Chapters authored
Evapotranspiration in Northern Agro-Ecosystems: Numerical Simulation and Experimental Comparison
Evapotranspiration and near-surface soil moisture dynamics are key-entangled variables regulating flux at the surface-atmosphere interface. Both are central in improving mass and energy balances in agro ecosystems. However, under the extreme conditions of high-latitude soils and weather pattern variability, the implementation of such coupled liquid and vapor phase numerical simulation remain to be tested. We consider the nonisothermal solution of the vapor flux equation that accounts for the thermally driven water vapor transport and phase changes. Fully coupled flux model outputs are compared and contrasted against field measurements of soil temperature, heat flux, water content, and evaporation in a subarctic agroecosystem in Alaska. Two well-defined hydro-meteorological situations were selected: dry and wet periods. Numerical simulation was forced by time series of incoming global solar radiation and atmospheric surface layer thermodynamic parameters: surface wind speed, ambient temperature, relative humidity, precipitation, and soil temperature and soil moisture. In this simulation, soil parameters changing in depth and time are considered as dynamically adjusted boundary conditions for solving the set of coupled differential equations. Results from this evaluation give good correlation of modeled and observed data in net radiation (Rnet) (R2 of 0.92, root mean square error (RMSE) of 45 W m−2), latent heat (0.70, RMSE of 53 W m−2), and sensible heat (R2 = 0.63, RMSE = 32 W m−2) during the dry period. On the other hand, a poor agreement was obtained in the radiative fluxes and turbulent fluxes during the wet period due to the lack of representation in the radiation field and differences in soil dynamics across the landscape.
Part of the book: Current Perspective to Predict Actual Evapotranspiration
Protected Area Size Affecting Habitat Fragmentation: A Case Study of Protected Areas in Thailand
Habitat fragmentation is a big threat to biodiversity because habitat fragmentation reduces the total patch area, isolates the patches, and increases the edge of patches. The objectives of this study were to investigate how protected area (PA) size affects habitat fragmentation and what caused habitat fragmentation in the PAs. The study focused on 180 PAs in Thailand, including 58 wildlife sanctuaries and 122 national parks. The land use/land cover data of Thailand were acquired from the Department of Land Development of Thailand and used to quantify forest habitat fragmentation in terms of the number of patches, patch density, proportion of forest, and clumpiness index. There were significant linear relationships between the total area and number of patches and between total area and patch density. Large PAs, with a total area larger than 1, 600 km2, had significantly lower patch density than medium and small PAs. However, 128 of the 180 PAs in Thailand were small-sized with high patch density due to agricultural expansion making up approximately 10% of the protected areas. Large PAs with a size of 1600 km2 or larger are preferable over small PAs in order to reduce habitat fragmentation and contribute to biodiversity conservation.
Part of the book: Sustainable Forest Management