Phenology of Woody Species Along the Climatic Gradient in West Tropical Africa

Seghieri, Josiane; Chauvaud, Frédéric; Devineau, Jean-Louis; Fournier, Anne

doi:10.5772/33729

Cited by 24 publications

(40 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The difference between the onsets of rainy season and growing season is inversely correlated with tree fraction (Figure d, R 2 = 0.73, p < 0.0001), indicating that ecosystem structure can explain most spatial variance in vegetation phenology. These results confirm numerous other studies that have found many savanna tree species to green‐up before the onset of the rains [ Borchert , ; Fuller and Prince , ; Do et al ., ; Higgins et al ., ; Seghieri et al ., , ].…”

Section: Resultsmentioning

confidence: 99%

“…It turns out that only open savannas southern Africa have high correlations between the onsets of rainy season and growing season (Figures and S6), with a weaker and more dispersed correlation pattern in northern Africa, mostly due to the low interannual variability of rainy season onsets in the northern Africa (Figure b). Since rainy season onset does not cue on the start of the growing season (e.g., leaf flushing) in woodlands, other environmental cues may trigger leaf flushing of woodlands, such as photoperiod, insolation, or vapor pressure deficit [ Do et al ., ; Seghieri et al ., , ].…”

Section: Resultsmentioning

confidence: 99%

“…In addition, this first‐order seasonal correspondence could not explain what specific environmental factors trigger canopy leaf flushing and senescence and what factors control interannual variability in these phenological properties. For example, early leaf flushing in the African Miombo Woodlands has been widely observed before the arrival of seasonal rainfall [ Chidumayo , ; Fuller and Prince , ; Seghieri et al ., , ], with delayed senescence in many woody species after the end of the rainy season [ Bie et al ., ; Seghieri et al ., ]. These unresolved phenological behaviors call for a more detailed study on the relationships between the rainy season and regional land surface phenology, including canopy growth onset and senescence.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Terrestrial hydrological controls on land surface phenology of African savannas and woodlands

Guan

Wood

Medvigy

et al. 2014

J. Geophys. Res. Biogeosci.

136

122

View full text Add to dashboard Cite

This paper presents a continental-scale phenological analysis of African savannas and woodlands.We apply an array of synergistic vegetation and hydrological data records from satellite remote sensing and model simulations to explore the influence of rainy season timing and duration on regional land surface phenology and ecosystem structure. We find that (i) the rainy season onset precedes and is an effective predictor of the growing season onset in African grasslands. (ii) African woodlands generally have early green-up before rainy season onset and have a variable delayed senescence period after the rainy season, with this delay correlated nonlinearly with tree fraction. These woodland responses suggest their complex water use mechanisms (either from potential groundwater use by relatively deep roots or stem-water reserve) to maintain dry season activity. (iii) We empirically find that the rainy season length has strong nonlinear impacts on tree fractional cover in the annual rainfall range from 600 to 1800 mm/yr, which may lend some support to the previous modeling study that given the same amount of total rainfall to the tree fraction may first increase with the lengthening of rainy season until reaching an "optimal rainy season length," after which tree fraction decreases with the further lengthening of rainy season. This nonlinear response is resulted from compound mechanisms of hydrological cycle, fire, and other factors. We conclude that African savannas and deciduous woodlands have distinctive responses in their phenology and ecosystem functioning to rainy season. Further research is needed to address interaction between groundwater and tropical woodland as well as to explicitly consider the ecological significance of rainy season length under climate change.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Terrestrial hydrological controls on land surface phenology of African savannas and woodlands

Guan

Wood

Medvigy

et al. 2014

J. Geophys. Res. Biogeosci.

136

122

View full text Add to dashboard Cite

show abstract

“…The second site is located in a woodland, the most widespread vegetation type in tropical Africa [White, 1983], near Bellefoungou village (latitude 9.791°N, longitude 1.718°E, 445 m asl) (hereafter Bellefoungou (BE)). Vegetation of this woodland consists in an open stand of trees with crown heights of around 15 m (Figure 1b), covering 60%-80% of the total soil area [Ago et al, 2016] [Seghieri et al, 2012]. This species composition is reasonably homogeneous around the BE flux tower and contributes to the observed footprint (about 60,000 m 2 ) whatever the season [Mamadou, 2014].…”

