Establishment behaviors
In this document:
Establishment parameters
Substrate Dependent Seed Survival No Gap Status
Substrate Dependent Seed Survival With Gap Status
Substrate Based Seed Survival With Microtopography
Light Dependent Seed Survival
Storm Light Dependent Seed Survival
Density Dependent Seed Survival
Proportional Seed Survival
Seed Establishment
Establishment with Microtopography
Establishment behaviors assess seed survival and create new seedlings from seeds. Establishment behaviors do not create or distribute the seeds. The Disperse behaviors perform that function.
The seed survival behaviors act to reduce the number of seeds based on various environmental effects. They can be used alone or in combination. Once they have completed their work, the number of surviving seeds can be turned into seedlings by either the Seed Establishment or Establishment with Microtopography behaviors.
- Beam Fraction of Global Radiation The fraction of total solar radiation that is direct beam radiation (as opposed to diffuse). Expressed as a value between 0 and 1. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Clear Sky Transmission Coefficient Used to determine the amount of solar radiation seen at the plot location. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- First Day of Growing Season for GLI Light Calculations The first day of the growing season, as a Julian day (number between 1 and 365). Seeds only get light during the growing season. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Fraction Seeds Germinating on Canopy Decayed Logs The proportion of those seeds that land on decayed logs under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival No Gap Status and Substrate Dependent Seed Survival With Gap Status behaviors.
- Fraction Seeds Germinating on Canopy Fresh Logs The proportion of those seeds that land on fresh logs under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival No Gap Status and Substrate Dependent Seed Survival With Gap Status behaviors.
- Fraction Seeds Germinating on Canopy Forest Floor Litter The proportion of those seeds that land on forest floor litter under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival No Gap Status and Substrate Dependent Seed Survival With Gap Status behaviors.
- Fraction Seeds Germinating on Canopy Forest Floor Moss The proportion of those seeds that land on forest floor moss under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival No Gap Status and Substrate Dependent Seed Survival With Gap Status behaviors.
- Fraction Seeds Germinating on Canopy Scarified Soil The proportion of those seeds that land on scarified soil under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival No Gap Status and Substrate Dependent Seed Survival With Gap Status behaviors.
- Fraction Seeds Germinating on Canopy Tip-Up The proportion of those seeds that land on tip-up mounds substrate under canopy conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival No Gap Status and Substrate Dependent Seed Survival With Gap Status behaviors.
- Fraction Seeds Germinating on Gap Decayed Logs The proportion of those seeds that land on decayed logs under gap conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival With Gap Status behavior.
- Fraction Seeds Germinating on Gap Fresh Logs The proportion of those seeds that land on fresh logs under gap conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival With Gap Status behavior.
- Fraction Seeds Germinating on Gap Forest Floor Litter The proportion of those seeds that land on forest floor litter under gap conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival With Gap Status behavior.
- Fraction Seeds Germinating on Gap Forest Floor Moss The proportion of those seeds that land on forest floor moss under gap conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival With Gap Status behavior.
- Fraction Seeds Germinating on Gap Scarified Soil The proportion of those seeds that land on scarified soil under gap conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival With Gap Status behavior.
- Fraction Seeds Germinating on Gap Tip-Up The proportion of those seeds that land on tip-up mounds substrate under gap conditions that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Dependent Seed Survival With Gap Status behavior.
- Fraction Seeds Germinating on Ground Decayed Logs The proportion of those seeds that land on decayed logs ground substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Ground Forest Floor Litter The proportion of those seeds that land on forest floor litter ground substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Ground Forest Floor Moss The proportion of those seeds that land on forest floor moss ground substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Ground Fresh Logs The proportion of those seeds that land on fresh logs ground substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Ground Scarified Soil The proportion of those seeds that land on scarified soil ground substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Ground Tip-Up The proportion of those seeds that land on tip-up ground substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Mound Decayed Logs The proportion of those seeds that land on decayed logs mound substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Mound Forest Floor Litter The proportion of those seeds that land on forest floor litter mound substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Mound Forest Floor Moss The proportion of those seeds that land on forest floor moss mound substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Mound Fresh Logs The proportion of those seeds that land on fresh logs mound substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Mound Scarified Soil The proportion of those seeds that land on scarified soil mound substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Fraction Seeds Germinating on Mound Tip-Up The proportion of those seeds that land on tip-up mound substrate that survive to become seedlings. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- GLI of Optimum Establishment, 0-100 The GLI value of optimum survival for seeds, as a value between 0 and 100. Used by the Light Dependent Seed Survival behavior.
