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Ecological Intelligence

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Ecological Intelligence / Subject

rainfall

Peer-reviewed Transregional

Arid streams in a rainfall gradient produced more secondary biomass than wetter ones

Evidence
Peer-reviewed
Geography
Nine rivers across a natural precipitation gradient
System
Freshwater food webs; riverine secondary production

WHAT THE EVIDENCE SAYS

Across nine rivers over three years, researchers compared invertebrate and vertebrate secondary production. Wetter streams had food-web energy concentrated in detritivorous invertebrates; arid streams showed more vertebrate herbivory and approximately twice the secondary production and biomass turnover.

WHY IT MATTERS / OUR READ

A changing rainfall regime can reorganize an aquatic food web even when the river still appears to flow; production depends on which trophic pathways carry energy.

CAVEATS / UNCERTAINTY

Site contrasts along a rainfall gradient are not a controlled climate-change experiment; geology, productivity and local biota may also differ. Reported production ratios are context-bound.

SOURCE

Ecology — primary comparative multi-river study
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Nine rivers tracked for three years shifted from detritivore-heavy food webs in wetter settings toward vertebrate herbivory in drier settings.

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Peer-reviewed Africa

In Kakamega Forest, the season changed the butterfly community more than the habitat label did

Evidence
Peer-reviewed
Geography
Kakamega Forest ecosystem, Kenya
System
Tropical rainforest fragment / butterfly community

WHAT THE EVIDENCE SAYS

Weekly surveys from January through June 2024 recorded 10,334 butterflies representing 146 species across six cover types. Abundance, richness and Shannon diversity rose in the wet season, community composition separated by season, and one-month-lagged rainfall was the strongest abundance predictor. Natural and secondary forest still supported the highest abundance and diversity, but season explained more overall community variation than habitat type.

WHY IT MATTERS / OUR READ

Biodiversity monitoring can misread habitat differences when sampling windows do not span seasonal transitions. For tropical insects especially, timing is part of the survey design—not background noise.

CAVEATS / UNCERTAINTY

This is one six-month study in one rainforest fragment. It does not establish a long-term climate trend, and seasonal dominance in this system should not be generalized to other taxa, years or tropical forests.

SOURCE

Journal of Tropical Ecology
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Six months of weekly surveys across six forest-cover types found wet–dry transitions explaining more community variation than habitat type, with lagged rainfall the strongest abundance predictor.

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