El Niño events, precipitation patterns, and rodent outbreaks are statistically associated in semiarid Chile

In the last two decades, several researchers have noted rodent population outbreaks in semiarid South America, in association with unusually high precipitation that seemingly concurs with El Niño events. To date, no studies have been conducted to determine the statistical relationships between ENSO (El Niño Southern Oscillation) events, increased precipitation, and rodent irruptions. Here we show that: 1) there is a statistical association between ENSO events and inereased precipitation in the semiarid region of northern Chile: 2) the occurrence of rodent outbreaks in that region is statistically related with the precipitation levels of the same year: 3) the multi-annual patterns of the total annual precipitation levels and population abundance of those rodents during the summer are positively associated. The putative chain of effects seems to start with unusually high rainfall brought by ENSO to semiarid environments, which thus respond with inereased primary productivity (herbage and seeds), which then fuels the rodent outbreaks.     

Remotely sensed vegetation phenology for describing and predicting the biomes of South Africa

Questions: What are the patterns of remotely sensed vegetation phenology, including their inter‐annual variability, across South Africa? What are the phenological attributes that contribute most to distinguishing the different biomes? How well can the distribution of the recently redefined biomes be predicted based on remotely sensed, phenology and productivity metrics? Location: South Africa. Method: Ten‐day, 1 km, NDVI AVHRR were analysed for the period 1985 to 2000. Phenological metrics such as start, end and length of the growing season and estimates of productivity, based on small and large integral (SI, LI) of NDVI curve, were extracted and long‐term means calculated. A random forest regression tree was run using the metrics as the input variables and the biomes as the dependent variable. A map of the predicted biomes was reproduced and the differentiating importance of each metric assessed. Results: The phenology metrics (e.g. start of growing season) showed a clear relationship with the seasonality of rainfall, i.e. winter and summer growing seasons. The distribution of the productivity metrics, LI and SI were significantly correlated with mean annual precipitation. The regression tree initially split the biomes based on vegetation production and then by the seasonality of growth. A regression tree was used to produce a predicted biome map with a high level of accuracy (73%). Main conclusion: Regression tree analysis based on remotely sensed metrics performed as good as, or better than, previous climate‐based predictors of biome distribution. The results confirm that the remotely sensed metrics capture sufficient functional diversity to classify and map biome level vegetation patterns and function.     

Variation in a sparrow's reproductive success with rainfall: food and predator-mediated processes

From 1997 to 1999, we monitored the reproductive success of individual rufous-crowned sparrows (Aimophila ruficeps) in coastal sage scrub habitat of southern California, USA. Annual reproductive output of this ground-nesting species varied strongly with annual variation in rainfall, attributed to the El Niño-Southern Oscillation. Birds fledged 3.0 young per breeding pair in 1997, when rainfall was near the long-term mean, 5.1 offspring per pair in 1998, a wet El Niño year, and 0.8 fledglings per pair in 1999, a dry La Niña year. Variation in many components of reproductive output was consistent with the hypothesis that food availability was positively correlated with rainfall. However, the factor most responsible for the high reproductive output in 1998 was low early season nest predation which, combined with favorable nesting conditions, enabled more pairs to multiple-brood. Cool, rainy El Niño conditions may have altered the activity of snakes, the main predator of these nests, in the early season of 1998. Overall, more of the annual variation in fecundity was attributable to variation in within-season components of reproductive output (mean number of nests fledged per pair) than to within-nest components (mean brood size). Annual variation in rufous-crowned sparrow fecundity appears to be driven primarily by food resource-mediated processes in La Niña years and by predator-mediated processes in El Niño years.     

Moisture‐induced greening of the South Asia over the past three decades

South Asia experienced a weakening of summer monsoon circulation in the past several decades, resulting in rainfall decline in wet regions. In comparison with other tropical ecosystems, quantitative assessments of the extent and triggers of vegetation change are lacking in assessing climate‐change impacts over South Asia dominated by crops. Here, we use satellite‐based Normalized Difference Vegetation Index (NDVI) to quantify spatial–temporal changes in vegetation greenness, and find a widespread annual greening trend that stands in contrast to the weakening of summer monsoon circulation particularly over the last decade. We further show that moisture supply is the primary factor limiting vegetation activity during dry season or in dry region, and cloud cover or temperature would become increasingly important in wet region. Enhanced moisture conditions over dry region, coinciding with the decline in monsoon, are mainly responsible for the widespread greening trend. This result thereby cautions the use of a unified monsoon index to predict South Asia's vegetation dynamics. Current climate–carbon models in general correctly reproduce the dominant control of moisture in the temporal characteristics of vegetation productivity. But the model ensemble cannot exactly reproduce the spatial pattern of satellite‐based vegetation change mainly because of biases in climate simulations. The moisture‐induced greening over South Asia, which is likely to persist into the wetter future, has significant implications for regional carbon cycling and maintaining food security.     

