In connectscape/Makurhini: Makurhini: Analyzing landscape connectivity
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## Example 1: Assessing the overall connectivity and the importance of habitat patches for terrestrial mammals in central Mexico.
In this example, the `MK_dPCIIC()` function was applied to estimate the connectivity of 404 remnant habitat patches, which were modeled to 40 non-volant mammal species of the Trans-Mexican Volcanic System (TMVS) by Correa Ayram et al., (2017). The landscape resistance to dispersal was estimated at a 100-meter resolution using a spatial human footprint index, land use intensity, time of human landscape intervention, biophysical vulnerability, fragmentation, and habitat loss (Correa Ayram et al., 2017). The raster was aggregated by a factor of 5 to change its original resolution from 100m to 500m. To represent different dispersal capacities of multiple species we considered the following median (associated to a probability of 0.5) distance thresholds: 250, 1500, 3000, and 10,000 meters. These four distances group the 40 species according to their dispersal distance requirements
### Load R packages
```r
library(Makurhini)
library(sf)
library(raster)
library(ggplot2)
Loading inputs
#Habitat nodes
data("habitat_nodes", package = "Makurhini")
nrow(habitat_nodes)
#Study area
data("TMVS", package = "Makurhini")
#Resistance
data("resistance_matrix", package = "Makurhini")
raster_map <- as(resistance_matrix, "SpatialPixelsDataFrame")
raster_map <- as.data.frame(raster_map)
colnames(raster_map) <- c("value", "x", "y")
ggplot() +
geom_tile(data = raster_map, aes(x = x, y = y, fill = value), alpha = 0.8) +
geom_sf(data = TMVS, aes(color = "Study area"), fill = NA, color = "black") +
geom_sf(data = habitat_nodes, aes(color = "Habitat nodes"), fill = "forestgreen") +
scale_fill_gradientn(colors = c("#000004FF", "#1B0C42FF", "#4B0C6BFF", "#781C6DFF",
"#A52C60FF", "#CF4446FF", "#ED6925FF", "#FB9A06FF",
"#F7D03CFF", "#FCFFA4FF"))+
scale_color_manual(name = "", values = "black")+
theme_minimal() +
theme(axis.title.x = element_blank(),
axis.title.y = element_blank())
Using euclidean distance
One of the most crucial parameters of the Makurhini functions is distance, which is a list of parameters associated with the distancefile() function. This function is used to establish the distance between each pair of nodes. The distances between nodes can be classified as either Euclidean distances (also known as straight-line distances) or effective distances (also known as cost distances). In the case of Euclidean distances, two of the most crucial parameters in the list are type and keep. The type parameter is employed to select one of the distances, namely "centroid" (which is faster) or "edge". Meanwhile, keep is utilized to streamline the shapes of the polygons representing the nodes. Furthermore, additional simplification of the shape (through vertex removal) can significantly accelerate the processing time, particularly in the case of the "edge" type.
In this example we will use centroid distance:
PC_example_1 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
distance = list(type = "centroid"),
parallel = NULL,
metric = "PC",
probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000))
PC_example_1 <- readRDS("C:/Users/Usuario/Documents/R/TEST_Folder/PC_example_1.rds")
We obtain a list object where each element is a result for each distance threshold.
class(PC_example_1)
names(PC_example_1)
head(PC_example_1$d10000)
We can use ggplot2 or tmap to map the results:
interv <- c(0.0000021, 0.0596058, 0.1612625, 0.2943665, 0.4937340, 0.8902072, 1.1303198, 1.7556675, 3.4064392, 80.7958156)
#We can use some package to get intervals for example classInt R Packge:
library(classInt)
interv <- classIntervals(PC_example_1$d10000$dPC, 9, "jenks")[[2]] #9 intervalos
ggplot()+
geom_sf(data = TMVS)+
geom_sf(data = PC_example_1$d10000, aes(fill = cut(dPC, breaks = interv)), color = NA)+
scale_fill_brewer(type = "qual",
palette = "RdYlGn",
name = "dPC",
na.translate = FALSE)+
theme_minimal() +
theme(
legend.position = "inside",
legend.position.inside = c(0.1,0.21),
legend.key.height = unit(0.2, "cm"),
legend.key.width = unit(0.3, "cm"),
legend.text = element_text(size = 5.5),
legend.title = element_text(size = 5.5)
) + labs(title="Euclidean distance")
Using least-cost distances between centroids
The landscape resistance to dispersal was estimated at a 100-meter resolution using a spatial human footprint index, land use intensity, time of human landscape intervention, biophysical vulnerability, fragmentation, and habitat loss (Correa Ayram et al., 2017). The raster was aggregated by a factor of 5 to change its original resolution from 100m to 500m.
