期刊名称：Science et changements planétaires / Sécheresse
印刷版ISSN：1147-7806
电子版ISSN：1777-5922
出版年度：2011
卷号：22
期号：3
页码：159-170
DOI：10.1684/sec.2011.0311
出版社：John Libbey Eurotext
摘要：Figures See all figures Authors Viviane Djoufack Manetsa , Télesphore Brou , Bernard Fontaine , Maurice Tsalefac Université de Bourgogne Centre de recherches de climatologie 6, Boulevard Gabriel 21000 Dijon France, Université d’Artois 9, rue du temple BP 665 65030 Arras France, Université de Dschang BP 96 Dschang Cameroun Key words: Cameroon, rainfall, space-time distribution, vegetation DOI : 10.1684/sec.2011.0311 Page(s) : 159-70 Published in: 2011 The intraseasonal variability of rainfall and its relationship with vegetation cover variability is studied in northern Cameroon (6̊N-13̊N and 11̊E 16̊E). Daily data from twenty stations is used through 15-days data of the NDVI (Normalized Difference Vegetation Index) at 8-km spatial resolution over the period 1982-2002. The rainy seasons (monthly amounts > 50mm) extend from April to October in the Sudanese area (south of 9̊N), and from May to September in the Sahelian area (north of 9̊N). Overall, seasonal anomalies are significantly correlated (Monte Carlo test, 95%) with the number of days with low and moderate rainfall (≤40mm) since heavy rainfall (>40mm) represents only 15% of seasonal amounts. Correlations between the annual cycles of precipitation and the corresponding NDVI (average of the closest three pixels) show that both parameters change synchronously in the Sudanese belt, whereas in the Sahelian area the start of vegetation occurs approximately one month after the onset of rainfall. We are particularly interested in dry spells longer than five days and their impact on vegetation during the early growing season, which is a critical period for the dormancy breaking of most species. Correlations (dry spells > 5 days/NDVI) are not significant (Monte Carlo test, 95%) in the Sudanese area, while only a few stations are concerned in the Sahelian area. If the pluviometric impact on vegetation is stronger in the latter region, the evolution of the primary productivity also answers to demographic factors that it would be important to integrate into future studies.