Section: Study Sitesmentioning

confidence: 99%

Dynamics of water vapor and energy exchanges above two contrasting Sudanian climate ecosystems in Northern Benin (West Africa)

et al. 2016

View full text Add to dashboard Cite

Natural ecosystems in sub‐Saharan Africa are experiencing intense changes that will probably modify land surface feedbacks and consequently the regional climate. In this study, we have analyzed water vapor (QLE) and sensible heat (QH) fluxes over a woodland (Bellefoungou, BE) and a cultivated area (Nalohou, NA) in the Sudanian climate of Northern Benin, using 2 years (from July 2008 to June 2010) of eddy covariance measurements. The evaporative fraction (EF) response to environmental and surface variables was investigated at seasonal scale. Soil moisture was found to be the main environmental factor controlling energy partitioning. During the wet seasons, EF was rather stable with an average of 0.75 ± 0.07 over the woodland and 0.70 ± 0.025 over the cultivated area. This means that 70–75% of the available energy was changed into actual evapotranspiration during the investigated wet seasons depending on the vegetation type. The cumulative annual actual evapotranspiration (AET) varied between 730 ± 50 mm yr−1 at the NA site and 1040 ± 70 mm yr−1 at the BE site. With similar weather conditions at the two sites, the BE site showed 30% higher AET values than the NA site. The sensible heat flux QH at the cultivated site was always higher than that of the woodland site, but observed differences were much less than those of QLE. In a land surface conversion context, these differences are expected to impact both atmospheric dynamics and the hydrological cycle.

show abstract

“…For most species, the photosynthetic activity is confined to the rainy season suggesting that it is mainly controlled by the water availability (Borchert, ). However, water availability appears not to be the main environmental trigger of leaf flushing in woody species in the central Sahel as in fact most Sahelian species produce new leaves before the beginning of the first rains (Seghieri, Carreau, et al, ; Seghieri, Do, Devineau, & Fournier, ). In southern Africa, a similar greening before the onset of the rainy season was observed by satellite (Ryan, Williams, Grace, Woollen, & Lehmann, ; Tian et al, ).…”

Section: Introductionmentioning

confidence: 99%

Leaf phenology of thirteen African origins of baobab (Adansonia digitata (L.)) as influenced by daylength and water availability

Lucchio

Fensholt

Markussen

et al. 2018

Ecology and Evolution

View full text Add to dashboard Cite

Water availability is often described as one of the main drivers of phenology of tropical dry forests but experimental studies to identify the cues triggering phenological changes are few. In a greenhouse trial, we exposed seedlings of thirteen origins, seven from West and six from East Africa, respectively, of Adansonia digitata L.(baobab) to a well‐watered control treatment and a water withholding treatment in combination with exposure to three different daylengths (11.5, 12.0, and 12.5 hr). Responses were measured in terms of meristematic activity, number of leaves, and height growth followed over 6.5 months. Multi‐level mixed‐effects statistical models were used to analyze how environmental and inter‐population variables affected phenological behavior. Flushing was influenced by the daylength with the lowest degree of meristematic activity observed in the short daylength treatment. Daylength also influenced the number of leaves through an interaction with the water regime. The water regime influenced all variables through interactions with the origins. Seedlings subjected to water stress had higher meristematic activity, but initially lower numbers of leaves than continuously watered plants. Height growth in continuously watered plants was fastest or at par with water‐stressed plants, depending on the origin. Origins from West Africa tended to have higher meristematic activity and their phenology was found to be less influenced by water withholding than East African origins. There were no signs of significant differences between origins in their response to photoperiod. In conclusion, baobab seedlings show opportunistic behavior, setting leaves when water is available, but larger activity is found when days are long. We discuss the results in terms of triggering factors for baobab phenology and adaptation to specific environmental conditions at the site of origins.

show abstract

Phenology of Woody Species Along the Climatic Gradient in West Tropical Africa

Cited by 24 publications

References 72 publications

Terrestrial hydrological controls on land surface phenology of African savannas and woodlands

Terrestrial hydrological controls on land surface phenology of African savannas and woodlands

Dynamics of water vapor and energy exchanges above two contrasting Sudanian climate ecosystems in Northern Benin (West Africa)

Leaf phenology of thirteen African origins of baobab (Adansonia digitata (L.)) as influenced by daylength and water availability

Contact Info

Product

Resources

About