Applying Fuzzy Logic to Comparative Distribution Modelling: A Case Study with Two Sympatric Amphibians
Table 1
Factors and their related variables used to model the distributions of Bufo bufo, Epidalea calamita, and the combined presences of the two species. Sources: (1)U. S. Geological Survey (1996); (2)Font (1983, 2000); (3)I.G.N. (1999); data on the number of inhabitants of urban centres taken from Enciclopédia Universal (http://www.universal.pt) for Portugal and from the Instituto Nacional de Estadística (http://www.ine.es/) for Spain, both in 1999.
Factor
Variable
Code
Topography
Mean altitude (m)(1)
alti
Mean slope (degrees) (calculated from Alti)
slop
Water availability
Mean annual precipitation (mm)(2)
prec
Mean relative air humidity in January at 07:00 hours (%)(2)
hjan
Mean relative air humidity in July at 07:00 hours (%)(2)
hjul
Environmental energy
Mean annual insolation (hours/year)(2)
inso
Mean annual solar radiation (kwh/m2/day)(2)
srad
Mean temperature in January (°C)(2)
tjan
Mean temperature in July (°C)(2)
tjul
Mean annual temperature (°C)(2)
temp
Mean annual number of frost days (min. temperature ≤ 0°C)(2)
dfro
Mean annual potential evapotranspiration (mm)(2)
pet
Productivity
Mean annual actual evapotranspiration (mm) (=min [PET, Prec])
aet
Environmental disturbance
Maximum precipitation in 24 hours (mm)(2)
mp24
Relative maximum precipitation (=MP24/Prec)
rmp
Climatic variability
Mean annual number of days with precipitation ≥ 0,1 mm(2)
dpre
Annual temperature range (°C) (=TJul-TJan)
tran
Annual relative air humidity range (%) (=)
hran
Human activity
Distance to a highway (km)(3)
dhi
Distance to a town with more than 100,000 inhabitants (km)(3)
u100
Distance to a town with more than 500,000 inhabitants (km)(3)
