Satellite remote sensing for applied ecologists: opportunities and challenges

Summary1. Essential Biodiversity Variable, Natural Capital, Biodiversity Indicator and Ecosystem Service are four concepts that underpin the most popular frameworks currently considered for helping to coordinate and structure biodiversity monitoring efforts worldwide. Satellite Remote Sensing (SRS) has considerable potential to inform these initiatives. To date, however, discussions on the role of SRS in supporting these frameworks have mostly evolved independently; tend to be led by different groups; sometimes target slightly different scales; and are likely to reach different audiences. Because of this, there is some confusion among environmental managers and policymakers as to what the potential of SRS is or whether there is prospect in considering and promoting the use of satellite data for biodiversity conservation.2. Here, we provide a brief overview of the role of SRS to date in informing these frameworks. Through a case study focused on the Sahara Desert ecosystem, we also demonstrate the current potential for SRS‐based methodologies to support conservation in data‐deficient areas and discuss the relative applicability of SRS‐based metrics to each of these frameworks.3. The relevance and use of SRS across the four frameworks are clearly variable, due to differences and ambiguity in definitions, and due to differences in monitoring priorities. Our case study illustrates the particularly high potential for SRS approaches to provide key information relevant to the Biodiversity Indicators framework in desert ecosystems; it also identifies SRS‐based metrics relevant to all frameworks.4. Altogether, this work highlights how more dialogue is required within the biodiversity‐monitoring community for SRS to reach its full potential in conservation. In particular, agreement on what is needed in priority, given the realm of what is possible, will be of paramount importance to developing SRS‐based products that are used by policymakers and international conventions.

<p>Biodiversity is rapidly declining and monitoring biodiversity change is thus of key importance to prevent the destabilization of ecosystems and their services. A key component of monitoring biodiversity change is the development of Essential Biodiversity Variables (EBVs) which facilitate the harmonization and standardization of raw data from disparate sources. In this context, consistent and adequate geospatial information needs to be available to ecologists and policymakers around the world, even for countries in which comprehensive in-situ biodiversity measurements cannot be taken on a regular basis. Satellite remote sensing (SRS) currently represents the only tool which allows to acquiree spatially contiguous and temporally replicated observations for monitoring biodiversity over continental or (near-)global spatial extents. Observations from SRS already provide a wealth of information on the distribution, structure and functioning of ecosystems, but user requirements of ecologists and policymakers have not been systematically quantified for allowing the development of roadmaps by SRS experts.</p><p>In response, we performed a top-down user requirement analysis combined with a bottom-up technical review to highlight (i) how currently available remote sensing products can contribute to biodiversity monitoring, and (ii) which immature SRS products could be prioritized for further development. We performed a systematic review of the Post2020 goals (for 2050) and biodiversity targets (for 2030) of the Convention on Biological Diversity (CBD) and their corresponding biodiversity indicators. Subsequently we evaluated SRS products according to relevance (to biodiversity indicators), (im)maturity, feasibility, and suitability for provisioning user-adequate spatio-temporal information. We found that currently existing CBD-relevant biodiversity indicators mainly use EBV-related information on ecosystem structure and distribution (e.g. available from remote sensing products of landcover and Leaf Area Index, LAI) or on species populations (predominantly acquired from in-situ biodiversity measurements because current SRS products are too limited in the spatio-temporal resolutions of their sensors). Moreover, only few biodiversity indicators derived from SRS currently focus on species traits or community composition EBVs, as both the identification of individual species and the quantification of species traits such as LAI and foliar nitrogen, phosphorus, kalium and chlorophyll content remain challenging. We outline how further advances in data-science techniques (e.g. merging SRS observations of high spectral and high spatial resolution) provide tremendous opportunities for advancing community composition and species-focused EBVs for global biodiversity monitoring.</p>

