Knowing the species Survival Rates within their forestry projects over time helps foresters make important decisions.
Terraware calculates Survival Rates for Planting Sites based on initial plant densities and subsequent live and dead counts of plants observed during Assigned Plot Plant Monitoring Observations. These Survival Rates are calculated and shown in Observations at the Planting Site, Stratum, and monitoring plot levels. Survival Rates will also be shown in the Plants Dashboard.
In order for Terraware to calculate Survival Rates for Planting Sites, the initial plant densities will need to be set for each permanent plot and/or for each Planting Site Stratum for temporary plots for the Planting Site. The plant densities for these permanent plots and temporary plots can be set once there is a completed Observation for the Planting Site. The status of the Observation must be "Completed" or "Completed (Ended)."
The Survival Rate Settings for each Planting Site can be found in the Observations page of the Planting Site. Users with Administrator and Manager roles can access and manage Survival Rate Settings.
Survival Rate Settings link in Observations page
Setting Plant Densities for Permanent Plots
For every permanent plot, you will need to select or enter the data that will be used to provide the initial plant density per plot for survival rate calculations. This initial plant density is a part of the post-planting t0 data (aka "t0 planting data" and "t0 data") that is collected in monitoring plots as soon as planting has been completed in the plot. (Note: This post-planting t0 data differs from baseline t0 data, which is collected prior to the start of planting activities within a Planting Site.)
This t0 data must be set for all permanent plots assigned to the Planting Site. All the permanent plots for which t0 data must be set are in the Permanent Plots tab in the Survival Rate Settings page.
t0 data set for all Permanent Plots in a Planting Site
Completed Observations that include a permanent plot can be used for the permanent plot’s t0 data. Ideally, the data in the first Observation completed for the Planting Site, conducted right after planting has been completed, is used as t0 data.
To use an Observation for t0 data for a plot, select the "Use Observation Data" option and then select the Observation to use for t0 data. Only Observations that included the plot can be used as a t0 Observation for the plot. Observations that do not include the plot will not appear in the Observation selector. If there are no Observations that include the plot, you will not be able to use the "Use Observation Data" option for the plot.
You will be able to see the t0 data from the selected Observation, which Terraware will use for calculating Survival Rates. Terraware will automatically calculate and show Survival Rates in Observations completed after the t0 Observation.
Selecting a completed Observation as the t0 Observation for permanent plots
Alternatively, initial plant densities can be entered per species observed within the plot.
To enter plant densities per species, select the "Provide plant density per species" option. Species that were withdrawn for planting in the Planting Site are listed. You will need to provide plant densities for each species listed. Any species that is not listed can be added using the "Add Species" feature.
For every species, either enter a number for the Plant Density or select to use the calculated plant density from withdrawals. The densities in the Calculated Plant Density from Withdrawals reflect the densities of the species as of the latest planting withdrawal to the substratum in which the plot is located. When new planting withdrawals are made to the substratum, the density will be updated, and any new species planted will be newly listed. When new species are listed, the densities to use for t0 data will need to be set in order for Survival Rates to be calculated.
Providing Plant Densities to use for t0 data for permanent plots
If the t0 data selected or entered for a plot is changed, survival rates will be recalculated based on the new selection.
When t0 data is set for all permanent plots, you will see "t0 is set" in the plot and "t0 is set for Permanent Plots" in the Settings page. If a plot does not have t0 data set, you will see "Not set" in the plot.
Setting Plant Densities for Temporary Plots
Temporary plots can be used for Survival Rate calculations. Temporary plot data may be desired to be used, in addition to permanent plot data when the rationale is that including the additional data in calculations may result in Survival Rates that are closer to reality within the Planting Site.
If temporary plots are used for survival rate calculations, t0 data must be set for all Strata.
To use temporary plots in Survival Rate calculations, you will need to select the option in the Temporary Plots tab in the Survival Rate Settings page. Check the box to include temporary plots in Survival Rate calculations. Uncheck the box to exclude temporary plots. Survival Rates will be recalculated any time the setting is changed.
Selecting to use for Temporary Plots for Survival Rate calculations
After you select to use temporary plots, provide plant densities per species within all of the Planting Site Strata.
Providing Plant Densities to use for t0 data for temporary plots
If the t0 data selected for a Stratum is changed, survival rates will be recalculated based on the new selection.
When t0 data is set for all Strata, you will see "t0 is set" in the Strata and "t0 is set for Temporary Plots" in the Settings page. If a Stratum does not have t0 data set, you will see "Not set" in the Stratum.
Survival Rate Formulas
Permanent Plots
When observation data is used to provide the t0 plant density:
Plot survival rate = (Living planted plants from the most recent observation) / (Living and dead planted plants from t0 observation)Species survival rate = (Living plants of species from the most recent observation) / (Living and dead planted plants of species from t0 observation)When manually entered plant density data is used to provide the t0 plant density per plot:
Plot survival rate = (Living planted plants from the most recent observation) / (Sum of(Manually entered plant density by species for the plot in plants/ha) * 0.09ha)Species survival rate = (Living plants of species from the most recent observation) / (Manually entered plant of species density for the plot in plants/ha * 0.09ha)
Temporary Plots
When temporary plot usage is enabled for the site and Stratum-level t0 data has been entered:
Plot survival rate = (Living planted plants from the most recent observation) / (Sum of(Manually entered plant density by species for the plot in plants/ha) * 0.09ha)Species survival rate = (Living plants of species from the most recent observation) / (Manually entered plant of species density for the plot in plants/ha * 0.09ha)Note: Plot ha = 0.09ha
Survival Rate calculations do not include plants recorded within Observations as "Existing" and "Can't Tell" (aka unknown) or recorded by adding a species through the "Other" feature.
Survival Rates will not be able to be calculated if...
- Not all permanent plots have t0 data (and temporary plots are not being used for calculations).
- Temporary plots are being used for calculations, and not all Strata have t0 data.
- Planting Site geometry has changed, and there is not yet a subsequent Observation.
When Survival Rates are not able to be calculated, you will not see the rates in Observations and you will see "Cannot be calculated" messaging in the Survival Rate section of the Plants Dashboard.
Note: Survival Rates are not calculated for Ad Hoc Plant Monitoring Observations.