PC_example_2 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
distance = list(type = "least-cost",
resistance = resistance_matrix),
parallel = NULL,
metric = "PC",
probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000))
PC_example_2 <- readRDS("C:/Users/Usuario/Documents/R/TEST_Folder/PC_example_2.rds")
We obtain a list object where each element is a result for each distance threshold.
class(PC_example_2)
names(PC_example_2)
head(PC_example_2$d10000)
Each element of the list is a vector type object that can be exported using the sf functions and in its vector formats (e.g., shp, gpkg) using the sf package (Pebesma et al., 2024), for example:
write_sf(PC_example$d10000, “.../dPC_d0000.shp”)
We can use ggplot2 or tmap to map the results:
#Keep the same range of values of PC_example_1 for comparison, only the highest range changes.
interv[length(interv)] <- max(PC_example_2$d10000$dPC)
ggplot()+
geom_sf(data = TMVS)+
geom_sf(data = PC_example_2$d10000, aes(fill = cut(dPC, breaks = interv)), color = NA)+
scale_fill_brewer(type = "qual",
palette = "RdYlGn",
name = "dPC",
na.translate = FALSE)+
theme_minimal() +
theme(
legend.position = "inside",
legend.position.inside = c(0.1, 0.21),
legend.key.height = unit(0.2, "cm"),
legend.key.width = unit(0.3, "cm"),
legend.text = element_text(size = 5.5),
legend.title = element_text(size = 5.5)
)+ labs(title="Least-cost distance")
In the event that the values of the resistance raster are integers, it is possible to estimate the cost distances between patches by utilizing the Java options that Makurhini integrates with the R package graph4lg (Savary et al., 2023). It is therefore possible to add the options least_cost.java and cores.java to the input list within the distance parameter. The first of these activates the Java mode, while the second specifies the number of cores to be used for parallelising the process (the default value is 1):
PC_example <- MK_dPCIIC(nodes = patches, attribute = NULL, area_unit = "ha",
distance = list(type = "least-cost",
resistance = resistance_matrix,
least_cost.java = TRUE,
cores.java = 4),
metric = "PC", overall = TRUE, probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000),
intern = FALSE)
#155.59 sec elapsed
Overall connectivity
To obtain the overall connectivity value for the study region we can use the parameter overall. At this point it is important to use the parameter unit_area to set the area units we will work with, which will be used to interpret the metric EC, also called ECA, the default is "m2". For example, get overall and work with hectares:
PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
area_unit = "ha",
distance = list(type = "centroid"),
parallel = NULL,
metric = "PC",
probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000),
overall = TRUE, intern = FALSE)
PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
area_unit = "ha",
distance = list(type = "centroid"),
parallel = NULL,
metric = "PC",
probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000),
overall = TRUE)
class(PC_example_3)
class(PC_example_3$d10000$node_importances_d10000)
class(PC_example_3$d10000$overall_d10000)
PC_example_3$d10000$overall_d10000
Nodes importance prioritization:
PC_example_3$d10000$node_importances_d10000
Overall:
PC_example_3$d10000$overall_d10000
You can also use the onlyoverall parameter to obtain only the global connectivity value without prioritizing the nodes. If the LA parameter is not included while using overall or onlyoverall parameter, then the PC or IIC indices are not obtained.
#Maximum landcape attribute or LA = total area of the estudy area
Area <- unit_convert( st_area(TMVS), "m2", "ha") #hectares
PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
area_unit = "ha",
distance = list(type = "centroid"),
parallel = NULL,
metric = "PC",
probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000),
LA = Area,
onlyoverall = TRUE, intern = FALSE)
#Maximum landcape attribute or LA = total area of the estudy area
Area <- unit_convert( st_area(TMVS), "m2", "ha") #hectares
PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
area_unit = "ha",
distance = list(type = "centroid"),
parallel = NULL,
metric = "PC",
probability = 0.5,
distance_thresholds = c(250, 1500, 3000, 10000),
LA = Area,
onlyoverall = TRUE)
class(PC_example_3)
class(PC_example_3$d10000)
PC_example_3$d10000
IIC index
To estimate the IIC index we only need to specify it in the metric parameter, as it is a binary index it is not necessary to specify the connection probability.
