Policy ForumEcology

Essential Biodiversity Variables

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Science  18 Jan 2013:
Vol. 339, Issue 6117, pp. 277-278
DOI: 10.1126/science.1229931

Reducing the rate of biodiversity loss and averting dangerous biodiversity change are international goals, reasserted by the Aichi Targets for 2020 by Parties to the United Nations (UN) Convention on Biological Diversity (CBD) after failure to meet the 2010 target (1, 2). However, there is no global, harmonized observation system for delivering regular, timely data on biodiversity change (3). With the first plenary meeting of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) soon under way, partners from the Group on Earth Observations Biodiversity Observation Network (GEO BON) (4) are developing—and seeking consensus around—Essential Biodiversity Variables (EBVs) that could form the basis of monitoring programs worldwide.

Despite progress in digital mobilization of biodiversity records and data standards (5), there is insufficient consistent national or regional biodiversity monitoring and sharing of such information. Along with inadequate human and financial resources (6), a key obstacle is the lack of consensus about what to monitor. Many initiatives collect data that could be integrated into an EBV global observation network (see the table), though important gaps remain. Different organizations and projects adopt diverse measurements, with some important biodiversity dimensions, such as genetic diversity, often missing (7).

The EBV process is inspired by the Essential Climate Variables (ECVs) that guide implementation of the Global Climate Observing System (GCOS) by Parties to the UN Framework Convention on Climate Change (UNFCCC) (8). EBVs, whose development by GEO BON has been endorsed by the CBD (Decision XI/3), are relevant to derivation of biodiversity indicators for the Aichi Targets (9). Although CBD biodiversity indicators are designed to convey messages to policy-makers from existing biodiversity data (1), EBVs aim to help observation communities harmonize monitoring, by identifying how variables should be sampled and measured.

Given the complexity of biodiversity change (3), the challenge of developing a global observation system can appear insurmountable. Nearly 100 indicators have been proposed for the 2020 CBD targets (ongoing work seeks to identify a more limited subset) (9). Two-thirds of reports recently submitted by Parties to the CBD lacked evidence-based information on biodiversity change (10).

EBVs help prioritize by defining a minimum set of essential measurements to capture major dimensions of biodiversity change, complementary to one another and to other environmental change observation initiatives. EBVs also facilitate data integration by providing an intermediate abstraction layer between primary observations and indicators (fig. S1). An EBV estimating population abundances for a group of species at a location sits between raw observations (e.g., from different sampling events or methods) and an aggregated population trend indicator that averages multiple species and locations.

Essential Biodiversity Variables in Practice

We define an EBV as a measurement required for study, reporting, and management of biodiversity change. Hundreds of variables potentially fit this definition. We developed and tested a process, still ongoing, to identify the most essential (11). Dozens of biodiversity variables were screened to identify those that fulfill criteria on scalability, temporal sensitivity, feasibility, and relevance. These variables were scored for importance, checked for redundancy, and organized into six classes on the basis of commonalities, general enough for use across taxa and terrestrial, freshwater, and marine realms (see the table).

Often, it is not possible to generalize observations from point locations to the regional scale. Variables selected as EBVs harness remote sensing (RS) to measure continuously across space (e.g., habitat structure), or local sampling schemes that can be integrated to enable large-scale generalizations. For instance, citizen scientists contribute locally to species population monitoring across extensive regions (12). Ecosystem function or community composition variables often need intensive in situ measurements feasible only at a few locations, but models and proxies detectable by RS can be used to extrapolate from point locations to the regional scale (13, 14). Such models are also important to predict the response of EBVs (e.g., species distributions) to environmental drivers (15), and can be used to develop scenarios exploring different policy options (16), a core activity of IPBES.

Many biodiversity assessments emphasize species inventories, e.g., identification of all species in a region, and there have been calls for redoubled efforts to describe all species in the world (17). The EBV framework instead emphasizes repeated measures for the same taxa at the same locations or regions mainly at short-term intervals (1 to 5 years), although a few may be medium term (10 to 50 years).

Key determinants of observation system feasibility are the number of variables that need monitoring and their measurability. Although determination of the 50 ECVs requires elaborate observation and modeling systems, the end result is often outwardly simple (e.g., air temperature or pressure) (8). This is also true of some EBVs, particularly those related to ecosystem structure and function. However, EBVs relating to species populations or traits and to genetic or community composition require representative sampling across taxonomic groups or community types. These EBVs need to balance specificity and generality, enabling valid aggregation of data from multiple monitoring programs, while allowing for flexibility in the species or taxonomic groups addressed by these programs.

Variables selected as EBVs fill a niche not covered by global observation initiatives looking at environmental pressures [e.g., GCOS (8), Essential Ocean Variables (18)]. An EBV such as species abundance provides data for indicators such as the Living Planet, Wild Bird, and Red List indices (LPI, WBI, and RLI) (see the table). Assessing ecosystem services (ES) requires knowledge of changes in beneficial species, functional groups, or ecosystem processes; additional physical, social, and economic data (fig. S1) can be obtained from valuation studies, surveys, and national statistics (19). Complementary spatial information on responses implementation (e.g., coverage of protected areas) can inform indicators of the effectiveness of policy and management (fig. S1). This fundamental, but flexible, role of EBVs confers robustness to the system: EBVs are insulated from changing technologies at the observation level and from changing approaches at the indicator level.

Building Consensus and Capacity

Identification of EBVs and definition of sampling protocols are done by an open process that requires engagement of scientific, policy, and other communities. Major roles can be played by IPBES, national biodiversity authorities, space agencies, nongovernmental organizations, and citizen-science communities. Information on the EBV process is updated at (11); written contributions can be sent to GEO BON. Side events will be organized in scientific and policy meetings over the next year. This will refine the EBV list, which, once stable, will periodically be updated by GEO BON in a process similar to that used for ECVs (8).

Coordination of sampling schemes by GEO BON across countries and scales can minimize costs and improve spatial representativeness. Developing suitable financial mechanisms to share costs between developing countries, where most biodiversity occurs, and developed countries, which share in the benefits but drive many of the pressures (20), will play a key role in the development of a truly global system. We hope that EBVs will catalyze investment in biodiversity observations, as ECVs have done for climate.

  • * For complete addresses, see supplementary materials.

References and Notes

  1. CBD, Decision X/2, The Strategic Plan for Biodiversity 2011–2020 and the Aichi Biodiversity Targets, Nagoya, Japan, 18 to 29 October 2010.
  2. Acknowledgments: NASA, DIVERSITAS, GEO, ESA-ESRIN, and the Department of Science and Technology (South Africa) provided resources. H.M.P. was supported by FCT grant PTDC/AACAMB/114522/2009. M. Paganini helped organize a workshop. H.M.P., S.F., M. Walters, G.N.G., R.H.G.J., R.J.S., D.P.F., C.H., R.H., R.S., S.N.S., and M. Walpole are on the GEO BON steering committee. Abbreviations spelled out in SM.

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