and co-workers [39] develops a152
general index that may serve as a proxy of ecosystem resilience from an information theory perspective.153
The authors report that attempts have been made to describe and evaluate resilience, but an overall154
predictive or theoretical connection between resilience characteristics and ecosystem dynamics has yet155
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Figure 6. Organizations of origin for the documents that cite the set of reviewed ones
Figure 7. Number of documents that cite the set of reviewed ones
Figure 8. Distribution of documents that cite the set of reviewed ones in terms of
research field
to be advanced. Similarly, much has been discussed about possible interactions between stability and156
structure and, generally speaking, predictable interactions between resilience characteristics and how157
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Figure 9. Summary of concepts and narratives in selected papers
ecosystems work are not intuitively evident and may not exist.158
To this end, they turn to Ulanowicz’s Ascendancy Theory [? ] which is a measure of the magnitude of159
the information flow through an ecosystem’s network framework. Some constraints for its use are that it160
requires a comparatively full description of the nature and magnitude of all species interactions.161
Ascendancy is defined by the average mutual information as presented [105] between component a to162
b is:163
As = K∑i∑
j
p(ai,b j)log
[
p⟨
b j|ai
⟩
p⟨
b j
⟩
]
, (2)
where, p⟨
b j|ai
⟩
, the probability of b j given that ai has occurred; and p(b j), the probability that b j164
will occur.165
The upper limit of ascendancy is the capacity for growth, and the distinction between ability and ascen-166
dancy is called the overhead system, which represents a multiplicity of paths and can therefore eventually167
be linked with the complexity of the ecosystem.[116]. A complex structure is key for sustainability [45]168
because the diversity of processes plays a crucial role on system survives [106]. In particular, to enhance169
ecosystem’s long-term sustainability, a particular densely connected network structure is advantageous.170
Such a scheme is sufficiently effective and sufficiently varied. Efficiency-diversity equilibrium is essential171
to ecosystem resilience. Ultimately, ascendancy captures in a single index the capacity of an ecosystem to172
prevail against disruption by virtue of its combined organisation and size, it was suggested that, in order173
to attain sustainability, it should always be possible for systems of human use to regain their ascendancy174
within culture and ecosystems [88].175
2.3 Ecosystems response to perturbations176
The main interest in the selected paper form Cabezas and co-workers [12] is not ecosystem integrity nor177
resilience per se but sustainability. A concept they relate to integrated systems comprising humans and the178
rest of nature (probably a socioecosystem). They emphasize that the structures and operation of the human179
element (in terms of culture, economy, law, etc.) must be such that they strengthen or encourage the180
persistence of the natural component’s structures and operation (in terms of ecosystem trophic connections,181
biodiversity, biogeochemical cycles, etc.), and vice versa. It is in the idea that ”persistence” and ”operation182
of the natural component” that the connection is made. From their perspective a sine qua non condition to183
achieve sustainability [83] is ecosystem stability which they conceptualize using Fisher information [11],184
view that is further developed in several papers [24, 50, 70, 69, 115, 2, 51, 35].185
Following [30] and [69] Consider the central problem of estimating the actual value θ forstate variable.
The estimation comes from an inference process from imperfect observation y = θ + x in the presence
of some random noise x. This kind of measurement-inference process will hence be called “smart
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Vital Landscape Attributes (VLAs)
Type, number and range of landform
The number of ecosystems
Type, number and range of land units
Diversity, length and intensity of former human uses
Diversity of present human uses
Number and proportions of land use types
Number and variety of ecotunes-zones
Number and types of corridors
Diversity of selected critical groups of organisms (functional groups)
Range and modalities of organisms
regularly crossing ecotunes
Cycling indexes of the flow and exchanges of water,
nutrients, and energy within and among ecosystems
Pattern and tempo water and nutrient movement
Level of anthropogenic transformation of landscape
Spread of disturbance
Number and importance of biological invasions
Nature and intensity of the different sources of
degradation, whether legal or illegal
Table 4. Vital Landscape Attributes as proposed by [4]
measurement” of θ whose result is an estimator θ that is a function of an imperfect observation θ(y). This
is a closed system, meaning that it’s well described by {y, θ ,x} without the need to consider additional
sources of noise. Consider also that the estimator is unbiased in terms of being a good estimator on
average⟨
θ(y)⟩
= θ . In this case, the mean-square error obeys the Cramer-Rao inequality
e2I ≥ 1, (3)
where I is the Fisher Information of the system, calculated as186
I =∫
dy
P0(y|θ)
[
dP0(y|θ)
dθ
]2
, (4)
in which P0(y|θ) is the probability density function of measuring a particular value of y given the true187
value θ of the state variable in question. Then, since the error decreases as information increases, Fisher188
information may be understood as the quality of the estimation θ from a smart measurement. Then,189
if the system is characterized by a phase space with m state variables xi that define the phase vector190
s = (x1, ...,xi,...,xm) associated with a smart measurement y, then we can prove that191
I (s) =1
T
T∫
0
s′′2
s′4dt, (5)
where T is the time period required for one cycle of the system; s′(t) is the tangential speed and s′′(t) is192
scalar acceleration tangential to the system path in phase space. Both are calculated in terms of the state193
variables xi as194
s′ (t) =
√
m
∑i
(
dxi
dt
)2
, (6)
s′′ (t) =1
s′ (t)
m
∑i
(
dxi
dt
d2xi
dt2
)
. (7)
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A simple and robust approach to calculating tangential velocity and acceleration uses the three-point195
difference scheme196
dxi
dt=
αxi(t +∆ta)− (α2 −1)xi(t)− xi(t −α∆ta)
α(α +1)∆ta, (8)
d2xi