IIC_example_4 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
area_unit = "ha",
distance = list(type = "centroid"),
parallel = NULL,
metric = "IIC",
probability = NULL,
distance_thresholds = c(250, 1500, 3000, 10000),
LA = Area,
overall = TRUE, intern = FALSE)
IIC_example_4 <- MK_dPCIIC(nodes = habitat_nodes,
attribute = NULL,
area_unit = "ha",
distance = list(type = "centroid"),
parallel = NULL,
metric = "IIC",
probability = NULL,
distance_thresholds = c(250, 1500, 3000, 10000),
LA = Area,
overall = TRUE)
class(IIC_example_4)
class(IIC_example_4$d10000$node_importances_d10000)
class(IIC_example_4$d10000$overall_d10000)
Nodes importance prioritization:
IIC_example_4$d10000$node_importances_d10000
Overall:
IIC_example_4$d10000$overall_d10000
References
-
Correa Ayram, C. A., Mendoza, M. E., Etter, A., & Pérez Salicrup, D. R. (2017). Anthropogenic impact on habitat connectivity: A multidimensional human footprint index evaluated in a highly biodiverse landscape of Mexico. Ecological Indicators, 72, 895-909. https://doi.org/10.1016/j.ecolind.2016.09.007
-
Pascual-Hortal, L. & Saura, S. 2006. Comparison and development of new graph-based landscape connectivity indices: towards the priorization of habitat patches and corridors for conservation. Landscape Ecology 21 (7): 959-967.
-
Saura, S. & Pascual-Hortal, L. 2007. A new habitat availability index to integrate connectivity in landscape conservation planning: comparison with existing indices and application to a case study. Landscape and Urban Planning 83 (2-3): 91-103.
-
Savary, P., Vuidel, G., Rudolph, T., & Daniel, A. (2023). graph4lg: Build Graphs for Landscape Genetics Analysis (1.8.0) [Software]. https://cran.r-project.org/web/packages/graph4lg/index.html
connectscape/Makurhini documentation built on Jan. 12, 2025, 8:16 p.m.
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knitr::opts_chunk$set(echo = TRUE)
```{css, echo=FALSE} / CSS to style chunk headers / .chunk-title { background-color: #f0f0f0; / Background color / border: 1px solid #ccc; / Border / padding: 8px 10px; / Padding / margin-top: 20px; / Top margin / margin-bottom: 10px; / Bottom margin / font-weight: bold; / Font weight / }
## Example 1: Assessing the overall connectivity and the importance of habitat patches for terrestrial mammals in central Mexico. In this example, the `MK_dPCIIC()` function was applied to estimate the connectivity of 404 remnant habitat patches, which were modeled to 40 non-volant mammal species of the Trans-Mexican Volcanic System (TMVS) by Correa Ayram et al., (2017). The landscape resistance to dispersal was estimated at a 100-meter resolution using a spatial human footprint index, land use intensity, time of human landscape intervention, biophysical vulnerability, fragmentation, and habitat loss (Correa Ayram et al., 2017). The raster was aggregated by a factor of 5 to change its original resolution from 100m to 500m. To represent different dispersal capacities of multiple species we considered the following median (associated to a probability of 0.5) distance thresholds: 250, 1500, 3000, and 10,000 meters. These four distances group the 40 species according to their dispersal distance requirements ### Load R packages ```r library(Makurhini) library(sf) library(raster) library(ggplot2)
Loading inputs
#Habitat nodes data("habitat_nodes", package = "Makurhini") nrow(habitat_nodes) #Study area data("TMVS", package = "Makurhini") #Resistance data("resistance_matrix", package = "Makurhini")
raster_map <- as(resistance_matrix, "SpatialPixelsDataFrame") raster_map <- as.data.frame(raster_map) colnames(raster_map) <- c("value", "x", "y") ggplot() + geom_tile(data = raster_map, aes(x = x, y = y, fill = value), alpha = 0.8) + geom_sf(data = TMVS, aes(color = "Study area"), fill = NA, color = "black") + geom_sf(data = habitat_nodes, aes(color = "Habitat nodes"), fill = "forestgreen") + scale_fill_gradientn(colors = c("#000004FF", "#1B0C42FF", "#4B0C6BFF", "#781C6DFF", "#A52C60FF", "#CF4446FF", "#ED6925FF", "#FB9A06FF", "#F7D03CFF", "#FCFFA4FF"))+ scale_color_manual(name = "", values = "black")+ theme_minimal() + theme(axis.title.x = element_blank(), axis.title.y = element_blank())
Using euclidean distance
One of the most crucial parameters of the Makurhini functions is distance, which is a list of parameters associated with the distancefile() function. This function is used to establish the distance between each pair of nodes. The distances between nodes can be classified as either Euclidean distances (also known as straight-line distances) or effective distances (also known as cost distances). In the case of Euclidean distances, two of the most crucial parameters in the list are type and keep. The type parameter is employed to select one of the distances, namely "centroid" (which is faster) or "edge". Meanwhile, keep is utilized to streamline the shapes of the polygons representing the nodes. Furthermore, additional simplification of the shape (through vertex removal) can significantly accelerate the processing time, particularly in the case of the "edge" type.