Biological diversity

In November 2011, botanists on a remote island off Papua New Guinea discovered a new species of orchid—uniquely and mysteriously night-flowering [1]. New to science, and with so much more to understand, this flower is threatened by deforestation [2]. Also in November 2011, a survey of 583 conservation scientists reported a unanimous (99.5%) view that 'it is likely a serious loss of biological diversity is underway at a global extent' and that, for scientists, 'protection of biological diversity for its cultural and spiritual values and because of its usefulness to humans were low priorities, which suggests that many scientists do not fully support the utilitarian concept of ecosystem services' [3]. In terms of management, some scientists now advocate controversial conservation strategies such as triage (prioritization of species that provide unique or necessary functions to ecosystems) [4, 5].

The ecosystem approach—as endorsed by the Convention on Biological Diversity (CDB) in 2000—is a strategy for holistic, sustainable, and equitable natural resource management, to be implemented via the 12 Malawi Principles. These principles describe the need to manage nature in terms of dynamic ecosystems, while fully engaging with local peoples. It is an ambitious concept. Today, the term is common throughout the research and policy literature on environmental management. However, multiple meanings have been attached to the term, resulting in confusion. We reviewed references to the ecosystem approach from 1957 to 2012 and identified 3 primary uses: as an alternative to ecosystem management or ecosystem-based management; in reference to an integrated and equitable approach to resource management as per the CBD; and as a term signifying a focus on understanding and valuing ecosystem services. Although uses of this term and its variants may overlap in meaning, typically, they do not entirely reflect the ethos of the ecosystem approach as defined by the CBD. For example, there is presently an increasing emphasis on ecosystem services, but focusing on these alone does not promote decentralization of management or use of all forms of knowledge, both of which are integral to the CBD’s concept. We highlight that the Malawi Principles are at risk of being forgotten. To better understand these principles, more effort to implement them is required. Such efforts should be evaluated, ideally with comparative approaches, before allowing the CBD’s concept of holistic and socially engaged management to be abandoned or superseded. It is possible that attempts to implement all 12 principles together will face many challenges, but they may also offer a unique way to promote holistic and equitable governance of natural resources. Therefore, we believe that the CBD’s concept of the ecosystem approach demands more attention.La Necesidad de Desenredar Conceptos Clave del Argot Ambiente-EstrategiaResumenLa estrategia ambiental – como es promocionada por la Convención Biológica sobre Diversidad en 2000 – es una estrategia para un manejo holístico, sustentable y equitativo de recursos naturales, que habrá de implementarse por vía de los 12 Principios de Malawi. Estos principios describen la necesidad de manejar la naturaleza en términos de ecosistemas dinámicos, mientras se compromete totalmente con las personas locales. Es un concepto ambicioso. Hoy en día, el término es común en la investigación y la literatura de políticas sobre el manejo ambiente. Sin embargo, se han relacionado múltiples significados con el término, lo que resulta en confusión. Revisamos referencias a la estrategia ambiental de 1957 a 2012 e identificamos tres usos principales: como una alternativa para manejo ambiental o basado en ecosistemas; en referencia a una estrategia integrada y equitativa para el manejo de recursos según la CBD; y como un término que indica un enfoque en el entendimiento y la valuación de los servicios ambientales. Aunque los usos de este término y sus variantes pueden traslaparse en su significado, típicamente no reflejan en su totalidad los valores de la estrategia ambiental como fue definida por la CBD. Por ejemplo, actualmente hay un énfasis creciente en los servicios ambientales, pero enfocarse solamente en estos no promueve la descentralización del manejo o el uso de todas las formas de conocimiento, siendo ambas integrales para el concepto de la CBD. Resaltamos que los Principios de Malawi están en riesgo de ser olvidados. Para entender mejor estos principios, se requiere de más esfuerzo para implementarlos. Dichos esfuerzos deben ser evaluados, idóneamente con estrategias comparativas, antes de permitir que el concepto de la CBD de manejo holístico y comprometido socialmente sea abandonado o reemplazado. Es posible que los intentos por implementar los 12 principios juntos enfrentarán muchos obstáculos, pero también pueden ofrecer una forma única de promover el gobierno holístico y equitativo de los recursos naturales. Así, creemos que el concepto de estrategia ambiental de la CBD exige mayor atención.