dt=
αxi(t +∆ta)− (α +1)xi(t)− xi(t −α∆ta)
α(α +1)∆t2a/2
, (9)
where xi(t) is a central data point, xi(t −∆ta) is the next point following the center xi and xi(t −∆tp) is197
the previous point to it. For evenly-spaced points ∆ta = ∆tp and α = ∆tp/∆ta is the ratio of the previous198
and following time space.199
The thesis suggested by [? ] is that a shift in Fisher information may signal a change of regime in a200
dynamic system to [? ]:201
• Fisher information is a function of measurement variability. Low variability results in high Fisher202
information and low Fisher information results in high variability.203
• Systems in stable regime tends to exhibit constant Fisher information. Then, organization losses204
points to greater variability and a decrease of Fisher information.205
• Self-organizing systems reduce their variability and gain Fisher information.206
• ”If resilience is defined by the intensity, frequency, and duration of a perturbation that a system can207
withstand before fundamentally changing in function and structure, then we would hypothesize that208
Fisher information would return to the same value or higher in more resilient systems.” [12]209
We found this last point of much interest because not only it provides a formal definition of the210
resilience concept, but it also provides a specific way to measure it via Fisher information. In order to test211
this idea, we analyze NDVI data for ”US-Me1: Metolius - Eyerly burn” Ameriflux site [40] site in Oregon212
for which is documented as an intermediately aged ponderosa pine forest that was severely burned in213
the 2002 Eyerly wildfire. The AmeriFlux network of approximately 100 research stations is the main214
research group and information supplier for big terrestrial carbon cycling syntheses in the Americas and215
has established a database for micrometeorological, meteorological and biological information.216
Data of NDVI was downloaded using the application for Extracting and Exploring Analysis Ready217
Samples (AppEEARS) that enables users to subset geospatial data-set using spatial, temporal, and218
band/layer parameters (https://lpdaacsvc.cr.usgs.gov/appeears/). In particular, we219
used MOD13A3.006 1km2 resolution monthly data of NDVI from 01-01-1990 to 01-01-2018.220
Focusing into the 2002 wildfire, we show in Figure10 that as expected, with the wildfire disturbance221
the system experience both great changes in NDVI and its corresponding Fisher information. We found222
that Fisher information returns to previous values after 18 months approximately but not the NDVI values.223
On the one hand, recovering Fisher information could be related to the way Filotas and co-workers224
[27] understand ecological resilience as ”the amount of change that an ecosystem can absorb before it225
loses its ability to maintain its original function and structure”. After a disturbance, the authors claim that226
a resilient system has the ability to recover its initial structure, features, and feedback ; in other words, its227
integrity.228
On the other hand, it seems then that the criterion of Fisher information is necessary but not sufficient229
to ensure ecosystem resilience. For example one should expect that after a disturbance, essential variables230
as the ones proposed by Schmeller and co-workers [92], which could be seen as a modern version of231
Aronson’s Vital Ecological Attributes [4], return to previous values. In a recent work Dutrieux [23]232
combine into one index signaling from TM and ETM+ B4 band, corresponding to Near Infra Red233
(NIR) with wavelength of 770−900nm which provide information about canopy biomass; and B5 band234
corresponding to Short Wave Infra-Red (SWIR1) with wavelength of 1550− 1750nm which provide235
information about canopy moisture content:236
NDMI =NIR−SWIR1
NIR+SWIR1. (10)
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Figure 10. In red the normalized NDVI time series for the 1km2 pixel corresponding
to the coordinates of the US-Me1 site of Ameriflux with a monthly sampling. In blue,
the corresponding values of Fisher’s information using the Cabezas and collaborators
algorithm (https://github.com/csunlab/fisher-information)
Low NDMI values for bare soils and thin forest canopies are anticipated, while greater values237
correspond to thicker, completely developed forest canopies. [111].238
The author created the following harmonic model to compare values before and after a disturbance:239
yt = αi+3
∑1
γisin
(
2π jt
f+δ j
)
+ εt , (11)
where the dependent variable y at a given time t is expressed as the sum of an intercept αi, a sum240
of different frequency harmonic components representing seasonality and an error εt . In the model j241
corresponds to the harmonic order, 1 being the annual cycle, γ j and δ j correspond respectively to the242
amplitude and phase of the harmonic order j, and f is the known frequency of the time-series (i.e., number243
of observations per year).244
New values are then estimated for each spectral band and each time series observation using the245
corresponding matched model, enabling Euclidean distance to be calculated with the following formula.:246
Dt =
√
√
√
√
k
∑i=1
(yit − yit)2. (12)
The author then applies it to spectral recovery time for a set of 3596 Landsat time-series sampled247
from regrowing forests across the Amazon basin, thus producing estimates of recovery time in spectral248
properties, which he calls spectral resilience. On average, he found that spectral resilience takes about 7.8249
years, with a large variability (sd =5.3 years) for disturbed forests to recover their spectral properties. Now250
we have a new problem, how to determine the thresholds for (a) distance between initial and final values251
for both state (essential/vital) variables and their Fisher information; (b) the time scale these recovering252
should occur. In principle we believe (a) could be determined from ecological integrity measurements,253
but it is currently an open research question we are not addressing here.254
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In another line of thoughts, Sidle and co-workers [94] focus on ascertaining under what circumstances255
ecosystems exhibit resilience, tipping points or episodic resetting. They point out that while ecosystem256
resilience originated from ecological perspective, latest debates concentrated on geophysical characteris-257
tics and that it is acknowledged that dynamic system properties may not return to their former state after258
