A key technique in agroecology and promotion of agrodiversity is the identification and creation of microclimates: localised areas with distinctive conditions, for example of temperature, humidity, or exposure to sun or wind. Species and varieties that could not grow productively in the wider climate might flourish in a favourable microclimate, allowing cultivation of a wider range of crops. Microclimates also support distinctive communities of native species, increasing ecological diversity.
In the face of climate change, crops that become less well suited to new conditions may nonetheless be able to grow in specially created microclimates. Others previously restricted to specific microclimates may turn out to thrive in new conditions, allowing their cultivation on a wider scale. This is one way in which agrodiversity maintains a reservoir of crops with high collective resilience to climate change.
At Krameterhof, 1500 metres above sea level in the Austrian Alps, Sepp Holzer creates microclimates using many different techniques. Terraces and raised beds inclined towards the sun experience higher temperatures and greater intensity of sunlight. Curves in terraces, beds and paths vary this effect, creating multiple niches that favour particular species or ecological communities. Raised beds include buried organic matter that releases heat as it breaks down, elevating temperatures. Organic materials are also used as mulch, retaining water and heat at soil level. Carefully placed rocks act as reflectors and stores of heat. During the day, the south side of the rock acts as a suntrap where heat-loving plants can grow. The rock absorbs heat throughout the day and releases it at night, supporting plants that can not tolerate low temperatures. Locating rocks on the north side of ponds enhances these effects, as sunlight reflects onto the rock from the water surface. Techniques such as these allow cultivation of plants otherwise unknown at such altitudes and latitudes – including cherry, kiwi, sweet chestnut, apricots, grapes, and prickly pears – and prolong growing seasons for many others.
The Central Rocky Mountains Permaculture Institute (CRMPI), at an altitude of 2200m in the state of Colorado, USA, actively experiments in montane agriculture as a source of resilience to climate change. Its highly variegated site encompasses wide natural differences in relief and aspect, enhanced by a design plan that uses built structures to create additional microclimates. This allows onsite cultivation of crop species and varieties from all over the world, a bank of agrodiversity to support adaptation to whatever climatic conditions come to prevail. As climate change makes current practices in commercial fruit production in adjacent lowland areas inviable, mountain agriculture using novel crops and techniques will become increasingly important for regional economic, livelihood and food security.
CRMPI's greenhouses and indoor gardens house plants native to tropical, subtropical, desert and mediterranean climates, including multiple varieties of bananas, figs, grapes, apricots, apples, pears, plums, pomegranate, and edible cactus. They also extend growing seasons for temperate plants. Several technical measures retain internal temperatures conducive to plant health despite wide diurnal and seasonal variation outdoors. These include use of fan-driven heat exchangers known as climate batteries, shading and venting to reduce direct heating, and exchange of heat with other household elements. Greenhouses thus form integral elements in an overall system of bioclimatic building.
- Holzer, S., 2010 (2004). Sepp Holzer's Permaculture. East Meon: Permanent Publications.
- Bane, P., 2012. The Permaculture Handbook. Gabriola Island: New Society Publishers. Pp. 181-185. Ostentowski, J., 2015. The Forest Garden Greenhouse. White River Junction: Chelsea Green. www.crmpi.org