Abstract: A healthy ecosystem underpins the sustainable development of human. The health condition of an urban ecosystem can be used as an important monitoring index for assessing the sustainable development of a city. In this study, the assessment index system for ecosystem health was established under a framework of vigor, organization, resilience and contribution. The township was used as a spatial unit, and the ecosystem health of Guangzhou City was evaluated based on land use data (level II) in 2000, 2005, 2010, and 2015. The results showed that the overall health condition of the ecosystem was not optimistic in Guangzhou City. Less than 1/5 of the towns were healthy and relatively healthy in 2015. From 2000 to 2015, the healthy levels of 75% towns remained constant (with no improvement). The towns with significant enhancement or significant deterioration each accounted for only 1% of the total. The towns with enhancement and deterioration were 5% and 20%, respectively. During the study period, the numbers of towns dominated by singlefactor and doublefactor increased, while this value for threefactor or fourfactor decreased. Meanwhile, the number of towns dominated by nonfactor remained stable. Generally, the vigor of ecosystem of Guangzhou City had been improved but its resilience had obviously decreased from 2000 to 2015. The health condition of the whole ecosystem showed a downward trend, which was not conducive to the sustainable development of the urban ecosystem.

Key words: crop water requirement, reference evapotranspiration, crop coefficient, air temperature.