Prolonged drought constrains pine cone production but not its consumption

Abstract

Seed production is vital for plant recruitment, shaped by tree traits, climate, and biotic pressures. Droughts can strongly affect reproductive processes, with cascading effects on squirrels. Their feeding behaviour responds to cone size and availability, both climate-driven. This study evaluates how a prolonged drought (three years below average precipitation) affects pine cone production and red squirrel foraging behaviour. Specifically, we (1) analyse tree- and environmental-related drivers of production, (2) quantify squirrel consumption relative to cone availability, and (3) explore links between cone size, production, and exploitation. From 2019–2024, we recorded 32,531 produced and 13,013 consumed cones across 36 transects, with Aleppo pine being dominant. Production varies by species, reflecting distinct reproductive phenologies and species-specific climatic sensitivities. Across pine species, production was negatively associated with drought-related conditions during key reproductive stages, indicating shared vulnerability to water limitation. Rather than long-term trends, these responses reflect interannual climatic variability as a reproductive bottleneck, promoting cross-species synchronization and local homogenization. Crown diameter and habitat significantly affected production. Habitat also shaped squirrel consumption, with mixed forests showing higher rates. Tree diameter and crown size affected cone length, which influenced squirrel feeding. Despite reduced production, squirrel consumption remained stable or even increased during low-production years, with some areas exceeding 75 % of available cones. This suggests that reduced seed availability combined with sustained foraging pressure may impair forest regeneration. Overall, our findings show that climate extremes can synchronize reproductive failure across co-occurring pine species, reveal drought‑driven pollination limits while intensifying trophic pressures in drought-prone ecosystems.