- Height in m At Which to Calculate GLI The height, in meters, at which to calculate GLI at the center of each grid cell. Used by Light Dependent Seed Survival behavior.
- Last Day of Growing Season for GLI Light Calculations The last day of the growing season, as a Julian day (number between 1 and 365). Seeds only get light during the growing season. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Light Extinction Coeff of Complete Damage Trees (0-1) The fraction of light transmitted by the crowns of trees with complete Storm damage. Not required if storms are not used. Expressed as a value between 0 and 1. If storms are used, a value must be supplied for every species. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Light Extinction Coeff of Medium Damage Trees (0-1) The fraction of light transmitted by the crowns of trees with medium Storm damage. Not required if storms are not used. Expressed as a value between 0 and 1. If storms are used, a value must be supplied for every species. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Light Extinction Coeff of Undamaged Trees (0-1) The fraction of light transmitted by the crowns of regular live trees (and if storms are being used, trees with no Storm damage). Expressed as a value between 0 and 1. A value must be supplied for every species. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Mean Height of Fresh Log Substrate, in m The mean height of fresh log substrate, in meters. Used by the Establishment with Microtopography behavior.
- Mean Height of Mounds, in m The mean height of mounded areas, in meters. Used by the Establishment with Microtopography behavior.
- Minimum Solar Angle for GLI Calculations, in rad This is the minimum angle at which sunlight is seen, in radians. Below this value the sky is assumed to be dark due to shading neighbors. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Number of Altitude Sky Divisions for GLI Light Calculations Number of grid cells into which the sky is divided from horizon to zenith, for the purpose of calculating light direction. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- Number of Azimuth Sky Divisions for GLI Light Calculations Number of grid cells into which the sky is divided around the horizon, for the purpose of calculating light direction. See Light Behaviors for more on GLI calculations. Used by the Light Dependent Seed Survival behavior.
- # Years Respite from Fern Shading for Seeds on Fresh Logs The maximum number of years that seeds can get respite from fern shading, as implemented by the Beer's law light filter behavior. Used by the Establishment with Microtopography behavior.
- Proportion Germinating Between 0 and 1 The proportion of seeds of a species that survive germination, as a value between 0 and 1. Used by the Proportional Seed Survival behavior.
- Proportion of Plot Area that is Mound The proportion of plot area that is mound area, as opposed to ground area. Expressed as a value between 0 and 1. Used by the Substrate Based Seed Survival With Microtopography behavior.
- Slope of Density Dependence The slope of the density dependence function for determining how many seedlings establish per square meter (c in the equations below). Used by the Density Dependent Seed Survival behavior.
- Slope of Dropoff Above the Optimum GLI The slope of the line describing the drop off in seedling survival as a function of GLI above the optimum GLI. Used by the Light Dependent Seed Survival behavior.
- Slope of Dropoff Below Optimum GLI The slope of the line describing the dropoff in seedling survival as a function of GLI below the optimum GLI. Used by the Light Dependent Seed Survival behavior.
- Steepness of Density Dependence The steepness of the density dependence function for determining how many seedlings establish per square meter (δ in the equations below). Used by the Density Dependent Seed Survival behavior.
- Snag Age Class 1 Light Extinction Coefficient (0-1) Fraction of light transmitted through the snag tree crown for each species. Applies to those snags whose age is less than or equal to "Upper age (yrs) of snag light extinction class 1". Expressed as a fraction between 0 and 1. If your run does not work with snags, you can ignore this. Otherwise, a value must be provided for all species. Used by the Light Dependent Seed Survival behavior.
- Snag Age Class 2 Light Extinction Coefficient (0-1) Fraction of light transmitted through the snag tree crown for each species. Applies to those snags whose age is greater than "Upper age (yrs) of snag light extinction class 1", but is less than or equal to "Upper age (yrs) of snag light extinction class 2". Expressed as a fraction between 0 and 1. If your run does not work with snags, you can ignore this. Otherwise, a value must be provided for all species. Used by the Light Dependent Seed Survival behavior.
- Snag Age Class 3 Light Extinction Coefficient (0-1) Fraction of light transmitted through the snag tree crown for each species. Applies to those snags whose age is greater than "Upper age (yrs) of snag light extinction class 2". Expressed as a fraction between 0 and 1. If your run does not work with snags, you can ignore this. Otherwise, a value must be provided for all species. Used by the Light Dependent Seed Survival behavior.
- Standard Deviation of Fresh Log Substrate Height, in m The standard deviation of height of fresh log substrate, in meters. Used by the Establishment with Microtopography behavior.
