首页 | 本学科首页   官方微博 | 高级检索  
     


High-frequency monitoring of hydrological and biogeochemical fluxes in forested catchments of southern Chile
Authors:Cristián Frêne  Juan J. Armesto  Freddy Véliz  Fernando D. Alfaro  Kathleen C. Weathers
Affiliation:1. Ecosystem Ecology, Instituto de Ecología y Biodiversidad, Universidad de Chile, Santiago, Chile;2. Ecosystem Ecology, Instituto de Ecología y Biodiversidad, Universidad de Chile, Santiago, Chile

Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile

Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile

Ecosystem Ecology, Cary Institute of Ecosystem Studies, Millbrook, New York, USA;3. Facultad de Ciencias Agrarias, Universidad Agraria del Ecuador, Guayaquil, Ecuador;4. GEMA Center for Genomics, Ecology and Environment, Universidad Mayor, Santiago, Chile;5. Ecosystem Ecology, Cary Institute of Ecosystem Studies, Millbrook, New York, USA

Abstract:The variability of rainfall-dependent streamflow at catchment scale modulates many ecosystem processes in wet temperate forests. Runoff in small mountain catchments is characterized by a quick response to rainfall pulses which affects biogeochemical fluxes to all downstream systems. In wet-temperate climates, water erosion is the most important natural factor driving downstream soil and nutrient losses from upland ecosystems. Most hydrochemical studies have focused on water flux measurements at hourly scales, along with weekly or monthly samples for water chemistry. Here, we assessed how water and element flows from broad-leaved, evergreen forested catchments in southwestern South America, are influenced by different successional stages, quantifying runoff, sediment transport and nutrient fluxes during hourly rainfall events of different intensities. Hydrograph comparisons among different successional stages indicated that forested catchments differed in their responses to high intensity rainfall, with greater runoff in areas covered by secondary forests (SF), compared to old-growth forest cover (OG) and dense scrub vegetation (CH). Further, throughfall water was greatly nutrient enriched for all forest types. Suspended sediment loads varied between successional stages. SF catchments exported 455 kg of sediments per ha, followed by OG with 91 kg/ha and CH with 14 kg/ha, corresponding to 11 rainfall events measured from December 2013 to April 2014. Total nitrogen (TN) and phosphorus (TP) concentrations in stream water also varied with rainfall intensity. In seven rainfall events sampled during the study period, CH catchments exported less nutrients (46 kg/ha TN and 7 kg/ha TP) than SF catchments (718 kg/ha TN and 107 kg/ha TP), while OG catchments exported intermediate sediment loads (201 kg/ha TN and 23 kg/ha TP). Further, we found significant effects of successional stage attributes (vegetation structure and soil physical properties) and catchment morphometry on runoff and sediment concentrations, and greater nutrients retention in OG and CH catchments. We conclude that in these southern hemisphere, broad-leaved evergreen temperate forests, hydrological processes are driven by multiple interacting phenomena, including climate, vegetation, soils, topography, and disturbance history.
Keywords:catchment morphometry  forest succession  nutrient fluxes  rainfall events  sediments dynamics  temperate forests
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号