the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
30 Jun 2021
30 Jun 2021
Spatial variability in the relation between fire weather and burned area: patterns and drivers in Portugal
- 1cE3c: centre for Ecology, Evolution and Environmental changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- 2Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal
- 3Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas (CITAB), Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal
- 4IDL, Universidade de Lisboa, Lisboa, Portugal
- 5Soil Physics and Land Management group, Wageningen University and Research, Wageningen, Netherlands
- 1cE3c: centre for Ecology, Evolution and Environmental changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- 2Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal
- 3Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas (CITAB), Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal
- 4IDL, Universidade de Lisboa, Lisboa, Portugal
- 5Soil Physics and Land Management group, Wageningen University and Research, Wageningen, Netherlands
Abstract. Fire weather indices are used to assess the effect of weather conditions on wildfire behaviour and the high Daily Severity Rating percentile (DSRp) is strongly related to the total burned area (BA) in Portugal. The aims of this study were to: 1) assess if the 90th DSRp (DSR90p) threshold is adequate for Portugal; 2) identify and characterize regional variations of the DSRp threshold that justifies the bulk of BA; and, 3) analyse if vegetation cover can explain the DSRp spatial variability. We used wildfire data, weather reanalysis data from ERA5, for the 2001–2019 period, and the land use map for Portugal. DSRp were computed for an extended summer period and combined with individual large wildfires. Cluster analysis was performed using the relationship between DSRp and BA, in each municipality. Results revealed that the DSR90p is an adequate threshold for Portugal and well related to large BA. However, at the municipality scale, differences appear between the DSRp linked to the majority of accumulated BA. Cluster analysis revealed that municipalities where large wildfires occur in high DSRp present higher BA in forests and are located in coastal areas. In contrast, clusters with lower DSRp present greater BA in shrublands and are situated in eastern regions. These findings can support better prevention and fire suppression planning.
Tomás Calheiros et al.
Status: final response (author comments only)
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RC1: 'Comment on nhess-2021-173', Anonymous Referee #1, 04 Aug 2021
The paper "Spatial variability in the relation between fire weather and burned area: patterns and drivers in Portugal" aims at analysing large (>100 ha) summer forest fires in mainland Portugal. Although the dataset is sound and of potential interest, I found several flaws in the methods and results interpretations. The use of statistics is not always appropriate, expecially the use of OA, UA and K (they are used for classification accuracy against a reference). Furthermore no analyses on the spatial pattern are provided, simply a description of the maps. The relationships between LULC and weather and fire occurence need to be deepen analysed. The authors need to clarify and explain better the reason why they divided in cluster the dataset, the significant differences between groups,.... Other multivariate analysis methods can be adopted considering more variables (e.g. geographical gradients, inhabitants,...) in order to obtain a strong explanatory analysis and then building relationships or models to be tested.
The discussion section is mainly a list of municipalities in the different groups or sentences related to parameters not considered in the study. The first part is belonging to methods. The conclusion is redundant, repeating results and discussion elements.
In its current version I think the manuscript needs a complete revision and is not eligible for publication.
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RC2: 'Comment on nhess-2021-173', Anonymous Referee #2, 28 Oct 2021
The manuscript from Calheiros et al is very difficult to read. It reads as a series of bullet points linked together and the authors did not even bother at breaking the text into paragraphs or making any effort to increase readability. This is not a result of the authors not being native English speakers (I believe paragraphs also exist in Portuguese) but rather denotes a major lack of attention to detail.
The authors examine thresholds in burnt area associated with DSRp and how they differ across Portugal. The way they present the data is somewhat misleading: they make us believe that DSR has a very high correlation with burnt area. These types of correlations have been described before and they result from the ordering of values (from small to large). If that order is removed and simple scatter plot of burnt area DSR is presented, that relationship usually breaks, or is much weaker. I would thus encourage the authors to be more careful when using these types of analyses.
I’m not familiar with the clustering techniques used by the authors, and I will not comment on those. I will just point out that the results are rather shocking because pretty much all clusters are distributed across all Portugal, but it is well known that fires in N PT differ substantially from S PT (the authors actually state this in their introduction as well).
Tomás Calheiros et al.
Tomás Calheiros et al.
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