Article: ‘Uncertainty audit’ for ecosystem accounting: Satellite-based ecosystem extent is biased without design-based area estimation and accuracy assessment

Authors: Zander S. Venter, Bálint Czúcz, Erik Stange, Megan S. Nowell, Trond Simensen, Bart Immerzeel, David N. Barton

Abstract:

There are currently no guidelines in the System of Environmental-Economic Accounting Ecosystem Accounting (SEEA EA) for quantifying and disclosing uncertainty. However, without quantifying uncertainty, it is unclear whether or not accounting tables contain biased (erroneous) area estimates which do not reflect real land cover changes. We use Oslo municipality in Norway as a case study to illustrate best practices in quantifying unbiased area estimates using design-based statistical methods. As input for ecosystem extent accounts, we compared a custom Sentinel-2 land cover map with a globally available one called Dynamic World for 2015, 2018 and 2021. The design-based area estimation involved (i) generating a stratified probability sample of locations using the satellite-based maps to define strata, (ii) assigning ecosystem type labels to the samples using photointerpretatioaccording to a response design protocol, and (iii) applying a stratified area estimator to produce 95% confidence intervals around opening, closing and change stocks in the extent accounting table. We found that pixel counting practices, currently adopted by the SEEA EA community, led to biased extent accounts, particularly for ecosystem conversions, with biases averaging 195% of the true change value derived from design-based methods. We found that the uncertainty inherent in state-of-the-art satellite-based maps exceeded the ability to detect real change in extent for some ecosystem types including water and bare/artificial surfaces. In general, uncertainty in extent accounts is higher for ecosystem type conversion classes compared to stable classes, and higher for 3-yr compared to 6-yr accounting periods. Custom, locally calibrated satellite-based maps of ecosystem extent changes were more accurate (81% overall accuracy) than globally available Dynamic World maps (75%). We suggest that rigorous accuracy assessment in SEEA EA will ensure that ecosystem extent (and consequently condition and service) accounts are credible. A standard for auditing uncertainty in ecosystem accounts is needed.

Full publication is available here.

Article: Bias and precision of crowdsourced recreational activity data from Strava

Authors

Zander S. Venter, Vegard Gundersen, Samantha L. Scott, David N. Barton

- Norwegian Institute for Nature Research (NINA)

Abstract

Recreational activity is the single most valuable ecosystem service in many developed countries with a range of benefits for public health. Crowdsourced recreational activity data is increasingly being adopted in management and monitoring of urban landscapes, however inherent biases in the data make it difficult to generalize patterns to the total population. We used in-situ observations and questionnaires to quantify accuracy in Strava data - a widely used outdoor activity monitoring app – in Oslo, Norway. The precision with which Strava data captured the spatial (R2 = 0.9) and temporal variation (R2 = 0.51) in observed recreational activity (cyclist and pedestrian) was relatively high for monthly time series during summer, although precision degraded at weekly and daily resolutions and during winter. Despite the precision, Strava exhibits significant biases relative to the total recreationist population. Strava activities represented 2.5 % of total recreationist activity in 2016, a proportion that increased steadily to 5.7 % in 2020 due to a growing usership. Strava users are biased toward cyclists (8 % higher than observed), males (15.7 % higher) and middle-aged people (20.4 % higher for ages 35–54). Strava pedestrians that were able to complete a questionnaire survey (>19 years) were biased to higher income brackets and education levels. Future studies using Strava data need to consider these biases – particularly the under-representation of vulnerable age (children/elderly) and socio-economic (poor/uneducated) groups. The implementation of Strava data in urban planning processes will depend on accuracy requirements of the application purpose and the extent to which biases can be corrected for.

Full publication available here.

Master Thesis: Kelp cultivation in the Oslofjord

Author

Marius Lysø

- Faculty of Landscape and Society, Norwegian University of Life Sciences

Abstract

How can public authorities plan and facilitate for kelp cultivation to contribute to local food production and better water quality in the fjord «Oslofjorden»? This is interesting because of the objectionable environmental quality in the Oslofjord, and an ever-increasing demand for locally produced food. This thesis is based on Røiseland & Vabo's understanding of governance, and Bellato, et al.'s reflections on regeneration. Through qualitative analysis, answers are given to how public authorities can plan and facilitate kelp cultivation in the Oslofjord. I have conducted in-depth interviews with 11 informants in the private and public sector. It has been important to let all relevant actors have their say, so that the findings have as much explanatory power as possible. Nevertheless, it is hard to generalize based on the findings in qualitative studies.

Read more here: https://hdl.handle.net/11250/3080767

Master Thesis: Knowledge about ecology and landscape in land-use planning for the Oslofjord - Ecosystem accounting and a relational landscape perspective as tools in future planning

Author

Helene Delphin

- Faculty of Landscape and Society, Norwegian University of Life Sciences

Abstract

The environmental state of the Oslofjord is poor, and its ecosystems are under great pressure. The cause of the fjord’s poor environmental condition is complex, but the Norwegian government’s “comprehensive action plan” for the Oslofjord points at good management of both land and sea areas as one of the important factors to achieve a good environmental condition (Regjeringen, 2021a). With this as point of departure the thesis is directed towards current and future land-use planning of the shoreline in the Oslo fjord, with the research question being ”What kind of knowledge about ecology and landscape is used and can be used in land-use planning of the shoreline in the Oslofjord?”

Read more here: https://hdl.handle.net/11250/3082529

Book Chapter: Coastal-Marine Ecosystem Accounting to Support Integrated Coastal Zone Management

Authors

Wenting Chen*, David N. Barton**, and Gunnar Sander*

Significance Statement

Coastal and marine ecosystems face historical deterioration worldwide. This negatively affects the provisioning of ecosystem services to society. The UN has recently approved a statistical standard for ecosystem accounting to measure the contribution of ecosystem services to the national economy and track changes in the value of naturel capital. It has been suggested that ecosystem accounting can also be used to support policy and management at regional and local level. This study presents an exploratory assessment of ecosystem accounting’s role in supporting integrated coastal zone planning using the Oslofjord in Norway as a case. The authors discuss how ecosystem accounting, and ecosystem service use and monetary accounts in particular, could be useful to support various aspects of integrated coastal zone planning, nature conservation and financing.

Full publication available here.

* Norwegian Institute for Water Research (NIVA), Oslo, Norway

** Norwegian Institute for Nature Research (NINA), Oslo, Norway