Dynamics Of Aboveground And Belowground Biomass For Herbaceous Plant Based On Stoichiometry

Grassland ecosystem is the world's most widely distributed terrestrial ecosystem, and its carbon reserve estimation is of great significance to the carbon cycle of terrestrial ecosystem. The research on grassland aboveground biomass tends to reach perfection, but grassland belowground biomass lacks research data and accuracy because of the dif-ficulty of collecting and other reasons. The above-and-below-ground biomass allocation mechanism of grassland vegetation has dispute mainly on the isometric growth hypothesis and the optimal partitioning hypothesis. Turchin once built regrowth dynamics model of herbaceous plant, which analyzed the alternating process of the plant's above and below ground biomass.In addition to Turchin's model, this thesis is based on nutrient dynamics and sto-ichiometry. It improves regrowth dynamics model of herbaceous plant on the strength of energy and the consideration of element cycling, analyzes the dynamics of model, and gives sufficient condition on the density of the above and below ground biomass which is close to zero. Using numerical simulation discusses the effects of nutrition and light intensity on the dynamic behavior of the system. The study finds that plants grow faster and the aboveground nitrogen concentration increases with an increase in nutrition. This thesis also makes conclusions that the herbaceous plant's biomass allocation mechanism of aboveground and belowground at the beginning of growth is in conformity of opti-mal partitioning, and the allocation mechanism obeys the conclusion of isometric growth after some time. The thesis makes a comparison between the experimental data and the theoretical data of the model which gives the conclusion that the improved plant's regrowth dynamics model can well express the quantitative change of aboveground and belowground and also the relationship between aboveground biomass and belowground biomass. At last, this thesis applies the improved plant's regrowth dynamics model to the producer-grazer to establish regrowth-herbivore model and analyze the effects of nu-trition and light intensity on the dynamic behavior of the system, and also discuss the differences between the dynamic behaviors of this model and LKE Model and the causes of the differences.