Document Detail


Tree-based modeling of complex interactions of phosphorus loadings and environmental factors.
MedLine Citation:
PMID:  19324395     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Phosphorus (P) enrichment has been observed in the historic oligotrophic Greater Everglades in Florida mainly due to P influx from upstream, agriculturally dominated, low relief drainage basins of the Everglades Agricultural Area (EAA). Our specific objectives were to: (1) investigate relationships between various environmental factors and P loads in 10 farm basins within the EAA, (2) identify those environmental factors that impart major effects on P loads using three different tree-based modeling approaches, and (3) evaluate predictive models to assess P loads. We assembled thirteen environmental variable sets for all 10 sub-basins characterizing water level management, cropping practices, soils, hydrology, and farm-specific properties. Drainage flow and P concentrations were measured at each sub-basin outlet from 1992-2002 and aggregated to derive monthly P loads. We used three different tree-based models including single regression trees (ST), committee trees in Bagging (CTb) and ARCing (CTa) modes and ten-fold cross-validation to test prediction performances. The monthly P loads (MPL) during the monitoring period showed a maximum of 2528 kg (mean: 103 kg) and maximum monthly unit area P loads (UAL) of 4.88 kg P ha(-1) (mean: 0.16 kg P ha(-1)). Our results suggest that hydrologic/water management properties are the major controlling variables to predict MPL and UAL in the EAA. Tree-based modeling was successful in identifying relationships between P loads and environmental predictor variables on 10 farms in the EAA indicated by high R(2) (>0.80) and low prediction errors. Committee trees in ARCing mode generated the best performing models to predict P loads and P loads per unit area. Tree-based models had the ability to analyze complex, non-linear relationships between P loads and multiple variables describing hydrologic/water management, cropping practices, soil and farm-specific properties within the EAA.
Authors:
S Grunwald; S H Daroub; T A Lang; O A Diaz
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-03-25
Journal Detail:
Title:  The Science of the total environment     Volume:  407     ISSN:  0048-9697     ISO Abbreviation:  Sci. Total Environ.     Publication Date:  2009 Jun 
Date Detail:
Created Date:  2009-04-28     Completed Date:  2009-06-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0330500     Medline TA:  Sci Total Environ     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  3772-83     Citation Subset:  IM    
Affiliation:
Soil and Water Science Department, University of Florida, McCarty Hall 2169, Gainesville, Fl 32611, USA. sabgru@ufl.edu
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MeSH Terms
Descriptor/Qualifier:
Agrochemicals / analysis*
Environmental Monitoring / methods*
Models, Statistical*
Phosphorus / analysis*
Regression Analysis
Water Pollutants, Chemical / analysis
Chemical
Reg. No./Substance:
0/Agrochemicals; 0/Water Pollutants, Chemical; 7723-14-0/Phosphorus

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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