[Ipmpack-users] Projecting population growth using the IPM kernel

[Vieira Neto, Ernane Henrique Monteiro]

Dear fellow IPMers!

I kindly ask for your help in an apparent silly question. I am trying to use my initial population vector to project the pop. growth of my focal species over time. I constructed a discrete density-independent kernel using IPMpack (and also manually in R) without problems so far, which means that I can run the eigen analyses with no issues. However, I am having problems projecting the population using the basic equation nt1 = A*nt. This is very straightforward for matrix population models, where the initial population nt is a column matrix with the number of individuals in each stage class, but not so much (at least for me) for IPMs where A would be the Kernel (calculated using the midpoint rule).

The difficulty for me has been to implement this equation for the IPM because I don't know how to prepare this initial vector. In my understanding the length of the initial pop. vector should be equal to the size of the Kernel (let's say 100), but I have populations smaller or larger than this and don't know how to structure these vectors correctly to implement the equation above. I have searched in many available IPM sources and could not find a direct answer to this (or maybe the answer was there and I simply did not understand). Does IPMpack have a function to output initial and final population vectors, or to extract the initial vector from the kernel?

In addition, I need to add some individuals to the new population vector nt1. These added individuals are not used for the calculation of the kernel in year t but will nonetheless be part of the kernel in year t+1. However, I cannot add anything without knowing how to structure the initial population vector.

I am still learning the IPM and IPMpack various facets and am truly stuck in this analysis, so any help (or correction, if I said something wrong) is very much appreciated!

Thanks in advance for your attention!

Best regards,

Ernane Vieira-Neto
University of Florida
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