Last updated: 2021-03-16

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Knit directory: mapme.protectedareas/

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Rmd 45f3a67 Ohm-Np 2021-03-16 add biomes name column & slight modifications
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html b548133 Ohm-Np 2021-03-15 create wwf teow rmd

# load required libraries
library("sf")
library("wdpar")
library("dplyr")
library("mapview") # usef for interactive maps in this website. not essential for analysis
library("rmarkdown") # only used for rendering tables  for this website

starttime<-Sys.time() # mark the starttime of this routine to calculate processing time at the end

Introduction

Terrestrial Ecoregions of the World (TEOW) is a biogeographic regionalization of the Earth’s terrestrial biodiversity. The biogeographic units are ecoregions, which are defined as relatively large units of land or inland water containing a distinct assemblage of natural communities sharing a large majority of species, dynamics, and environmental conditions. There are 867 terrestrial ecoregions, classified into 14 different biomes such as forests, grasslands, or deserts. Ecoregions represent the original distribution of distinct assemblages of species and communities.Visit Link for more information on TEOW from WWF.

Datasource and Metadata Information

  • Dataset: Terrestrial Ecoregions of the World - World Wildlife Fund [1]
  • Geographical Coverage: Global
  • Temporal Coverage: 2001
  • Temporal Resolution: Cross-sectional
  • Unit: hectare
  • Data downloaded: 15th March, 2021
  • Metadata Link
  • Download Link

Here we are going to carry out an analysis that intersects WDPA polygons with the Ecoregions to calculate the area of different ecoregions and biomes within supported PAs.

Processing Workflow

To carry out this analysis, we will follow this processing routine:

Download and prepare WDPA polygons

First of all, we will try to get the country level polygon data from wdpar package. wdpar is a library to interface to the World Database on Protected Areas (WDPA). The library is used to monitor the performance of existing PAs and determine priority areas for the establishment of new PAs. We will use Brazil - for other countries of your choice, simply provide the country name or the ISO3 name e.g. Gy for Guyana, COL for Colombia

# fetch the raw data from wdpar of country
br_wdpa_raw <- wdpa_fetch("Brazil")

Since there are more than 3000 enlisted protected areas in Brazil, we will demonstrate this routine using only three wdpa polygons: - Reserva Biologica Do Rio Trombetas - wdpaid 43, - Reserva Extrativista Rio Cajari - wdpaid 31776, and - Estacao Ecologica Do Jari - wdpaid 4891

For this, we have to subset the country level polygon data to the PAs level.

# subset three wdpa polygons by their wdpa ids
br_wdpa_subset<-
  br_wdpa_raw%>%
  filter(WDPAID %in% c(43,4891,31776))

The next immediate step is to clean the fetched raw data with the functionality provided with routines from the wdpar package. Cleaning is done by the package following this steps:

  • exclude protected areas that are not yet implemented
  • exclude protected areas that are UNESCO reserves
  • removing points with no reported area:
  • replace missing data codes (e.g. “0”) with missing data values (i.e. NA)
  • replace protected areas represented as points with circular protected areas that correspond to their reported extent
  • repair any topological issues with the geometries
  • (erase overlapping areas) -> which might be important for area reporting on country level but is not done in our context here

For more information see the package documentation of wdpar. In the end of this step we will project the data back to WGS84 for the intersection.

# clean the data
br_wdpa_subset <- wdpa_clean(
  br_wdpa_subset, 
  erase_overlaps = F
  )
# we can create an interactive map to see the three selected polygons
mapView(br_wdpa_subset)

Since, we prepared WDPA polygon data for our analysis, we now load the TEOW global shapefile layer from archived file.

