Habitat Equivalency Analysis Research Articles

Challenges in Using Habitat Equivalency Analysis for Scaling Compensatory Restoration

ABSTRACT Some oil spills cause losses of ecological services in coastal wetlands, other shoreline environments, intertidal ecosystems, and upland environments. In the United States, habitat equivalency analysis (HEA) is being used frequently in natural resource damage assessments for such oil spills to determine the scale of compensatory-restoration projects needed to offset the ecological service losses. The cost of the scaled compensatory-restoration project(s) that offset the ecological service losses is the measure of natural resource damages for the lost ecological services. Our paper describes the HEA process and provides an example of its application. Then we examine several challenges that arise in some HEA applications, including the role of leasing versus purchasing compensatory habitat, increasing values of compensatory habitat over time due to decreasing availability, accounting for service gains from compensatory habitat in the distant future when the present value of those services is essentially zero, and addressing uncertainties in estimating HEA inputs (such as the magnitude of annual service losses and gains). The final section of our paper provides our conclusions with respect to these challenges.

Calculating resource restoration for an oil discharge in Lake Barre, Louisiana, USA.

Under the United States Oil Pollution Act of 1990, natural resource trustees are charged with assessing natural resource impacts due to an oil spill and determining the type and amount of natural resource restoration that will compensate the public for the impacts. Habitat equivalency analysis is a technique through which the impacts due to the spill and the benefits of restoration are quantified; both are quantified as habitat resources and associated ecological services. The goal of the analysis is to determine the amount of restoration such that the services lost are offset by services provided by restoration. In this paper, we first describe the habitat equivalency analysis framework. We then present an oil spill case from coastal Louisiana, USA, where the framework was applied to quantify resource impacts and determine the scale of restoration. In the Louisiana case, the trustees assessed impacts for oiled salt marsh and direct mortality to finfish, shellfish, and birds. The restoration project required planting salt-marsh vegetation in dredge material that was deposited on a barrier island. Using the habitat equivalency analysis framework, it was determined that 7.5 ha of the dredge platform should be planted as salt marsh. The planted hectares will benefit another 15.9 ha through vegetative spreading resulting in a total of 23.4 ha that will be enhanced or restored as compensation for the natural resource impacts.

Determining ecological equivalence in service-to-service scaling of salt marsh restoration.

The amount of ecological restoration required to mitigate or compensate for environmental injury or habitat loss is often based on the goal of achieving ecological equivalence. However, few tools are available for estimating the extent of restoration required to achieve habitat services equivalent to those that were lost. This paper describes habitat equivalency analysis (HEA), a habitat-based "service-to-service" approach for determining the amount of restoration needed to compensate for natural resource losses, and examines issues in its application in the case of salt marsh restoration. The scientific literature indicates that although structural attributes such as vegetation may recover within a few years, there is often a significant lag in the development of ecological processes such as nutrient cycling that are necessary for a fully functioning salt marsh. Moreover, natural variation can make recovery trajectories difficult to define and predict for many habitat services. HEA is an excellent tool for scaling restoration actions because it reflects this ecological variability and complexity. At the same time, practitioners must recognize that conclusions about the amount of restoration needed to provide ecological services equivalent to those that are lost will depend critically on the ecological data and assumptions that are used in the HEA calculation.

The Lake Barre Oil Spill Nrda: From Response To Restoration

ABSTRACT A release of approximately 6,561 barrels of crude oil from a Texaco pipeline into Lake Barre in May 1997 injured marsh, birds, and aquatic fauna. Texaco was proactive in dealing with the trustees in the Natural Resource Damage Assessment (NRDA) process and stayed directly involved throughout; resulting in a cooperative assessment. The trustees focused quickly on the key injuries that required assessment. There was early agreement to conduct a cooperative, restoration-based NRDA, and to design field studies for the injured marsh to provide inputs for scaling using habitat equivalency analysis (HEA). It also was agreed that for this incident, field studies to assess bird and aquatic faunal injury would not be cost-effective or likely improve the accuracy of injury estimates. Although agreement on a common quantification approach for faunal injury was not reached, the two sides agreed on how much restoration was appropriate. The parties developed an extensive list of restoration alternatives, and although the trustees retained the final decision making authority, there were no significant disagreements on how various alternatives ranked according to restoration selection criteria. The selected project is planting saltmarsh vegetation on a platform of dredged material placed on East Timbalier Island by the Coastal Wetland Planning, Protection, and Restoration Act (CWPPRA) program. No CWPPRA funds were available for planting. In scaling the restoration, Texaco will only get credit for the ecological services provided by their planting above that which would occur in the absence of planting. Factors such as erosion rates expected with and without planting and the rate of natural colonization of marsh in the absence of planting were considered in the scaling calculations. The trustees and Texaco jointly briefed attorneys for both sides throughout the NRDA process, but were not active participants in meetings regarding technical matters. These briefings ensured a quick transition from the injury assessment and restoration project selection process to settlement negotiations. A consent decree was lodged with the court in September 1999. Texaco will implement the restoration and the monitoring plan, and pay all trustee assessment and restoration oversight costs as part of the settlement.

