Contrasting carbon cycle along tropical forest aridity gradients in West Africa and Amazonia.

Tropical forests cover large areas of equatorial Africa and play a substantial role in the global carbon cycle. However, there has been a lack of biometric measurements to understand the forests' gross and net primary productivity (GPP, NPP) and their allocation. Here we present a detailed field assessment of the carbon budget of multiple forest sites in Africa, by monitoring 14 one-hectare plots along an aridity gradient in Ghana, West Africa. When compared with an equivalent aridity gradient in Amazonia, the studied West African forests generally had higher productivity and lower carbon use efficiency (CUE). The West African aridity gradient consistently shows the highest NPP, CUE, GPP, and autotrophic respiration at a medium-aridity site, Bobiri. Notably, NPP and GPP of the site are the highest yet reported anywhere for intact forests. Widely used data products substantially underestimate productivity when compared to biometric measurements in Amazonia and Africa. Our analysis suggests that the high productivity of the African forests is linked to their large GPP allocation to canopy and semi-deciduous characteristics.

Large invertebrate decomposers contribute to faster leaf litter decomposition in Fraxinus excelsior-dominated habitats: Implications of ash dieback.

Leaf litter decomposition is a major component of nutrient cycling which depends on the quality and quantity of the leaf material. Ash trees (Fraxinus excelsior, decay time âˆ¼ 0.4 years) are declining throughout Europe due to a fungal pathogen (Hymenoscyphus fraxineus), which is likely to alter biochemical cycling across the continent. The ecological impact of losing species with fast decomposing leaves is not well quantified. In this study we examine how decomposition of three leaf species with varying decomposition rates including ash, sycamore (Acer pseudoplatanus, decay time âˆ¼ 1.4 years), and beech (Fagus sylvatica, decay time âˆ¼ 6.8 years) differ in habitats with and without ash as the dominant overstorey species. Ten plots (40 m × 40 m) were set up in five locations representing ash dominated and non-ash dominated habitats. In each plot mesh bags (30 cm × 30 cm, 0.5 mm aperture) with a single leaf species (5 g) were used to include (large holes added) and exclude macrofauna invertebrates (with a focus on decomposer organisms such as earthworms, millipedes, and woodlice). The mesh bags were installed in October 2020 and retrieved without replacement at exponential intervals after 6, 12, 24 and 48 weeks. Total leaf mass loss was highest in the ash dominated habitat (ash dominated: 88.5%, non-ash dominated: 66.5%) where macrofauna were the main contributor (macrofauna: 96%, microorganisms/mesofauna: 4%). The difference between macrofauna vs microorganisms and mesofauna was less pronounced in the non-ash dominated habitat (macrofauna: 68%, microorganisms/mesofauna: 31%). Our results suggest that if ash dominated habitats are replaced by species such as sycamore, beech, and oak, the role of macrofauna decomposers will be reduced and leaf litter decomposition rates will decrease by 25%. These results provide important insights for future ash dieback management decisions.

Strategies to manage tree pest and disease outbreaks: a balancing act.

Tree diseases are one of the major threats to forests worldwide. As the frequency and severity of disease outbreaks increase, effective prevention and mitigation strategies are urgently needed. Emerging methods are available to tackle this issue, however, trade-offs and potential ecological consequences should be considered for successful forest preservation.

Termite Diversity in Ecuador: A Comparison of Two Primary Forest National Parks.

Termites are one of the key ecosystem engineers in tropical forests where they play a major role in decomposition rates, both above and belowground. The interest in termite ecology and biogeography has increased in the last few decades; however, the lack of comparable data has limited the wider impact of termite research. For Ecuador, termite studies are relatively rare and comparable data that are collected using standardized sampling methods are missing. In this study, we aim to 1) provide comparable data of termite species and feeding-group diversity from two primary forests in Ecuador and 2) explore the differences in termite species and feeding-group diversity between the two forest sites. Sampling took place in the national parks of Yasuní and Podocarpus where three belt transects (100 × 2 m) following Jones and Eggleton (2000) were conducted in each forest. We found that termite species richness was higher in Yasuní (56 species) than in Podocarpus (24 species) and that 57% of the sampled termite genera had never previously been recorded in Ecuador. The inter-site species dissimilarity was almost complete (Bray Curtis (±SD), 0.91 ±â€…0.01), which may have been linked to the difference in tree density and species richness in the two forests. Termite feeding-groups diversity was significantly higher in Yasuní than in Podocarpus with the exception of soil-feeding termites which may have been due to competition between humus- and soil-feeding species.

