Young trees in karst forests resist drought poorly; long-term insect monitoring avoids the tropics; Collodaria plankton get sugars from algae
Young trees in karst forests resisted drought poorly. Long-term insect monitoring avoids the tropics where diversity is highest. Collodaria plankton get sugars from algae and sulphur compounds from seawater.
Science··Evening
Young trees in karst forests resist drought poorly
Tree-ring records from 849 trees at 40 sites in southwest China, combined with satellite estimates of regolith water loss, carbon isotope measurements and mortality observations, indicate that bedrock type shapes drought vulnerability alongside climate, soil and tree traits: in karst forests younger and smaller trees resisted and recovered less well than older and larger ones, while non-karst forests showed the opposite pattern. Regolith water loss rate served as a proxy for near-surface water retention capacity. The contrast sharpened under prolonged drought, and site-level isotope and mortality evidence pointed to physiological stress and growth decline consistent with it. The study is observational and regional, so it identifies bedrock lithology as a structural constraint on where drought damage falls without measuring how much mortality any single drought will cause.[1]
Long-term insect monitoring avoids the tropics
A Perspective article argues that long-term insect monitoring is concentrated in temperate regions holding a small share of global insect species, while the tropics that hold most insect diversity contribute only a small fraction of long-term datasets. The widely cited 76 per cent fall in flying insect biomass over 27 years comes from German Malaise-trap sites. The article puts the average global decline of terrestrial insects at about 9 per cent per decade and notes that roughly 50 per cent of tropical forest has already been cleared or converted to agriculture, so pesticide exposure and habitat loss are rising fastest where the monitoring infrastructure is thinnest. The piece is a Perspective; it presents no new field data and argues about the geography of measurement.[2]
Collodaria plankton get sugars from algae
Collodaria are marine protists that host photosynthetic algae and contribute substantially to primary production in nutrient-poor ocean regions. Combining stable isotope labelling with metabolomic profiling, the authors traced where the holobiont's carbon comes from and found that inorganic carbon fixed by the algae supplies glucose and fructose and then other metabolites including ribose. Uptake of dissolved organic compounds from labelled algal lysate did not feed those carbohydrates, while dimethylsulfoniopropionate and betaines came mainly through that route, with only a minor contribution from the photosymbionts. The two nutritional modes fill different roles in the same organism, which matters for how carbon and sulphur fluxes through plankton are modelled.[3]
