The key finding
When different plant species grow together rather than in monocultures, ecosystems produce 15.2% more biomass on average, according to a 2025 meta-analysis of 452 experiments conducted worldwide. Of this productivity boost, 65.6% comes from “complementarity effects” — when species cooperate and use resources differently — while 34.4% comes from “selection effects” — when more productive species naturally dominate mixtures. The benefits were strongest in grasslands and forests, and weaker in croplands and container experiments. Remarkably, the cooperation benefits increased over time while dominance effects decreased, suggesting that diverse plant communities become more efficient as they mature.
What the study looked like
Researchers compiled data from 452 plant diversity experiments spanning multiple continents and ecosystem types, including grasslands, forests, croplands, aquatic systems, and container studies. These experiments compared monocultures (single species) to mixtures with an average species richness of 2.6 species. The team measured total biomass production and calculated two key metrics: complementarity effects (whether species together produce more than expected from their individual performances) and selection effects (whether mixtures favor highly productive species). They also examined how these effects varied with phylogenetic diversity (evolutionary relatedness), functional traits like leaf nitrogen content, whether nitrogen-fixing species were included, climate conditions, and time since planting.
Why researchers think this happened
The dominance of complementarity effects suggests three main mechanisms are at work. First, niche partitioning allows different species to use resources in complementary ways — some plants might have deep roots while others have shallow ones, or differ in when they’re most active during the growing season. Second, biotic feedback includes beneficial interactions like mycorrhizal networks or pest reduction. Third, abiotic facilitation occurs when certain species improve conditions for others, particularly when nitrogen-fixing plants like legumes make nutrients available to neighboring species. The finding that complementarity increased with phylogenetic diversity supports this interpretation: more evolutionarily distant species likely have more different resource needs. The time trends — complementarity strengthening while selection weakens — align with prior ecological theory suggesting that as ecosystems mature, species increasingly specialize and reduce competition rather than simply outcompeting each other.
How to read this carefully
This meta-analysis aggregates hundreds of experiments, but several limitations deserve attention. The average mixture contained only 2.6 species, far fewer than natural ecosystems, so the 15.2% productivity increase may not scale linearly to highly diverse communities. Many experiments were relatively short-term, and while the study tracked time trends, decades-long dynamics remain less certain. The weaker effects in croplands and container experiments suggest context matters enormously — controlled conditions or human management may diminish diversity benefits. Additionally, this study measures biomass productivity, not necessarily other ecosystem services like carbon storage, water filtration, or resilience to disturbance. The mechanisms proposed are correlative patterns from the meta-analysis, not direct experimental proof of causation for any specific interaction.
What this means for everyday life
These findings offer practical insights for anyone managing land, from backyard gardens to conservation projects. The results suggest that mixing species — especially those with different traits or evolutionary histories — may create more productive systems than monocultures. For gardeners, this might mean combining plants with different root depths or including a nitrogen-fixing species like clover alongside other plants. For land managers and restoration ecologists, the study highlights that diversity benefits strengthen over time, meaning patience may reward those who plant diverse communities. The stronger effects in grasslands and forests compared to croplands also suggests that working with ecological processes rather than against them through intensive management could enhance productivity. Given these patterns, it might be worth considering how small increases in plant diversity in managed landscapes could contribute to both productivity and conservation goals simultaneously.