Introduction
The debate around the SARS-CoV-2 pandemic has raised multiple and incompletely answered
questions regarding how zoonoses are transmitted from wild populations to humans,
how they spread within human communities, over regions and across continents, how
countries and societies can fight or counter pandemics and how landscapes will have
to be effectively managed for limiting the spread of diseases keeping communities
safe and healthy.
A broader long-standing debate on the (un)sustainability of ongoing development models
where biodiversity, climate, and socio-economic crises are central, both as causes
and effects, has received additional attention in the context of the current pandemic.
This has stressed the urgency of changing development paradigms to reduce pressures
on ecosystems and biodiversity, increase investments in ecosystem and landscape restoration
and integrate natural capital and ecosystem services valuation into decision-making
processes, also at the urban scale.
The SARS-CoV-2 pandemic has also highlighted a third debate on the epistemology of
science and the discipline of landscape ecology. There is clearly a need to acknowledge
the increasing need for holistic, integrative, and inter and transdisciplinary conceptual
frameworks and research methods in science and broader applications such as human
health.
There has been a convergence between environmental and health disciplines over recent
years highlighting the importance of the human–environment relationship in all aspects
of human life, from economic, ecological, social and political perspectives, and the
need for integrative and transdisciplinary approaches in science and practice (Jia
et al. 2019; Spano et al. 2020). In general, human diseases spread by insects and
other vectors, water, and food, and/or transmitted within groups through other processes
(respiratory droplets, contact routes), are best understood by considering the environment
as a whole. A holistic vision, using landscapes as a framework to gain a spatial understanding
of human diseases and their spread, has previously been described in the literature
(e.g. Cumming et al. 2015; Lambin et al. 2010; Paull et al. 2012; Reisen 2010). A
landscape epidemiological approach calls for interdisciplinary cooperation and, as
such, needs to be complemented by knowledge from other fields such as climatology,
biology, medical anthropology, archeology and environmental economic history, among
others, to understand processes from the past that influence the present (Ziegler
2016). We have to recognize the importance of the human-environment relationship in
all aspects of human life from economic, ecological, social and political perspectives
(Jia et al. 2019; Spano et al. 2020).
‘All in all’, medical science alone provides insufficient grounds to fully understand
and deal with complex epizootics and only an interdisciplinary approach will be able
to do so. Multi and interdisciplinary approaches such as landscape epidemiology, disease
ecology or disease biogeography, require that a whole set of new factors and pressures
interconnected to landscape patterns and processes, the core of landscape ecology,
is taken into the study of the spread of diseases. At the same time, landscape ecology,
as a consolidated but evolving scientific discipline, is able to respond to these
emerging challenges based on its theoretical grounds as well as on a wide range of
methods and tools representative of the multi and interdisciplinarity of landscape
ecology, that are essential to prevent, avoid and reduce the impact of both known
and emerging diseases. This can contribute significantly to the One Health approach
of the World Health Organization, of designing and implementing political, technical,
legislative and research initiatives at different scales through communication and
common work across sectors (WHO 2019).
This editorial is motivated by a webinar organized by the IUFRO (International Union
of Forest Research Organizations) Forest Landscape Ecology Working Group (https://iufrole-wp.weebly.com/)
held on June 24th, 2020. We discuss here what landscape ecology has to learn from
this unprecedented crisis generated by the coronavirus pandemic and, simultaneously,
demonstrate how this discipline can be useful to support integrated solutions to minimize
the spread of diseases and to create increasingly safer, and sustainable landscapes.
Diseases and landscapes
Nearly two-thirds of human infectious diseases arise from pathogens shared with wild
or domestic animals (Karesh et al. 2012). Natural habitat destruction is one of the
main drivers, not just of species loss but also of spread of diseases. Physical changes
in habitats and in the environment can affect populations of disease-related organisms
through changes in climatic conditions and the creation of new breeding sites for
disease vectors, favoring the emergence of zoonotic diseases. Changes in habitat type
can have both positive and negative effects on the prevalence of infectious diseases.
