Living on a precipice-the mountains

Mountains provide most of the world's people with fresh water and a substantial portion of their timber and minerals.²⁴ They shelter more than half the world's biodiversity and nurture varied cultures in a wide range of latitudes, from the polar regions to the temperate, subtropical, and tropical zones (figure 4.4). But their slope, altitude, relief, temperature, isolation, and rainfall make them one of the most highly variable and differentiated ecosystems. The concentration of people dispersed in many small communities in rugged areas has implications for their subsistence and for the sustainability of mountain production systems. Agricultural potential in mountains is limited by the small size of arable plots, climatic variability, and more difficult growing conditions, including shorter growing seasons, which contribute to higher levels of poverty. The people living in these fragile areas are surviving by deftly managing the mosaic of land available to them.²⁵