Pessimistic plant: Optimal growth schedule in stochastic environments

The optimal growth schedule of a plant is studied when the environmental resource level fluctuates following Markovian processes. The plant must decide whether to invest photosynthate to vegetative growth or to reproductive activity, based on the future resource level etimated using currently available information. The stochastic dynamic programming model is analyzed in two cases: (1)the environmental resource level jumps randomly between two levels, and (2) it fluctuates continuously following diffusion processes. The model predicts that the scheme of stochasticity to which the plant has been adapted greatly affects its growth reaction to a given resource level. If the plant is adapted to a slowly changing environment, it should continue to grow until late in a favorable environment but should start reproduction earlier in an unfavorable one, showing large phenotypic plasticity. In contrast, plants adapted to a quickly changing environment should use an almost fixed growth schedule, irrespective of the current level of the environmental resource supply. Consequently, a plant adapted to the environment with usualy low nutrient level with occasional short flushes of nutrient supply would not produce a large vegetative organ when placed in a nutrient rich environment. This explains the paradox of slow-growing plants.