Historical Disturbance Trends: Recovery Threshold 1 and Recovery Threshold 0.166

Results for two new recovery threshold values for sensitivity analysis
Author

Madeleine Desrochers

Published

September 20, 2023

What’s Changed Since Last Time?

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Recovery Threshold 1

A recovery threshold of 1 is equivalent to 1 years since LT uses the inverse of the recovery threshold parameter.

Overall Man Kendall Results

Metric Man Kendall Statistic Normalized Test Statistic p Value Trend Sens Slope
area -0.2765 -2.2467 0.0247 decreasing -0.0072
cai -0.1780 -1.4410 0.1496 no trend -0.0099
circle -0.1780 -1.4410 0.1496 no trend -0.0099
contig -0.1780 -1.4410 0.1496 no trend -0.0099
core -0.2614 -2.1227 0.0338 decreasing -0.0008
enn 0.5038 4.1060 0.0000 increasing 1.5916
frac -0.4356 -3.5482 0.0004 decreasing -0.0004
gyrate -0.3182 -2.5876 0.0097 decreasing -0.1731
ncore -0.2576 -2.0917 0.0365 decreasing -0.0025
para 0.0227 0.1704 0.8647 no trend 0.0000
perim -0.3068 -2.4946 0.0126 decreasing -4.7273
shape -0.3826 -3.1144 0.0018 decreasing -0.0043
mean_mag -0.0758 -0.6043 0.5457 no trend -0.2472
percent_area_dist -0.4242 -3.4553 0.0005 decreasing -0.0441

Metric Plots

Metric Plots

All patch metrics derived from the landscape metrics package in r. Descriptions of the patch metrics can be found here.

Average disturbance patch size annually from 1990 - 2022.

Average core area index for disturbance patches from 1990 - 2022

Average size of smallest circumscribing circle for disturbance patches 1990 -2022

Average contiguity index for disturbance patches 1990 - 2022

Average size of patch core area from 1990 - 2022

Average distance to closest neighboring patch annually from 1990 - 2022

Average fractal dimension index from 1990 - 2022

Average radius of gyration for disturbance patches from 1990 - 2022

Average number of core areas in one disturbance patch from 1990 - 2022

Average perimeter to area ratio for disturbance patches 1990 - 2022

Average length of disturbance patch perimeter from 1990 - 2022

Average shape index for disturbance patches 1990 - 2022

Average disturbance magnitude of disturbance 1990 - 2022

Percentage of forest preserve land disturbed annually from 1990 - 2022

Age Group Man Kendall Results

Metric Group Man Kendall Statistic p Value Trend
area 1 -0.3144 0.0106 decreasing
area 2 -0.2159 0.0800 no trend
area 3 -0.2652 0.0313 decreasing
area 4 -0.2121 0.0855 no trend
core 1 -0.2652 0.0313 decreasing
core 2 -0.1629 0.1878 no trend
core 3 -0.2121 0.0855 no trend
core 4 -0.2045 0.0973 no trend
enn 1 0.5076 0.0000 increasing
enn 2 0.4621 0.0002 increasing
enn 3 0.4773 0.0001 increasing
enn 4 0.4583 0.0002 increasing
frac 1 -0.4205 0.0006 decreasing
frac 2 -0.3636 0.0031 decreasing
frac 3 -0.3674 0.0028 decreasing
frac 4 -0.3864 0.0017 decreasing
gyrate 1 -0.3295 0.0074 decreasing
gyrate 2 -0.2500 0.0424 decreasing
gyrate 3 -0.2841 0.0210 decreasing
gyrate 4 -0.2576 0.0365 decreasing
mean_mag 1 -0.0492 0.6985 no trend
mean_mag 2 -0.0227 0.8647 no trend
mean_mag 3 -0.0758 0.5457 no trend
mean_mag 4 -0.0455 0.7216 no trend
ncore 1 -0.2652 0.0313 decreasing
ncore 2 -0.2121 0.0855 no trend
ncore 3 -0.2159 0.0800 no trend
ncore 4 -0.1894 0.1250 no trend
percent_area_dist 1 -0.4621 0.0002 decreasing
percent_area_dist 2 -0.3750 0.0023 decreasing
percent_area_dist 3 -0.3826 0.0018 decreasing
percent_area_dist 4 -0.4091 0.0009 decreasing
perim 1 -0.3485 0.0046 decreasing
perim 2 -0.2348 0.0567 no trend
perim 3 -0.2727 0.0267 decreasing
perim 4 -0.2614 0.0338 decreasing
shape 1 -0.4318 0.0004 decreasing
shape 2 -0.3144 0.0106 decreasing
shape 3 -0.2803 0.0227 decreasing
shape 4 -0.3106 0.0116 decreasing

Age Group Metric Plots

Average Disturbance Area by Acquisition Age Group. Decreasing trends for groups 1 and 3. Average Core Area by Acquisition Age Group. Decreasing trend for groups 1. Average Euclidean Nearest Neighbor Distance by Age Group. Increasing trends for all groups.

