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The Amazon rainforest is dominated by relatively few tree species, yet the degree to which this hyperdominance influences carbon cycling remains unknown. Here, the authors analyse 530 forest plots and show that ∼1% of species are responsible for 50% of the aboveground carbon storage and productivity.

Analysis combining multiple global tree databases reveals that whether a location is invaded by non-native tree species depends on anthropogenic factors, but the severity of the invasion depends on the native species diversity.

A global research network monitoring the Amazon for 30 years reports in this study that tree size increased by 3% each decade.

Species’ traits and environmental conditions determine the abundance of tree species across the globe. Here, the authors find that dominant tree species are taller and have softer wood compared to rare species and that these trait differences are more strongly associated with temperature than water availability.

The authors analyse tree responses to an extreme heat and drought event across South America to understand long-term climate resistance. While no more sensitive to this than previous lesser events, forests in drier climates showed the greatest impacts and thus vulnerability to climate extremes.

Peatland pyrogenic carbon from past fires in the Amazon plays a key role in the global carbon budget, accounting for 1.6% of the total organic carbon in Amazonian peatlands, based on an analysis of six cores from northwestern Amazonian peatlands using hydrogen pyrolysis.

Trees come in all shapes and size, but what drives this incredible variation in tree form remains poorly understood. Using a global dataset, the authors show that a combination of climate, competition, disturbance and evolutionary history shape the crown architecture of the world’s trees and thereby constrain the 3D structure of woody ecosystems.

Wood density is a key control on tree biomass, and understanding its spatial variation improves estimates of forest carbon stock. Sullivan et al. measure >900 forest plots to quantify wood density and produce high resolution maps of its variation across South American tropical forests.

Wood density is an important plant trait. Data from 1.1 million forest inventory plots and 10,703 tree species show a latitudinal gradient in wood density, with temperature and soil moisture explaining variation at the global scale and disturbance also having a role at the local level.

Analysis of ground-sourced and satellite-derived models reveals a global forest carbon potential of 226 Gt outside agricultural and urban lands, with a difference of only 12% across these modelling approaches.

Analysing >1,700 inventory plots from the Amazon Tree Diversity Network, the authors show that the majority of Amazon tree species can occupy floodplains and that patterns of species turnover are closely linked to regional flood patterns.

Inventory data from more than 1 million trees across African, Amazonian and Southeast Asian tropical forests suggests that, despite their high diversity, just 1,053 species, representing a consistent ~2.2% of tropical tree species in each region, constitute half of Earth’s 800 billion tropical trees.

Tree mortality has been shown to be the dominant control on carbon storage in Amazon forests, but little is known of how and why Amazon forest trees die. Here the authors analyse a large Amazon-wide dataset, finding that fast-growing species face greater mortality risk, but that slower-growing individuals within a species are more likely to die, regardless of size.

Unlike Amazonian forests, African forests have maintained their carbon sink until recently but by 2030 the African carbon sink will have shrunk by 14 per cent and the Amazonian sink will reach almost zero.

The role of non-structural carbohydrates (NSC) in mediating the impacts of drought in tropical trees is unclear. Here, the authors analyse leaf and branch NSC in 82 Amazon tree species across a Basin-wide precipitation gradient, finding that allocation of leaf NSC to soluble sugars is higher in drier sites and is coupled to tree hydraulic status.

Most Amazon tree species are rare but a small proportion are common across the region. The authors show that different species are hyperdominant in different size classes and that hyperdominance is more phylogenetically restricted for larger canopy trees than for smaller understory ones.

A pan-Amazon study of forests shows large variations in drought tolerance traits and finds that forests in regions of pronounced climate change are losing biomass and may be operating beyond their hydraulic limits.

Inventory data from 90 lowland Amazonian forest plots and a phylogeny of 526 angiosperm genera were used to show that taxonomic and phylogenetic diversity are both predictive of wood productivity but not of biomass variation.

Although plant functional trait combinations reflect ecological trade-offs at the species level, little is known about how this translates to whole communities. Here, the authors show that global trait composition is captured by two main dimensions that are only weakly related to macro-environmental drivers.

Alternative stable states in forests have implications for the biosphere. Here, the authors combine forest biodiversity observations and simulations revealing that leaf types across temperate regions of the NH follow a bimodal distribution suggesting signatures of alternative forest states.

Integrating inventory data with machine learning models reveals the global composition of tree types—needle-leaved evergreen individuals dominate, followed by broadleaved evergreen and deciduous trees—and climate change risks.

The world’s tropical forests represent a terrestrial carbon sink, yet its size is uncertain. Espírito-Santo et al.characterize full Amazon disturbances combining forest inventories and remote sensing data, and use statistical modelling to quantify the Amazon aboveground forest carbon balance.

The South American Cerrado has an estimated ~1605 tree species, yet > 2% make up half of all trees. Since 1995, the savanna lost 24 billion trees, threatening its biodiversity. Urgent conservation is needed to prevent irreversible loss.

Capacity for carbon capture and storage in forests may not be monolithic but instead a function of complex dynamics of forest strata and age. The smaller trees that make up the understory in African tropical forests store their carbon longer as compared to sub-canopy and canopy trees and they represent a disproportionately large share of the carbon sink, in spite of their small size.

Using 13 functional traits we characterize the Amazonian trees and the communities they form. Amazonian tree communities are distributed along a fast-slow-spectrum. This results in clear differences in traits among these forests, as well as their biomass and biomass productivity.

Tree species turnover across Amazonian forests unveils sharp floristic transitional zones, that are linked with changes in soil fertility and climate.

This study reports data from a network of long-term monitoring plots across African tropical forests, which finds that above-ground carbon storage in live trees increased by 0.63 Mg C ha⁻¹ yr⁻¹ between 1968 and 2007. The data is extrapolated to unmeasured forest components, and by scaling to the continent, a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr⁻¹ is estimated. These results provide evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon.

A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.

A spatially explicit global map of tree symbioses with nitrogen-fixing bacteria and mycorrhizal fungi reveals that climate variables are the primary drivers of the distribution of different types of symbiosis.