Effects of large-scale climatic fluctuations on survival and production of young in a Neotropical migrant songbird, the yellow warbler Dendroica petechia

Migrant songbirds are vulnerable to changes in climatic conditions on both the breeding and wintering grounds. For North American Neotropical migrants, the El Niño/Southern Oscillation (ENSO), via its effects on global precipitation and temperature, modulates the productivity of their temperate and tropical terrestrial ecosystems used during the course of their annual cycle. We evaluated how a densely nesting population of yellow warblers Dendroica petechia in a riparian forest in southern Manitoba, Canada, responded to the El Niño/Southern Oscillation (ENSO) between 1992 and 2001. Standardized mist netting was used to estimate apparent annual survival of adults and production of young. Both adult survival and the production of young were positively correlated with the Southern Oscillation Index (SOI). More specifically, values of both these demographic parameters were lowest during El Niño years and highest during La Niña years. These findings demonstrate the influence of climate on populations of Neotropical migrants in North America. The more frequent El Niños predicted to result from future global climate change could negatively affect populations of yellow warblers and other Neotropical migrants breeding in this region.     

Ecological effects of El Niño in terrestrial ecosystems of western South America

I make a summary review of how El Niño/Southern Oscillation (ENSO) determines peculiar atmospheric and oceanographic conditions in western South America, thus affecting precipitation patterns in adjacent land masses, with cascading effects on marine and terrestrial plants, on sea and land birds, and on marine and terrestrial mammals. With regard to terrestrial ecosystems, I discuss the following biotic responses to El Niño-driven precipitation: 1) aboveground vegetation flushes immediately among herbs but not among shrubs. 2) The seed bank is quickly replenished of ephemeral seeds, but perennial seeds recover one year later. 3) Small rodents Irrupt within months of El Niño arrival, but larger ones take a full year to increase. 4) Predator numbers lag one year behind their mammal prey, with smaller predators responding more quickly. Considering these responses, I offer a simplified model of El Niño-driven bottom-up control in terrestrial ecosystems of western South America. Apart from the direct links already described, there is a weak feedback loop between the plant compartments (vegetation and seeds) and their herbivores: primary productivy is the driving force, and is little affected by herbivory. Another weak feedbaek loop links herbivores and their predators: the latter seem to just "surf" over prey levels, skimming excess prey.     

Inter-hemispheric synchrony of forest fires and the El Niño-Southern Oscillation

Fire histories were compared between the south-western United States and northern Patagonia, Argentina using both documentary records (1914–87 and 1938–96, respectively) and tree-ring reconstructions over the past several centuries. The two regions share similar fire–climate relationships and similar relationships of climatic anomalies to the El Niño–Southern Oscillation (ENSO). In both regions, El Niño events coincide with above-average cool season precipitation and increased moisture availability to plants during the growing season. Conversely, La Niña events correspond with drought conditions. Monthly patterns of ENSO indicators (southern oscillation indices and tropical Pacific sea surface temperatures) preceding years of exceptionally widespread fires are highly similar in both regions during the 20th century. Major fire years tend to follow the switching from El Niño to La Niña conditions. El Niño conditions enhance the production of fine fuels, which when desiccated by La Niña conditions create conditions for widespread wildfires. Decadal-scale patterns of fire occurrence since the mid-17th century are highly similar in both regions. A period of decreased fire occurrence in both regions from c. 1780–1830 coincides with decreased amplitude and/or frequency of ENSO events. The interhemispheric synchrony of fire regimes in these two distant regions is tentatively interpreted to be a response to decadal-scale changes in ENSO activity. The ENSO–fire relationships of the south-western USA and northern Patagonia document the importance of high-frequency climatic variation to fire hazard. Thus, in addition to long-term trends in mean climatic conditions, multi-decadal scale changes in year-to-year variability need to be considered in assessments of the potential influence of climatic change on fire regimes.     

