congresos y reuniones científicas
Land use planning in dynamic landscapes: a case study for northern Patagonian forests
Campos de Jordao, Brasil
Congreso; 2009 Latin American IALE Conference; 2009
Institución organizadora:
<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Land use planning is an effort to organize conflicting human activities (such as production, conservation, restoration and urbanization) within a given landscape. In regions with high conversion rates that appear to be unidirectional (e.g. native forests converted to agriculture or urbanization), the potential distribution of natural communities is given little importance, and efforts are centered on protecting the most valuable areas of remaining “pristine” forests. However, the intensity of human activities has varied over longer periods, so that drastic changes in historical land use may induce lagged legacy effects on landscapes. These effects constitute an additional force influencing current processes of landscape change and consequently land use planning decisions.   Northern Patagonian forests have witnessed major changes in land use during the last 150 years that are reflected in current landscape patterns. Perhaps, the most striking change has been a major shift in fire regimes caused by the demise of aboriginal culture along the forest-steppe ecotone; and the colonization of native forests by Euro-Argentineans. These historic events have induced an initial increase in fire frequency and grazing followed by a century-long sharp reduction of fire occurrence in the region.  We hypothesized that north Patagonian landscapes are still responding to past land use changes and that these lagged responses are conditioning our land use planning decisions.        To test this hypothesis, we combined an analysis of land use change patterns over a period of 1914-2003 with analyses of potential distribution of dominant species of the northern Patagonian forests. Specifically, we tested whether major land cover transitions were accurately predicted by species distribution envelopes. Additionally, we assessed the value of these spatial models in the resolution of land use conflicts.   Northern Patagonian landscapes display an evident pattern of natural afforestation during the last century, characterized by a replacement of cover types dominated by resprouting fire tolerant species by types dominated by obligate seed dispersed fire intolerant longer lived species. Second, current distribution of major forest types comprise a low fraction of their potentially highly suitable area, thus indicating that the natural afforestation is an ongoing process in the landscape. We propose that models of potential distribution of native forest types can help us in planning new land uses such as afforestation with exotic conifers by determining areas of potential conflict between conservation, restoration, management of native forests and conversion to forest plantations. Landuse policy should integrate and balance processes of current “active” conversion with “passive” landscape processes related to landscape legacies. Methodologies that combine analyses of long term landscape change and species distribution models may help go into this direction.