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Lianas (woody vines and climbing monocots) are increasing in abundance in many tropical forests with uncertain consequences for forest functioning and recovery following disturbances. At a global scale, these increases are likely driven by disturbances and climate change. Yet, our understanding of the environmental variables that drive liana prevalence at regional scales is incomplete and geographically biased towards Latin America. To address this gap, we present a comprehensive study evaluating the combined effects of climate, soil, disturbance and topography on liana prevalence in the Australian Wet Tropics. We established 31 20 × 20 m vegetation plots along an elevation gradient in low disturbance (canopy closure ≥ 75%) and high disturbance (canopy closure ≤ 25%) forest stands. In these plots, all tree and liana (defined as all woody dicot vines and climbing monocots, i.e., rattans) stems ≥ 1 cm DBH were measured and environmental data were collected on climate, soil and topography. Generalised linear models were used with multi‐model averaging to quantify the relative effects of the environmental variables on measures of liana prevalence (liana–tree basal area ratio, woody vine basal area and stem density and rattan stem density). Liana prevalence decreased with elevation but increased with disturbance and mean annual precipitation. The increase in the liana–tree ratio with precipitation was more pronounced for highly disturbed sites. Like other tropical regions, disturbance is an important driver of liana prevalence in Australian rainforests and appears to interact with climate to increase liana–tree ratios. The observed increase in liana–tree ratio with precipitation contrasts findings from elsewhere but is confounded by correlated changes in elevation and temperature, which highlights the importance of regional studies. Our findings show that forests with high disturbance and climatic conditions favourable to lianas are where lianas most likely to outcompete trees and impede forest recovery. Lianas (woody vines and climbing monocots) are highly important in tropical forests; however, our understanding of the environmental variables that drive their proliferation at regional scales is incomplete and geographically biased. We address this gap through a study in the Australian Wet Tropics and find that disturbance and climate are important drivers of liana prevalence. This provides further support for the concern that global change may be contributing to increasing lianas relative to trees, with serious consequences for rates of tropical forest recovery and carbon sequestration.

A single-molecule approach is used to investigate the kinetics of assembly of the translation initiation complex, revealing that there is more than one pathway by which the necessary factors can assemble. Kinetics of translation initiation Translation initiation involves the association of the two ribosomal subcomplexes and a host of initiation factors. Joseph Puglisi and colleagues use a sophisticated single-molecule approach to look at the kinetics of assembly of the translation initiation complex. They find that there is more than one pathway by which the factors can assemble, and identify the crucial event that transitions the complex from initiation to elongation. The initiation of translation establishes the reading frame for protein synthesis and is a key point of regulation 1 . Initiation involves factor-driven assembly at a start codon of a messenger RNA of an elongation-competent 70S ribosomal particle (in bacteria) from separated 30S and 50S subunits and initiator transfer RNA. Here we establish in Escherichia coli , using direct single-molecule tracking, the timing of initiator tRNA, initiation factor 2 (IF2; encoded by infB ) and 50S subunit joining during initiation. Our results show multiple pathways to initiation, with orders of arrival of tRNA and IF2 dependent on factor concentration and composition. IF2 accelerates 50S subunit joining and stabilizes the assembled 70S complex. Transition to elongation is gated by the departure of IF2 after GTP hydrolysis, allowing efficient arrival of elongator tRNAs to the second codon presented in the aminoacyl-tRNA binding site (A site). These experiments highlight the power of single-molecule approaches to delineate mechanisms in complex multicomponent systems.