VARIATION IN TOXIN PRODUCTION OF SYNCHRONIZED CULTURES OF CHRYSOCHROMULINA POLYLEPIS (PRYMNESIOPHYTA)

We studied spatial variability in giant kelp ( Macrocystis pyrifera ) forests at 84 sites along the west coast of North America in order to assess the impacts of the 1997–98 El Niño. Our sites spanned the geographic range of giant kelp in the Northern Hemisphere and were surveyed just before, immediately following, several months after, more than one year after, and nearly two years after the El Niño. Interspersion of sample units allowed us to compare the effects of this disturbance among spatial scales ranging from a few meters to more than a thousand kilometers. Variance components analyses revealed that El Niño shifted the relative importance of factors that regulate giant kelp communities from factors acting at the scale of a few meters (local control) to factors operating at hundreds of kilometers (regional control). Moreover, El Niño resulted in a near-to-complete loss of giant kelp populations throughout nearly two-thirds of the species' range. Evaluation of these effects along with oceanographic data (at the "appropriate" spatial scales), along with closer examination of giant kelp populations in the most severely impacted region (Baja) suggested that the among-region differences in giant kelp survival was due, at least in part, to El Niño-induced differences in ocean climate. Giant kelp recovery following El Niño was also scale-dependent, but driven by factors different from those of the disturbance. Here, we present results for several species of macroalgae in an attempt to relate the importance of El Niño to that of other processes in creating scale-dependent patterns of variability.     

Dynamics of the shallow-water fish assemblage of the Patos Lagoon estuary (Brazil) during cold and warm ENSO episodes

In southern Brazil, cold ( La Niña ) and warm ( El Niño ) episodes of the El Niño Southern Oscillation (ENSO) phenomenon cause drought and high rainfall, respectively. The low precipitation and freshwater outflow associated with La Niña during 1995–1996 were associated with an increase in the abundance of marine species in the Patos Lagoon estuary. During the 1997–1998 El Niño , high precipitation and river discharge were associated with low abundance of marine species in the estuary. ANOVA results showed a higher abundance during La Niña than El Niño for estuarine resident (RES) and estuarine dependent (DEP) fishes. During La Niña catch per unit of effort (CPUE) of RES increased from the marine to estuarine area, but during El Niño CPUE increased at the marine area and diminished during summer and autumn in some estuarine sites. DEP fishes had an opposite abundance pattern. During La Niña , these fishes were abundant at the coastal marine area and along some estuarine sites, but during El Niño , CPUE remained almost the same at the marine area but dropped along some estuarine sites. These different abundance patterns for dominant fish groups yielded a positive interaction between stations and climatic events. With higher river discharge and the consequent decline of dominant euryhaline fishes, such as Mugil platanus and Atherinella brasiliensis , freshwater species increased in abundance and richness in the shallow waters of the stuary. The ENSO phenomenon influences precipitation and estuarine salinity in southern Brazil and thereby seems to have a strong influence on recruitment, immigration, and emigration dynamics of fish species living within and adjacent to estuarine habitats.     

Landscape patterns and environmental controls of deciduousness in forests of central Panama

Aim Dry season deciduousness affects intra‐ and inter‐annual patterns of carbon, water and energy balance in seasonal tropical forests. Because it is affected by rainfall, temperature and solar radiation, deciduousness may be an indicator of the response of vegetation to climate change. Better understanding of how spatial patterns of deciduousness are affected by climate and other environmental gradients will improve the ability to predict responses to climate change. This study develops remote sensing methods for quantifying tropical forest deciduousness and examines the relationship between deciduousness and environmental factors in semi‐deciduous tropical forest. Location Central Panama. Methods I applied spectral mixture analysis (SMA) and the normalized difference vegetation index (NDVI) to Landsat images to predict deciduousness which was ground‐truthed with field observations of the percentage of overstorey deciduous trees. Using predicted deciduousness from SMA, patterns of deciduousness at three spatial scales were analysed. I determined how deciduousness varied spatially with rainfall and geological substrate. Results Both SMA and NDVI had strong correlations (r > 0.9) with field observations of deciduousness. On a landscape scale, deciduousness increased as rainfall decreased, but geological substrate altered this relationship. On some geological substrates, deciduousness was much greater than expected for a given rainfall total or showed a slight but significant increase with rainfall. At an intermediate spatial scale, there were highly deciduous patches from 3 to 250 ha in size embedded in non‐deciduous forest, which may have resulted from topography, soil variation or past land use. Main conclusions Dry season deciduousness can be accurately quantified using satellite images indicating that remote sensing can be a valuable tool for detecting change and understanding ecosystem processes in tropical forests from landscape to regional scales.     

