Hydrological Controls on Nutrient Exportation from Old-Growth Evergreen Rainforests and <i>Eucalyptus nitens</i>Plantation in Headwater Catchments at Southern Chile  

作　　者：Carlos E. Oyarzun Pedro Hervé-Fernández Dries Huygens Pascal Boeckx Niko E. C. Verhoest 

机构地区：[1]Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile [2]Laboratory of Hydrology and Water Management, Faculty Bioscience Engineering, Ghent University, Ghent, Belgium [3]Isotope Bioscience Laboratory (ISOFYS), Ghent University, Ghent, Belgium [4]Institute of Agricultural Engineering and Soil Science, Faculty of Agricultural Sciences, Universidad Austral de Chile, Valdivia, Chile [5]Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina

出　　处：《Open Journal of Modern Hydrology》2015年第2期19-31,共13页现代水文学期刊（英文）

摘　　要：Soil cover disturbances have a direct effect on biogeochemistry, potentially enhancing nutrient loss, land degradation and associated changes in ecosystem services and livelihood support. The objective of this study was to assess how canopy affected throughfall chemistry and how hydrology affected stream nutrient load responses in two watersheds dominated by native old-growth evergreen rainforest (NF) and exotic plantation of Eucalyptus nitens (EP), located at the Coastal mountain range of southern Chile (40&deg;S). We measured nitrogen (NO3-N, NH4-N, Organic-N, Total-N) and total phosphorus (Total-P) at catchment discharge, and δ18O in throughfall precipitation and stream discharge in both catchments, in order to separate throughfall (or new water) contributions during storm events. It was hypothesized that all nutrients showed an increase in concentration as discharge increased (or enhanced hydrological access), in EP;but not in NF. Our results indicated that Organic-N, Total-N and Total-P concentrations were positively related to discharge. However, NO3<sup style="margin-left:-7px;">--N showed a negative correlation with catchment discharge. Organic-N and Total-P showed a flush during storm events;the opposite was observed for NO3<sup style="margin-left:-7px;">--N. However, this behavior suggested that NO3<sup style="margin-left:-7px;">--N was being retained by charged particles or soil micro biota, whether Organic-N was flushed as it was more concentrated in big pore water that was not tightly attached, compared with NO3<sup style="margin-left:-7px;">--N.Soil cover disturbances have a direct effect on biogeochemistry, potentially enhancing nutrient loss, land degradation and associated changes in ecosystem services and livelihood support. The objective of this study was to assess how canopy affected throughfall chemistry and how hydrology affected stream nutrient load responses in two watersheds dominated by native old-growth evergreen rainforest (NF) and exotic plantation of Eucalyptus nitens (EP), located at the Coastal mountain range of southern Chile (40&deg;S). We measured nitrogen (NO3-N, NH4-N, Organic-N, Total-N) and total phosphorus (Total-P) at catchment discharge, and δ18O in throughfall precipitation and stream discharge in both catchments, in order to separate throughfall (or new water) contributions during storm events. It was hypothesized that all nutrients showed an increase in concentration as discharge increased (or enhanced hydrological access), in EP;but not in NF. Our results indicated that Organic-N, Total-N and Total-P concentrations were positively related to discharge. However, NO3<sup style="margin-left:-7px;">--N showed a negative correlation with catchment discharge. Organic-N and Total-P showed a flush during storm events;the opposite was observed for NO3<sup style="margin-left:-7px;">--N. However, this behavior suggested that NO3<sup style="margin-left:-7px;">--N was being retained by charged particles or soil micro biota, whether Organic-N was flushed as it was more concentrated in big pore water that was not tightly attached, compared with NO3<sup style="margin-left:-7px;">--N.

关 键 词：Native RAINFORESTS Exotic Plantations Nutrient Fluxes HYDROLOGICAL CONTROLS HEADWATER Catchments 

分 类 号：R73[医药卫生—肿瘤]