Development and Validation of Ecological Site Quality Model: An Example of Chamaecyparis formosensis in Taiwan

An ecological site quality model was developed to aid in predicting the suitability of new locations for growing tree species. This model uses environmental variables to evaluate potential productivity. Data was input into a geographic information system, including 3rd Forest Resources and Land Use Inventory of Taiwan by integrated data from the climate data of the Central Weather Bureau of Taiwan, the Taiwan Forest Bureau, the Council of Agriculture in Taiwan, and the United States Naval Observatory to model the distributions of elevation, slope, aspect, solar radiation, rainfall, evapotranspiration, temperature, and soil nitrogen within Taiwan. Ecological requirements of Chamaecyparis formosensis were derived from the literature and from 211 ground survey plots. Using 22,501,993 40 m × 40 m grids within Taiwan, we modeled the requirements of C. formosensis for solar radiation, temperature, evapotranspiration, soil moisture, and soil nitrogen. We tested the model by comparing predicted sites to its known distribution of C. formosensis in Taiwan. All of the known locations of C. formosensis fell within the area predicted by the model and about 63.91% of the ecological site quality (ESQ) values were above 0.6. It showed that the model is good for evaluating the site quality for the tree species.