Important ecological processes happen over long periods of time and at the landscape scale. Effective conservation of biodiversity and management of natural resources and ecosystem services requires an understanding of these processes. Unfortunately, it is often impractical to conduct appropriate long-term, landscape-scale studies. Modelling offers an alternative approach. Complete ecosystems are too complex to model practically, but simulations of simplified systems provide useful insights of practical value. LandBaSE-P is an individual-based model for Puya hamata that provides information about impacts of fire on ecological processes in the páramo of the Reserva Ecológica El Ángel, Ecuador. Puya hamata is a flagship plant affected by fires and plays a key role in a number of ecological processes. This research found Puya hamata germinated much more frequently after fires, can form large aggregations of single recruitment cohorts, suffers very low mortality (with and without fires) once established, and lives up to 28 years. The spatial aggregation of Puya hamata plants reduced effective reproductive output, consistent with the theory that pollinator behaviour around large groups of Puya plants reduces cross-pollination, leading to inbreeding depression and poorer seed viability and germination. Puya hamata’s population structure can be an indicator of recent fire regime. LandBaSE-P simulations showed that population size is not affected by rare, long-distance seed dispersal. However, in the simulations of páramo grasslands, Puya relative germination is maintained in high numbers by burning. Puya hamata has an important role in ecology and biodiversity. The model LandBaSE-P is a complementary tool for conservation and sustainable land management. This thesis shows how fieldwork combined with laboratory studies and modelling, can provide a good understanding of complex dynamics of real-world populations, and generate ideas for management and future research.

Current models of rangeland system dynamics were evaluated in Cosapa, a pastoral community on the Bolivian altiplano. Two specific models were tested: the "equilibrium" model, which assumes biotic interactions dominate rangeland dynamics and lead to system stability , and the "nonequilibrium" model, in which stochastic, abiotic factors control systems such that equilibrium is never attained. A livestock development project (called "Project Alpaca ") working in the community was then assessed in terms of how its assumptions of system dynamics compared with empirical findings. The goal of Project Alpaca was to increase incomes for camelid (i.e., llama and alpaca) herders on the Bolivian altiplano by improving the processing, production, and marketing of alpaca wool. Project implementation was carried out by an indigenous herders' association, with funds provided for construction of a modern alpaca wool processing plant and technical interventions at the farm level. Specific research objectives were to determine which conceptual model of system dynamics (equilibrium or nonequilibrium) best approximated the vegetation and livestock dynamics in Cosapa, and determine the impacts of technical innovations introduced by Project Alpaca . Vegetation dynamics were assessed by comparing plant species composition and production between grazed and ungrazed sites. Pastoral management strategies, livestock population dynamics between 1982 to 1995, and project impacts were assessed using a household survey. Results from the vegetation analyses showed that grazing protection had little impact on plant productivity, but reduced species diversity in wetland areas. The vegetation thus exhibited nonequilibrial characteristics. Regarding livestock dynamics, populations were relatively stable (over 13 years), although mortality was affected by severe drought, suggesting a combination of equilibrial and nonequilibrial interactions . Project Alpaca assumed an equilibrium model by emphasizing system stability and production maximization. The technical interventions showed positive, negative, and neutral associations with animal productivity. Construction of fenced exclosures on communal land has increased conflicts over land tenure rights, and may marginalize poorer households and increase social stratification . Development recommendations include shifting efforts away from intensification interventions that limit movement and flexibility, and strengthening social and economic networks that buffer the impacts of system variability.

Current models of rangeland system dynamics were evaluated in Cosapa, a pastoral community on the Bolivian altiplano. Two specific models were tested: the "equilibrium" model, which assumes biotic interactions dominate rangeland dynamics and lead to system stability , and the "nonequilibrium" model, in which stochastic, abiotic factors control systems such that equilibrium is never attained. A livestock development project (called "Project Alpaca ") working in the community was then assessed in terms of how its assumptions of system dynamics compared with empirical findings. The goal of Project Alpaca was to increase incomes for camelid (i.e., llama and alpaca) herders on the Bolivian altiplano by improving the processing, production, and marketing of alpaca wool. Project implementation was carried out by an indigenous herders' association, with funds provided for construction of a modern alpaca wool processing plant and technical interventions at the farm level. Specific research objectives were to determine which conceptual model of system dynamics (equilibrium or nonequilibrium) best approximated the vegetation and livestock dynamics in Cosapa, and determine the impacts of technical innovations introduced by Project Alpaca . Vegetation dynamics were assessed by comparing plant species composition and production between grazed and ungrazed sites. Pastoral management strategies, livestock population dynamics between 1982 to 1995, and project impacts were assessed using a household survey. Results from the vegetation analyses showed that grazing protection had little impact on plant productivity, but reduced species diversity in wetland areas. The vegetation thus exhibited nonequilibrial characteristics. Regarding livestock dynamics, populations were relatively stable (over 13 years), although mortality was affected by severe drought, suggesting a combination of equilibrial and nonequilibrial interactions . Project Alpaca assumed an equilibrium model by emphasizing system stability and production maximization. The technical interventions showed positive, negative, and neutral associations with animal productivity. Construction of fenced exclosures on communal land has increased conflicts over land tenure rights, and may marginalize poorer households and increase social stratification . Development recommendations include shifting efforts away from intensification interventions that limit movement and flexibility, and strengthening social and economic networks that buffer the impacts of system variability.