In this example we will use centroid distance:
PC_example_1 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, distance = list(type = "centroid"), parallel = NULL, metric = "PC", probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000))
PC_example_1 <- readRDS("C:/Users/Usuario/Documents/R/TEST_Folder/PC_example_1.rds")
We obtain a list object where each element is a result for each distance threshold.
class(PC_example_1) names(PC_example_1) head(PC_example_1$d10000)
We can use ggplot2 or tmap to map the results:
interv <- c(0.0000021, 0.0596058, 0.1612625, 0.2943665, 0.4937340, 0.8902072, 1.1303198, 1.7556675, 3.4064392, 80.7958156)
#We can use some package to get intervals for example classInt R Packge: library(classInt) interv <- classIntervals(PC_example_1$d10000$dPC, 9, "jenks")[[2]] #9 intervalos
ggplot()+ geom_sf(data = TMVS)+ geom_sf(data = PC_example_1$d10000, aes(fill = cut(dPC, breaks = interv)), color = NA)+ scale_fill_brewer(type = "qual", palette = "RdYlGn", name = "dPC", na.translate = FALSE)+ theme_minimal() + theme( legend.position = "inside", legend.position.inside = c(0.1,0.21), legend.key.height = unit(0.2, "cm"), legend.key.width = unit(0.3, "cm"), legend.text = element_text(size = 5.5), legend.title = element_text(size = 5.5) ) + labs(title="Euclidean distance")
Using least-cost distances between centroids
The landscape resistance to dispersal was estimated at a 100-meter resolution using a spatial human footprint index, land use intensity, time of human landscape intervention, biophysical vulnerability, fragmentation, and habitat loss (Correa Ayram et al., 2017). The raster was aggregated by a factor of 5 to change its original resolution from 100m to 500m.
PC_example_2 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, distance = list(type = "least-cost", resistance = resistance_matrix), parallel = NULL, metric = "PC", probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000))
PC_example_2 <- readRDS("C:/Users/Usuario/Documents/R/TEST_Folder/PC_example_2.rds")
We obtain a list object where each element is a result for each distance threshold.