# load TEOW global polygons
teow <- 
  read_sf(paste("data/Terrestrial_Ecoregions_World.shp", sep=""))

Intersect TEOW and WDPA Polygon layer

To analyse how much of wdpa area is within which part of the ecoregion, intersection function is applied. st_intersection allows us to see that result. To be able to apply st_intersection, the polygon layers should be provided as an object with the sf class. To carry out intersection function, coordinate reference system of both the polygons should be harmonized. For this, we use st_transform to achieve this. We than compare the number of polygons in both the original and the resulting WDPA layer to see whether our process split up any polygon from the intersection

# reproject teow to match WDPA
teow <-
  st_transform(teow,crs = st_crs(br_wdpa_subset))
# apply intersection
teow_wdpa_intersection <- 
  st_intersection(teow, br_wdpa_subset)
# compare the number of polygons in both layers 
nrow(br_wdpa_subset)
[1] 3
nrow(teow_wdpa_intersection)
[1] 4

We can see that there is one intersection in the research area i.e that we now have four polygons whereas before the intersection we had only three.

Calculate Areas

Since, we already achieved the intersection, now we want to extract the actual area of intersection between wdpa polygons and teow polygons.

# extract areas (SqKm) and save it as new column
teow_wdpa_intersection$teow_intersect_sqkm <- 
  st_area(teow_wdpa_intersection)/1000000
# tibble - turns existing object to tibble dataframe from library `dplyr`
myData <- as_tibble(teow_wdpa_intersection)
# select only necessary columns from the intersected polygon
myData_f <- myData %>% 
  select(WDPAID, BIOME_NAME, ECO_NAME, teow_intersect_sqkm)

With the results looking like this

In the end we are going to have a look how long the rendering of this file took so that people get an idea about the processing speed of this routine.

stoptime<-Sys.time()
print(starttime-stoptime)
Time difference of -5.119396 secs

References

[1] Olson, D. M., Dinerstein, E., Wikramanayake, E. D., Burgess, N. D., Powell, G. V. N., Underwood, E. C., D’Amico, J. A., Itoua, I., Strand, H. E., Morrison, J. C., Loucks, C. J., Allnutt, T. F., Ricketts, T. H., Kura, Y., Lamoreux, J. F., Wettengel, W. W., Hedao, P., Kassem, K. R. 2001. Terrestrial ecoregions of the world: a new map of life on Earth. Bioscience 51(11):933-938.


sessionInfo()
R version 4.0.3 (2020-10-10)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Big Sur 10.16

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRblas.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices datasets  utils     methods   base     

other attached packages:
[1] rmarkdown_2.5   mapview_2.9.0   dplyr_1.0.5     wdpar_1.0.6    
[5] sf_0.9-7        workflowr_1.6.2

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.6              countrycode_1.2.0       lattice_0.20-41        
 [4] png_0.1-7               class_7.3-17            leaflet.providers_1.9.0
 [7] assertthat_0.2.1        rprojroot_2.0.2         digest_0.6.27          
[10] R6_2.5.0                stats4_4.0.3            evaluate_0.14          
[13] e1071_1.7-4             httr_1.4.2              pillar_1.4.7           
[16] rlang_0.4.10            curl_4.3                rstudioapi_0.13        
[19] whisker_0.4             raster_3.4-5            webshot_0.5.2          
[22] stringr_1.4.0           htmlwidgets_1.5.3       munsell_0.5.0          
[25] compiler_4.0.3          httpuv_1.5.4            xfun_0.19              
[28] pkgconfig_2.0.3         base64enc_0.1-3         htmltools_0.5.0        
[31] tidyselect_1.1.0        tibble_3.0.4            codetools_0.2-16       
[34] crayon_1.3.4            later_1.1.0.1           rappdirs_0.3.3         
[37] grid_4.0.3              jsonlite_1.7.1          lwgeom_0.2-5           
[40] satellite_1.0.2         lifecycle_1.0.0         DBI_1.1.0              
[43] git2r_0.27.1            magrittr_2.0.1          units_0.6-7            
[46] scales_1.1.1            KernSmooth_2.23-17      stringi_1.5.3          
[49] renv_0.13.0             fs_1.5.0                promises_1.1.1         
[52] leaflet_2.0.4.1         sp_1.4-5                ellipsis_0.3.1         
[55] generics_0.1.0          vctrs_0.3.6             RColorBrewer_1.1-2     
[58] tools_4.0.3             leafem_0.1.3            glue_1.4.2             
[61] purrr_0.3.4             crosstalk_1.1.1         yaml_2.2.1             
[64] colorspace_2.0-0        classInt_0.4-3          knitr_1.30