Feeding nine to ten billion people by 2050 and preventing dangerous climate change are two of the greatest challenges facing humanity. Both challenges must be met whilst reducing the impact of land management on ecosystem services that deliver vital goods and services, and support human health and well-being. Few studies to date have considered the interactions between these challenges. In this study we briefly, outline the challenges, review the supplyand demand-side climate mitigation potential available in the Agriculture, Forestry and Other Land Use (AFLOU) sector, and options for delivering food security. We briefly outline some of the synergies and trade-offs afforded by mitigation practices, before presenting an assessment of the mitigation potential possible in the AFOLU sector under possible future scenarios in which demand-side measures co-delivery to aid food security.We conclude that whilst supply-side mitigation measures, such as changes in land management, might either enhance or negatively impact food security, demand-side mitigation measures, such as reduced waste or demand for livestock products, should benefit both food security and greenhouse gas (GHG) mitigation. Demand-side measures offer a greater potential (1.5-15.6 Gt CO 2 -eq. yr -1 ) in meeting both challenges than do supply-side measures (1.5-4.3 Gt CO 2 -eq. yr -1 at carbon prices between 20 and 100 US$ tCO 2 -eq.given the enormity of challenges, all options need to be considered. Supply-side measures should be implemented immediately, focussing on those that allow the production of more agricultural product per unit of input. For demand-side measures, given the difficulties in their implementation and lag in their effectiveness, policy should be introduced quickly, and should aim to co-deliver to other policy agendas, such as improving environmental quality, or

[1] Using closed chamber techniques, soil fluxes of NO, N 2 O, and CO 2 were measured from September 1999 to November 2000 in savanna areas of central Brazil (cerrado) subjected to prescribed fires. Our studies focused on two vegetation types, cerrado stricto sensu (20-50% canopy cover) and campo sujo (open, grass dominated), which were either burned every 2 years or protected from fire. Soil moisture and vegetation type were more important in controlling NO and CO 2 fluxes than fire regime (early dry season, middle dry season or late dry season burning). N 2 O fluxes, however, were very low and below detection limit in any of the vegetation-fire treatments. NO emissions increased after burning (1.0 ng NO-N cm À2 h À1 ), but flux returned quickly to prefire levels and even lower. In comparison, NO emissions increased 100-fold (to 10.5 ng NO-N cm À2 h À1 ) during a water-addition experiment in unburned campo sujo, and to 1.0 ng NO-N cm À2 h À1 in unburned cerrado and 1.9 ng NO-N cm À2 h À1 in burned cerrado with the first rains. Low NO and N 2 O emissions, low nitrification rates, and the majority of inorganic N in the form of NH 4 + all indicate a conservative N cycle in the cerrado. CO 2 fluxes increased with the onset of the rainy season and after artificial water addition. The highest CO 2 measured in the wet season was 6.3 mmol CO 2 m À2 s À1 in burned campo sujo. During the dry season, soil respiration in burned and unburned treatments were similar (average flux = 1.6-2.3 mmol CO 2 m À2 s À1 ). Differences between fire treatments of cerrado and campo sujo CO 2 fluxes are attributed to differences in relative litter production and root activity.

Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/gcb.12591 This article is protected by copyright. All rights reserved. Accepted ArticleThis article is protected by copyright. All rights reserved. Running head: AFOLU GHG mitigation barriers and policiesKeywords: agriculture, forestry, AFOLU, GHG, mitigation, climate, food security, ecosystem service Accepted ArticleThis article is protected by copyright. All rights reserved.forestry toward global sharing of innovative technologies for the efficient use of land resources. Different policy instruments, especially economic incentives and regulatory approaches, are currently being applied however for its successful implementation it is critical to understand how land use decisions are made and how new social, political and economic forces in the future will influence this process.

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Nutrient resorption efficiency of woody plants, litterfall and nutrient fluxes were investigated in a burned and an unburned cerrado plot between October 1997 and September 1999. A large experiment (Fire Project, Brasília, Brazil) on the effects of prescribed burnings was initiated in 1992. Cerrado plots were delimited and subjected to different fire regimes. Seasonal trend of litterfall was similar in both plots but the production in the burned plot was 42.2 g m−2 y−1 before the fourth prescribed fire (September 1998) and decreased by 22% 1 y after burning while in the unburned plot it was around 230 gm−2 y−1. Although nutrient concentrations in leaf litter were higher in the burned plot, the nutrient fluxes were 60–80% lower than in the unburned plot. Nutrient use efficiency (ecosystem level) was 4373 for P and 137 for N. Measured resorption efficiency for 10 cerrado species ranged from 14.5 to 37.2% for N and from 40 to 70.4% for P and in general, there were no differences between plots. N is in short supply, partly because of fire history, but the results, both at ecosystem and species levels (mean N/P in fresh leaves was 18), indicated a stronger limitation by P than by N.