- Standard Deviation of Mound Height, in m The standard deviation of the height of mounded areas, in meters. Used by the Establishment with Microtopography behavior.
- Upper Age (Yrs) of Snag Light Extinction Class 1 The upper age limit, in years, defining the first age class of snag light extinction. Snags with an age less than or equal to this age have a light extinction coefficient matching "Snag age class 1 light extinction coefficient". If your run does not work with snags, you can ignore this. Used by the Light Dependent Seed Survival behavior.
- Upper Age (Yrs) of Snag Light Extinction Class 2 The upper age limit, in years, defining the second age class of snag light extinction. Snags with an age greater than the upper limit for size class 1, but less than or equal to this age, have a light extinction coefficient matching "Snag age class 2 light extinction coefficient". Snags with an age greater than this value are in age class three. If your run does not work with snags, you can ignore this. Used by the Light Dependent Seed Survival behavior.
Substrate Dependent Seed Survival No Gap Status
This behavior assesses seed survival based on substrate conditions.
How it works
The behavior takes the substrate composition of each grid cell in the Substrate grid and converts it into a single number for each species, called the substrate favorability index. The favorability index is the sum of the proportions of each substrate multiplied by the proportion of seeds that germinate on that substrate. This index represents the proportion of total seeds of that species that are expected to survive in that area of the plot. This index is stored in the grid Substrate Favorability. (In the parameters list, above, the proportions used are the canopy proportions.)
The behavior then goes through each grid cell in the Dispersed Seeds grid and assesses the survival for the seeds of those species to which it applies. This behavior starts by giving each seed a random temporary location within the Dispersed Seeds grid cell. Then, it retrieves the substrate favorability at that point from the Substrate Favorability grid. It then compares a random number to the substrate favorability to determine whether the seed lives. This method ensures that we can assess substrate favorabilities correctly when the Dispersed Seeds and Substrate grids have different grid cell resolutions.
Once this process is complete, the number of surviving seeds for each species is assigned back to the Dispersed Seeds grid.
How to apply it
This behavior may be applied to seeds of any species. A species to which this is applied must also have a Disperse behavior applied. Also, the Substrate behavior must be used in the run.
Behavior reference string: No Gap Substrate Seed Survival
Substrate Dependent Seed Survival With Gap Status
This behavior assesses seed survival as a function of both the substrate composition of the grid cells in which seeds land and the cells' forest cover (gap or canopy). This behavior allows for different germination favorability for substrates under the two forest covers.
How it works
The behavior takes the substrate composition of each grid cell in the Substrate grid and converts it into a single number for each species, called the substrate favorability index. The favorability index is the sum of the proportions of each substrate multiplied by the proportion of seeds that germinate on that substrate under that cell's cover (canopy or gap). This index represents the proportion of total seeds of that species that are expected to survive in that area of the plot. This index is stored in the grid Substrate Favorability.
The behavior then goes through each grid cell in the Dispersed Seeds grid and assesses the survival for the seeds of those species to which it applies. This behavior starts by giving each seed a random temporary location within the Dispersed Seeds grid cell. Then, it retrieves the substrate favorability at that point from the Substrate Favorability grid. It then compares a random number to the substrate favorability to determine whether the seed lives. This method ensures that we can assess substrate favorabilities correctly when the Dispersed Seeds and Substrate grids have different grid cell resolutions.
Once this process is complete, the number of surviving seeds for each species is assigned back to the Dispersed Seeds grid.
How to apply it
This behavior may be applied to seeds of any species. A species to which this is applied must also have the Gap spatial disperse behavior applied. Also, the Substrate behavior must be used in the run.
Behavior reference string: Gap Substrate Seed Survival
Substrate Based Seed Survival With Microtopography
This behavior assesses seed survival based on substrate conditions, allowing for site microtopography to influence seed survival. In this scenario, the plot is divided into small-scale mounds. The portion of the plot that is slightly elevated is "mound". The portion of the plot between the mounds, at lower elevation, is "ground". The size of the mounds and their height is not important.
How it works
The area of the plot that is "mound" and the area that is "ground" are in fixed relative proportion to each other. This fixed proportion is entered in the Proportion of Plot Area that is Mound parameter. Each grid cell in the Substrate grid has been divided by the Substrate behavior into six substrate types; each of those types is further divided into "mound" and "ground" according to the fixed proportion, making twelve total substrate types. For example, if 20% of a grid cell's area is forest floor litter, and 60% of the plot area is mound, then the area of the grid cell that is forest floor litter mound substrate is 12% and the area of grid cell that is forest floor litter ground substrate is 8%.
