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UBC Theses and Dissertations

Functional diversity in cover crops and ecosystem services Furey, George Neil

Abstract

Management of our agroecosystems faces a dual problem where we need to produce more food, fiber and fuel with the same amount of land while limiting the impact of this production on the earth’s biodiversity and environment. A solution to this problem is to manage agroecosystems for augmented biodiversity to increase the provision of Ecosystem Services (ES). Increasing on-farm diversity can improve ES beyond the provision of food to help reduce the use of environmentally costly inputs through ES provision such as growing nitrogen-fixing plants to supply nitrogen to food crops in lieu of other inputs. Cover crops are plants that can be grown temporal or spatially isolated from food crops with limited negative impacts on yield and can provide significant positive impacts to both the farmer’s profitability and the environment. Increasing the biodiversity of cover crops is one key strategy to sustainably intensify agriculture by helping to improve yields while limiting the environmental impact of agricultural production. To determine if increasing cover crop biodiversity leads to greater ES provision, experiments were conducted that manipulated cover crop functional diversity in three settings, a field trial at the UBC Farm, a pot experiment in the UBC Horticultural Greenhouse, and a litter-bag study at the UBC Farm. A functional group framework was applied to cover crops using a grass (Rye Secale cereale L.), a legume (Lana Vetch Vicia villosa ssp. dasycarpa Roth.) and a forb (Chicory Cichorium intybus L.) in mixtures of varying degrees of diversity. The general conclusion from these analyses was that mixtures were capable of providing a comparable magnitude of ES to the best monoculture while providing a range of ES greater than any one monoculture. In monoculture, rye was the best for carbon fixation (biomass production and CO₂ uptake) and weed suppression; Lana vetch was the best for improving soil fertility (nitrogen and phosphorus release); and chicory was the best for soil cover (leaf area) and residue decomposition. There was sufficient evidence to support the use of cover crop mixtures to provide ES that reduce the environmental impact of agricultural production with potential to improve crop yields.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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