The hydrological ecosystem services of Amazonian forests must be valued, says conservation biologist Carlos Peres.

The hardy jatropha tree as a biofuel source may not be the panacea for smallholders that some have claimed, say Miyuki Iiyama and James Onchieku.

Soil science and agroforestry can help tackle climate change and boost crop yields, say M. S. Swaminathan and Dennis Garrity.

Practicalities of trading carbon and protecting forests make meeting high expectations for REDD hard, say Esteve Corbera and Manuel Estrada.

To get the best for and from Africa, REDD negotiators must hear African viewpoints, says head of the African Forest Forum, Godwin Kowero.

Without knowing REDD's true costs we can't analyse the benefits, says the ASB Partnership for the Tropical Forest Margins' Peter A. Minang.

Growing trees among crops could sustain both environments and livelihoods in Africa, say F.K. Akinnifesi, B. Muys and O.C. Ajayi.

South Asian countries must be rewarded for afforestation, reforestation and carbon stock growth, say N. H. Ravindranath and Shamama Afreen.

Essential field trials of GM trees are being hindered by anti-GM activists working through the Convention on Biological Diversity, say Steven H. Strauss and colleagues.

Safeguarding and replanting forests are key to reducing flooding and protecting wood supplies, says Lester R. Brown.

Forests are valuable assets, and reduced emissions from deforestation and degradation (REDD) should be prioritised, says Virgilio M. Viana.

Training tree fellers in forest management can cut tree damage and carbon emissions from degradation, argue Francis E. Putz and colleagues.

The time is right for Europe to change its carbon trading rules, giving Africa access to the market, writes Louis V. Verchot.

Strong international policies are needed to stop the biofuel revolution threatening food security for the poor, says Siwa Msangi.

Biofuels offer huge potential, but pose challenges best countered with strong and coherent development policies, says S. Arungu-Olende.

Environmental groups should buy palm oil plantations to fund biodiversity-saving nature reserves, say Lian Pin Koh and David S. Wilcove.

Collecting comprehensive national and regional data could thwart the spread of malaria in Africa as conditions warm, argues Suad Sulaiman.

Research sites on fragments of the Amazon rainforest are in danger of being fragmented themselves, say William Laurance and Regina Luizão.

Biodiversity is a complex issue, says Camilla Toulmin, and the G8 report on its economic value faces many challenges.

Brazilian president Luiz Inácio Lula da Silva, stands up for biofuels' role in sustainable development.