Ecosystem Services and Species Richness Interactions

Abstract

Ecosystem services -- the benefits that ecosystems provide to human wellbeing, including provisioning (food; water; fibre), regulating (climate regulation; pollination; flood control; water purification), cultural (recreation; spiritual; aesthetic), and supporting services (nutrient cycling; soil formation) -- are fundamentally dependent on the species richness and functional diversity of the ecological communities that generate them. The biodiversity-ecosystem function (BEF) relationship has been extensively studied in controlled experiments, consistently showing that higher species richness increases ecosystem functioning (productivity; nutrient cycling; stability) through complementarity and facilitation effects. Translating the BEF relationship into a biodiversity-ecosystem services (BES) relationship -- quantifying how richness loss translates to service degradation in real landscapes -- remains one of the major challenges in applied ecology. This study provides the most comprehensive multi-service, multi-landscape BES analysis yet conducted, integrating service assessments from 247 landscape study units across 84 countries for eight ecosystem services against species richness and functional diversity data from simultaneous biological surveys. A non-linear BES relationship was universally found: services declined slowly until approximately 40% species loss, then declined rapidly -- the 'tipping point' threshold confirmed for all eight services examined. Functional diversity was a stronger predictor of service provision than species richness for six of eight services, while pollination and biological pest control depended most strongly on species richness rather than functional diversity. Economic valuation of service loss from observed richness declines (from the BIOCHANGE database paper 260) yielded a mean annual service value loss of EUR 1,847 per hectare at the 18.4% mean richness decline documented over 52 years -- substantially exceeding the cost of conservation interventions that could prevent it.