Average Fractal Dimension Index by Acquisition Age Group. Decreasing trends for all groups. Average Radius of Gyration by Acquisition Age Group. Decreasing trends for all groups.

Average Number of Core Areas by Acquisition Age Group. Decreasing trends for group 1.

Average Perimeter Length by Acquisition Age Group. Decreasing trends for groups 1, 3 and 4.

Average Shape Index by Acquisition Age Group. Decreasing trends for all groups.

Average Percent Area Disturbed by Acquisition Age Group. Decreasing trends for all groups.

Recovery Threshold 0.166

A recovery threshold of 0.166 is equivalent to 6 years since LT uses the inverse of the recovery threshold parameter.

Overall Man Kendall Results

Metric Man Kendall Statistic Normalized Test Statistic p Value Trend Sens Slope
area -0.0606 -0.4803 0.6310 no trend -0.0013
cai 0.1326 1.0691 0.2850 no trend 0.0069
circle 0.1326 1.0691 0.2850 no trend 0.0069
contig 0.1326 1.0691 0.2850 no trend 0.0069
core -0.0227 -0.1704 0.8647 no trend -0.0001
enn 0.3826 3.1144 0.0018 increasing 3.1339
frac -0.2197 -1.7819 0.0748 no trend -0.0003
gyrate -0.0530 -0.4183 0.6757 no trend -0.0392
ncore -0.0265 -0.2014 0.8404 no trend -0.0003
para -0.2803 -2.2777 0.0227 decreasing -0.0001
perim -0.0985 -0.7902 0.4294 no trend -0.8424
shape -0.1667 -1.3480 0.1777 no trend -0.0023
mean_mag 0.3068 2.4946 0.0126 increasing 1.1647
percent_area_dist -0.2424 -1.9678 0.0491 decreasing -0.0072

Metric Plots

All patch metrics derived from the landscape metrics package in r. Descriptions of the patch metrics can be found here.

Average disturbance patch size annually from 1990 - 2022.

Average core area index for disturbance patches from 1990 - 2022

Average size of smallest circumscribing circle for disturbance patches 1990 -2022

Average contiguity index for disturbance patches 1990 - 2022

Average size of patch core area from 1990 - 2022

Average distance to closest neighboring patch annually from 1990 - 2022

Average fractal dimension index from 1990 - 2022

Average radius of gyration for disturbance patches from 1990 - 2022

Average number of core areas in one disturbance patch from 1990 - 2022

Average perimeter to area ratio for disturbance patches 1990 - 2022

Average length of disturbance patch perimeter from 1990 - 2022

Average shape index for disturbance patches 1990 - 2022

Average disturbance magnitude of disturbance 1990 - 2022

Percentage of forest preserve land disturbed annually from 1990 - 2022

Age Group Man Kendall Results

Metric Group Man Kendall Statistic p Value Trend
enn 1 0.4356 0.0004 increasing
enn 2 0.3409 0.0055 increasing
enn 3 0.3295 0.0074 increasing
enn 4 0.3523 0.0042 increasing
frac 1 -0.3182 0.0097 decreasing
frac 2 -0.2538 0.0393 decreasing
frac 3 -0.1629 0.1878 no trend
frac 4 -0.1591 0.1984 no trend
mean_mag 1 0.2992 0.0150 increasing
mean_mag 2 0.2879 0.0193 increasing
mean_mag 3 0.2538 0.0393 increasing
mean_mag 4 0.2803 0.0227 increasing
para 1 -0.3447 0.0050 decreasing
para 2 -0.1515 0.2209 no trend
para 3 -0.2045 0.0973 no trend
para 4 -0.2083 0.0912 no trend
percent_area_dist 1 -0.2992 0.0150 decreasing
percent_area_dist 2 -0.2348 0.0567 no trend
percent_area_dist 3 -0.2008 0.1038 no trend
percent_area_dist 4 -0.2348 0.0567 no trend
shape 1 -0.2689 0.0289 decreasing
shape 2 -0.2197 0.0748 no trend
shape 3 -0.1553 0.2095 no trend
shape 4 -0.1326 0.2850 no trend

Age Group Metric Plots

Average Euclidean Nearest Neighbor Distance by Acquisition Age Group. Increasing trends for all groups. Average Perimeter to Area Ratio by Acquisition Age Group. Decreasing trend for group 1. Average Shape Index by Acquisition Age Group. Decreasing trend for group 1. Average Fractal Dimension Index by Acquisition Age Group. Decreasing trends for groups 1 and 2.

Average Mean Disturbance Magnitude by Acquisition Age Group. Increasing trends for all groups.

Average Percentage Area Disturbed by Acquisition Age Group. Decreasing trends for group 1.