from external  or internal  sources—including traditional ones.

1.2.1     Agroecology, climate and natural resources
The agroecological zones in ESAP countries range from warm arid tropics to cool subtropics. This diversity is impor­tant because agricultural production systems are sensitive to local climate, soil and other biophysical attributes, making them less transferable (Pardey et al., 2006). The agroeco­logical zone determines the vegetation and the length of the growing period. ESAP has eight major agroecological zone classifications.

     ESAP has very divergent climatic zones, from temper­ate to arid. Monsoon, the region's most important climate feature, is the wind system that dominates the climate of South Asia and the area around the Indian Ocean. Differ­ential heating and cooling of landmass and oceans between summer and winter creates seasonal reversals of direction. The wind blows from the northeast, toward the sea, in win­ter—the dry monsoon—and from the southwest, toward the land, in summer—the wet monsoon (Banglapedia, 2006).
     Annual rainfall varies from over 10,000 mm in parts of the Central Highlands of Papua New Guinea to almost zero in the Gobi and Australian deserts. Likewise, across