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.

Parameters for this 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:

• A disperse behavior must be applied
• The Substrate behavior must be applied
• The Beer's Law light filter behavior must be applied