资源环境科技发展态势分析平台

Fine-scale satellite data are used to quantify forest harvest rates in 26 European countries, finding an increase in harvested forest area of 49% and an increase in biomass loss of 69% between 2011-2015 and 2016-2018.

The cryo-electron microscopy structure of the ER membrane complex provides insight into its overall architecture, evolution and function in co-translational protein insertion.

The endoplasmic reticulum (ER) membrane complex (EMC) cooperates with the Sec61 translocon to co-translationally insert a transmembrane helix (TMH) of many multi-pass integral membrane proteins into the ER membrane, and it is also responsible for inserting the TMH of some tail-anchored proteins(1-3). How EMC accomplishes this feat has been unclear. Here we report the first, to our knowledge, cryo-electron microscopy structure of the eukaryotic EMC. We found that the Saccharomyces cerevisiae EMC contains eight subunits (Emc1-6, Emc7 and Emc10), has a large lumenal region and a smaller cytosolic region, and has a transmembrane region formed by Emc4, Emc5 and Emc6 plus the transmembrane domains of Emc1 and Emc3. We identified a five-TMH fold centred around Emc3 that resembles the prokaryotic YidC insertase and that delineates a largely hydrophilic client protein pocket. The transmembrane domain of Emc4 tilts away from the main transmembrane region of EMC and is partially mobile. Mutational studies demonstrated that the flexibility of Emc4 and the hydrophilicity of the client pocket are required for EMC function. The EMC structure reveals notable evolutionary conservation with the prokaryotic insertases(4,5), suggests that eukaryotic TMH insertion involves a similar mechanism, and provides a framework for detailed understanding of membrane insertion for numerous eukaryotic integral membrane proteins and tail-anchored proteins.

Variation in vegetation and climate affects the long-term changes in bird communities in intensive-agriculture habitats, but not in diversified-agriculture or natural-forest habitats, by changing the local colonization and extinction rates.

Agricultural practices constitute both the greatest cause of biodiversity loss and the greatest opportunity for conservation(1,2), given the shrinking scope of protected areas in many regions. Recent studies have documented the high levels of biodiversity-across many taxa and biomes-that agricultural landscapes can support over the short term(1,3,4). However, little is known about the long-term effects of alternative agricultural practices on ecological communities(4,5) Here we document changes in bird communities in intensive-agriculture, diversified-agriculture and natural-forest habitats in 4 regions of Costa Rica over a period of 18 years. Long-term directional shifts in bird communities were evident in intensive- and diversified-agricultural habitats, but were strongest in intensive-agricultural habitats, where the number of endemic and International Union for Conservation of Nature (IUCN) Red List species fell over time. All major guilds, including those involved in pest control, pollination and seed dispersal, were affected. Bird communities in intensive-agricultural habitats proved more susceptible to changes in climate, with hotter and drier periods associated with greater changes in community composition in these settings. These findings demonstrate that diversified agriculture can help to alleviate the long-term loss of biodiversity outside natural protected areas(1).

The onset of plant cultivation is one of the most important cultural transitions in human history(1-4). Southwestern Amazonia has previously been proposed as an early centre of plant domestication, on the basis of molecular markers that show genetic similarities between domesticated plants and wild relatives(4-6). However, the nature of the early human occupation of southwestern Amazonia, and the history of plant cultivation in this region, are poorly understood. Here we document the cultivation of squash (Cucurbita sp.) at about 10,250 calibrated years before present (cal. yr bp), manioc (Manihot sp.) at about 10,350 cal. yr bp and maize (Zea mays) at about 6,850 cal. yr bp, in the Llanos de Moxos (Bolivia). We show that, starting at around 10,850 cal. yr bp, inhabitants of this region began to create a landscape that ultimately comprised approximately 4,700 artificial forest islands within a treeless, seasonally flooded savannah. Our results confirm that the Llanos de Moxos is a hotspot for early plant cultivation and demonstrate that-ever since their arrival in Amazonia-humans have markedly altered the landscape, with lasting repercussions for habitat heterogeneity and species conservation.

Tracking data from 17 marine predator species in the Southern Ocean are used to identify Areas of Ecological Significance, the protection of which could help to mitigate increasing pressures on Southern Ocean ecosystems.

Southern Ocean ecosystems are under pressure from resource exploitation and climate change(1,2). Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels. Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf. Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent. At present, 7.1% of the ocean south of 40 degrees S is under formal protection, including 29% of the total AESs. The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.