ENSO Drives interannual variation of forest woody growth across the tropics.

Meteorological extreme events such as El Niño events are expected to affect tropical forest net primary production (NPP) and woody growth, but there has been no large-scale empirical validation of this expectation. We collected a large high-temporal resolution dataset (for 1-13 years depending upon location) of more than 172 000 stem growth measurements using dendrometer bands from across 14 regions spanning Amazonia, Africa and Borneo in order to test how much month-to-month variation in stand-level woody growth of adult tree stems (NPPstem) can be explained by seasonal variation and interannual meteorological anomalies. A key finding is that woody growth responds differently to meteorological variation between tropical forests with a dry season (where monthly rainfall is less than 100 mm), and aseasonal wet forests lacking a consistent dry season. In seasonal tropical forests, a high degree of variation in woody growth can be predicted from seasonal variation in temperature, vapour pressure deficit, in addition to anomalies of soil water deficit and shortwave radiation. The variation of aseasonal wet forest woody growth is best predicted by the anomalies of vapour pressure deficit, water deficit and shortwave radiation. In total, we predict the total live woody production of the global tropical forest biome to be 2.16 Pg C yr-1, with an interannual range 1.96-2.26 Pg C yr-1 between 1996-2016, and with the sharpest declines during the strong El Niño events of 1997/8 and 2015/6. There is high geographical variation in hotspots of El Niño-associated impacts, with weak impacts in Africa, and strongly negative impacts in parts of Southeast Asia and extensive regions across central and eastern Amazonia. Overall, there is high correlation (r = -0.75) between the annual anomaly of tropical forest woody growth and the annual mean of the El Niño 3.4 index, driven mainly by strong correlations with anomalies of soil water deficit, vapour pressure deficit and shortwave radiation.This article is part of the discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Breaking the cipher: ant eavesdropping on the variational trail pheromone of its termite prey.

Predators may eavesdrop on their prey using innate signals of varying nature. In regards to social prey, most of the prey signals are derived from social communication and may therefore be highly complex. The most efficient predators select signals that provide the highest benefits. Here, we showed the use of eusocial prey signals by the termite-raiding ant Odontoponera transversaO. transversa selected the trail pheromone of termites as kairomone in several species of fungus-growing termites (Termitidae: Macrotermitinae: Odontotermes yunnanensis, Macrotermes yunnanensis, Ancistrotermes dimorphus). The most commonly predated termite, O. yunnanensis, was able to regulate the trail pheromone component ratios during its foraging activity. The ratio of the two trail pheromone compounds was correlated with the number of termites in the foraging party. (3Z)-Dodec-3-en-1-ol (DOE) was the dominant trail pheromone component in the initial foraging stages when fewer termites were present. Once a trail was established, (3Z,6Z)-dodeca-3,6-dien-1-ol (DDE) became the major recruitment component in the trail pheromone and enabled mass recruitment of nest-mates to the food source. Although the ants could perceive both components, they revealed stronger behavioural responses to the recruitment component, DDE, than to the common major component, DOE. In other words, the ants use the trail pheromone information as an indication of suitable prey abundance, and regulate their behavioural responses based on the changing trail pheromone component. The eavesdropping behaviour in ants therefore leads to an arms race between predator and prey where the species specific production of trail pheromones in termites is targeted by predatory ant species.

The Customer Isn't Always Right-Conservation and Animal Welfare Implications of the Increasing Demand for Wildlife Tourism.

Tourism accounts for 9% of global GDP and comprises 1.1 billion tourist arrivals per annum. Visits to wildlife tourist attractions (WTAs) may account for 20-40% of global tourism, but no studies have audited the diversity of WTAs and their impacts on the conservation status and welfare of subject animals. We scored these impacts for 24 types of WTA, visited by 3.6-6 million tourists per year, and compared our scores to tourists' feedback on TripAdvisor. Six WTA types (impacting 1,500-13,000 individual animals) had net positive conservation/welfare impacts, but 14 (120,000-340,000 individuals) had negative conservation impacts and 18 (230,000-550,000 individuals) had negative welfare impacts. Despite these figures only 7.8% of all tourist feedback on these WTAs was negative due to conservation/welfare concerns. We demonstrate that WTAs have substantial negative effects that are unrecognised by the majority of tourists, suggesting an urgent need for tourist education and regulation of WTAs worldwide.