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Dehesa Australis: Productive Oak Savannah in Australia
Byron Joel
Published May 2020 in International Oaks No. 31: 49–62
Abstract
The oak dominated, silvo-pastoral systems of the Iberian Peninsula are known collectively as dehesa (or montado in Portuguese). They represent a high-potential model for regenerative1 agricultural systems within climatically appropriate regions of Australia and beyond. The vast majority of the Australian continent is brittle2 ecosystem and in both pre- and post-colonial contexts savannah is a dominant biome type (Gammage 2011). Savannahs provide a vast suite of critical ecosystem services, notably a general mitigating of environmental extremes. These are particularly valuable in brittle environments. Furthermore, the extra-environmental yields that semi-domesticated savannah models provide result in numerous benefits to agricultural production such as increased stock animal wellbeing and significant supplementary feed sources (Vargas et al. 2013). Research also suggests that due to the hundreds of thousands of years of evolution within similar biomes, Homo sapiens has a deep genetic and cultural proclivity toward savannah systems. The resulting positive response to these environments increases psychological wellbeing in local human populations (Wilson 1984). This paper explores the dehesa model of agroforestry, arguing that such a model is one that could work in Australia and contribute to solving some of the serious environmental and food-production issues facing the country.
1 Regeneration describes a dynamic state in which a system increases its own resource base by preforming its default processes. Regenerative agriculture is the study, trial and practice of eco-agricultural systems which seek to provide humanity with all of its material needs (food, fibre, energy, etc.) while simultaneously increasing ecological function.
2 The Brittleness Scale is a simple 1-10 rating system which, more than just a reference to precipitation levels, describes the atmospheric humidity at soil level (AMSL) throughout the year. Sufficient AMSL is required throughout the seasons for soil biology to metabolise and maintain generative ecosystem functions. In brittle environments the agent of humidity is not the atmosphere itself but in fact the digestive systems of the myriad herds of large, grazing herbivores. In such brittle environments the greater wellbeing of the rangeland ecosystems is dependent on the obligate relationship between 1: the soil and the grasses and forbs it hosts, 2: the large herds of grazing herbivores and 3: the predators that prey upon the grazers thus effecting their behavior (Savory 1998).
Keywords
climatic analogue, Mediterranean Climate Regions, dehesa, silvopasture, arboretum, tree crops, pannage
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