class(PC_example_2) names(PC_example_2) head(PC_example_2$d10000)
Each element of the list is a vector type object that can be exported using the sf functions and in its vector formats (e.g., shp, gpkg) using the sf package (Pebesma et al., 2024), for example:
write_sf(PC_example$d10000, “.../dPC_d0000.shp”)
We can use ggplot2 or tmap to map the results:
#Keep the same range of values of PC_example_1 for comparison, only the highest range changes. interv[length(interv)] <- max(PC_example_2$d10000$dPC) ggplot()+ geom_sf(data = TMVS)+ geom_sf(data = PC_example_2$d10000, aes(fill = cut(dPC, breaks = interv)), color = NA)+ scale_fill_brewer(type = "qual", palette = "RdYlGn", name = "dPC", na.translate = FALSE)+ theme_minimal() + theme( legend.position = "inside", legend.position.inside = c(0.1, 0.21), legend.key.height = unit(0.2, "cm"), legend.key.width = unit(0.3, "cm"), legend.text = element_text(size = 5.5), legend.title = element_text(size = 5.5) )+ labs(title="Least-cost distance")
In the event that the values of the resistance raster are integers, it is possible to estimate the cost distances between patches by utilizing the Java options that Makurhini integrates with the R package graph4lg (Savary et al., 2023). It is therefore possible to add the options least_cost.java and cores.java to the input list within the distance parameter. The first of these activates the Java mode, while the second specifies the number of cores to be used for parallelising the process (the default value is 1):
PC_example <- MK_dPCIIC(nodes = patches, attribute = NULL, area_unit = "ha", distance = list(type = "least-cost", resistance = resistance_matrix, least_cost.java = TRUE, cores.java = 4), metric = "PC", overall = TRUE, probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000), intern = FALSE) #155.59 sec elapsed
Overall connectivity
To obtain the overall connectivity value for the study region we can use the parameter overall. At this point it is important to use the parameter unit_area to set the area units we will work with, which will be used to interpret the metric EC, also called ECA, the default is "m2". For example, get overall and work with hectares:
PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, area_unit = "ha", distance = list(type = "centroid"), parallel = NULL, metric = "PC", probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000), overall = TRUE, intern = FALSE)
PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, area_unit = "ha", distance = list(type = "centroid"), parallel = NULL, metric = "PC", probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000), overall = TRUE)
class(PC_example_3) class(PC_example_3$d10000$node_importances_d10000) class(PC_example_3$d10000$overall_d10000) PC_example_3$d10000$overall_d10000
Nodes importance prioritization:
PC_example_3$d10000$node_importances_d10000
Overall:
PC_example_3$d10000$overall_d10000
You can also use the onlyoverall parameter to obtain only the global connectivity value without prioritizing the nodes. If the LA parameter is not included while using overall or onlyoverall parameter, then the PC or IIC indices are not obtained.
#Maximum landcape attribute or LA = total area of the estudy area Area <- unit_convert( st_area(TMVS), "m2", "ha") #hectares PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, area_unit = "ha", distance = list(type = "centroid"), parallel = NULL, metric = "PC", probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000), LA = Area, onlyoverall = TRUE, intern = FALSE)
#Maximum landcape attribute or LA = total area of the estudy area Area <- unit_convert( st_area(TMVS), "m2", "ha") #hectares PC_example_3 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, area_unit = "ha", distance = list(type = "centroid"), parallel = NULL, metric = "PC", probability = 0.5, distance_thresholds = c(250, 1500, 3000, 10000), LA = Area, onlyoverall = TRUE)
class(PC_example_3) class(PC_example_3$d10000) PC_example_3$d10000
IIC index
To estimate the IIC index we only need to specify it in the metric parameter, as it is a binary index it is not necessary to specify the connection probability.
IIC_example_4 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, area_unit = "ha", distance = list(type = "centroid"), parallel = NULL, metric = "IIC", probability = NULL, distance_thresholds = c(250, 1500, 3000, 10000), LA = Area, overall = TRUE, intern = FALSE)
IIC_example_4 <- MK_dPCIIC(nodes = habitat_nodes, attribute = NULL, area_unit = "ha", distance = list(type = "centroid"), parallel = NULL, metric = "IIC", probability = NULL, distance_thresholds = c(250, 1500, 3000, 10000), LA = Area, overall = TRUE)
class(IIC_example_4) class(IIC_example_4$d10000$node_importances_d10000) class(IIC_example_4$d10000$overall_d10000)
Nodes importance prioritization:
IIC_example_4$d10000$node_importances_d10000
Overall:
IIC_example_4$d10000$overall_d10000
References
-
Correa Ayram, C. A., Mendoza, M. E., Etter, A., & Pérez Salicrup, D. R. (2017). Anthropogenic impact on habitat connectivity: A multidimensional human footprint index evaluated in a highly biodiverse landscape of Mexico. Ecological Indicators, 72, 895-909. https://doi.org/10.1016/j.ecolind.2016.09.007
-
Pascual-Hortal, L. & Saura, S. 2006. Comparison and development of new graph-based landscape connectivity indices: towards the priorization of habitat patches and corridors for conservation. Landscape Ecology 21 (7): 959-967.
-
Saura, S. & Pascual-Hortal, L. 2007. A new habitat availability index to integrate connectivity in landscape conservation planning: comparison with existing indices and application to a case study. Landscape and Urban Planning 83 (2-3): 91-103.
-
Savary, P., Vuidel, G., Rudolph, T., & Daniel, A. (2023). graph4lg: Build Graphs for Landscape Genetics Analysis (1.8.0) [Software]. https://cran.r-project.org/web/packages/graph4lg/index.html
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