Integrating food production and biodiversity : energy and scale issues in implementation
Sammanfattning: The aim of this thesis was to test the hypotheses that (1) biodiversity at a farm level differs between small and large farms, and (2) it is possible to combine high biodiversity at farm level with high food production, sustainable nutrient circulation, and self-sufficiency in fuels. In the research area in SE Sweden, six small farms (<52 ha) and six large farms (>135 ha) were selected for the studies. The farm with the highest biodiversity was selected as a case study farm for the productivity and biofuel studies. Differences in biodiversity between small and large farms were assessed by comparing number of birds and herbaceous plant species plus the number of bird territories, bumblebees, and butterflies. Both on-farm heterogeneity and surrounding landscape heterogeneity were measured by calculating the Shannon-Wiener Diversity Index. Productivity was measured as the number of people supplied with food with different livestock combinations and types of biofuels. The biofuel scenarios were evaluated regarding their impact on the number of people supplied with food, and NPK fluxes at farm level. The biofuels were crude rapeseed oil, horse draft, ethanol from wheat, and ethanol from potatoes. The results showed that twice as many butterflies, breeding bird species and bird territories, five times as many bumblebees, and almost twice as many herbaceous non-crop plant species were found on the small farms compared to the large farms. The small farms also had significantly higher on-farm landscape heterogeneity. Globally, on average, 0.2 ha of farmland is available per capita, i.e. every ha supports 5 persons. This production, and even slightly more was achieved when using a combination of a workhorse and a crude rapeseed oil-fuelled tractor. Ethanol from wheat had the largest impact on food production. All biofuels tested resulted in a positive balance for N, but in deficits for P and K. The results show that high biodiversity and high production of food and biofuels can be combined on the same farm. The results also suggest that this combination of high biodiversity and high production is enhanced by small-scale farming.
Denna avhandling är EVENTUELLT nedladdningsbar som PDF. Kolla denna länk för att se om den går att ladda ner.