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, measured vegetation characteristics, quantified human activities, and evaluated ant-community responses by grouping ants into service-providing units (SPUs), defined as a group of organisms and their populations that perform specific ecosystem services, to provide an understanding of urbanization impacts on biodiversity and their delivery of ecosystem services. Species richness and abundance peaked at intermediate levels of urban development, as did the richness of 3 types of ant SPUs (aerators, decomposers, and compilers). With increasing land development aerator and decomposer ants significantly declined in abundance, whereas compiler ants significantly increased in abundance. Competing models demonstrated that precipitation was frequently among the strongest influences on ant community structure; however, urban development and human activities also had a strong, negative influence on ants, appearing in most models with DeltaAIC(c) < 2 for species richness and abundance patterns of SPUs and generalists. Response diversity was observed within SPUs, which suggests that the corresponding ecosystem services were maintained until development reached 30-40%. Our data provide evidence that ecosystem functions, such as water infiltration and soil productivity, may be diminished at sites subject to greater levels of urbanization and that conserving ant communities and the ecosystem services they provide could be an important target in land-use planning and conservation efforts.

Biodiversity Offsets and Infrastructure

Advancing the green infrastructure approach in the Province of Barcelona: integrating biodiversity, ecosystem functions and services into landscape planning

The Sustainable Development Goals (SDGs) established to be achieved by 2030 are an ensemble of 17 goals to address global environmental and social economic concerns [1]. SDG 15 concerns the protection of terrestrial ecosystems to halt biodiversity loss. Target 15.9 states that by 2020, ecosystem and biodiversity values should be integrated into national and local planning, and is related to Aichi Biodiversity Target 2 of the Strategic Plan for Biodiversity 2011-2020, which also involves integrating biodiversity values into national accounting and reporting systems [2]. The importance of maintaining ecosystem integrity is becoming widely recognized, not only to halt biodiversity loss, but also to preserve Nature’s benefits to human well-being, and has been included in many other targets such as the EU 2020 Biodiversity Strategy’s target 2, which requires the restoration of at least 15% of degraded ecosystems as well as the establishment of green infrastructures to enhance ecosystem services (ES) [3]. The Green Infrastructures (GI) framework is used as a policy tool and promotes the multi-functional use of landscapes to improve biodiversity conservation and benefits to society. It is formulated as a “strategically planned network of natural and semi-natural areas” [4] and is based on three main pillars: key habitats for target species, connectivity and ES [5]. As part of ERA-PLANET’s GEOEssential project (Essential Variables workflows for resource efficiency and environmental management), our study aims at demonstrating how the GI framework can be implemented at any geographical area or time-period through reproducible modeling workflows from field data to Essential Variables (EV) data products and policy relevant indicators to monitor and inform advances towards environmental targets. A proof of concept workflow was already set in place for computing the indicator 15.1.2: Proportion of important sites for terrestrial and freshwater biodiversity that are covered by protected areas, by ecosystem, while other workflows will follow. The execution platform is the GEOEssential Virtual Laboratory, a cloud-based virtual platform which enables access to, and execution of workflows for the ecosystem science community of practice and even more. REFERENCES: 1. UNSD, 2016. Sustainable Development Goals Report. https://unstats.un.org/sdgs/report/2016/ (accessed 18 May 2018). 2. CBD Secretariat, 2010. The Strategic Plan for Biodiversity 2011-2020, and the Aichi Biodiversity Targets. Secretariat of the Convention on Biological Diversity, Nagoya. 3. European Commission, 2011. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions - Our life insurance, our natural capital: an EU biodiversity strategy to 2020, Brussels. 4. European Commission, 2013. Green infrastructure (GI) - Enhancing Europe’s Natural Capital, Brussels. 5. Liquete, C., Kleeschulte, S., Dige, G., Maes, J., Grizzetti, B., Olah, B., & Zulian, G., 2015. Mapping green infrastructure based on ecosystem services and ecological networks: A Pan-European case study. Environmental Science & Policy, 54, 268–280.