disturbances (see for example [16, 36, 60, 85, 74, 100]). Tipping points generally arise when chronic259
(typically anthropogenic but sometimes natural) changes push ecosystems to thresholds that cause process260
and function collapse even in a permanent way. Resetting ecosystems happens when episodic natural261
disasters break thresholds with little or no warning resulting in long-term modifications in environmental262
characteristics or functioning of the ecosystem. Of special interest is the work of Steffen and co-workers263
[100] who consider earth biosphere as a whole system and study its possible trajectories under the current264
planetary crisis. In particular, they explore the risk of self-reinforcing feedback that could eventually push265
the Earth’s biosphere system to a planetary threshold that, if crossed, could prevent climate stabilization266
near the Holocene temperature regime (the pre-industrial conditions set out in the Paris Agreement). In267
the worst case scenario Earth could be driven into the ongoing warming track of a ”Hothouse Earth” path,268
even though human emissions were lowered.269
As in other papers reviewed, Sidle and co-workers [94], state that ”if a system is viewed as resilient, it270
is generally perceived as remaining within specified bounds, probably close to the optimal operational271
points” mentioned in [25]. Which sets again the question of which should be the variables under the272
“bounded ecosystem” and how to determine the range of values to consider the ecosystem as resilient.273
More to the point, how much time should be spanned between an ecosystem perturbation for the resilience274
variable returning to their bound limits? In principle, we consider that this should be in the same order of275
magnitude that the -natural characteristic time scale of the ecosystem. But once again, the measurement276
of characteristic time scale for an arbitrary state variable of the ecosystem is an open question. The277
main problem is that in most cases we will not have a mechanistic model for the variable in question278
but time-series only. In [1] the authors use the Wigner function to explore if there is an special time279
scale under which the system reaches an optimal representation. For multiple time series observed, they280
contrasted entropy values covering a variety of distinct time domains. For their natural characteristic time,281
they found that entropy is highly likely to be minimal, implying minimum uncertainty in time-frequency282
space. Another alternative might be to consider the τ0 time in which the system’s memory tends to283
be zero, defined by the absolute τ time value for which the C(τ) auto-correlation function crosses the284
horizontal axis [? ].285
2.4 Complexity perspective286
The Filotas and co-workers reviewed paper [27] provides a remarkable introduction to complexity. The287
authors decompose complexity into eight features an then goes to relate them into a new narrative for288
forests, making as a result an interesting connection with resilience and integrity. Generally speaking, a289
system is complex either it presents a sufficiently number of components with strong enough interaction290
or it exhibits changes in the configuration space comparable to the observer’s time scale, and in most291
cases both. Forests as a system and forest management, certainly occupy a high position in the complexity292
gradient.293
The authors focus on forests, but clearly what they describe is applicable to all types of ecosystems.294
Nevertheless, forests are a good model because they are both widely and intensively managed, and also295
because they are deeply coupled with human systems. The designed approach can thus assist forest296
scientists and managers in conceptualizing forests as integrated socio-ecological systems and provide297
concrete examples of how to manage forests as complex adaptive systems.298
There are at least 800 different definitions of a forest. Some of them are used simultaneously in the299
same country for different purposes or scales [64]. This is in part due to the fact that forest types differ300
widely, depending on factors such as latitude, climate patterns, soil properties, and human interactions. It301
also depends on who is defining it. An economist could describe a forest in a very distinct manner to a302
forester or a farmer, in accordance with their specific interests. One of the most widely used definitions is303
that by FAO (1998), that defines a forest as ”the track of land with area over 0.5 ha, tree canopy cover304
larger than 10%, which is not primarily subject to agricultural or other specific non-forest uses”. For young305
forests or regions where tree growth is suppressed by climatic factors, trees should be capable of reaching a306
height of at least 5 m in situ while meeting the requirement for canopy cover. In general, forest definitions307
are based on two different perspectives. One, associated with quantitative cover/density variables such as308
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minimum area cover, minimum tree height, or minimum crown size. The other, relates to characteristic309
spatial features of the territory such as the presence of plantations, agricultural activities or non-forest310
trees within the forest itself [56, 57, 58, 64, 107]. The issue is that when natural forests are significantly311
degraded or superseded by plantations, essential ecosystem services such as CO2 sequestration may be312
lost ; but they may technically continue to be classified as forests under many definitions.313
Thus, a fundamental key characteristic of ecosystems is essentially missing in most forest definitions,314
its complexity. The authors point out that complex systems science provides a transdisciplinary framework315
to study systems characterized by (1) heterogeneity, (2) hierarchy, (3) self-organization, (4) openness, (5)316
adaptation, (6) memory (homeostasis?), (7) non-linearity, and (8) uncertainty. These eight characteristics317
are shared by complex systems regardless of the nature of their constituents and the article exemplifies318
them in ”forest terms”. The conclusion they reach in terms that complex systems approach has inspired319
both theory and applied approaches to improve ecosystem resilience and adaptability is most relevant320
to our article. While forests are prime examples of complex systems (Perry 1994), forest ecology and321
management approaches are only starting to emerge and complex systems are seldom invoked in the field.322
