A study of farmer’s decision and incentive scheme to reduce highland maize farming in Thailand

During the past 15 years, there has been a considerable increase in highland maize farming in Nan, a province in northern Thailand. The increase in farming area causes an excessive forest encroachment and environmental problems, e.g. soil degradation, landslide, and pesticide contamination. This research explores the mechanism and factors which drive a sustainable transformation from highland maize farming to reforestation. We survey 107 farmers in Nammeed and Sopsai watersheds in where the reverses of growing trend of deforestation in Thailand have been observed. Comparative statistical analysis and regression are used to analyse factors affecting farmer’s decisions and compare differences between the two sites. We find that the fundamental mechanism driving a sustainable transformation from highland maize farming to reforestation comprises 3 pillars. These are 1) realization of adequate economic, health or environmental benefits derived from the alternatives; 2) a sense of belonging and attachment towards the forest and 3) effective enforcements of communal rules and regulations. While natural transformation in Nammeed area highlights the roles of flatland as key driver of the change, subsidy schemes can supplement the transformation during transitional period as seen in Sopsai area.     

Species Invasion as Catastrophe: The Case of the Brown Tree Snake

This paper develops a two-stage model for the optimal management of a potential invasive species. The arrival of an invasive species is modeled as an irreversible event with an uncertain arrival time. The model is solved in two stages, beginning with the post-invasion stage. Once the arrival occurs, the optimal path of species removal is that which minimizes the present value of damage and removal costs plus the expected present value of prevention costs. An expenditure-dependent, conditional hazard rate describing species arrival is developed based on discussions with natural resource managers. We solve for the optimal sequence of prevention expenditures, given the minimum invasion penalty as just described. For the case of the Brown Tree Snake potentially invading Hawaii, we find that pre-invasion expenditures on prevention are inverse U-shaped in the hazard rate. Efficient prevention should be approximately $2.9?million today and held constant until invasion. Once invasion occurs, optimal prevention requires $3.1?million annually and $1.6?million per year on species removal to keep the population at its steady state level, due to high search costs at very small population levels.     

Renewable resource management with stock externalities: Coastal aquifers and submarine groundwater discharge

We model coastal groundwater management and its effects on submarine groundwater discharge, nearshore marine water quality, and marine biota. Incorporating the stock externality effects on nearshore resources increases the optimal sustainable steady-state levels of both the aquifer head and the stock of a keystone native algae species. Numerical simulations are illustrated using data from the Kuki’o region on the Island of Hawaii. Two different approaches for incorporating the nearshore resource are examined. Including algae's market value in the objective function results in only slightly lower rates of groundwater extraction. When a minimum constraint is placed on the stock of the keystone species, however, greater conservation may be indicated. The constraint also results in non-monotonic paths of water extraction, head level, and marginal opportunity cost of water in the optimal solution.