ecotoner: Tool to extract geographic and geometric measures of ecotones...

In dschlaep/ecotoner: ecotoner - ecotones / ecological boundaries across environmental gradients

Description

Tool to extract geographic and geometric measures of ecotones for R.

Methods to locate a transect

1. Select random points in edge cells of vegetation 1

2. Locate a second point within a neighborhood of specified size by one of four methods:

   • at the highest elevation (EcotonerSettings@transect_type == 1)

   • following the steepest slope outside a minimum distance (EcotonerSettings@transect_type == 2)

   • by the flowpath (EcotonerSettings@transect_type == 3)

   • by sufficient area of homogeneous aspect (EcotonerSettings@transect_type == 4)

3. Extend line connecting these two points in both directions

4. Trim line to the section between the lowest and highest elevation

Determine if transect is a suitable ecotone / ecological boundary

1. Transect is empty (i.e., trivial condition)

2. Definition of 'zone of ecotone / ecological boundary' is not met

Definition of 'zone of ecotone / ecological boundary'

Operational definition of zone of ecological boundary (v5): Process:

1. Apply definition to vegetation 1 and 2

2. Apply definition to majority type of vegetation 1 and majority type of vegetation 2

Definition:

• Transect orientation (from low to high elevation, i.e., from left to right)

• Density = rolling mean [over 90 m = 3 cell widths] of the mean column density (over the 200 cell wide band) at a 0.01 resolution

• Overall start :=

  • Leftmost position within minimum zone (= first run of sufficiently low values, <= EcotonerSettings@vegDefiningDensityTransect_low) of veg2 such that

  • There is at least one point of the maximum zone (= last run of sufficiently high values, >= EcotonerSettings@vegDefiningDensityTransect_high) of veg1 to the right and that

  • All of veg1 between overall start and the rightmost point of the maximum zone of veg1 have sufficient density (i.e., > EcotonerSettings@vegDefiningDensityTransectExtended_min)

• Overall end :=

  • Rightmost position within minimum zone (=last low run after the last high run) of veg1 such that

  • Overall start is on the left,

  • There is at least one point of the maximum zone (=first high run after the last low run) of veg2 to the left and that

  • All of veg2 between the lefmost point of the maximum zone of veg1 and overall end have sufficient density (i.e., > EcotonerSettings@vegDefiningDensityTransectExtended_min)

• No remaining BSE or TF vegetation should attain a maximal density (i.e., < EcotonerSettings@vegDefiningDensityTransectExtended_min)

• Zone of ecological boundary := from overall start to overall end

dschlaep/ecotoner documentation built on May 15, 2019, 2:57 p.m.