The behavior takes the substrate composition of each grid cell in the Substrate grid, calculates the amount of the twelve substrate types, and converts it into a single number for each species, called the substrate favorability index. The favorability index is the sum of the proportions of each substrate multiplied by the proportion of seeds that germinate on that substrate. This index represents the proportion of total seeds of that species that are expected to survive in that area of the plot. This index is stored in the grid Substrate Favorability.
The behavior then goes through each grid cell in the Dispersed Seeds grid and assesses the survival for the seeds of those species to which it applies. This behavior starts by giving each seed a random temporary location within the Dispersed Seeds grid cell. Then, it retrieves the substrate favorability at that point from the Substrate Favorability grid. It then compares a random number to the substrate favorability to determine whether the seed lives. This method ensures that we can assess substrate favorabilities correctly when the Dispersed Seeds and Substrate grids have different grid cell resolutions.
Once this process is complete, the number of surviving seeds for each species is assigned back to the Dispersed Seeds grid.
How to apply it
This behavior may be applied to seeds of any species. A species to which this is applied must also have a Disperse behavior applied. Also, the Substrate behavior must be used in the run.
Behavior reference string: Microtopographic Substrate Seed Survival
This behavior assesses seed survival as a function of the Global Light Index (GLI) of the location in which a seed lands. Light level calculations can take into account the change in light blocking by snags and trees with storm damage, if desired.
The effects of light levels on seed survival is graphed as:
How it works
To assess the effects of light level on the number of seeds that survive, this behavior calculates the GLI at the center of each grid cell in the Dispersed Seeds grid at the height specified in the Height in m At Which to Calculate GLI parameter (value is in meters). The calculation proceeds exactly as described in the Light Behaviors. In order to perform these GLI calculations, this behavior requires its own copy of the key GLI setup parameters.
If you wish to use storms in your run, this behavior can take into account the fact that storm-damaged trees may have different light extinction coefficients. These light extinction coefficients are specified in the Light Extinction Coeff of Complete Damage Trees (0-1) and Light Extinction Coeff of Medium Damage Trees (0-1) parameters.
Once GLI has been calculated, the proportion of seeds that survive for a given species is calculated as:
- If GLI < GLIopt, LE = 1 - (Slo(GLIopt - GLI))
- If GLI = GLIopt, LE = 1
- If GLI > GLIopt, LE = 1 - (Shi(GLI - GLIopt))
where
- GLI is the GLI at the center of the Dispersed Seeds grid cell at the height in the Height in m At Which to Calculate GLI parameter
- GLIopt is the GLI of Optimum Establishment, 0-100 parameter
- Slo is the Slope of Dropoff Below Optimum GLI parameter
- Shi is the Slope of Dropoff Above the Optimum GLI parameter
Once the proportion of seeds that survive at the given GLI has been calculated, this value is multiplied by the number of seeds to reduce them by the proper amount. The new reduced number of seeds is put back in the Dispersed Seeds grid.
How to apply it
Apply this behavior to seeds of your desired species. Any species to which it is applied must also have a Disperse behavior applied. Storm damage is optional.
Behavior reference string: Light Dependent Seed Survival
This behavior assesses seed survival as a function of the light level of the location in which a seed lands. Light level calculations are performed by the Storm Light behavior. (This behavior is exactly like Light Dependent Seed Survival except for the method of light level calculation.)
The effects of light levels on seed survival is graphed as:
How it works
To assess the effects of light level on the number of seeds that survive, this behavior retrieves the light level from the Storm Light grid that corresponds to the point in the center of each Dispersed Seeds grid cell.
The proportion of seeds that survive for a given species is calculated as:
- If GLI < GLIopt, LE = 1 - (Slo(GLIopt - GLI))
- If GLI = GLIopt, LE = 1
- If GLI > GLIopt, LE = 1 - (Shi(GLI - GLIopt))
where
- GLI is the light level at the center of the Dispersed Seeds grid cell
- GLIopt is the GLI of Optimum Establishment, 0-100 parameter
- Slo is the Slope of Dropoff Below Optimum GLI parameter
- Shi is the Slope of Dropoff Above the Optimum GLI parameter
Once the proportion of seeds that survive at the given light level has been calculated, this value is multiplied by the number of seeds to reduce them by the proper amount. The new reduced number of seeds is put back in the Dispersed Seeds grid.
How to apply it
Apply this behavior to seeds of your desired species. Any species to which it is applied must also have a Disperse behavior and the Storm Light behavior applied.