Short‐term propagation of rainfall perturbations on terrestrial ecosystems in central California

Question: Does vegetation buffer or amplify rainfall perturbations, and is it possible to forecast rainfall using mesoscale climatic signals? Location: Central California (USA). Methods: The risk of dry or wet rainfall events was evaluated using conditional probabilities of rainfall depending on El Niño Southern Oscillation (ENSO) events. The propagation of rainfall perturbations on vegetation was calculated using cross‐correlations between monthly seasonally adjusted (SA) normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR), and SA antecedent rainfall at different time‐scales. Results: In this region, El Niño events are associated with higher than normal winter precipitation (probability of 73%). Opposite but more predictable effects are found for La Niña events (89% probability of dry events). Chaparral and evergreen forests showed the longest persistence of rainfall effects (0‐8 months). Grasslands and wetlands showed low persistence (0‐2 months), with wetlands dominated by non‐stationary patterns. Within the region, the NDVI spatial patterns associated with higher (lower) rainfall are homogeneous (heterogeneous), with the exception of evergreen forests. Conclusions: Knowledge of the time‐scale of lagged effects of the non‐seasonal component of rainfall on vegetation greenness, and the risk of winter rainfall anomalies lays the foundation for developing a forecasting model for vegetation greenness. Our results also suggest greater competitive advantage for perennial vegetation in response to potential rainfall increases in the region associated with climate change predictions, provided that the soil allows storing extra rainfall.     

Climate variability and change over southern Africa: impacts and challenges

In this paper, the influence of climate variability and change on the environment was studied over southern Africa using ground-based and remotely sensed data. A time series analysis of rainfall and temperature anomalies indicated that there was a high rainfall and temperature variability in the region. The influence of global teleconnections on rainfall patterns over southern Africa showed that in some areas there was a spatial variation in their strength, increasing from west to east. Maps of NDVI, from 1982 to 2004, showed that changes in vegetation cover were more apparent during the dry season than during the wet season. The study also revealed that climate variability and change are linked to decreasing rainfall and hence, decreasing regional water resources and biodiversity and increasing environmental degradation. With the regional population expected increase, this depletion of resources poses the greatest regional environmental challenge to humankind.     

Impacts of changes in climate variability on regional vegetation in China: NDVI-based analysis from 1982 to 2000

Three methods were used to distinguish the characteristics of changes in climate variability and normalized difference vegetation index (NDVI) during the period from 1982 to 2000 in China. Great changes in climate variability and an increased trend in NDVI were observed. The changes in precipitation variability were greater than the changes in temperature variability in each month, which is attributed to changes in the monsoon system in East Asia. The abrupt changes in climate and NDVI were more significant in 1983 than in the other years due to the impacts of El Niño/Southern Oscillation (ENSO). Using these results, the influences of changes in climate variability on vegetation were studied in the whole nation, and eight regions were defined according to the vegetation division map of China. The results show that abrupt climate changes at a small scale cannot cause abrupt NDVI changes directly. At a nationwide level, over a longer time scale the persistence of above/below average temperature determines the changes in NDVI; at a shorter time scale, changes in the magnitude of precipitation influence NDVI significantly. Such regional climate variability affects vegetation in different ways owing to the diversity of vegetation types, climatic conditions and topography of the land.     

Rainfall‐Tuned Management Facilitates Dry Forest Recovery

Regeneration of original dry forests and shrublands in degraded arid and semiarid ecosystems can be a slow and difficult process. It has been hypothesized that restoration efforts during periods of increased water availability may potentially trigger shifts back to a high vegetation cover depending on several environmental factors that govern the response of vegetation to rainfall. Tuning restoration efforts to climate variability will likely become increasingly important under climate change conditions. The experiences evaluated here are a pioneering effort to reforest arid South American forests. We used a combination of field monitoring and remote sensing images to evaluate the long‐term effects of seeding and herbivore control in local reforestation projects tuned to the forecasted rainy El Niño Southern Oscillation (ENSO) events of 1991/1992 and 1997/1998 in North Peru and to assess the regional response of vegetation to these rainy events at a regional scale. We found that managing seed availability in combination with seedling protection from herbivores only yielded persistent higher vegetation cover when implemented on sites without calcareous layers and relatively high water availability determined by the surrounding topography. Our study shows that management tuned to forecasted rainfall events is able to trigger a long‐lasting shift toward higher vegetation cover. We provide a better insight in how environmental factors shape vegetation response to increased rainfall and discuss the implications for ecosystem resilience and restoration.     

