• Energy Research

Thermal sensitivity of tropical trees A key uncertainty in climate change models is the thermal sensitivity of tropical forests and how this value might influence carbon fluxes. Sullivan et al. measured carbon stocks and fluxes in permanent forest plots distributed globally. This synthesis of plot networks across climatic and biogeographic gradients shows that forest thermal sensitivity is dominated by high daytime temperatures. This extreme condition depresses growth rates and shortens the time that carbon resides in the ecosystem by killing trees under hot, dry conditions. The effect of temperature is worse above 32°C, and a greater magnitude of climate change thus risks greater loss of tropical forest carbon stocks. Nevertheless, forest carbon stocks are likely to remain higher under moderate climate change if they are protected from direct impacts such as clearance, logging, or fires. Science , this issue p. 869

Building resilient sustainable social-ecological systems (SES) requires communities to enhance their adaptive capacities. Communal participative land-use planning (Zonificación Participativa Comunal—ZPC) is a tool designed for communities to integrating local and scientific knowledge to sustainably organize and manage their SES. Between 2006 and 2011, a ZPC was developed with communities in the buffer zone of Cordillera Azul National Park (Peru), where rapid demographic changes are converting pre-montane seasonally dry forest into agricultural land. Herein, we analyse how the ZPC enhanced adaptive capacity, enabling the SES to cope with environmental, political and economic changes. Based on qualitative, semi-structured interviews, communities are analysed along their capacities in the dimensions social capital, learning, adaptive management and governance. An analysis of yearly high-resolution forest cover data supports our findings. Deforestation activities in biologically sensitive zones decreased rapidly during the time of the ZPC implementation. We find that particularly the long-term presence of the bridging institution and the continuous testing and reflection of the integrated “hybrid knowledge” enabled communities to develop adaptive capacities. The analysis of ZPC our results reveals the enabling conditions for promoting the learning process to develop a sustainable land-use management in the context of migration and rapid changes.

AbstractPeatland pole forest is the most carbon-dense ecosystem in Amazonia, but its spatial distribution and species composition are poorly known. To address this knowledge gap, we quantified variation in the floristic composition, peat thickness, and the amount of carbon stored above and below ground of 102 forest plots and 53 transects in northern Peruvian Amazonia. This large dataset includes 571 ground reference points of peat thickness measurements across six ecosystem types. These field data were also used to generate a new land-cover classification based on multiple satellite products using a random forest classification. Peatland pole forests are floristically distinctive and dominated by thin-stemmed woody species such asPachira nitida(Malvaceae),Platycarpum loretense(Rubiaceae), andHevea guianensis(Euphorbiaceae). In contrast, palm swamps and open peatlands are dominated byMauritia flexuosa(Arecaceae). Peatland pole forests have high peat thickness (274 ± 22 cm, mean ± 95% CI,n= 184) similar to open peatlands (282 ± 46 cm,n= 46), but greater than palm swamps (161 ± 17 cm,n= 220) and seasonally-flooded forest, terra firme, and white-sand forest where peat is rare or absent. As a result, peatland pole forest has exceptional carbon density (1,133 ± 93 Mg C ha−1). The new sites expand the known distribution of peatland pole forest by 61% within the Pastaza-Marañón Foreland basin, mainly alongside the Tigre river, to cover a total of 7540 km2in northern Peruvian Amazonia. However, only 15% of the pole forest area is within a protected area, whilst an additional 26% lies within indigenous territories. The current low levels of protection and forest degradation but high threat from road paving projects makes the Tigre river basin a priority for conservation. The long-term conservation of peatland pole forests has the potential to make a large contribution towards international commitments to mitigate climate change.

Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.