Industrial agriculture, road building, mining pits, and logging can all create new
breeding habitats for insect vectors as well as paths for their proliferation. Human
workers in these areas can also work as vectors. MacDonald and Mordecai (2019) found
that deforestation significantly increases malaria transmission in the Amazon. Another
study in the Peruvian Amazon showed that the biting rate of the malaria vector Anopheles
darlingi was proportional to the area of land use modification and inversely proportional
to the area of remaining forest (Vittor et al. 2006). In western Uganda, Bloomfield
et al. (2020) found that fragmentation around households (edge density) and human
behaviors (collection of small trees for construction, foraging and hunting for food)
in forested habitat increased the likelihood of contacts between humans and wild nonhuman
primates. Changes caused by deforestation (habitat loss, road building, etc.) on landscape
patterns, namely in terms of the extension of forest edge, increase the chance of
emergence of infectious diseases exponentially.
Encouraged by trade, bushmeat increases contacts between forest animals, domestic
animals and humans (Baudron and Liegeois 2020). Encroachment into forest lands is
thought to have been a relevant factor in the emergence of several viral diseases,
including Ebola, Marburg, Nipah and Ross River Viruses (Chua et al. 2002). In addition,
road building and the associated increase in bushmeat hunting and trade are thought
to have played a part in the original zoonosis of HIV and simian foamy virus (Wolfe
et al. 2004). The present coronavirus crisis has brought renewed calls to stop the
trading of wildlife, opening up a long conflict and rumbling tensions between those
who want to conserve species, and those pushing for their sustainable use. This crisis
provides evidence on the lack of awareness of the impact that human activities can
have on nature, and of the nexus between human health and biodiversity.
Besides, the recent emergence of the devastating SARS-CoV-2 is thought to have originated
in cave-dwelling bats that have increasingly come into contact with both humans and
other possible mammalian hosts (Hu et al. 2017). As deforestation has increased, so
have the incidences of zoonotic transfer to human populations - it is estimated that
50% of all zoonotic diseases have emerged since 1940, correlated with vast increases
in forest loss and encroachment (Jones et al. 2008).
Despite the recognized importance of forests, we continue suffering record losses
of these ecosystems across the world. Fires are creating astonishing impacts in primary
and other forests in Europe (Ceccherini et al. 2020) but most noticeably in tropical
regions in countries like Bolivia and Brazil where fires are strongly connected to
deforestation and commodity-based farming practices. Worldwide, primary forest loss
in 2019 was 2.8% higher than the previous years and the third highest loss since the
turn of the century, after 2016 and 2017, equivalent to the loss of a football pitch
every six seconds according to the latest Global Forest Watch Report (WRI, 2020 https://www.wri.org/).
Deforestation and landscape homogenization driven by industrial agriculture/forestry
intensification have triggered a wave of extinction, threat, and local population
declines that may be comparable in both rate and magnitude with the five previous
mass extinctions of Earth’s history (Barnosky et al. 2011). Indeed, patterns of “defaunation”,
produced by humans in the past 500 years, as presented by Dirzo et al. (2014), extend
across taxonomic groups, but are also selective, with some taxonomic groups and regions
being particularly affected more than others (Cardillo et al. 2008; Di Marco et al.
2015). Losses and degradation of forest habitat, changes in landscape configuration,
and impoverishment of ecosystems due to local extinctions increase the potential for
the emergence and spread of zoonotic diseases and the causes for this degradation
needs to be addressed within efforts to prevent both current and future pandemics.
The landscape ecology legacy
Landscape ecology, both conceptually and methodologically, can play an active role
in explaining, describing, modeling and forecasting the emergence and spread of zoonosis
diseases and in informing decision-making to minimize spread and to foster disease-safe
landscapes. Landscape ecology has inspired health related disciplines such as landscape
epidemiology (Kitron 1998; Reisen 2010), approaches to achieve nutrition-sensitive
landscapes (Kennedy et al. 2017) and the interactions between pathology and landscape
ecology are growing rapidly (e.g. Cumming et al. 2015, Morandeira et al. 2019). There
is, nevertheless, much more that landscape ecology can offer to a comprehensive scientific
and technical effort to deal with the pandemics and to find solutions for the problems
it produces. The holistic approach followed in landscape ecology to address structure
and processes (and their interactions) can accommodate the integration of factors
and effects of the spread of diseases. These, operating at different scales, both
spatially and temporally, are required to analyze and model interactions of pathogens
with complex socio-ecological systems. Hierarchy theory (O’Neill 1986) underpins this
perspective by providing the conceptual framework for structuring complex systems
such as multi-functional landscapes, fundamental in formalizing research and practical
applications. Relevant theoretical models and developments emerging from or applied
in landscape ecology with interest for epidemiology include the conceptual landscape
structure model (patch-corridor-matrix) of Forman and Godron (1987) and patch theory
(Wiens 1995), percolation theory (O’Neill et al. 1988), and graph theory (Pascual-Hortal
and Saura 2006), among others. These provide the conceptual background to the definition
of entities of interest, their spatial and temporal scales, articulation among them,
definition and description of processes related to the spread of diseases and the
mechanistic or statistical formulation of models directed to the study or forecast
of behavior and distribution of pathogens.
