542 Nature Index General framework, statistical method and data collection for Norway Grégoire Certain Olav Skarpaas NINA Publications NINA Report (NINA Rapport) This is a electronic series beginning in 2005, which replaces the earlier series NINA commissioned reports and NINA project reports. This will be NINA’s usual form of reporting completed research, monitoring or review work to clients. In addition, the series will include much of the institute’s other reporting, for example from seminars and conferences, results of internal research and review work and literature studies, etc. NINA report may also be issued in a second language where appropri- ate. NINA Special Report (NINA Temahefte) As the name suggests, special reports deal with special subjects. Special reports are produced as required and the series ranges widely: from systematic identification keys to information on impor- tant problem areas in society. NINA special reports are usually given a popular scientific form with more weight on illustrations than a NINA report. NINA Factsheet (NINA Fakta) Factsheets have as their goal to make NINA’s research results quickly and easily accessible to the general public. The are sent to the press, civil society organisations, nature management at all lev- els, politicians, and other special interests. Fact sheets give a short presentation of some of our most important research themes. Other publishing In addition to reporting in NINA’s own series, the institute’s employees publish a large proportion of their scientific results in international journals, popular science books and magazines. Norwegian Institute for Nature Research Nature Index General framework, statistical method and data collection for Norway Grégoire Certain Olav Skarpaas NINA Report 542 Certain, G. and Skarpaas, O. 2010. Nature Index: General framework, statistical method and data collection for Norway – NINA Report 542. 47 pp. Oslo, February 2010 ISSN: 1504-3312 ISBN: 978-82-426-2117-7 COPYRIGHT © Norwegian Institute for Nature Research The publication may be freely cited where the source is ac- knowledged AVAILABILITY Open PUBLICATION TYPE Digital document (pdf) EDITION First QUALITY CONTROLLED BY Nigel Yoccoz SIGNATURE OF RESPONSIBLE PERSON Research director Erik Framstad (sign.) CLIENT(S) The Directorate for Nature Management CLIENTS’ CONTACT PERSON(S) Signe Nybø COVER PICTURES Jan Ove Gjershaug, Espen Dahl Lie, Jarle Werne Bjerke, Olav Skarpaas, Nina Eide, Gro & Terje Van der Meeren, Grégoire Certain. KEY WORDS Biodiversity, indicators, Norway NØKKELORD Biologisk mangfold, indikatorer, Norge CONTACT DETAILS NINA head office NINA Oslo NINA Tromsø NINA Lillehammer NO-7485 Trondheim Gaustadalléen 21 Polarmiljøsenteret Fakkelgården Norway NO-0349 Oslo NO-9296 Tromsø NO-2624 Lillehammer Phone: +47 73 80 14 00 Norway Norway Norway Fax: +47 73 80 14 01 Phone: +47 73 80 14 00 Phone: +47 77 75 04 00 Phone: +47 73 80 14 00 Fax: +47 22 60 04 24 Fax: +47 77 75 04 01 Fax: +47 61 22 22 15 www.nina.no 2 NINA Report 542 Abstract Certain, G. and Skarpaas, O. 2010. Nature Index: General framework, statistical method and data collection for Norway – NINA Report 542, 47 pp. The Nature Index for Norway has been developed to be an aggregated measure of biodiversity in Norway, reflecting the state of terrestrial and marine ecosystems and providing comprehen- sive information to environmental managers and to the public in a simplified and understand- able way. It consists of a set of 310 biodiversity indicators that encompass important aspects of natural biodiversity. The present report is a general description of the Nature Index framework. It summarises the basic concepts and definitions used, and displays the associated mathematical developments. The report builds on and extends previous pilot studies on concepts and practical implementa- tion (NINA Reports 347, 425 and 426). The final results of the Nature Index will be presented elsewhere (Nybø (ed.) 2010a,b); here we present the data collection process and an analysis of the indicator set collected so far in order to provide information on the ecological significance and on the inferences that can be expected. Data on indicators were collected from experts who provided estimates of the indicator values at several points in time using expert judgement, monitoring data or models. Experts also pro- vided an estimate of uncertainty with each data point in the form of quartiles, and they were asked to indicate where insufficient information was available to provide an estimate of the in- dicator value. To combine the indicators to produce an index, the indicators are scaled by a reference value, i.e. their value in a reference state. This serves two purposes: First, the reference state, for each indicator, is