More than 61 million km2 (40%) of the planet's surface experiences dry seasonal climates (Miles et al. 2006; Portillo-Quintero and Sánchez-Azofeifa 2010). Colombia has a 1.14 million km2 continental extension, 245,342 km2 of which are dry ecosystems ranging from arid to semiarid and subhumid dryCONTENTS3.1 Introduction ..................................................................................................35 3.2 Dry Forests in Colombia ............................................................................. 37 3.3 Upper Magdalena River Valley's Dry Forest: Biophysical Aspects ...... 413.3.1 Climatological Aspects ................................................................... 41 3.3.2 Physiography and Soils ...................................................................42 3.3.3 Soil Degradation ..............................................................................43 3.3.4 Managing the Region's Soils ..........................................................43