Correspondingly, there is a diversity of models used in landscapes (Scheller and Mladenoff
2007, Synes et a. 2016) conceived for and operating at several levels of complexity,
from individual organisms (Boyce et al. 2017) to metapopulations (Levins 1970) and
from predator-prey, consumer-resources systems, species distribution models (Zurrell
et al. 2018) to spread of disturbances (Perera et al. 2015) and landscape change dynamics
models (Baker 1989; Houet et al. 2010), just to mention a few with direct links to
the context of epidemics. Remotely sensed data and remote sensing technology have
been pivotal for the early development of landscape ecology. As such, landscape ecology
today can provide key applications to derive spatially explicit operational territorial
answers and systems understanding for use in disease risk and spatial dynamics assessment,
management and monitoring. In addition, landscape ecology applications in fields such
as forestry, land planning, hydrology, urban planning, conservation, climate change,
adaptive management, and others are adaptable to tackle societal problems that can
be put at the service of prevention and fighting epidemic diseases.
The consolidation of landscape (socio)ecology in the time of pandemics
As Ziegler (2016) pointed out, epidemics are a product of landscapes shaped by humans
to fit our purposes, if not always optimally our needs, and are therefore not entirely
‘pristine’ (Barrett and Armelagos 2013). In the context of the Anthropocene, we encounter
growing uncertainties, but we need to better understand and improve the dynamic relationship
of humans and landscape elements necessary to maintain biodiversity and ecological
functions, while supporting human well-being. In that vein, landscape ecology can
have an important role given the discipline has evolved towards an integrated and
multidisciplinary scientific field. The adoption of concepts, research frameworks
and methods from social sciences in addition to biology, ecology, technology (remote
sensing and GIS), make landscape ecology a promising transdisciplinary field. Similarly,
landscape sustainability science (LSS), has grown as a place-based, use-inspired science
(Opdam et al. 2018; Liao et al. 2020), providing important insights to planning and
managing sustainable landscapes, and for supporting the implementation of the UN Sustainable
Development Goals (SDGs). The widening of the scope of landscape ecology has brought
it closer to problems that contemporary societies face. Similarly, the landscape ecology
community is increasingly engaged in the detection and implementation of solutions
to these current socio-ecological problems. The following three key aspects are essential
to understand the evolution of landscape ecology and the emergence of a transdisciplinary,
integrated science directed to solutions, which is being stressed by the current covid-19
pandemics
Landscape ecology as a socio-ecological science
Landscapes are recognized as a combination of natural structures/processes and anthropogenic
pressures modeled by individual and collective decision making, dependent on socioeconomic
conditions, including economic markets (especially food markets), but also on contrasting
components such as cultural or historical legacies. Landscapes are intrinsically socio-ecological
systems (Sunderland et al. 2017) and landscape ecology is increasingly recognized
as a socio-ecological science (Helfenstein et al. 2014; Frazier et al. 2019).
Ecosystem services and landscape ecology
The rapid evolution of landscape ecology as a socio-ecological science is related
to the ecosystem services (ES) concept and framework. ES has boosted the importance
of landscape ecology given that most ecosystem services depend on landscape scale
pattern/processes or are even landscape services (Iverson et al. 2014). ES highlight
the importance of assessing ecological processes further from discrete events and
looking at ecological phenomenon as continuous events. Landscape ecology tools and
methods can then be used to understand, at different scales, where ecosystem services
are produced, how those change over time and how the supply of ecosystem services
relates to its demand.