-(Floristic composition and structure of woody vegetation in a cerrado rupestre, Cocalzinho de Goiás, Goiás State, Brazil). A vegetation survey of the woody species (at least 5 cm of trunk diameter at 30 cm above the ground) was conducted in a savanna on rocky soil (cerrado rupestre) in Cocalzinho de Goiás municipality, Goiás State, Brazil (15°48' S and 48°45' W). The objective was to compare the structure characteristics and the floristics of cerrado rupestre with those features found in cerrado stricto sensu areas occuring on deep soils in Central Brazil. The sample consisted in 1.0 hectare (ten plots, 20 × 50 m) in cerrado rupestre. The cerrado rupestre studied showed structural similarities with the physiognomy of open cerrado (cerrado ralo). The richness and the species diversity are similar with other Brazilian savanna (cerrado stricto sensu areas of Brazil Central). The floristic composition revealed species predominantly from other physiognomies from the cerrado stricto sensu and to a lesser extent, species from forest formations from the bioma and endemics from this rocky environment. The floristic richness and diversity is similar to other savanna areas of Central Brazil. In structural terms, the density and basal area are similar to values found in open cerrado vegetation. The limiting environmental conditions, mainly edaphics, do not result in expressive changes in floristic composition, richness, and species diversity, but promoted reduction in density and basal area of the wood species in the cerrado rupestre studied.Key words -Central Brazil, Cerrado, phytosociology, rocky soil environment RESUMO -(Composição florística e estrutura da vegetação arbustivo-arbórea em um cerrado rupestre, Cocalzinho de Goiás, Goiás). Foi realizado um levantamento da vegetação arbutivo-arbórea (indivíduos com diâmetro a 30 cm do solo ≥ 5 cm), em 1,0 hectare de cerrado rupestre (dez parcelas de 20 × 50 m), localizado em Cocalzinho de Goiás, Goiás, Brasil (15°48' S e 48°45' W). O objetivo foi avaliar e comparar as relações florísticas e as características estruturais deste cerrado sobre afloramentos rochosos com aquelas encontradas nos estudos já realizados em áreas de cerrado sentido restrito sobre solos profundos, localizados no Brasil Central. A composição florística do cerrado rupestre estudado é formada predominantemente por espécies das fitofisionomias do cerrado sentido restrito e em menor contribuição por espécies das formações florestais do bioma e espécies endêmicas de ambientes rupestres. A riqueza e a diversidade de espécies estão dentro dos limites normalmente encontrados para as áreas de cerrado sentido restrito do Brasil Central. Em termos estruturais, a densidade e área basal se assemelham aos valores registrados na subdivisão fitofisionômica de cerrado ralo. As condições ambientais limitantes, principalmente edáficas, não resultaram em mudanças expressivas na composição florística, riqueza e diversidade de espécies, mas refletiram em redução da densidade e área basal da vegetação arbustivo-arbó...

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The Cerrado Domain comprises one of the most diverse savannas in the world and is undergoing a rapid loss of habitats due to changes in fire regimes and intense conversion of native areas to agriculture. We reviewed data on the biogeochemical functioning of Cerrado ecosystems and evaluated the potential impacts of regional climate changes. Variation in temperature extremes and in total amount of rainfall and altitude throughout the Cerrado determines marked differences in the composition of species. Cerrado ecosystems are controlled by interactions between water and nutrient availability. In general, nutrient cycles (N, P and base cations) are very conservative, while litter, microbial and plant biomass are important stocks. In terms of C cycling, root systems and especially the soil organic matter are the most important stocks. Typical cerrado ecosystems function as C sinks on an annual basis, although they work as source of C to the atmosphere close to the end of the dry season. Fire is an important factor altering stocks and fluxes of C and nutrients. Predicted changes in temperature, amount and distribution of precipitation vary according to Cerrado sub-regions with more marked changes in the northeastern part of the domain. Higher temperatures, decreases in rainfall with increase in length of the dry season could shift net ecosystem exchanges from C sink to source of C and might intensify burning, reducing nutrient stocks. Interactions between the heterogeneity in the composition and abundance of biological communities throughout the Cerrado Domain and current and future changes in land use make it difficult to project the impacts of future climate scenarios at different temporal and spatial scales and new modeling approaches are needed.Keywords: Savanna, nutrient cycling, fire, land use, climate change, carbon. Os impactos potenciais das mudanças climáticas no funcionamento biogeoquímico dos ecossistemas de cerradoResumo O Domínio Cerrado é composto por uma das savanas mais diversas do mundo e está passando por uma rápida perda de habitats devido às mudanças nos regimes de fogo e intensa conversão de áreas nativas para a agricultura. Os dados sobre o funcionamento biogeoquímico do Cerrado foram revisados, avaliando-se os potenciais impactos das mudanças climáticas regionais. As variações na temperatura, na precipitação e altitude ao longo do Cerrado determinam diferenças marcantes na composição das espécies. Os ecossistemas de Cerrado são controlados por interações entre a água e a disponibilidade de nutrientes. Em geral, a ciclagem de nutrientes (N, P e cátions) são muito conservadores, enquanto a serapilheira, a biomassa microbiana e vegetal são importantes compartimentos de estoque. Em termos de ciclagem de C, o sistema radicular e, especialmente, a matéria orgânica do solo são os estoques mais importantes. Em bases anuais, o ecossistema de cerrado típico funciona como sumidouros de C embora o opere como fonte de C para a atmosfera ao final da estação seca. O fogo é um fator importante alterando...