1. Calibrating indices of animal abundance to true densities is critical in wildlife studies especially when direct density estimations are precluded by high costs, lack of required data or model parameters, elusiveness and rarity of target species. For studies deploying camera traps, the use of photographic rate (photographs per sampling time) as an index of abundance potentially applies to the majority of terrestrial mammals where individual recognition, and hence capture—recapture analysis, are unfeasible. The very few studies addressing this method have either been limited by lack of independence between trapping rates and density estimations, or because they combined different species, thus introducing potential bias in camera trap detection rates. This study uses a single model species from several sites to analyse calibration of trapping rates to independently derived estimations of density. The study also makes the first field test of the method by Rowcliffe et al. (2008) for density derivation from camera trapping rates based on modelling animal-camera contacts. 2. We deployed camera traps along line transects at six sites in the Udzungwa Mountains of Tanzania and correlated trapping rates of Harvey's duiker Cephalophus harveyi with densities estimated from counts made along the same transects. 3. We found a strong, linear relationship (R² = 0·90) between trapping rate and density. Sampling precision analysis indicates that camera trapping rates reach satisfactory precision when trapping effort amounts to 250-300 camera days. Density estimates using Rowcliffe et al.'s (2008) gas model conversion are higher than from transect censuses; we discuss the possible reasons and stress the need for more field tests. 4. Synthesis and applications. Subject to rigorous and periodic calibration, and standardization of sampling procedures in time and over different sites, camera trapping rate is shown to be, in this study, a valid index of density in the target species. Comparative data indicate that this may also apply to forest ungulates in general. The method has great potential for standardizing monitoring programmes and reducing the costs of wildlife surveys, especially in remote areas.

An approach to derive the below-bandgap absorption in GaSb/GaAs self-assembled quantum dot devices using room-temperature external quantum efficiency measurement results is presented. Devices with five layers of delta-doped quantum dots placed in the intrinsic, n- and p-regions of a GaAs solar cell are studied. The importance of incorporating an extended Urbach tail absorption in analyzing the absorption strength of quantum dots and the transition states is demonstrated. The theoretically integrated absorbance via quantum dot ground states is calculated as 1.04 × 1015 cm−1s−1, which is in reasonable agreement with the experimentally derived value 8.1 × 1015 cm−1s−1. The wetting layer and quantum dot absorption contributions are separated from the tail absorption and their transition energies are calculated. Using these transition energies and the GaAs energy gap of 1.42 eV, the heavy hole confinement energies for the quantum dots (320 meV) and for the wetting layer (120 meV) are estimated.

Defaunation is causing declines of large-seeded animal-dispersed trees in tropical forests worldwide, but whether and how these declines will affect carbon storage across this biome is unclear. Here we show, using a pan-tropical data set, that simulated declines of large-seeded animal-dispersed trees have contrasting effects on aboveground carbon stocks across Earth’s tropical forests. In our simulations, African, American and South Asian forests, which have high proportions of animal-dispersed species, consistently show carbon losses (2–12%), but Southeast Asian and Australian forests, where there are more abiotically dispersed species, show little to no carbon losses or marginal gains (±1%). These patterns result primarily from changes in wood volume, and are underlain by consistent relationships in our empirical data (∼2,100 species), wherein, large-seeded animal-dispersed species are larger as adults than small-seeded animal-dispersed species, but are smaller than abiotically dispersed species. Thus, floristic differences and distinct dispersal mode–seed size–adult size combinations can drive contrasting regional responses to defaunation. Defaunation is linked to the decline of tree species that depend on large animals for seed dispersal, but it is unclear if this affects carbon storage. Here the authors show that defaunation effects on carbon storage vary across continents, driven by relationships between seed dispersal strategies and adult tree size.

Thermophilization is the directional change in species community composition towards greater relative abundances of species associated with warmer environments. This process is well-documented in temperate and Neotropical plant communities, but it is uncertain whether this phenomenon occurs elsewhere in the tropics. Here we extend the search for thermophilization to equatorial Africa, where lower tree diversity compared to other tropical forest regions and different biogeographic history could affect community responses to climate change. Using re-census data from 17 forest plots in three mountain regions of Africa, we find a consistent pattern of thermophilization in tree communities. Mean rates of thermophilization were +0.0086 °C·y −1 in the Kigezi Highlands (Uganda), +0.0032 °C·y −1 in the Virunga Mountains (Rwanda-Uganda-Democratic Republic of the Congo) and +0.0023 °C·y −1 in the Udzungwa Mountains (Tanzania). Distinct from other forests, both recruitment and mortality were important drivers of thermophilzation in the African plots. The forests studied currently act as a carbon sink, but the consequences of further thermophilization are unclear. Thermophilization is a change in species community composition towards greater abundances of species associated with warmer environments. This study provides evidence of thermophilization in understudied Afromontane forests, but with drivers that are distinct from other forest types.

