AICME II abstracts Matrix models of population dynamics: straightforward ...
Combination of generative and vegetative phases of reproduction in an age-stage structured population Nicolai N. Zavalishin1 . A population of raspberry Rubus idaeus often occupying felled forest areas is described by generative and vegetative reproduction types which follow one by one during some first years after felling. The population structure can be described by a set of age-stage groups of individu-als differing both in the ontogenetic stage and chronological age for each type of reproduction separately. During first two or three years the population dynamics is fully determined by shrubs of a generative reproduction type and demonstrates an exponential growth but then such external factors as interspecific competition with trees, lack of light for young individuals start to play an essential role and further succession is connected in general with only vegetative reproduction mechanism. It can provide a competitive coexistence with tree species or, if competition is strong, the population degrades. This biological description gives the sufficiently complex rasp-berry life-cycle graph making one to notice a nonlinear character of growth process and inducing a corresponding nonlinear model. Nevertheless, a linear matrix approach appears to be applica-ble for modelling an age-stage structured population without taking into account another com-peting species. Data aggregated in the Central Forest Reserve (Tverskoi Region, Russia) separately for generative and vegetative cohorts give the opportunity to simulate the population dy-namics at two periods with specific potential-growth indicator for each other as a function of the demographic parameters. During the first three-four years generative shrubs dominate and model parameters are calibrated allowing for two different
Matrix models of population dynamics: straightforward ... AICME II abstracts
time scales one year and a half of a year due to intensive extinction processes for young generative individuals within a vegetation time interval. Vegetative type of succession has a simpler life-cycle graph and one-year time scale. Calibration process for both models faces with two types of problems: underdetermined and overdetermined linear systems for parameters which can be solved using additional hypothesis. Thus combining two phases of reproduction within a class of linear matrix models can partially predict dynamics of an age-stage structured population and makes possible to estimate reproduc-tive properties of its age-stage groups.
1
Institute of atmosheric physics RAS, 3, Pyzhevsky Lane, 119017, Moscow, Russia (e-mail:
[email protected];
[email protected]).
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