Brundrett, M.

Context The global diversity hotspot in Southwest Australia has >480 orchids facing increasing threats from climate extremes, fire and habitat decline. Aims To develop effective and consistent tools for measuring climate impacts on productivity in a diverse urban orchid community. Methods Annual variations in flower and seed production for 17 orchids were determined using thousands of records over a decade with extreme climate variability. Key results Rainfall deficits and temperatures in autumn, winter and spring increased substantially over 125 years. Seasonal climate anomalies reduced flowering and seed production for orchids, but this varied between species and seasons. These effects were summarised by climate response (CRI) and sensitivity (CSI) indexes. Early or late flowering species were most vulnerable to seasonal drought, and visually deceptive pollination preferred warm dry conditions. CRIs were strongly correlated with orchid pollination syndromes and flowering times. Effects on mycorrhizal fungi and pollinators were also observed. Extrapolating climate trends to 2100 predicted further impacts on orchid productivity (-5-40%). Conclusions Orchid climate responses were diverse and deeply integrated with pollination, phenology, fire sensitivity and other key traits. Implications Research in an urban climate observatory produced a climate analysis framework that is likely relevant to many orchids and other biota.