Heterogeneity or how ecosystem components are distributed in space is important from several points323
of view. For example, the spatial distribution of resources imposes restrictions on animal foraging and324
ultimately significant patterns. It has widely been proved that the foraging patterns of a variety of animals325
involve many spatio-temporal scales, as described by Levy walks [108, 84, 73]. This statistical behavior326
is present even in human movement patterns [10], and has been linked to evolutionary advantages in terms327
of search strategies in complex environments [6]. Further more, resources distribution patterns induce328
foraging behaviours linked to seed dispersal. Those patterns feedback into the ecosystem dynamics and329
influence the distribution of resources in time [8]. In the reviewed paper, the authors point out that human330
influence on ecosystems may reduce ecosystem complexity by altering spatial heterogeneity. For instance,331
forest cover and resident biota have been homogenized by intensifying and standardizing cultivation332
methods within and between woodlots. Changing these patterns can significantly influence the capacity333
of the landscape to maintain materials and energy effectively processed and host the region’s biota; this334
change in turn decreases its integrity, resulting in a loss of resilience. Even more, in the context of the335
Anthropocene [99] or Technocene [62], Human impact in extreme cases may modify forest heterogeneity336
generating new ecological patterns (niche construction) and interactions, without historical equivalents337
[93].338
Spatial heterogeneity can be altered by invasive species threaten biodiversity through predation339
[21, 86], competition [42], disease transmission [114], and facilitation of the establishment of further340
invasive species [97]).It has been reported that the decrease and extinction of native species due to invasive341
predators can generate cascade effects that extend through the whole ecosystem and beyond. [14]. In342
particular depredation effects resulting from human introduced species can be severe [96, 22]. Both rats343
(Rattus rattus), cats (Felis catus) and dogs (Canis lupus familiaris) are recognized as the worst threat344
species following recent studies [48]. In natural areas worldwide, dogs are threatening some 200 species,345
some of them even included in IUCN threat categories. Likewize, Feral cats and red fox (Vulpes vulpes)346
predation processes has been documented as a cause of the decline or extinction of two thirds of Australia’s347
digging mammal species [28, 112]. Reduced disturbance to soil in the absence of digging mammals has348
led to impoverished landscapes where little organic matter incorporates into the soil and rates of seed349
germination is low [28]. The predation of seabirds through introduced Arctic foxes (Alopex lagopus) in350
the Aleutian archipelago has reduced nutrient input and soil fertility, eventually causing vegetation to shift351
from grassland to dwarf shrubland.352
In a recent work [18], a deep relation between Levy walks and resilience has been shown. In this353
work, Danneman and coworkers unveil an essential yet unexplored multi-scale movement property of354
Levy walks, how it play an important role in the stability of populations dynamics.Using Lotka-Volterra355
models, they predict that generally diffusing foragers tend to become extinct in fragile fragmented habitats,356
while their populations become resilient to degraded circumstances and have maximized abundance when357
individuals undertake Levy flights. Their analytical and simulated findings, change the scope of multi-358
scale foraging from individual to population level, making it of major value to a wide scope of applications359
in biology of conservation.Their findings indicate that Levy flights reach a balance between exploration360
and exploitation, which in turn will benefit the stability and resilience of the population. In that way,361
modern forest management is becoming more compatible with this complexity feature (heterogeneity) by362
promoting it through strategic cuts that emulate natural disturbances; leave intact some structures and363
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organisms, Including dead and living trees and intact patches of forests ; and promote mixtures of tree364
species. These methods are similar to the comparatively recent strategy of using biodiversity to boost365
yield and resilience in natural and managed ecosystems [27]. Generalizing these ideas we reckon there is366
important evidence suggesting that in order to preserve ecosystem integrity and resilience, management367
systems should consider maintaining minimum levels of ecosystem complexity.368
Of course, this poses a new challenge: How to measure complexity? Following Gershenson and369
co-authors [31] one may measure complexity using again the Shannon information. In this information370
theory framework, in order to have new information, the old one has to be transformed. Thus, we can371
define information emergence E as the rate of information transformation. therefor emergence is identified372
directly with Shannon’s information H or I. In addition, self-organization (S), a key feature of complex373
systems, has been correlated with an increase in order (i.e. as a reduction of entropy) [31]. Thus, if374
emergence implies an increase in information, which is analogous to entropy; self-organization should be375
anti-correlated with emergence in such a way that376
S = 1− I = 1−E. (13)
In this way, following [31, 26] complexity can be measured as377
C = 4∗E ∗S. (14)
378
Under the complex systems perspective ecosystems are not systems that can simplistically be managed379
top-down. We must explicitly consider that the interactions take place in multiple and hierarchical levels.380
This is a general feature of complex systems, components are organized hierarchically in such a way that381
elements at different levels interact to form an architecture that characterizes the system. In this way,382
complexity asserts that a phenomenon occurring at one scale cannot be understood without considering383
cross-scale interactions. But it also means that environmental policy, management and intervention needs384
to be rethought in terms of scale. In this respect Taleb is assembling ”Principles of policy under complexity”385
(draft version available at: http://www.academia.edu/38433249/Fractal_Localism_386