supposed to reflect an ecologically sustainable state for the indicator, and the scaled value measures the departure from this state. Second, because the scaled values are all dimensionless numbers between 0 and 1, they can be averaged across, for instance, mu- nicipality, major habitat, or taxonomic group. Thus the use of a reference value facilitates a flexible combination of indicators expressed in different measurement units, such as abun- dance or species richness. Plain averaging of scaled indicators implies a “complete equivalence” assumption, i.e. that no municipality, no major habitat, and no indicator is more important than another. This assump- tion is not always true. Moreover, despite efforts to balance the indicator set, the indicators are not homogeneously distributed among taxonomic groups, pressures, major habitats etc. In the specific case of Norway, we decided, with the support of the Ecological Reference group for the Nature Index, to apply weighting mainly to deal with heterogeneities within the indicator set. Weights were applied across two axes of the Nature Index: across the spatial axis, so that the index remains area-representative, and across the indicator axis, to solve issues concerning the ecological significance of the index. Equivalence was maintained between major habitats because this ensures that the nature index will be maximised with beta (regional) diversity as well as alpha (local) diversity: complete loss of a major habitat implies a decrease in beta di- versity, and this will always result in a decrease of the index under equivalence between major habitats. In the Nature Index framework data uncertainty and missing data are analysed and actively used in several ways: At the level of individual indicators, information on the source of esti- mates (expert opinion, data, models), the uncertainty in the estimates, and the cases where there is a complete lack of knowledge, can be used to guide future research. Uncertainty in the indicator estimates is aggregated to the index level using Monte Carlo methods, sampling from distributions fitted to the mean and quartiles of each indicator. 3 NINA Report 542 In conclusion, we show that the Nature Index is able to synthesize and compare information coming from all fields of ecological science, encompassing oceanic and terrestrial areas. There are two kinds of information that can be produced by the Nature Index framework: information on the current state of ecosystems, given the current knowledge of the Ecological Research Network; and also information on lack of knowledge and lack of data can be displayed, in order to better inform, and therefore optimise, research and management policies. Information ex- tracted from the Nature index framework can be aggregated or disaggregated across several dimensions, such as spatial units, ecological units or management themes, giving this frame- work the potential to become an efficient management tool, an efficient catalyst for Ecological Research Network in Norway, and a strong basis for international applications. Gregoire Certain, Norwegian Institute for Nature Research (NINA), NO-7485 Trondheim, [email protected] Olav Skarpaas, Norwegian Institute for Nature Research (NINA), Gaustadalléen 21, NO-0349 Oslo, [email protected] 4 NINA Report 542 Sammendrag Certain, G. and Skarpaas, O. 2010. Nature Index: General framework, statistical method and data collection for Norway – NINA Rapport 542. 47 s. Naturindeksen er et sammensatt mål for biologisk mangfold i Norge som gjenspeiler tilstanden i terrestre og marine natursystemer og formidler denne omfattende informasjonen til miljøfor- valtningen og allmenheten på en forenklet og forståelig måte. Den består av 310 indikatorer som dekker viktige aspekter ved biologisk mangfold. Denne rapporten gir en generell beskrivelse av rammeverket for Naturindeksen. Den gjennomgår grunnleggende begreper og definisjoner, og tilhørende matematiske formuleringer. Rapporten bygger videre på tidligere forslag til rammeverk og pilotstudier (NINA Rapport 347, 425 og 426). Hovedresultatene for naturindeksen presenteres i to kommende DN-utredninger (Nybø (ed.) 2010a,b); her presenterer vi metoder for datainnsamling og en analyse av indikatorsettet for å informere om den økologiske betydningen av naturindeksen og slutningene man kan forvente å gjøre på grunnlag av denne. Data om indikatorene ble samlet inn fra eksperter som ga estimater av indikatorverdier på flere tidspunkter på grunnlag av ekspertvurderinger, overvåkingsdata eller modeller. Ekspertene ga også et estimat av usikkerheten til hver verdi i form av kvartiler, og de ble bedt om å angi i hvilke tilfeller grunnlaget var for svakt til å gi estimater. For å kunne kombinere indikatorene til en indeks,