Active involvement of landscape ecologists in solutions
Related to the previously mentioned changes, landscape ecology has been more than
ever involved in the development of solutions for evolving societal problems. Landscape
ecology research and its applications have been more frequently used in the assessment
of risk and effects of disturbances at larger scales (Loehman et al. 2017), land planning
for conservation (Karimi and Hockings 2018; Solmundson et al. 2020) and adaptive management
(Chacón-Moreno et al. 2020) determining spatially explicit vulnerability to climate
change (Mayer et al. 2016).
The definitive recognition of urban landscapes
Considering that a large proportion of the world population lives in urban areas and
that urban populations, due to their high density, are more vulnerable to infection
but also contribute the most to disease transmission within and between cities, urban
landscapes require particular attention in times of pandemics at least in two ways.
Firstly, urban landscapes, as a habitat for humans, with their green infrastructure
(UGI) provide ecosystem services, food production, and other benefits that maintain
human physical and mental health, especially during lockdown periods. A non-secondary
aspect in improving human health is linked to the improvement of the psychological
status of urban populations determined by the presence of green spaces close to the
place of ‘social confinement’ during lockdown. Lockdown has shown, however, inequities
in the provision of UGI in most countries around the world, with more profound inequities
occurring for economies with larger Gini index, a popular measure of income inequality
in a nation (Ceriani and Verme 2012). By using landscape approaches to assess the
quality, quantity and distribution of green spaces and eventually UGI, we can create
cities that are more resilient and better prepared to provide ecosystem services and
positively improve human well-being and health for all city inhabitants under complete
lockdown or semi-lockdown (Ramirez-Rubio et al. 2019). Secondly, urban landscapes,
as barriers, buffers, or low contagion spatial systems, can contribute to halt or
slow down the spread of diseases. Improving urban green infrastructure and green spaces
accessibility and distribution can aid in changing the mobility patterns that have
led to higher rates of contagion and incidence of the pandemic. Urban landscape planning
should consider mobility, not only of people, but of other components of the ecosystem.
Understanding the dispersion of plants and animals in urban landscapes and how those
connect to the surrounding natural might help in detecting possible zoonosis expansion
and can aid in designing cities that are capable of providing a safer environment
for urban dwellers. Moreover, biodiversity rich landscapes and UGI work as prevention
for zoonosis dispersion (Zhao et al. 2020). A scientific approach in organizing UGI
with multiple species and strata, and diverse green patches can prevent mobility of
hazardous biological vectors, which can contribute to understand as different urban
growth patterns appear to have significantly amplified the exposure of urban populations
to health risks (e.g. zoonoses) (Connolly et al. 2020).
Final remarks
Landscape ecology as an established scientific discipline with a relatively recent
evolution towards socio-ecological science, is a source of theoretical frameworks,
models and applications suitable to face challenges posed by emergent pandemics. The
holistic and integrative vision of landscape ecology will help to better understand
the notion that nature is not everlasting and that the society, including scientists,
should rethink and reshape economic growth and revolutionize the way development is
put in place and assessed, replacing the mistakenly perception that natural resources
on which we depend — from forests to fossil fuels — will always be there, by a sustainable
perspective based on the limits of natural capital. This vision not only requires
new approaches and perhaps also new languages to be implemented but also requires
a greater involvement of citizens and professionals in diverse sectors that are aware
of the complexity of the problems and how these require balanced and fair solutions.
The need to rethink development models, food production and distribution systems,
urban planning, mobility and transportation systems is a priority in the context of
sustainability and epidemics within a nexus thinking approach facilitating cross-scale
and cross-sectoral planning (Fürst et al. 2017; Luque et al. 2017). At the same time,
there is an urgent need to rethink policy and governance to protect habitats and avoid
zoonotic spillover. Landscape ecology makes the realization of the consequences of
decision making more real for politicians and decision makers.
Analysis at different scales to gain a holistic understanding of landscapes coupled
to a landscape ecology framework and methods allows us to realize the impact of local
decisions on the surrounding environment, helps realize the spillover effects of climate
change and helps us communicate the importance of certain areas or patches for maintaining
the resilience or sustainability of a landscape. For cities, it can help us not only
to identify critical areas to maintain connectivity for dispersion, ecosystem services
and human mobility, but also to know how we can achieve higher levels of resilience.