Political_Clarity_under_Complexity) which include the understanding of policies as scale387
dependent, and so we should consider that instead of aiming at one monolithic policy for managing388
ecosystem, we should go on to develop a range of them linked to different levels of application Such389
approach will be required to reduce the risk of catastrophic hidden effects.390
Understanding the coupling of natural and human sub-systems provide a whole new narrative that391
challenges management. Ecosystems management is the outcome of collective actions among different392
agents such as decision makers, scientists, managers, concerned citizens and so on. As complexity, key393
for ecosystem integrity and resilience, is at dynamic balance between emergence and self-organization394
(S) (Eq.2.4), some (and the correct type of) self-organization is necessary to be fostered, but too much395
of it is bad. Too much (form the wrong type) of S may sustain unwanted feedbacks with detrimental396
consequences. For instance, illegal logging in Borneo can be seen as a self-organizing phenomenon397
supported by interactions among all levels in the stakeholder hierarchy [82]. The mechanism is explained398
by Filotas and co-workers, starting with pit sawyers taking out livings and pirate loggers taking advantage399
of governance failures. This alone could not generate such a great impact, unless it couples with400
unscrupulous timber buyers and corrupt governmental officials laundering the illegal wood. Experience401
in Mexico suggests that corruption might be the common link in practically all-important ecosystem402
degradation processes. Finally, they say that savvy international traders are the higher link that provides403
lucrative outlets for ill-gotten goods. According to the authors narrative, where illegal logging occurs,404
wood markets are flooded, wood prices are depressed, and standing trees are undervalued. Under such405
conditions, community forest managers are not motivated to implement sustainable forest management406
practices, which often involve short-term investments for only long-term returns. These conditions result407
in a self-organized feedback that sustains illegal logging.408
The characteristic of complex systems not having a unique description scale is related to one of the409
most omnipresent system-wide phenomena, the 1/ f behavior on frequency space for the fluctuation time410
series.This so-called pink noise is one of a family of 1/ f β colored or fractal noises defined by the β411
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scaling exponent and deemed to be a criticality fingerprint. It is common to comparing and classifying412
fluctuation dynamics according to their resemblance to three archetypal noise groups: white (β ∼ 0),pink413
(β ∼−1)and Brownian (β ∼−2) [5, 59, 55, 79]. The universality of criticality is still under consideration414
and is known as the ’ ’ criticality hypothesis ” which states that systems in a dynamic system that shifts415
between order and disorder reach the greatest level of computing capacities when reaches a balance416
between robustness and flexibility(see [38] and references therein). This idea of criticality was recently417
used in an information theory approach to defining ecosystem health and sustainability [83]. In this paper,418
Ramırez-Carrillo et al. Consider that an ecosystem is healthy if it is in criticality, as a mixture of scale419
invariance (as power laws in power spectra) and a balance between adaptability and robustness.420
These power laws appear in numerous phenomena including earthquake statistics, solar flares, epi-421
demic outbreaks, etc., as summarized by [83]. [66, 76, 98]. They also are a common theme in biology422
[33, 34, 32, 110]. Several researchers reported evidence of dynamic criticality in physiological pro-423
cesses such as heart activity and suggested that it could be a main characteristic of a healthy state.424
[54, 49, 89]. Some studies [34, 90] found compelling evidence of a relationship between healthy hearts425
and scale-invariant noise, around 1/ f regime, backed by medical evidence.426
This complexity approach is clearly complementary to the ecosystem integrity narrative, and we427
should consider that an ecosystem is resilient if, in addition to maintaining its EVLs values inside a ”safe”428
range, it also keeps them within a critical dynamic region (scale invariance and “1/ f ” fluctuations) [83].429
2.5 Resilience features and properties II430
The main purpose of the Saint-Beat and co-workers reviewed paper [91] is to know how distinct ecosystems431
react to global change in terms of composition and dynamics and eventually, how persistence, strength, or432
resilience of the ecosystem can be assessed. The authors show that ecological network assessment (ENA)433
offers an effective approach for describing local stability, combining both quantitative and qualitative434
elements. They warn, however, that describing real conservation cases combining local and global stability435
remains an incomplete task. The authors focus on three resilience-related results that emerge from their436
ENA: (a) the role of species diversity in the structure and functioning of the ecosystem ; (b) the number of437
trophic links and strength of interactions ; (c) the stability of the ecosystem in terms of cycling capacity,438
omnivory spread and ascendancy.439
Native species richness generally improves ecosystem resistance. High biodiversity (without con-440
sidering non-native species) was proposed to contribute to minimize the threat of major ecosystem441
modifications in reaction to environmental disturbances [71]. Experiments on species invasion in grass-442
land parcels indicate that local biodiversity decreases the settlement and success of a variety of invaders443
[53].Similarly, studies on manipulation of grassland diversity indicate that elevated diversity improves444
inter-specific competition and thus decreases the danger of invasion [75, 44].In this line of thought, the445
authors proceed to summarize the proof. For instance, Brose [9] demonstrates that herbivorous existence in446
a society leads to the coexistence of manufacturers in a mixed predator-prey model and producer-nutrient447
model with a structural model of food-webs. Species diversity also contributes to reduce the impact on448
resistance and resilience for example in coastal ecosystem [113]. Similarly, the maintenance of integral449
