Determining the growing season of land vegetation on the basis of plant phenology and satellite data in Northern China |
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| Authors: | X Chen Zhongjun Tan Mark D Schwartz Chengxin Xu |
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| Institution: | (1) Department of Urban and Environmental Sciences, Peking University, Beijing 100871, China, CN;(2) Institute of Remote Sensing and GIS, Peking University, Beijing 100871, China, CN;(3) Department of Geography, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA, US |
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| Abstract: | The objectives of this study are to explore the relationships between plant phenology and satellite-sensor-derived measures
of greenness, and to advance a new procedure for determining the growing season of land vegetation at the regional scale.
Three phenological stations were selected as sample sites to represent different climatic zones and vegetation types in northern
China. The mixed data set consists of occurrence dates of all observed phenophases for 50–70 kinds of trees and shrubs from
1983 to 1988. Using these data, we calculated the cumulative frequency of phenophases in every 5-day period (pentad) throughout
each year, and also drew the cumulative frequency distribution curve for all station-years, in order to reveal the typical
seasonal characteristics of these plant communities. The growing season was set as the time interval between 5% and 95% of
the phenological cumulative frequency. Average lengths of the growing season varied between 188 days in the northern, to 259
days in the southern part of the research region. The beginning and end dates of the surface growing season were then applied
each year as time thresholds, to determine the corresponding 10-day peak greenness values from normalized difference vegetation
index curves for 8-km2 pixels overlying the phenological stations. Our results show that, at the beginning of the growing season, the largest average
greenness value occurs in the southern part, then in the northern, and finally the middle part of the research region. In
contrast, at the end of the growing season, the largest average greenness value is measured in the northern part, next in
the middle and lastly the southern part of the research region. In future studies, these derived NDVI thresholds can be applied
to determine the growing season of similar plant communities at other sites, which lack surface phenological data.
Received: 29 November 1999 / Revised: 14 March 2000 / Accepted: 15 March 2000 |
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| Keywords: | Growing season Plant phenology NDVI Northern China |
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