Methodology for Evaluating the Quality of Ecosystem Maps: A Case Study in the Andes

Dolors Armenteras,Tania González,Nelly Rodríguez,Francisco Luque,Denis López

doi:10.3390/ijgi5080144

Dolors Armenteras, Tania González + Show 3 more

Open Access

https://doi.org/10.3390/ijgi5080144

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Abstract

Uncertainty in thematic maps has been tested mainly in maps with discrete or fuzzy classifications based on spectral data. However, many ecosystem maps in tropical countries consist of discrete polygons containing information on various ecosystem properties such as vegetation cover, soil, climate, geomorphology and biodiversity. The combination of these properties into one class leads to error. We propose a probability-based sampling design with two domains, multiple stages, and stratification with selection of primary sampling units (PSUs) proportional to the richness of strata present. Validation is undertaken through field visits and fine resolution remote sensing data. A pilot site in the center of the Colombian Andes was chosen to validate a government official ecosystem map. Twenty primary sampling units (PSUs) of 10 × 15 km were selected, and the final numbers of final sampling units (FSUs) were 76 for the terrestrial domain and 46 for the aquatic domain. Our results showed a confidence level of 95%, with the accuracy in the terrestrial domain varying between 51.8% and 64.3% and in the aquatic domain varying between 75% and 92%. Governments need to account for uncertainty since they rely on the quality of these maps to make decisions and guide policies.

Highlights

Thematic maps are used throughout the environmental sector for research but mostly for supporting policy decisions and land planning
Many examples of accuracy assessment have been developed for ecosystem [6,7] and land cover maps, which are mainly constructed from remotely sensed data [5,8]
The size and shape of each final sampling units (FSUs) correspFoinnadl StaomspqliunagrUesniotsf(2F5SUhsa) ofor retfhereentecerruensittrsiaarledthoemspaaintiaalnudnittothhatesxearvgeosnass tohfe5bahsaisifnorththee aquatic domaincoinmploatriicsoannodf tlheenrteicferseunbcesycslatsesmifisca, twiohnearnedasthteheecotsryasntesmitisomnaapl.aTnhde stirzaenasnfdorsmhaepde oafqeuaachticFSuUnits used squares of 25 ha (Table 1). These areas correspond to the minimum mapping units included in the National Ecosystem Map are sampled within each stratum contained in the selected primary sampling units (PSUs)

Summary

Introduction

Thematic maps are used throughout the environmental sector for research but mostly for supporting policy decisions and land planning. Before being used, any map should undergo a process of some kind of accuracy assessment [5] as a way of testing whether the data set values fall within some limits of reliability This is of particular importance before making any decisions based on a map. Many examples of accuracy assessment have been developed for ecosystem [6,7] and land cover maps, which are mainly constructed from remotely sensed data [5,8]. A separate study on Latin America and the Caribbean [13] focused on land use changes from 2001 to 2010 They used visual interpretation of fine resolution images from Google Earth, Digital Globe’s QuickBird and IKONOS as reference data for the accuracy assessment and applied it to a sampling grid, providing error matrix analysis including details of producer (omission) and user (commission) error. The obcjeocntviveregsinogf tfhroismwbootrhkuaprleantoddanevdelolowplaannddaarepapsl.yThaesoeblejecctteivdessaomf tphlies wanodrkraerseptoondseevedleospigannduaspinpglyfine resolutaiosneleimcteadgesasmanplde fianedldrevsaploidnasetiodnesdigantausainngd ftioneasresseoslsutthioentihmeamgeastiacnadccfiuerldacvyaloidfatthioenredsautaltasn. d to assess the thematic accuracy of the results

Methods

First Stage

Sampling Size

Findings

Analysis