ecosystems and the services they provide is critical to human societies and the preservation of species450
diversity seems crucial to achieving this goal [13].451
However, the authors warns that the consideration of a single variable such as diversity can not452
be sufficiently thorough to evaluate the stability of ecosystems due to the complexity of ecosystems.453
Therefore, they suggest that building holistic indexes in the ENA framework is a better approach for a454
thorough knowledge of the food web structure and its role in the functioning of the ecosystem.455
If one would be able to construct a sufficiently detailed trophic network (something very difficult to do456
in general), one could use standard network analysis tools to understand, for example, the topology of the457
network, such as connectance. In that sense, the authors summarize evidence from the literature to show458
that an increase in links dissipates the impact of variability in species distribution and increases stability459
[65]. Higher connectivity thus improves the strength of the ecosystem as well as resilience [20] . If so,460
connectivity seems to be a useful measure of the robustness of food webs and indirectly of ecosystem461
stability.462
In addition to connectivity, they show the importance of interaction strength diversity. Following463
ideas of [104], They claim that ecosystem stability requires a balanced presence of weak and strong464
interactions. Suppression of weak interactions destabilizes the system for a certain amount of species.465
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Moreover, the food web would be stable if and only if main predator-prey interactions are combined466
with weak interactions in the context of high diversity. Thus, due to their ability to fluctuate and adapt467
within ecosystems, weak interactions function as a stabilizing force in food webs and consequently the468
ecosystem.469
To gain a deeper understanding of stability, Saint-Beat and colleagues examine the effect of cycling,470
the presence of omnivorous and ascending.471
For instance, the presence of omnivory gives an ecosystem trophic flexibility, a clear beneficial feature472
that reflects integrity and resilience of the ecosystem. The researchers claim that omnivory provides to473
the ecosystem a superior buffer to deal with environmental disturbances Because omnivorous species474
enable faster ecosystem reaction by rapidly moving trophic routes following disturbance.For example, if a475
disturbance impacts low trophic levels, omnivorous species that are directly linked to it, would respond476
rapidly. In comparison, a particular predator must wait until the disturbance reaches its own level ;477
therefore, the response time will be longer.478
As in the reviewed paper by Gustavson and co-workers [39], Saint-Beat and co-workers show how479
ascendency could be used as a key indicator to evaluate ecosystems functioning. The authors indicate that480
to understand the function of ”ascendancy” two kinds of stability must be differentiated. A system with481
elevated inner stability is a system with adequate inner limitations to enable a strongly organized structure,482
corresponding to a high ascendency (high mutual information). Typically under this condition, ecosystems483
are some how protected against internal perturbations but leave them vulnerable to external ones. On the484
other hand, since low ascendancy is linked to redundancy, ecosystems become more resilient to external485
disturbances. Interestingly enough, too high level of ascendancy is recognized as a a characteristic of486
stress and may indicate a decrease ecosystem resilience.487
Summarizing, in the dynamic response of ecosystems under the criticality framework a healthy488
ecosystem is found where a balance between robustness and adaptation develops. In the case of network489
topology, the ecosystems need to develop a good balance between strong and weak interactions in order490
to be stable. In the case of the ascendancy narrative, a stable ecosystem should develop a good balance491
between ascendancy and overhead, which seems to give resistance and resilience to ecosystems. This492
leads us to think what we develop in the next section, in which we will ascertain whether all these three493
kinds of balance could be particular cases of a more general evolutionary strategy of living systems: the494
antifragility.495
BEYOND RESILIENCE, ANTIFRAGILITY496
Living systems can and must do much more than merely react to the environment’s variability through497
random mutations followed by selection; they must certainty have built-in characteristics that enable them498
to discover alternatives to cope with adversity, variability and uncertainty. Anti-fragility is one of these499
characteristics [17, 101].500
If one considers what does really mean that something is fragile, the key property is that it gets501
damaged by environmental variability. Now if we ask our nearest colleague at random, about the exact502
opposite of fragile, most likely we would get concepts such as robustness or resilience. But at close503
inspection it is clear that none of them are the exact opposite of fragile. Both represent systems that are504
insensitive to environmental variability or get affected only momentarily, quickly returning to its initial505
state.506
The exact opposite of fragility as defined by Taleb is antifragility, which is a property that enhances507
the system’s functional capacity to response to external perturbations[102]. In other words, a system508
is antifragile if it benefits from environmental variability, works better after being disturbed. Then509
antifragility is beyond robustness or resilience. While the robust / resilient systems tolerate stress and510
remain the same, antifragile structures not only withstand stress but also gain from it. The immune system511
provide significant illustration of antifragile systems. When subjected to various germs at a young age, our512
immune system will improve and gain different capabilities to overcome new illnesses in the future[81].513
A formal definition of antifragility as convexity in the payoffs space is found in [103, 102]. Lets
consider a two times continuously differentiable “response” or payoff function f (x). Then the function’s
convexity will be defined by the relation∂ 2 f
∂x2 ≥ 0 which can be simplified under the right conditions
to 12[ f (x+∆x)+ f (x−∆x)] ≥ f (x). Then the response function f will exhibit non-linearity to dose,
