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A paddy rice ecosystem is a farming system composed of paddy, animals, microbes and other environmental factors in
specific time and space, with particular temporal and spatial dynamics. Since paddy rice is a main grain crop to feed
above half of population in China, the performance of paddy rice ecosystem is highly concerned to yield level of paddy
and food supply safety in China. Therefore, monitoring the performance of paddy rice ecosystem is very important to
obtain the required information for evaluation of ecosystem health. In the study we intend to develop an approach to
monitor the ecosystem performance spatially and dynamically in a regional scale using MODIS remote sensing data and
GIS spatial mapping. On the basis of key factors governing the paddy rice ecosystem, we accordingly develop the
following three indicators for the evaluation: Crop growing index (CGI), environmental Index (EI), and pests-diseases
index (PDI). Then, we integrated the three indicators into a model with different weight coefficients to calculate
Comprehensive ecosystem health index (CEHI) to evaluate the performance and functioning of paddy rice ecosystem in
a regional scale. CGI indicates the health status of paddy rice calculated from the normalizing enhanced vegetation Index
(EVI) retrieved from MODIS data. EI is estimated from temperature Index (TI) and precipitation Index (PI) indicating
heat and water stress on the rice field. PDI reflects the damage brought by pests and diseases, which can be estimated
using the information obtained from governmental websites. Applying the approach to Lower Yangtze River Plain, we
monitor and evaluate the performance of paddy rice ecosystem in various stages of rice growing period in 2006. The
results indicated that the performance of the ecosystem was generally very encouraging. During booting stage and
heading and blooming stage, the health level was the highest in Anhui province, which is the main paddy rice producer
in the region. During stage of yellow ripeness, Jiangsu province had the lowest level of performance. Yield level of
paddy rice in 2006 confirms that the applicability of the proposed approach for a rapid evaluation and monitoring of
agricultural ecosystem performance in Lower Yangtze River Plain. As a result, the new approach could supply scientific
basis for relevant departments taking policies and measures to make sure stable development of paddy yield.
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