RestorNet: Reveals controls on restoration seeding success across dryland ecosystems
Description: Dryland ecosystems form the largest global biome and support one third of the global human population but are highly vulnerable to land degradation via disturbance and climate change. Despite widespread demand for dryland restoration and rehabilitation, little information is available to help land managers effectively reestablish native perennial vegetation across drylands. RestoreNet is a restoration field trial network that systematically tests appropriate revegetation techniques across environmental gradients. We tracked seedling density and height following the use of different seed mixes and treatments to increase soil moisture at seven RestoreNet sites across Arizona from summer 2018 – 2019. Across sites, seedling recruitment was consistently controlled by treatment and seed mix type. Pitting and mulch treatments increased total seedling density, with pits promoting the highest seeded species recruitment while limiting non-native species establishment. Seeding increased total seedling density regardless of seed mix type, but cooler-adapted seed mixes promoted greater seeded species density and resulted in lower density of unseeded (non-native) species relative to warmer-adapted mixes. Seedling recruitment was also controlled by the temporal and environmental context of restoration with the positive effect of high precipitation greatest in the weeks immediately following seeding. Above-average precipitation during the study period across most of the sites may partially explain why the highest seeded species recruitment occurred in pit treatments and seed mixes with cooler, wetter niche requirements. Results from RestoreNet will help to better understand variation in the success of seeding and other restoration treatments across space and time in drylands. Relationships between restoration practices and environmental conditions in our study suggest the importance of anticipatory restoration strategies that forecast seasonal and sub-seasonal weather conditions and select plant species with climate niche requirements appropriate to current and future climate conditions. This information is critical to land managers tasked with improving ecosystem conditions across degraded dryland regions.
Presenter: Caroline Havrilla is an ecologist and postdoctoral scholar at the US Geological Survey Southwest Biological Science Center studying dryland ecology, restoration, and adaptation to climate change.