UBC Theses and Dissertations
Evaluating potential impacts of hedgerow and riparian buffer management options on habitat and carbon stocks within the Agricultural Land Reserve of the Lower Fraser Valley, British Columbia Rallings, Anna
Non-production perennial vegetation (NPPV) on farmland provides wildlife habitat and/or ecosystem services (ES). Increasing NPPV area could help reverse the simplification of agricultural landscapes by providing small but potentially important patches of habitat on the edges of farm fields as well as increase the multifunctionality of the landscape to meet concurrent agricultural production and environmental objectives. Conflicts among these objectives are currently a challenge for the rapidly urbanizing Lower Fraser Valley (LFV), the most intensive agricultural region of British Columbia. The objectives of this study were to 1. Characterize NPPV hedgerows; 2. Map the current distribution of NPPV and associated carbon stocks; 3. Better understand the drivers of NPPV distribution and identify areas at higher risk of conversion to agricultural production; 4. Model potential NPPV management options to identify those that maximize habitat and carbon storage while minimizing farm land loss. Cluster analysis of hedgerow field survey data distinguished three distinct types which differed in composition but not size: Planted Trees, Mixed Remnant and Invasives. Remote sensing analysis found NPPV on 33.2% of the study area’s farmland, of which 56.2% consisted of large, contiguous stands of trees. However, 0.98 – 1.86 MT of carbon (75.5% of all NPPV carbon) in these stands, is at high risk of conversion to agriculture given strong correlation between indicators of agricultural expansion (IAE) and removal of stands located on the highest quality farmland. Conversely Hedgerows and Riparian Buffers were found to have positive, synergistic correlations with IAE. Spatially-explicit normative scenarios were used to evaluate impacts of NPPV management options. The addition of the most extensive option, Hedgerows + Riparian Buffers (All), showed the greatest impact to landscape pattern and carbon with 36 % - 711% improvement in these measures. However, these improvements were at the highest farmland area cost. Hedgerows exhibited the greatest impact to landscape pattern with the least trade-off of production area but did not store as much carbon as other NPPV options. The analysis illustrated clear trade-offs between habitat, carbon storage and production, where no specific management option maximized all three and thus recommendations should depend on objectives of stakeholders.
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Attribution-NonCommercial-NoDerivs 2.5 Canada