In 2010 the Amazon Basin experienced unusually dry conditions, a second major drought in 5 years, a pattern which is remarkably similar to some predictions of the future climate of the region. This is because most climate models predict an increase in dry season intensity, and all an increase in temperature in the coming century as a consequence of global climate change. Whether or not long-term climate change is already involved the current event can help us evaluate how humid forest, deciduous forests and savanna ecosystems and species respond to drying, so helping assess the potential scale of impacts as the Amazon climate dries.
Our team has a large network of on-the-ground sample plots in the region, and because these are standardised they represent an excellent opportunity to measure the actual impacts of drought. We already did this with the severe 2005 drought (described then as 'the drought of the century' but surpassed in extent this year). In this proposal we focus on our sites at the southern fringes of Amazonia, an area very strongly affected by the 2010 drought.
This large area is a 'zone of tension' between Amazon moist forest species, deciduous species, and savanna, with the various vegetation types sometimes adjacent in the same sites. Here we have 30 permanent plots available so we are able for the first time to measure the on-the-ground impacts on different species and vegetation formations at this forest/savanna mixing zone. This is important because it is expected that within these zones of ecological tension that long-term vegetation changes will first be observed, and these areas of high diversity and high carbon storage could significantly affect regional carbon emissions.

We plan to do the following:
1) Recensus 30 southern Amazon plots to record tree growth and vegetation productivity.
2) Remeasure nearly 500 trees where we have pre-drought measures of details of their structure, to assess if drought has changed them.
3) Install high-precision measurement tools ("dendrometers") on trees of key species, to enable better monitoring of future droughts
4) Analyse data collected from (1) & (2) to test our hypotheses:

1. The 2010 drought caused biomass carbon loss from forest but not savanna. We expect savanna to prove more resilient than forest, and for forest responses to mirror those of 2005.
2. The 2010 drought accelerated tree death and reduced growth in the forest but not the savanna. We expect forest species to be more sensitive than savanna species when faced with the same degree of drying.
3. Forest & savanna plots that had the greatest biomass loss and/or mortality are those with shallowest soils. We expect soil depth to affect the drought response, with shallower soils having fewer moisture reserves.
4. Within each stand, species which also occur in drier areas were more drought-resistant than those already at the dry end of their range. We expect that the risk a tree faces from drought is related to its geographic distribution, so that species that are typically found in moister climates will be more drought-sensitive than their neighbours.
5. Species differences in drought sensitivity are related to variation in structural traits. We expect the more drought-resistant evergreen trees will have a more conservative hydraulic structure, such as denser wood.
The expected outcomes of this research are:
1) Improved quantification of the sensitivity of transitional Amazon forest to drought.
2) A first assessment of the differential sensitivity of forest and savanna trees to drought conditions.
3) By integrating (1) & (2), understand better the chances of savanna replacing forest in the "zone of tension", and even into core Amazon forests, as the climate dries.
4) Improved understanding of the physiological basis of drought-resistance and the importance of soil conditions.
5) The infrastructure installed to allow local collaborators to evaluate effects during future droughts.

Potential Impact:
The main beneficiaries of this research include:
* The wider scientific community
* The general public, both in the UK and in South America (and worldwide), because climate change, its impacts on nature, and devising effective mitigation and adaptation is at the forefront of public consciousness as one of the defining challenges of the century.
* Policy-makers, for the same reasons, and because there is special concern about the climate change risks to the southern Amazon region. Better understanding of the threats to potentially one of the most important 'hot spots' in the earth system will benefit public and policy-makers alike.
* Research staff and students, especially those in the countries where we work.

How?
* The team has a strong record of impact within the wider scientific community well beyond those in their immediate field. For example, Phillips, Feldpausch, Lloyd, & Malhi have more than 10,000 ISI citations, and their work has been published 10 times in Nature and Science. We anticipate submitting research results to high profile journals and substantial ensuing media coverage if successful. We will further aim to reach the general scientific community via an overview article in Ambio or similar journal.

* To further reach those in our field and the wider scientific community we will use our well-visited websites for disseminating outputs, protocols & metadata (www.rainfor.org) and the data (www.forestplots.net) where visitors also access data management and analysis tools. All new data will be uploaded to this portal following quality control. The global research community will have access to this data, after sufficient time for analysis, under the auspices of RAINFOR. Thus, we are able to assure long-term stewardship of resulting datasets for potential re use.

* The team has a strong record of engagement with public & policy-maker audiences. For example, the November 2009 executive update to the Physical Science basis of the IPCC Fourth Assessment Report (www.copenhagendiagnosis.com) presents the latest policy-relevant climate change science for a target global readership of policy-makers and the wider public, and draws heavily on the RAINFOR result quantifying the measured on-the-ground drought sensitivity of Amazon forests, as the critical complement to modelling scenarios of possible impacts of future drying. We anticipate that this new research based on the second major drought in five years, but now focussed on the forest/savanna interface zone, will draw substantial attention. Key, society-relevant messages on the climate sensitivity of the southern Amazon zone of tension, and the degree to which it may feedback on climate change, will be communicated by press releases, and distributed via existing media contacts of the project team as well as the University of Leeds press office.

* To further translation of key science messages, especially to the decision-makers in the actual zone of tension in Bolivia and Brasil, we will produce illustrated policy briefs. These will be made available as pdfs on our website in English, Spanish, & Portuguese, and printed for distribution among NGOs and government bodies involved in forest and savanna management policy.

* The project will also bring training & career development opportunities to staff and students at the two host institutions of our collaborators in Bolivia and Brazil. Each maintains a group of undergraduate & postgraduate student associates, as well as a number of field workers in their study sites. For these groups, the project is an opportunity to interact with leading scientists from the UK and Australia, in the field and at later analytical and writing phases, and so broaden and deepen these groups' research experiences. Because of the restricted funding associated with NERC Urgency grants we will not conduct formal workshops, but the field campaigns are an opportunity for on-site practical learning for less experienced staff