Effect of climate on tree growth in the Pampa biome of Southeastern South America: First tree-ring chronologies from Uruguay

Tree-ring research in the highland tropics and subtropics represents a major frontier for understanding climate-growth relationships. Nonetheless, there are many lowland regions – including the South American Pampa biome – with scarce tree ring data. We present the first two tree-ring chronologies for Scutia buxifolia in subtropical Southeastern South America (SESA), using 54 series from 29 trees in two sites in northern and southern Uruguay. We cross-dated annual rings and compared tree growth from 1950 to 2012 with regional climate variability, including rainfall, temperature and the Palmer Drought Severity Index – PDSI, the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Overall, ring width variability was highly responsive to climate signals linked to water availability. For example, tree growth was positively correlated with accumulated rainfall in the summer-fall prior to ring formation for both chronologies. Summer climate conditions were key for tree growth, as shown by a negative effect of hot summer temperatures and a positive correlation with PDSI in late austral summer. The El Niño phase in late spring/early summer favored an increase in rainfall and annual tree growth, while the La Niña phase was associated with less rainfall and reduced tree growth. Extratropical climate factors such as SAM had an equally relevant effect on tree growth, whereby the positive phase of SAM had a negative effect over radial growth. These findings demonstrate the potential for dendroclimatic research and climate reconstruction in a region with scarce tree-ring data. They also improve the understanding of how climate variability may affect woody growth in native forests – an extremely limited ecosystem in the Pampa biome.     

Modelling surface fine fuel dynamics across climate gradients in eucalypt forests of south‐eastern Australia

An understanding of the effects of climate on fuel is required to predict future changes to fire. We explored the climatic determinants of variations in surface fine fuel parameters across forests (dry and wet sclerophyll plus rainforest) and grassy woodlands of south‐eastern Australia. Influences of vegetation type and climate on fuel were examined through statistical modelling for estimates of litterfall, decomposition and steady state fine litter fuel load obtained from published studies. Strong relationships were found between climate, vegetation type and all three litter parameters. Litterfall was positively related to mean annual rainfall and mean annual temperature across all vegetation types. Decomposition was both negatively and positively related to mean annual temperature at low and high levels of warm‐season rainfall respectively. Steady state surface fine fuel load was generally, negatively related to mean annual temperature but mean annual rainfall had divergent effects dependent on vegetation type: i.e. positive effect in low productivity dry sclerophyll forests and grassy woodlands versus negative effect in high productivity wet sclerophyll forests and rainforests. The species composition of the vegetation types may have influenced decomposition and steady state fuel load responses in interaction with climate: e.g. lower decomposition rates in the low productivity vegetation types that occupied drier environments may be partially due to the predominance of species with sclerophyllous leaves. The results indicate that uncertain and highly variable future trends in precipitation may have a crucial role in determining the magnitude and direction of change in surface fine fuel load across south‐eastern Australia.     

Environmental controls of NDVI dynamics in Patagonia based on NOAA-AVHRR satellite data

Abstract. Variation in vegetation in extra-Andean Patagonia (Argentina) was analyzed using spectral data derived from AVHRR/NOAA satellite. The study of seasonal dynamics of the Normalized Difference Vegetation Index (NDVI, i.e. a combined index of the reflection in the red and infrared bands) highlighted similarities in functional aspects between regional vegetation units which are dissimilar in a geographical, physiognomical and/or floristical way, and also suggested that gross primary production is correlated with mean annual rainfall. The first axis in a Principal Component Analysis of NDVI data was correlated (r² = 0.90) with NDVI as integrated for the study period. The second axis was correlated (r² = 0.50) with the differences in NDVI during the growing season, reflecting seasonality. Mean annual rainfall accounted for 60% of integrated NDVI variability among vegetation units. Much of the residual variance (62%) was accounted for by the inverse of the distance to the Atlantic Ocean, which is interpreted as an ocean effect on vegetation functioning in the extra-Andean Patagonia.     