This perspective proposes a new wildfire risk prediction system by integrating plant functional traits with microwave-derived vegetation optical depth to detect critical moisture thresholds before ignition. By shifting from reactive, thermal-based detection to proactive, ecology-driven forecasting, this approach could enhance preparedness, guide targeted mitigation, and improve resource allocation globally and would help reduce wildfire impacts on biodiversity, infrastructure, and communities in an era of intensifying climate-driven fire risk.

Unauthorised feeding and touching of the animals by visitors to zoos and wildlife parks pose serious threats to the health of both animals and visitors alike. We tested the efficacy of four different \"do not feed\" signs designed to prevent zoo visitors from feeding a group of meerkats. Signs consisted of one of two different written messages and imagery of either a pair of watching human eyes, or meerkat pawprints as a control. Covert observation of visitor behaviour in the presence and absence of the signs was analysed. Visitors were significantly less likely to feed the meerkats when signs were present, than when they were absent. The effect of the signs was specific to the targeted behaviour in that feeding was reduced, but attempts to touch the meerkats increased with the presence of the signs. We did not find that the presence of watching eyes or the different wording on the signs affected the likelihood of visitors feeding the meerkats. We also examined factors that influenced the likelihood of visitors attending to the signs. We found that children were more likely to attend to signs than adults which has important implications for the design of such signs. Together our findings show that signs are effective in reducing the unwanted behaviours they target but may also result in displacement of these negative behaviours and that children are more likely to attend to these signs than adults.

Whilst the different forms of conventional (charge-based) memories are well suited to their individual roles in computers and other electronic devices, flaws in their properties mean that intensive research into alternative, or emerging, memories continues. In particular, the goal of simultaneously achieving the contradictory requirements of non-volatility and fast, low-voltage (low-energy) switching has proved challenging. Here, we report an oxide-free, floating-gate memory cell based on III-V semiconductor heterostructures with a junctionless channel and non-destructive read of the stored data. Non-volatile data retention of at least 10 4  s in combination with switching at ≤2.6 V is achieved by use of the extraordinary 2.1 eV conduction band offsets of InAs/AlSb and a triple-barrier resonant tunnelling structure. The combination of low-voltage operation and small capacitance implies intrinsic switching energy per unit area that is 100 and 1000 times smaller than dynamic random access memory and Flash respectively. The device may thus be considered as a new emerging memory with considerable potential.

The ribosome, a two-subunit macromolecular machine, deciphers the genetic code and catalyzes peptide bond formation. Dynamic rotational movement between ribosomal subunits is likely required for efficient and accurate protein synthesis, but direct observation of intersubunit dynamics has been obscured by the repetitive, multistep nature of translation. Here, we report a collection of single-molecule fluorescence resonance energy transfer assays that reveal a ribosomal intersubunit conformational cycle in real time during initiation and the first round of elongation. After subunit joining and delivery of correct aminoacyl-tRNA to the ribosome, peptide bond formation results in a rapid conformational change, consistent with the counterclockwise rotation of the 30S subunit with respect to the 50S subunit implied by prior structural and biochemical studies. Subsequent binding of elongation factor G and GTP hydrolysis results in a clockwise rotation of the 30S subunit relative to the 50S subunit, preparing the ribosome for the next round of tRNA selection and peptide bond formation. The ribosome thus harnesses the free energy of irreversible peptidyl transfer and GTP hydrolysis to surmount activation barriers to large-scale conformational changes during translation. Intersubunit rotation is likely a requirement for the concerted movement of tRNA and mRNA substrates during translocation.