188.8.131.52. Long-Term Adaptations
Long-term adaptations refer to major structural changes to overcome adversity
caused by climate change. These may include:
- Changes in land use result from the differential response of crops to climate
change. Studies reported by Parry et al. (1988) for central Europe show an "optimal
land use" in which the area cultivated with winter wheat, maize, and vegetables
increases while the allocation to spring wheat, barley, and potato, decreases.
Changes in land allocation also may be used to stabilize production. In this
case, crops with high interannual variability in production (e.g., wheat) may
be replaced by crops with lower productivity but more stable yields (e.g., pasture).
- Biotechnology offers another possibility to adapt to stresses (heat, water,
pests and disease, etc.) that are enhanced by climate change by allowing development
of "designer cultivars" (Goodman et al., 1987)-considering strictly the principles
of biosafety to avoid possible negative impacts of this technique. Species that
have not been used previously for agricultural purposes may be identified and
others already identified may be more quickly brought into use.
- Crop substitution
also may be useful for conservation of soil moisture. Some crops use a low amount
of water and are more water- and heat-resistant, so they tolerate dry weather
better than others do. For example, sorghum is more tolerant of hot and dry
conditions than maize.
- Microclimate modification may be used to improve WUE
in agriculture. Windbreaks, for example, reduce evaporative demand from the
plants they shelter. Sheltered plants remain better hydrated and thus are better
able to carry out photosynthesis (Rosenberg, 1979). A wide array of intercropping,
multi-cropping, relay cropping, and other techniques provide greater production
per unit area occupied and can be useful to improve WUE. Irrigation efficiency
can be improved considerably with new land-field techniques (laser-leveling
of fields, minimum tillage, chiseling compacted soils, stubble mulching, etc.)
or new management strategies (irrigation scheduling, monitoring soil moisture
status, etc.) (Kromm and White, 1990).
- Changes in farming systems may be necessary
in some areas for farming to remain viable and competitive. Specialized arable
farms with production of vegetables, cereals, seed crops, fruits, and other
crops often have only a few species on the farm, depending on soil and climate
conditions. These specialized farms, especially dairying and arable, may be
more affected by climate change than mixed farms. Mixed farms with both livestock
and arable production have more options for change and thus larger resilience
to change in the environment.
Studies on adapting farming systems to climate change need to consider all
of the agronomic decisions made at the farm level (Kaiser et al., 1993). Economic
considerations are very important in this context (Antle, 1996). Results of
farm-level analyses on the impacts of climate change generally have shown a
large reduction in adverse impacts when adaptation is fully implemented. However,
this will result in land-use changes (Parry et al., 1999).