The sensitivity of annual grassland carbon cycling to the quantity and timing of rainfall

Global climate models predict significant changes to the rainfall regimes of the grassland biome, where C cycling is particularly sensitive to the amount and timing of precipitation. We explored the effects of both natural interannual rainfall variability and experimental rainfall additions on net C storage and loss in annual grasslands. Soil respiration and net primary productivity (NPP) were measured in treatment and control plots over four growing seasons (water years, or WYs) that varied in wet‐season length and the quantity of rainfall. In treatment plots, we increased total rainfall by 50% above ambient levels and simulated one early‐ and one late‐season storm. The early‐ and late‐season rain events significantly increased soil respiration for 2–4 weeks after wetting, while augmentation of wet‐season rainfall had no significant effect. Interannual variability in precipitation had large and significant effects on C cycling. We observed a significant positive relationship between annual rainfall and aboveground NPP across the study (P=0.01, r²=0.69). Changes in the seasonal timing of rainfall significantly affected soil respiration. Abundant rainfall late in the wet season in WY 2004, a year with average total rainfall, led to greater net ecosystem C losses due to a ～50% increase in soil respiration relative to other years. Our results suggest that C cycling in annual grasslands will be less sensitive to changes in rainfall quantity and more affected by altered seasonal timing of rainfall, with a longer or later wet season resulting in significant C losses from annual grasslands.     

Rainfall manipulation experiments as simulated by terrestrial biosphere models: Where do we stand?

Changes in rainfall amounts and patterns have been observed and are expected to continue in the near future with potentially significant ecological and societal consequences. Modelling vegetation responses to changes in rainfall is thus crucial to project water and carbon cycles in the future. In this study, we present the results of a new model‐data intercomparison project, where we tested the ability of 10 terrestrial biosphere models to reproduce the observed sensitivity of ecosystem productivity to rainfall changes at 10 sites across the globe, in nine of which, rainfall exclusion and/or irrigation experiments had been performed. The key results are as follows: (a) Inter‐model variation is generally large and model agreement varies with timescales. In severely water‐limited sites, models only agree on the interannual variability of evapotranspiration and to a smaller extent on gross primary productivity. In more mesic sites, model agreement for both water and carbon fluxes is typically higher on fine (daily–monthly) timescales and reduces on longer (seasonal–annual) scales. (b) Models on average overestimate the relationship between ecosystem productivity and mean rainfall amounts across sites (in space) and have a low capacity in reproducing the temporal (interannual) sensitivity of vegetation productivity to annual rainfall at a given site, even though observation uncertainty is comparable to inter‐model variability. (c) Most models reproduced the sign of the observed patterns in productivity changes in rainfall manipulation experiments but had a low capacity in reproducing the observed magnitude of productivity changes. Models better reproduced the observed productivity responses due to rainfall exclusion than addition. (d) All models attribute ecosystem productivity changes to the intensity of vegetation stress and peak leaf area, whereas the impact of the change in growing season length is negligible. The relative contribution of the peak leaf area and vegetation stress intensity was highly variable among models.     

Ecosystem properties of semiarid savanna grassland in West Africa and its relationship with environmental variability

The Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ data. The studied variables include hydroclimatic variables, species composition, albedo, normalized difference vegetation index (NDVI), hyperspectral characteristics (350–1800 nm), surface reflectance anisotropy, brightness temperature, fraction of absorbed photosynthetic active radiation (FAPAR), biomass, vegetation water content, and land‐atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable for investigating relationships between ecosystem properties and hydroclimatic variables for semiarid savanna ecosystems of the region. There were strong interannual, seasonal and diurnal dynamics in NEE, with high values of ~?7.5 g C m^?2 day^?1 during the peak of the growing season. We found neither browning nor greening NDVI trends from 2002 to 2012. Interannual variation in species composition was strongly related to rainfall distribution. NDVI and FAPAR were strongly related to species composition, especially for years dominated by the species Zornia glochidiata. This influence was not observed in interannual variation in biomass and vegetation productivity, thus challenging dryland productivity models based on remote sensing. Surface reflectance anisotropy (350–1800 nm) at the peak of the growing season varied strongly depending on wavelength and viewing angle thereby having implications for the design of remotely sensed spectral vegetation indices covering different wavelength regions. The presented time series of in situ data have great potential for dryland dynamics studies, global climate change related research and evaluation and parameterization of remote sensing products and dynamic vegetation models.