Response to Critique of "The Insignificance of Thresholds in Environmental Impact Assessment: An Illustrative Case Study in Canada".

Our paper, "The Insignificance of Thresholds in Environmental Impact Assessment: An Illustrative Case Study in Canada" received a critique that challenged us on a number of grounds. Namely, that we defame EIA practitioners, that we advocate EIAs to become a scientific enterprise, that we do not recognize the complexity inherent in EIA, and that EIA undergo an independent assessment by regulators. We respond to all of these points, and argue that conflict of interest is an institutional issue (not one of corrupt practitioners), and that we critique the science that forms the basis of evidence in EIA. Further, we show that the complexity and uncertainty in the critique cannot explain the findings from our paper that all cases of impact threshold exceedance were determined to be not significant in EIA. Finally, we compare the significance determinations in proponent reports to final regulator decisions and determine that they are overwhelmingly identical (93-95%). Regulators are financially independent of proponents, but their decisions on significant are heavily dependent on the information and analysis provided by the proponent reports. As regulators rely on these reports, environmental impact assessments must be based on rigorous and transparent analysis.

The Insignificance of Thresholds in Environmental Impact Assessment: An Illustrative Case Study in Canada.

Environmental assessment is the process that decision-makers rely on to predict, evaluate, and prevent biophysical, social, and economic impacts of potential project developments. The determination of significance in environmental assessment is central to environmental management in many nations. We reviewed ten recent environmental impact assessments from British Columbia, Canada and systematically reviewed and scored significance determination and the approaches used by assessors, the use of thresholds in significance determination, threshold exceedances, and the outcomes. Findings of significant impacts were exceedingly rare and practitioners used a combination of significance determination approaches, most commonly relying upon reasoned argumentation. Quantitative thresholds were rarely employed, with less than 10% of the valued components evaluated using thresholds. Even where quantitative thresholds for significance were exceeded, in every case practitioners used a variety of rationales to demote negative impacts to non-significance. These reasons include combinations of scale (temporal and spatial) of impacts, an already exceeded baseline, model uncertainty and/or substituting less stringent thresholds. Governments and agencies can better protect resources by requiring clear and defensible significance determinations, by making government-defined thresholds legally enforceable and accountable, and by requiring or encouraging significance determination through inclusive and collaborative approaches.

Morphophysiological differences in leaves of Lavoisiera campos-portoana (Melastomataceae) enhance higher drought tolerance in water shortage events.

Lavoisiera campos-portoana Barreto (Melastomataceae) has two kinds of leaves, pubescent and glabrous, and branches may have one or both types of leaves at the same moment. The plant is endemic to high altitude rocky fields in Brazil where rainfall is very seasonal. We predicted that these two leaf types are adaptations to different regimes of water availability. In experimental conditions of drought stress, we measured relative water content (RWC), photosynthetic pigments, chlorophyll a fluorescence and osmotic potential, and we counted stomates and measured stomatal conductance on both sides of leaves and compared these between the two leaf types. Stomatal conductance and electron transport rate at a given photosynthetic photon flux were greater in pubescent leaves than in glabrous leaves, and both declined during drought stress. Excessive photon flux density in glabrous leaves was greater during stress and after rehydration. Photosynthetic pigment content and RWC did not change between leaves, and values reduced during the stress period. Both types of leaves showed osmotic adjustment capacity, which occurred earlier in glabrous ones. These morphophysiological differences highlight the adaptation strategies of this plant to withstand drought, since the glabrous portion of the plant presents a preventive behavior, while the pubescent portion only shows the same responses in more advanced stages of drought stress.