Manejar los ecosistemas para enfrentar el cambio climático

Notas del editor

• #6: Important to differentiate between products as safety nets for coping strategies and products as a major source of livelihood diversification for adaption strategies
• #7: Malawi: while farmers not practicing agroforestry experienced crop failure. Mexico: Coffee is very sensitive to microclimate fluctuations – for example, the optimal temperature range for Arabica coffee is 18– 21°C. Shade trees control temperature and humidity fluctuations and can also provide protection from wind and storm events that defoliate coffee trees. In Chiapas, Mexico, research in coffee systems showed that shade decreases temperature and humidity fluctuations and reduces vulnerability to water stresses.
• #8: In Flores, Indonesia, tropical forested watersheds have been shown to increase base flow (i.e. the proportion of stream flow coming from groundwater in the absence of rainfall) and reduce the impacts of drought on downstream agrarian communities. Under irregular rainfall, agricultural households in the proximity of forested watersheds have higher profits than other households. In the Philippines, the loss of lives and widespread economic damage due to tropical cyclones in 2004 were attributed to deforestation among other factors. The heavy rains caused landslides and debris flows from mountainous areas, and also river overflows, dam breaks and flooding. Impacts were exacerbated by the lack of forests on the slopes and watersheds to retain the soil and reduce peak flood flows.
• #9: In Vietnam, economic valuations showed that planting mangroves on the seaward side of sea dykes reduced the costs of maintaining these defenses, as mangroves dissipate destructive wave energy, stabilise the sea floor and its slope, and trap sediment.The annual benefits of mangrove restoration for dyke protection were estimated to be $70–130 per ha/year
• #10: Due to their altered surface covers, where built areas have replaced vegetation, urban areas face increased rates and volume of surface runoff. Modelling has shown that adding green cover in Manchester, UK, has the potential to reduce runoff during rainfall events. Urban heat islands UHI occur due to urban surfaces, such as concrete, brick, asphalt and stone which absorb short-wave solar radiation and then re-radiate it as long-wave radiation. In New Jersey, USA, urban trees are shown to reduce both the direct (e.g. heat stress) and indirect impacts of UHI (e.g. health impacts from air pollution). Areas with mature tree canopies can be 2.7–3.3°C cooler than areas with no trees. Trees are a better option than grasslands for greening urban areas because they are less sensitive to drought. In general, urban green spaces are very effective in reducing temperatures but cannot act as a stand-alone solution for reducing runoff. Other measures might be needed.
• #11: Tropical forests can have a cooling effect in the region through increased evaporation and cloud cover and influence precipitations through water pumping and rainfall recycling. Current estimates are that about 40% of rainfall over land masses originates from evapotranspiration over land. This influence can be over large distances: land-use change in the humid tropics can influence precipitation in the middle and higher latitudes. E.g. maps of atmospheric moisture transport suggest that virtually all water transpired by trees in East Africa will come back as rainfall elsewhere in Africa