| Description |
Ciénegas are a type of specialized systems that are found in desert landscapes and characterized by organic-rich and waterlogged soils. The existence of these systems corresponds with stability of the hydrologic cycle in arid landscapes so that when they are active they serve as a dependable source of water, as well as provide habitats for many different native plants and organisms. Ciénega Chimeneas and Ciénega San Faustino are desert wetlands located in the Sierra de Juárez of northern Baja California. Today, both sites are ephemerally active ciénegas, but our records indicate that changes in both the timing and amount of precipitation over the last 45 kcal BP have influenced the presence and state of these systems. From ~45-13 kcal BP (during the last glacial period) enhanced winter precipitation supported a landscape that was dominated by chaparral vegetation and increased fire activity at both sites. By ~13 kcal BP, both winter and summer precipitation helped to sustain perennial ciénega complexes and decrease fire activity into the early Holocene. Like many other records throughout southwest North America, we do not have a continuous record of the mid-to-late-Holocene because climate during this time was not conducive to creating an active depositional environment. In this paper, we will discuss how fluctuating moisture sources linked to phenomena such as the modern onset of the El Niño Southern Oscillation and North American Monsoon created enhanced interannual variability that altered sedimentation and productivity at our sites during this time. Our study of ciénega activity in northern Baja California indicate how these systems are sensitive to abrupt changes in precipitation and periods of increased climatic variability. Our findings will provide land managers with critical information about when and where changes in the seasonality of precipitation have occurred and how changes in the available moisture sources have influenced this region's climate and landscape over the last ~45 kcal BP. |
