Multi-phase Dynamic Modeling of Forest-to-Farm Transition and Sustainable Organic Agriculture

Abstract

We construct a dynamic model to explore the evolution of agroecosystems converted from forested areas, focusing on the key role of natural processes and human decisions. The process is divided into five stages: deforestation, initial agriculture, maturation of marginal habitats, ecosystem maturation, and organic agriculture transformation. In the deforestation stage, we calculated initial key data for the model such as soil nutrient content and weed biomass after deforestation.In the early stages of agriculture, we developed the Lotka-Volterra model and the Holling Type II model, which integrate crop, weed, insect, bird, and soil nutrient dynamics. By extending the traditional ecological models, we developed a coupled system of dynamic differential equations with multiple components incorporating events such as competition, predation, migration, seasonal sowing and harvesting, which were solved using a fourth-order Longe-Kuta method. Ablation experiments showed that cessation of herbicide use led to a 400% surge in weed biomass, which indirectly increased insect and bird populations by about 5% each, and led to a 100% surge in insect populations and a 200% increase in bird populations, which reduced the Ecosystem Stability Index (ESI). An earthworm-mediated soil-plant continuum model and a snake-mediated nutrient cascade dynamics model were introduced and constructed for the mature stage of marginal habitats. Simulation results showed that earthworms significantly increased soil nutrient content and crop growth by accelerating organic matter decomposition, while snakes negatively affected crop yield by influencing insect populations through bird predation. At the ecosystem maturity stage, herbicide deactivation resulted in a 66% decrease in yield and a significant reduction in ESI. To restore homeostasis, we introduced bats and nitrogen-fixing bacteria and compared them. Simulations showed that bats improved ecosystem stability and restored crop yields to 95% of their original levels. Nitrogen-fixing bacteria, although weaker overall, outperformed bats in localized soil restoration. Finally, the dual strategy of ecological prioritization and economic balance demonstrated complementary advantages in exploring paths of transformation in organic agriculture. The ecological priority model is suitable for ecologically fragile areas as it reduces soil erosion by 50 per cent and achieves a steady increase in yields through the implementation of crop rotation and cover crop cultivation. The Economic Balance model increases annual net income by about 12% through intercropping and precision agriculture and reduces fertilizer and pesticide use by 40-55%, despite a higher initial capital investment. Both models maintained ESI values above 0.9, indicating strong long-term sustainability. Based on these findings, we recommend the establishment of an Eco-Agriculture Transformation Fund to promote chemical-free agricultural practices.