Biodiversity losses can lead to global environmental crisis. Humans utilize biodiversity for a variety of ecosystem services. However, what drives biodiversity losses have become a critical question during the 21st century. Lately, the Hindu Kush Himalayan (HKH) region in Asia, one of the world’s pristine habitats with the origin of majestic river systems including Brahmaputra, Indus, Mekong, and Yangtze, has witnessed rapid climatic warming. The unprecedented rates of climate warming in HKH has threatened biodiversity losses, ecosystem functioning and ecosystem services, and consequently the existence of mankind in the region. The Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science and Policy Platform on Biodiversity and Ecosystem Services (IPBES) highlight the risks to humanity arising from unsustainable use of natural resources and loss of biodiversity worldwide under rapid climate warming condition. In addition, the growing economic transformation in HKH can have high environmental costs and biodiversity losses. By realizing this fact, the Convention on Biological Diversity addresses the key issues of biodiversity and ecosystem services in the HKH by liaising with the United Nations Framework Convention on Climate Change, Paris Agreement, and the Sustainable Development Goals (SDGs). Hence, the challenges of biodiversity losses, poor ecosystem functioning followed by reduced ecosystem services posed by climate warming and anthropogenic impacts needs to be addressed urgently by countries and multilateral agencies in HKH by identifying threatened ecosystem services and by providing better sustainability solutions. Here, I have outlined the current state of Himalayan biodiversity and ecosystem function and developed a framework for resilience management with an integrated approach of science and society to advance knowledge through learning. The resilience framework offers practical solutions comprising a robust and harmonized monitoring of climatic data, the use of multi-indicator approaches and modelling, and to make collaborated efforts among policy makers, implementers, and analysts to tackle evolving losses of biological diversity and reduction in ecosystem services in the HKH region.

I report a simulation study that tested the ability of a variety of experimental designs to achieve two fundamental goals: (1) to determine the association between loss of biological diversity and responses such as ecosystem functioning and (2) to determine which components of biodiversity, such as number of species, functional diversity, or a keystone species, were most responsible for that association. For the goal of reliably detecting an overall association, all designs I tested performed well and were unlikely to misidentify predominant patterns. Thus, this study affirms the common conclusion of many published biodiversity experiments that loss of biological diversity is often associated with a reduction in ecosystem functioning. However, for the goal of identifying the components of biodiversity that are most responsible for the effects, designs differed markedly. Some designs performed well in detecting number‐of‐species effects but poorly in detecting effects of unique species or functional groups. No design tested was able to discriminate both numeric effects and compositional effects in all situations. Thus, this study demonstrates that interpreting results about mechanisms from biodiversity experiments will be critically dependent on an experiment's design.

I report a simulation study that tested the ability of a variety of experimental designs to achieve two fundamental goals: (1) to determine the association between loss of biological diversity and responses such as ecosystem functioning and (2) to determine which components of biodiversity, such as number of species, functional diversity, or a keystone species, were most responsible for that association. For the goal of reliably detecting an overall association, all designs I tested performed well and were unlikely to misidentify predominant patterns. Thus, this study affirms the common conclusion of many published biodiversity experiments that loss of biological diversity is often associated with a reduction in ecosystem functioning. However, for the goal of identifying the components of biodiversity that are most responsible for the effects, designs differed markedly. Some designs performed well in detecting number-of-species effects but poorly in detecting effects of unique species or functional groups. No design tested was able to discriminate both numeric effects and compositional effects in all situations. Thus, this study demonstrates that interpreting results about mechanisms from biodiversity experiments will be critically dependent on an experiment's design.

