Summary Drought‐induced xylem embolism is considered to be one of the main factors driving mortality in woody plants worldwide. Although several structure–functional mechanisms have been tested to understand the anatomical determinants of embolism resistance, there is a need to study this topic by integrating anatomical data for many species. We combined optical, laser, and transmission electron microscopy to investigate vessel diameter, vessel grouping, and pit membrane ultrastructure for 26 tropical rainforest tree species across three major clades (magnoliids, rosiids, and asteriids). We then related these anatomical observations to previously published data on drought‐induced embolism resistance, with phylogenetic analyses. Vessel diameter, vessel grouping, and pit membrane ultrastructure were all predictive of xylem embolism resistance, but with weak predictive power. While pit membrane thickness was a predictive trait when vestured pits were taken into account, the pit membrane diameter‐to‐thickness ratio suggests a strong importance of the deflection resistance of the pit membrane. However, phylogenetic analyses weakly support adaptive coevolution. Our results emphasize the functional significance of pit membranes for air‐seeding in tropical rainforest trees, highlighting also the need to study their mechanical properties due to the link between embolism resistance and pit membrane diameter‐to‐thickness ratio. Finding support for adaptive coevolution also remains challenging.

1. As environmental change and degradation accelerate, perturbing insect populations, we need to better understand the resource use dynamics of diverse wild pollinators. Most tropical trees are adapted for biotic pollination, yet we still know little about plant-pollinator interactions in African rainforests.2. We addressed this gap from a community perspective, identifying what floral traits colour, scent, reward accessibility and visibilitystructure visitation patterns among insect functional groups to tree species flowering in the understory of Korup National Park, Cameroon. To understand how visitor groups share resources, we used joint modelling that explicitly considers zero-inflation in visitation rates and correlation among visitor groups.3. Most tree species had exposed floral rewards, and all were visited by multiple insect groups among which ants, bees, beetles, and flies were most abundant. Visitation rates varied more among tree species than among individual trees. Floral scent differences were important for structuring visits, particularly for flies, bees, and ants. Ant and bee visitation rates decreased while fly visits increased marginally throughout the season, correlated with the dry to wet season transition.4. Comparison with other lowland tropical understories suggests flies may be uniquely diverse and important to this system, and differences in seasonality and forest structure may be drivers of community differences. Floral scent is likely a key functional trait structuring flower-insect interactions in tropical forest environments and should be emphasised in future studies. Lastly, a joint modelling approach can elucidate community structure, particularly in communities with ecologically generalised interactions.

<p>Climate change affects ecosystems considerably worldwide, but as warming is happening at an accelerated pace at higher latitudes, it is essential to study how warming affects ecosystem structure and function in Arctic and sub-Arctic ecosystems.</p> <p>In this research, we looked at changes in the aboveground biomass (AGB) of two Icelandic sub-Arctic grasslands located at the ForHot site. The ForHot site is an exceptional studying site where the soils are naturally warmed. Thus, making it an important natural laboratory to assess and learn more about the long-term effect of global warming. At the research site, one grassland ecosystem has soils that have been warmed for over 60 years (long-term warming; LTW) and the other since 2008 (medium-term warming; MTW), when an earthquake disrupted geothermal channels in the underlying bedrock. Fifty permanent survey plots were established in the autumn of 2012 along the two grassland soil temperature gradients (ranging from 0 to +18°C).</p> <p>We assessed how vegetation structure (non-vascular; AGB<sub>non-vasc</sub> and vascular plants; AGB<sub>vasc</sub>) and the ecosystem's maximum aboveground total biomass(AGB<sub>tot</sub>) were affected by different levels of soil warming over multiple studied years (<em>i.e.</em> 2013, 2016, 2018, 2020, 2021 and 2022).</p> <p>Our preliminary results showed unexpectedly relatively small changes in AGB<sub>tot</sub> with warming. We hypothesise that changes in AGB<sub>vasc</sub> would typically induce opposite changes in AGB<sub>non-vasc,</sub> probably because of light competition. When looking separately at the vegetation structures, for AGB<sub>vasc</sub>, the duration of soil warming induced contrasted responses between MTW and LTW grasslands. That is, in the MTW grassland, there were no changes for most years (p > .05) and strong negative responses (p < .05) with warming in seasonally maximum AGB<sub>vasc</sub> for other years. Whereas in the LTW grassland, warming generally increased AGB for most years (p < .05), and also a strong negative response as observed in the MTW for the respective years despite statistically not significant. This strong negative response could be because of untypically high AGB production in control (unwarmed) plots during those years and less positive reactions with different levels of soil warming. We will show some potential drivers (environmental variables) for those unexpected temporal variations in the warming response. AGB<sub>non-vasc</sub>, such as lichens and mosses, have an unclear pattern across the soil warming gradient in both grassland ecosystems.</p>