Behavior reference string: Storm Light Dependent Seed Survival
This behavior assesses seed survival as a function of the local density of conspecific seeds.
How it works
This behavior takes the seeds that have been dispersed to each grid cell of the Dispersed Seeds grid and calculates how many will become survive. The number of seeds that survives is calculated as
Rsp = Ssp * exp(-c * Denspδ)
where:
- Rsp is the number of surviving seeds of a given species in the seed grid cell
- Ssp is the original number of seeds of that species in that grid cell
- Densp is the density of seeds (number per square meter) of that species in that grid cell
- c is the Slope of Density Dependence parameter
- δ is the Steepness of Density Dependence parameter
Once the number of surviving seeds has been determined, the behavior assigns that number back to the Dispersed Seeds grid cell. If there is only one seed in a grid cell, it always survives.
How to apply it
Apply this behavior to seeds of your desired species. Any species to which it is applied must also have any disperse behavior applied.
Behavior reference string: Density Dependent Seed Survival
Proportional Seed Survival
This behavior reduces the number of seeds by a set amount.
How it works
In each cell of the Dispersed Seeds grid, this multiples the number of seeds present by the Proportion Germinating Between 0 and 1 parameter, reducing the total number available. The new number of seeds is placed back in the Dispersed Seeds grid.
How to apply it
Apply this behavior to seeds of any species. Any species to which this is applied must have a Disperse behavior applied as
well.
Behavior reference string: germination
This behavior converts seeds into seedlings.
How it works
This behavior goes through each grid cell in the Dispersed Seeds grid and, for each species to which this behavior applies, converts each seed into a seedling. The seedlings are randomly placed within the grid cell area and have a slightly randomized value of New seedling diameter at 10 cm.
How to apply it
Apply this behavior to seeds of any species. A species to which this is applied must also have a Disperse behavior applied.
Behavior reference string: Establishment
Establishment with Microtopography
This behavior germinates seeds into seedlings. It simulates microtopography in the plot and assigns new seedlings a rooting height as a function of the type of
substrate on which they land (from the Substrate behavior). This behavior is designed to work with both the Substrate and the Beer's law light filter behaviors to simulate shading by ferns. The rooting height that seedlings get influences the amount of light they receive. Seeds that land on fresh logs, in addition, are eligible for a respite from the Beer's law light filter behavior.
How it works
Each timestep, the behavior starts by getting the substrate proportions for each cell of the Dispersed Seeds grid. The
six substrate types are further divided into mound and non-mound types of each according to the Proportion of Ground Area that is Mound parameter. The relative proportions of the different kinds of substrate are thus the same on mound and non-mound areas.
The seeds in the Dispersed Seeds grid cell are then divided up among the substrate types in that cell according to their proportions relative to each other (so if 60% of the cell area is mound forest floor moss, that's the substrate type that 60% of the seeds land on). A seedling is created from each seed. Seedlings are randomly placed within their seed grid cell area and have a slightly randomized value of New seedling diameter at 10 cm.
Each seedling then gets a rooting height according to the substrate type upon which it has germinated. If it has germinated on fresh logs, its rooting height is a random number drawn from a normal distribution controlled by the Mean Height of Fresh Log Substrate, in m and Standard Deviation of Fresh Log Substrate Height, in m parameters (no distinction is made between mound and non-mound fresh logs). If it's on a mound substrate, its rooting height is a random number drawn from a normal distribution controlled by the Mean Height of Mounds, in m and Standard Deviation of Mound Height, in m parameters. If it's on a non-mound substrate, its rooting height is zero.
If a seedling germinates on fresh log, it has the chance of getting a respite from the effects of the Beer's law light filter behavior, which it expects to simulate fern shading. Fallen logs crash through the fern layer, and it takes a while for the ferns to grow back over the top of the log. This length of time is the maximum possible respite length, and is set in the # Years Respite from Fern Shading for Seeds on Fresh Logs parameter. Substrate keeps track of the age of its fresh log cohorts, so that it is possible to randomly assign the seedling to a fresh log of a specific age, given the relative proportions of various-aged fresh log cohorts. The age of the log is subtracted from the maximum respite length, and this value is assigned to the seedling. Thus a log that fell this timestep would give a seedling the maximum respite, whereas a much older log may not give any respite at all.
How to apply it
Apply this behavior to seeds of your desired species. Any species to which it is applied must also satisfy the following requirements:
Behavior reference string: Micro Establishment
Last updated: 16-Nov-2005 09:40 AM