which means that a dose increase will have a much higher impact in relation to this increase. Taleb
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generalizes this result to a linear combination for which ∑αi = 1, 0 ≤ αi ≤ 1 in such a way that
∑ [αi f (xi)]≥ f [∑(αixi)]. Again simplifying the argument, under the correct conditions we end up with
f (nx) ≥ n f (x). This way, if X is a random variable with support in [a,b] where the function f is well
behaved, and f is convex, we get Jensen’s Inequality [6],
E( f (x))≥ f (E(x)). (15)
Without loss of generality, if its continuous distribution with density ϕ(x) and support in [a,b] belongs to
the location scale family distribution, with ϕ(x/σ) and σ > 0, then, with Eσ , the mapping representing
the expectation under a probability distribution indexed by the scale σ , we have:
∀σ2 > σ1,Eσ2[ f (x)]≥ Eσ1
[ f (x)] . (16)
514
This way, Taleb defines local antifragility as ”a situation in which, over a specific interval [a,b], either515
the expectation increases with the scale of the distribution as in Eq 2.5, or the dose-response is convex516
over the same interval”.517
Although Antifragility framework was developed by Taleb in the context of financial risk analysis, duo518
to its universal mathematical formalism it has track attention and has been applied far away its original519
scope. There are applications of the Antifraglity concept from molecular biology to urban planning520
(see [81] and references inside). In their work, Pineda and co-workers [81] proposed a straightforward521
implementation of antifragility by defining as payoff function the complexity of the system. which makes522
a lot of sense in the context of our review because complexity is highly related with critically and hence523
with these these trade-off balance between robustness and adaptability.524
The authors defined fragility as525
∮
=−∆C |∆x| , (17)
where ∆C is the change in system complexity due to a perturbation of degree |∆x|. As complexity can526
always be normalized to [0,1], then positive values of∮
define fragile systems; when∮
is zero the system527
is robust/resilient; and for negative values of∮
the system is antifragile.528
Then, Pineda and co-workers [81] apply it to random Boolean networks (RBNs) of a model of genetic529
regulatory works. They found that ordered RBNs are the most antifragile and demonstrated that, as530
expected, seven biological well studied networks such as CD4+ T cell differentiation and plasticity or531
Arabidopsis thaliana cell-cycle, are antifragile.532
We know, from Central Limit Theory, that normal distributions can only emerge from (simple)533
systems without interactions (probabilistic independence). When we take into account interactions (no534
probabilistic independence) then the corresponding probability distribution will have fat-tails. In that535
sense complexity is related with fat-tails and fat-tails with fragility/antifragility [101]. In Taleb’s narrative,536
normal distribution in the response function characterize robust systems; whereas left fat-tailed are fragile,537
and right fat-tailed are antifragile systems. Most interestingly, Fossion and co-workers [29] have related538
homeostasis (physiological resilience?) to pairs of physiological variables, one to be controlled (the539
one that remains in homeostasis) and another one that controls the former. The main idea is that in540
order to have a homeostatic physiological variable (normal), the body must use other variables (right541
fat-tailed) to absorb a random injection of matter, energy, information or any combination of them from542
the environment. In Figure 4 of their paper, they present results for variability analysis of heart rate543
HR and blood pressure BP for (a) healthy control(s), (b) recently diagnosed diabetic patient(s) and (c)544
long-standing diabetic patient(s). They show that for healthy patients BP is normal and HR is right545
fat-tailed. In the case of recently diagnosed diabetic patients, BP start to lose normality and develop a left546
tail and HR tends to normality. Eventually, long-standing diabetic patients, BP has a clearly left fat-tailed547
behavior and HR has become normal. This is very compelling evidence of the role of antifragility in548
human health.549
In a general manner, Taleb [101] Suggests the so-called barbell (or bimodal) approach as an archetypal550
strategy for achieving antifragility. The first step towards antifragility is to reduce downsides instead551
of increasing upsides. In other words, by reducing exposure to adverse low probability but elevated552
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adverse payoff occurrences (i.e. ’ ’ black swans ” events) and allowing natural antifragility to function on553
its own. We follow Taleb with a vulgar finance instance, where the idea is easiest to explain, although554
most of them are misunderstood. The barbel approach in finances comprises of placing 90% of your555
resources in safe instruments (provided that you are protected against inflation) or what is referred to as the556
”value repository number,” and 10% in very risky, maximal risky bonds, exposing yourself to unpredicted557
massive gains in a convex way. In this way, one ends up with some sort of bimodal optimization taking558
advantage of at the same time of the robustness of safe inversion and on the other hand the adaptability of559
high risky ones. Anyone who has a 100% stake in so-called ”medium” securities (unimodal optimization)560
is at danger of ”complete risk ruin”. This Barbel Strategy addresses the issue of incomputability and561
fragility in the assessment of the hazards of unusual occurrences.562
As in the barbell strategy, a basic mechanism to achieve antifragility, is a thorough strategy to risk563
management under fat-tailed distributions, and those are widely present in nature, then it should be very564
ubiquitous in natural systems. We identify this barbell risk strategy as the ”good balance” property in565
network topology by means of the relation of strong and weak interactions or between ascendancy and566
overhead; and balance robustness and adaptability, identified as fingerprint of critically (scale invariant567
and i/ f type of noise), in the dynamic of system’s fluctuations. All these three ”good balances” are568
related, as we showed with ecosystem integrity and resilience.569
Figure 11. Basic characteristics of systems in terms of antifragility, which is the
property of a system to respond in a convex way to perturbations or variability.
