title: Alternative stable states and the sustainability of forests, grasslands, and agriculture.
abstract: Endangered forest-grassland mosaics interspersed with expanding agriculture and silviculture occur across many parts of the world, including the southern Brazilian highlands. This natural mosaic ecosystem is thought to reflect alternative stable states driven by threshold responses of recruitment to fire and moisture regimes. The role of adaptive human behavior in such systems remains understudied, despite its pervasiveness and the fact that such ecosystems can exhibit complex dynamics. We develop a nonlinear mathematical model of coupled human-environment dynamics in mosaic systems and social processes regarding conservation and economic land valuation. Our objective is to better understand how the coupled dynamics respond to changes in ecological and social conditions. The model is parameterized with southern Brazilian data on mosaic ecology, land-use profits, and questionnaire results concerning landowner preferences and conservation values. We find that the mosaic presently resides at a crucial juncture where relatively small changes in social conditions can generate a wide variety of possible outcomes, including complete loss of mosaics; large-amplitude, long-term oscillations between land states that preclude ecosystem stability; and conservation of the mosaic even to the exclusion of agriculture/silviculture. In general, increasing the time horizon used for conservation decision making is more likely to maintain mosaic stability. In contrast, increasing the inherent conservation value of either forests or grasslands is more likely to induce large oscillations-especially for forests-due to feedback from rarity-based conservation decisions. Given the potential for complex dynamics, empirically grounded nonlinear dynamical models should play a larger role in policy formulation for human-environment mosaic ecosystems.
authors.affiliation: School of Environmental Sciences, University of Guelph, Guelph, ON, Canada N1H 2G1.
authors.forename: Kirsten A
authors.initials: KA
authors.lastname: Henderson
authors.affiliation: Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
authors.forename: Chris T
authors.initials: CT
authors.lastname: Bauch
authors.affiliation: School of Environmental Sciences, University of Guelph, Guelph, ON, Canada N1H 2G1; manand@uoguelph.ca.
authors.forename: Madhur
authors.initials: M
authors.lastname: Anand
mesh_terms: D000383:Agriculture / Q000379:methods*; D000465:Algorithms; D044822:Biodiversity; D001938:Brazil; D002980:Climate; D003247:Conservation of Natural Resources; D004463:Ecology; D065928:Forests; D065948:Grassland; D006801:Humans; D017711:Nonlinear Dynamics; D011157:Population Dynamics; D012919:Social Behavior; D014197:Trees
keywords: Human–environment coupling; ecosystem services valuation; forest–grassland mosaics; southern Brazil