Random forests as cumulative effects models: A case study of lakes and rivers in Muskoka, Canada
Cumulative effects assessment (CEA) ― a type of environmental appraisal ― lacks effective methods for modeling cumulative effects, evaluating indicators of ecosystem condition, and exploring the likely outcomes of development scenarios. Random forests are an extension of classification and regressio...
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| Published in: | Journal of environmental management Vol. 201; pp. 407 - 424 |
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| Main Authors: | , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
England
Elsevier Ltd
01-10-2017
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Cumulative effects assessment (CEA) ― a type of environmental appraisal ― lacks effective methods for modeling cumulative effects, evaluating indicators of ecosystem condition, and exploring the likely outcomes of development scenarios. Random forests are an extension of classification and regression trees, which model response variables by recursive partitioning. Random forests were used to model a series of candidate ecological indicators that described lakes and rivers from a case study watershed (The Muskoka River Watershed, Canada). Suitability of the candidate indicators for use in cumulative effects assessment and watershed monitoring was assessed according to how well they could be predicted from natural habitat features and how sensitive they were to human land-use. The best models explained 75% of the variation in a multivariate descriptor of lake benthic-macroinvertebrate community structure, and 76% of the variation in the conductivity of river water. Similar results were obtained by cross-validation. Several candidate indicators detected a simulated doubling of urban land-use in their catchments, and a few were able to detect a simulated doubling of agricultural land-use. The paper demonstrates that random forests can be used to describe the combined and singular effects of multiple stressors and natural environmental factors, and furthermore, that random forests can be used to evaluate the performance of monitoring indicators. The numerical methods presented are applicable to any ecosystem and indicator type, and therefore represent a step forward for CEA.
•Random forests were used to model biological and chemical attributes of lakes and rivers.•The best biological model explained 75% of the variance in an a multivariate index of community structure.•The best chemical model explained 76% of the variance in the conductivity of river water.•Random forests allow effects of multiple environmental factors to be understood collectively and individually.•Random forests can be used to evaluate indicators and explore consequences of development scenarios. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0301-4797 1095-8630 |
| DOI: | 10.1016/j.jenvman.2017.06.011 |