DISCUSSION AND CONCLUSIONS570
From the analysis of the literature, we found that the citation network from reviewed network is not571
percolated, what we interpret as a lack of unification in the research field and an opportunity for inter-572
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disciplinary work. We found (see Figure 9) three main narratives (a) Ecosystem properties that enable573
them to be more resilient; (b) Ecosystem response to perturbations; and (c) Complexity. From this and574
complementary literature consulted we have identified 11 possible indicators for ecosystem resilience575
(See Table 5). In particular we show how to apply Fisher information in a study case which we consider a576
very promising proxy of resilience, since it has a solid formal framework, it is easy to implement and it577
can be applied to any kind of system.578
Key Indicator Measure/proxy Requires Resilience
FI Fisher Information Stability Time series
First, more stable ecosystem are more resilient
and according to Cabezas et al. for a system to be
resilient, after a disturbance the FI values prior to
it must be recovered
Div DiversityOptional / use of
resource spacePresence field data
In general to greater diversity, greater resilience
But there are exceptions related to changes of
composition and use of resources
Co Network Conectance Stability
Knowing the networks and being
able to quantify the intensity of the
connections, Gustavson proposes ways
to deal with the lack of information about it
Increase in the number of connections dissipates the effect of
variation in distribution of species and enhances stability species
Omn Presence of omnivore species Communication between different scales Presence of omnivore species Presence of omnivore species enhance stability and resilience
NC Network Criticality
Balance between
robustness (strong Interactions) and
adaptability (Weak Interactions)
Knowing the networks and being
able to quantify the intensity of the
connections, Gustavson proposes ways
to deal with the lack of information about it
Observations show that ecosystems are more resilient when
there is a good balance between the number of strong and weak
connections
L-VCLotka-Volterra
Coefficients
Given a community matrix,
if all the real parts of its
eigenvalues are negative the
ecosystem is stable
Community matrix More stable ecosystem are more resilient
As Ascendency Mean mutual information
Given a network of interactions (i.e trophic
network) it measures how well, on average,
the network articulates a flow event between
any two nodes.
Capture in a single index the ability of an ecosystem
to prevail against disturbance by virtue of its
combined organization and size.
Levy Levy Flights
Scaling coefficient of foraging
patterns for key species such
as puma or jaguar
It is a proxy of resources spatial complexityIt has been shown that Levy flights foraging patterns
are related and enhance ecosystems resilience
Frac Fractality Spatial complexity High resolution satellite images More complex ecosystems should be more resilient
AF AntifragilityChange in the complexity of a biotic (i.e trophic)
network, in the face of disturbances
Network of interactions, can be a
Boolean network of co-occurrences
of a key species such as puma or jaguar
with its prey for example
Resilience would be an intermediate state between
fragility and antifragility
H Homeostasis System Homeostasis Time Series Equivalent of resilience
Table 5. Resilience measure found in the literature review and complementary papers
Nevertheless a new way to reinterpret resilience emerged from this critical literature review: an-579
tifragility. This novel framework developed by N.N. Taleb [101, 103, 102] is based on fat-tailed, non-580
linear responses of the system to variability (see Figure 11). In a simple way, if a system has a concave581
(non-linear) payoff function dependent of certain variable, then the system is fragile to it. On the contrary,582
if the payoff in convex then it is antifragile and if the system is essentially insensible to variability, then583
is robust /resilient. In Taleb’s work, antifragility is associated with bimodal risk strategy called “The584
Barbell” which we believe manifest itself in the narratives as “a good balance” between (i) strong and585
weak interactions in network topology; (ii) adaptability and robustness (criticality); and (iii) ascendancy586
and overhead.587
In the long term, considering the coupling of ecosystem with human systems (i.e. via climate change)588
we consider that antifragility is a more desirable feature than resilience. Thinking in socioecosystems, we589
can see that they usually not only keep on living, but they do flourish and evolve, even in the presence590
of great stressors such as climate crisis or land change. In fact, in a recent work [19], It has been shown591
that the outcome of using antifragility as a design criterion is that the scheme being studied demonstrates592
a more favorable behavior than a ”simply” robust model in a setting that is susceptible to black swans593
(unpredictable, very low frequency of ocurrancebut vey high impact events) . Then, for socioecosystem594
governance, planning or in general, any decision making perspective, antifragility might be a valuable and595
more desirable goal to achieve than a resilience aspiration [7].596
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