Studying the competition among native California grasses

Background/Question/Methods

In California’s Central Valley native perennial bunchgrasses are almost entirely extirpated due to habitat conversion and the influx of invasive species. As drought conditions become increasingly common in California, studying these plants is imperative to preserving the scant remaining native grasslands of the Central Valley, as well as the animal species that depend on them. In this study we examined competitive interactions between seven species of native California bunchgrasses. Seeds of each species were sown in a greenhouse in monocultures and polycultures of three, five or seven species and allowed to grow for four months. We quantified above ground dry biomass and germination rate as the primary indicators of competitive ability.

Results/Conclusions

There were clear winners and losers. Three species increased biomass per stem and germination rates when grown in polycultures as opposed to monocultures, while three species decreased in these metrics when grown in polycultures. These results may inform restoration and landscaping efforts in the Central Valley in light of the recent drought and continued climate change. We are cautious about generalizing our results too far, however. We shall repeat this study in outdoor systems and with non-native species to see if these results hold.