Impacts of urbanization on net primary productivity in the Pearl River Delta, China

Document Type: Research Paper

Authors

1 Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

2 School of Geographical Sciences, Guangzhou University, Guangzhou 510006, China.

3 Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China.

4 School of Life Sciences, Faculty of Science, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia.

5 Key Laboratory of vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.

Abstract

Great changes in land use/land cover from rapid urbanization have occurred in the Pearl
River Delta, China. As the primary cause of land development in the urbanization process,
urban expansion has mostly occurred on land with higher NPP, significantly impacting the
regional ecosystems. The primary purpose of this study was to reveal the impacts of urban
expansion on the regional NPP. The land cover datasets and three types of urban lands (urban,
peri-urban and non-urban areas) were obtained to quantify the urban expansion of the Pearl
River Delta from 2000 to 2010. The Carnegie-Ames-Stanford-Approach (CASA) model was
driven by the land cover types, NDVI data and climate data to calculate the NPP for the study
area and analyze its spatial-temporal variations, as well as the impacts on NPP from urban
expansion. The results showed: cropland and forest with higher NPP values and wetland were
the major source of urban expansion, which generally reduced the regional NPP values,
primarily by replacing vegetation with urban land. The conversion of land to urban use resulted
in a reduction of 0.103TgC from 2000 to 2005 and 0.034TgC from 2005 to 2010, cropland and
forest accounted for the largest proportion of the total NPP losses. In spatial distribution, the
NPP losses occurring in urban and peri-urban areas accounted for 89.63% and 75.04%,
respectively, which was primarily a result of the massive vegetation with high productivity
being replaced with impervious surfaces during the rapid urbanization process. These results
provided an indicator to understand and evaluate ecosystem changes in urban regions.


Keywords