Most plants do not produce regular annual seed crops, but switch between years of bumper seed crops (known as "mast years") and years with low seed production. Intriguingly, these bumper crops occur simultaneously in plants living alongside each other, and synchronisation can extend across hundreds of kilometres. For example, we have previously shown that in 1976, 1992, 1995 and most recently in 2011, beech trees across Western Europe (including the UK, Germany, France and Poland) all produced heavy seed crops in the same year. Interestingly, 1992 and 1995 were also bumper years for pine-cone production in spruce forests in the same region. This highly variable production of seeds is an important process in ecosystems. Producing seeds is a key step towards successfully establishing the next generation of plants. Masting is beneficial for plants because in years of bumper seed crops, seed predators cannot consume all the available seeds, which ensures that some survive to germinate the next spring. In ecosystems that are influenced by disturbance such as wildfires, windstorms and logging by humans, the timing of the next bumper seed year is also crucial to the ability of plants to regenerate. However, the importance of masting extends beyond plants. Bumper seed crops in forest trees represent a pulse of food resources, and cause population booms in small mammals (e.g. voles and mice) and seed-eating birds (e.g. woodpeckers and great tits). Low seed crops in sequential following years can eventually result in population crashes. These boom-and-bust cycles of small animals have further impacts on ecosystems. One of the most important for humans is the effect on tick numbers, which fluctuate in response to the number of host animals. Ticks act as a host for the Lyme disease pathogen, and research has shown that Lyme infection rates in humans peak two years after bumper seed crops in forest trees, including beech and oak. Masting is not just important in natural ecosystems, however. Many fruit and nut crops come from "masting" species. In agriculture, this phenomenon is usually known as "alternate cropping". Fruits grown in the UK, including apples and cherries, show this characteristic year-to-year variation in crop size, which causes variation in annual crop yield for farmers. It is also important in many other commercially valuable species, including olives, almonds and pistachios. For these reasons, we need to be able to predict seed crops in "masting" species accurately. This information is necessary for the management of natural ecosystems and agricultural systems that rely on masting species. Furthermore, predicting bumper seed crops will allow us to forecast years of high risk from infectious diseases carried by animal feeding vectors, such as Lyme. An important question is how seed production in masting species will change in the future with changes in climate. This project is designed as the first crucial step to achieving these objectives. It will establish an international network of researchers to build the datasets necessary to understand the causes of bumper seed crops, and to predict seed production in masting species. We will draw together data from the tropics with data from boreal forests to understand how masting varies between species, and will use long-term monitoring conducted by members of the network to understand how seed production varies over time, and what triggers bumper seed years. We will also search archives and scientific literature for useful data: in a previous project we found useful data on seed crops collected by 18th century foresters, demonstrating that in some species, there is potential to develop very long records of seed production. The datasets that we will build in this project will then act as a spring-board for future research, including projects linked to public health, habitat management, and agriculture, taking advantage of the wide range of network expertise.

Tropical forests store more than a half of the world's forest carbon and produce over one third of the productivity of all terrestrial systems. They are also biodiversity hotspots, and host a large proportion of the world's terrestrial flora and fauna. However, growing evidence shows that the ability of tropical forests to perform important ecosystem services (i.e. carbon sequestration and biodiversity conservation) has been dramatically reduced by multiple pressures associated with human-induced forest disturbances (e.g. agriculture, logging, fire and fragmentation) and extreme climate events. Of these disturbances, fire represents of the greatest threats. Rainforests have not co-evolved with fire, and species have not adapted to withstand fire or the changes it imposes on the forests. Yet today, ignition sources are common in most human-modified regions, as many local farmers living within tropical forests traditionally use fire as a management technique to prepare their land for planting. This is compounded by selective logging and fragmentation, which increase the flammability of the remaining forests. Critically, fires are much more likely to escape their target area and enter the surrounding forests during severe drought events. This is exactly what happened during the current 2015-16 El Niño Southern Oscillation (ENSO) - considered one of the three strongest events ever recorded. The prolonged dry season allowed thousands of fires to get out of control in Amazonian and SE Asian tropical rainforests. Specifically in the Brazilian Amazon, the end of 2015 was marked by over 87,000 fire events, a 48% increase in relation to 2014 (a non-ENSO year). As a result, the widespread wildfires affected half of our 20 permanent plots near the Santarém region in the state of Pará, while fortunately preserving the other ten plots unburned. The Sustainable Amazon Network (SAN) has established these plots along a gradient of forest modification in 2010, and since 2014 a joint project between UK and Brazilian scientists (ECOFOR) has been carrying out research in this region. Consequently, the work we are proposing here benefits from unique and detailed pre-fire information on carbon dynamics and plant functional traits (from ECOFOR) as well as the distribution of three distinct taxa (birds, dung beetles and plants) and secondary seed dispersal processes (from SAN). Uniquely our network of permanent plots is established along an existing gradient of forest modification before the 2015 fires, allowing us to undertake the first rigorous evaluation of fire effects across different forest disturbance classes. This ability to examine fire impacts using detailed pre-fire data allows us to develop three major avenues of research across a human-modified gradient of forest disturbances: (1) the impacts of very severe wildfires on plant communities and carbon dynamics, assessing therefore which plant functional traits may predict species mortality, survival and recruitment; (2) an investigation into the fire impacts on forest fauna (i.e. birds and dung beetles) and associated seed dispersal processes; and (3) the development of a detailed understanding of scale and impacts of the current extreme ENSO-event, exploring the relationship between remote sensing information and ground-based measures. The better linkages between remote-sensing products and actual measures of fire severity will allow us to scale up the carbon emission and biodiversity loss estimates across the whole region. The results fo AFIRE are critically important, as tropical forests around the world may be threatened by drier, hotter and longer dry seasons with climate change. Our findings will help inform mitigation strategies to manage the impacts of future ENSO-mediated droughts and severe wildfires on tropical forests. We also expect AFIRE plots to form the basis of much longer-term research on the impacts of tropical wildfire