ECOLOGICAL INTENSIFICATION FOR A PRODUCTIVE OAK-HAZELNUT SAVANNAH LANDSCAPE

The premise of our research is that agroecosystem sustainability requires practices that support multiple ecosystem services across the agricultural-wildlands matrix. We focus on Oregon's hazelnut industry, which is a booming industry, providing 99 percent of US hazelnuts. Production has doubled in the last 10 years, and is forecasted to double again by 2025. Key challenges for hazelnut production are pest management and the need for bare ground at harvest. Traditionally, farms have used intensive spraying, flailing, and scraping to eliminate pests and understory vegetation. These practices can lead to a loss of beneficial insects, and eroded orchard soils that do not hold moisture, and high herbicide and pesticide runoff rates. In addition, exchanges between hazelnut orchards and surrounding wildlands complicate agroecosystem management. Oregon hazelnut orchards are embedded in a landscape previously dominated by oak-prairie savannah. Pests from surrounding oak habitat can exacerbate pest loads in hazelnuts. The primary economic pest of hazelnuts is the filbertworm (Cydia latiferreana), a native moth that burrows into the nuts and renders them inedible. Remnant oak habitat in the agricultural matrix can support "source" populations of filbertworms that re-invade hazelnut stands, leading to a potential conflict between oak conservation and hazelnut production.Our overall goal is to test two forms of ecological intensification for hazelnut agroecosystems: grazing to reduce pest spillover from oak stands and cover crops to improve water resources and promote beneficial species. We will test whether and how these ecological intensifications achieve their targeted goals and their interactive implications for ecosystem services at the farm and landscape scale. Our three main objectives are to:1) Test whether grazing reduces pest spillover from oak to hazelnut stands. Pigs preferentially graze acorns, and acorn-fed pigs are a valuable commodity. We predict that grazing oak stands with pigs will physically remove infested acorns, reducing pest loads within oaks and spillover to adjacent hazelnut stands. Because adult moths have a large (~5 acre) flight radius, we expect the effectiveness of pig grazing will be highly scale-dependent, with the extent of grazing needed for pest control depending on the landscape context.2) Assess whether native cover crops effectively improve water and promote beneficial species. While cover crops are uncommon in hazelnuts due to a need for bare ground at harvest, there is growing pressure to use them to prevent runoff and retain soil moisture. We predict that native prairie plants will be ideal cover crops because they provide additional co-benefits, most notably by hosting natural predators and supporting native pollinators. We also predict that their characteristic summer senescence will allow populations to reseed without interfering with nut harvest. We will assess the viability and benefits of native compared to conventional cover crops.3) Determine whether there are synergies between livestock integration and orchard cover crops. In agricultural systems, pollinators typically live in surrounding wildlands and venture into farmland to collect pollen and/or nectar. We hypothesize the combination of cover crops and oak woodland conservation will enhance pollinators by increasing floral resources and nesting habitat. Wild bees often nest in the ground, and we predict that grazing will enhance nesting habitat by breaking up thick non-native ground vegetation.