Healthy ecosystems provide us with fertile soil, clean water, timber, and food. They reduce the spread of diseases. They protect against flooding. Worldwide, they regulate atmospheric concentrations of oxygen and carbon dioxide. They moderate climate. Without these and other “ecosystem services,” we’d all perish.1 One hallmark of the history of civilization is an ever-increasing exploitation of ecosystem services coupled with substitution of technology for these services, particularly where ecosystems have been exploited beyond their ability to provide.2 Agriculture is a hybrid of exploitation and substitution that enabled people to live in greater, denser populations that drove further exploitation and substitution. Modern plumbing made close quarters far less noxious but led to exploitation of ecosystems’ ability to break down sewage, and to substitution with expensive sewage treatment technologies. Exploitation of fossil fuels led to a slew of modern conveniences, including fishing fleets that are so effective at catching their prey that they threaten fisheries globally.3,4 All this exploitation strained ecosystems, but in the past, when the population was a fraction of what it is now, these strains were local rather than global phenomena. In 2005 the Millennium Ecosystem Assessment (MA),5 a sweeping survey conducted under the auspices of the United Nations, found that approximately 60% of 24 ecosystem services examined were being degraded or used unsustainably.6 “Every year we lose three to five trillion dollars’ worth of natural capital, roughly equivalent to the amount of money we lost in the financial crisis of 2008–2009,” says Dolf de Groot, leader of the Research Program on Integrated Ecosystem Assessment and Management at Wageningen University, the Netherlands. The value of ecosystem services typically goes unaccounted for in business and policy decisions and in market prices. For commercial purposes, if ecosystem services are recognized at all, they are perceived as free goods, like clean air and water. So it’s not surprising that much of the degradation of ecosystems is rooted in what the President’s Council of Advisors on Science and Technology (PCAST), an independent group of U.S. scientists and engineers, describes as “widespread under-appreciation of the importance of environmental capital for human well-being and . . . the absence of the value of its services from the economic balance sheets of producers and consumers.”7 PCAST and other groups are working to build recognition of ecosystem services and, importantly, to valuate them—that is, calculate values for these services to help policy makers and resource managers make rational decisions that factor important environmental and human health outcomes into the bottom line.

The large investments needed if loss of biological diversity is to be stemmed will likely lead to increased public and political scrutiny of conservation strategies and the science underlying them. It is therefore crucial to understand the degree of consensus or divergence among scientists on core scientific perceptions and strategies most likely to achieve given objectives. I developed an internet survey designed to elucidate the opinions of conservation scientists. Conservation scientists (n =583) were unanimous (99.5%) in their view that a serious loss of biological diversity is likely, very likely, or virtually certain. Scientists' agreement that serious loss is very likely or virtually certain ranged from 72.8% for Western Europe to 90.9% for Southeast Asia. Tropical coral ecosystems were perceived as the most seriously affected by loss of biological diversity; 88.0% of respondents familiar with that ecosystem type agreed that a serious loss is very likely or virtually certain. With regard to conservation strategies, scientists most often viewed understanding how people and nature interact in certain contexts and the role of biological diversity in maintaining ecosystem function as their priorities. Protection of biological diversity for its cultural and spiritual values and because of its usefulness to humans were low priorities, which suggests that many scientists do not fully support the utilitarian concept of ecosystem services. Many scientists expressed a willingness to consider conservation triage, engage in active conservation interventions, and consider reframing conservation goals and measures of success for conservation of biological diversity in an era of climate change. Although some heterogeneity of opinion is evident, results of the survey show a clear consensus within the scientific community on core issues of the extent and geographic scope of loss of biological diversity and on elements that may contribute to successful conservation strategies in the future.

Identifying effective approaches for monitoring national natural capital for policy use