NET ENVIRONMENTAL BENEFITS ANALYSIS TO EVALUATE MITIGATION ALTERNATIVES FOR A PIPELINE SITING

ABSTRACT A net environmental benefits analysis (NEBA) approach offers a powerful set of tools for rigorously evaluating and comparing the natural resource benefits of alternative mitigation, restoration, enhancement, and preservation actions for compensating for natural resource damages, site remediation and pipeline-siting projects, for example. Combining the results of the NEBA with an assessment of the costs of the alternative measures shows which alternative(s) achieve a net environmental benefit at least cost. NEBA uses environmental or monetary metrics to measure the change in the value of ecological services from the site under alternative actions compared to the baseline condition. This presentation describes a NEBA application to a pipeline-siting project. The approach is equivalent to evaluating compensatory restoration as part of a natural resource damage assessment (NRDA) under the Oil Pollution Act of 1990 (OPA 90). For example, under NRDA, a habitat equivalency analysis (HEA) model almost always is used in a two-sided NEBA, which sums the negative environmental benefits—interim losses—that result from the oil spill injury on the debit side and compares to the sum of the positive environmental benefits due to the compensatory restoration actions on the credit side. Most reports prepared as part of NRDAs are confidential. However, the NEBA used in the present pipeline-siting example is equivalent to how it has been applied in NRDA applications including two oil spills involving pipelines, the Colonial Pipeline Sugarland Run NRDA and the Colonial/Texaco Pipeline San Jacinto River Oil Spill. The present pipeline-siting example uses NEBA to determine the quantity of quality-adjusted acres of forested wetland that are needed to offset a loss in forested wetland acreage because of the construction and operation of the proposed pipeline.

The Cost of Certainty in Natural Resource Damage Assessment Under the Oil Pollution Act of 19901

ABSTRACT Pursuant to the Oil Pollution Act of 1990 (OPA 90), natural resource trustees are empowered to seek recovery for damages to natural resources caused by discharges of oil and/or certain threats of discharges of oil. To determine the proper amount of damages, trustees undertake the process of “scaling,” which is an attempt to calculate the size of restoration actions that would be required to expedite recovery of injured natural resources to baseline and compensate the public for interim lost resources and services. Trustees utilize various scaling methods, including service-to-service methods, such as habitat equivalency analysis, and value-to-value methods, such as hedonic price models and contingent valuation. Regardless of the method chosen, however, the scaling is directly dependent on the level of injury caused by a spill. Disputes between trustees and those parties designated as responsible for the spill (responsible parties or RPs) often occur in determining the level of injury. In many cases, as a result of either these disputes or the trustees' desire to determine the precise level of injury, trustees undertake costly and time-consuming injury studies. These studies oftentimes are inefficient because the resulting gains in certainty often are achieved through disproportionately expensive studies relative to the resulting gains in restoration. In certain instances, attempts to achieve greater certainty can destroy an otherwise efficient and cooperative restoration effort and run contrary to the OPA 90 regulations. Such attempts also can lead to costly litigation for both the public and the RP involved. Lastly, attempts to achieve greater certainty during injury assessment can unnecessarily increase the scale of compensatory restoration because of delays in implementing restoration actions. Both trustees and RPs must recognize those instances in which achieving greater certainty leads to increased costs to both the public and the RP. In such situations, stipulating to certain injury assumptions can lead to overall net gains for both the public and the RP. These stipulations can be used to induce RPs to increase other aspects of the restoration, thereby increasing overall gains for the public at less cost to the RP.

Restoration of coastal habitats: expectation and reality

Restoration today must satisfy a wide array of societal goals. In the past, success or failure of a project was dependent on minimal, measurable criteria. Simplistic designs and compliance criteria are being replaced by technically sophisticated projects and design goals that have variable criteria for success. Instead of a being static target, success criteria can be altered through a process termed Adaptive Management. Natural resource damage can be assessed accurately through a Habitat Equivalency Analysis. Acceptable progress toward compliance criteria is best measured by trends approaching a desired end point. An approach using natural variation of similar habitats also shows promise as a means of assessing compliance. Large-scale restoration projects are underway, directly and indirectly underwritten by the public. If the public is to continue support for restoration it must be a part of the decision-making process. This can be best accomplished through landscape management plans with clear objectives and goals that the public understands and that benefit the public at large. Technical problems in accomplishing and evaluating restoration projects will be solved if the experience gained at each site is used in future projects.

Integrating biology and economics in seagrass restoration: How much is enough and why?

Although success criteria for seagrass restoration have been in place for some time, there has been little consistency regarding how much habitat should be restored for every unit area lost (the replacement ratio). Extant success criteria focus on persistence, area, and habitat quality (shoot density). These metrics, while conservative, remain largely accepted for the seagrass ecosystem. Computation of the replacement ratio using economic tools has recently been integrated with seagrass restoration and is based on the intrinsic recovery rate of the injured seagrass beds themselves as compared with the efficacy of the restoration itself. In this application, field surveys of injured seagrass beds in the Florida Keys National Marine Sanctuary (FKNMS) were conducted over several years and provide the basis for computing the intrinsic recovery rate and thus, the replacement ratio. This computation is performed using the Habitat Equivalency Analysis (HEA) and determines the lost on-site services pertaining to the ecological function of an area as the result of an injury and sets this against the difference between intrinsic recovery and recovery afforded by restoration. Joining empirical field data with economic theory has produced a reasonable and typically conservative means of determining the level of restoration and this has been fully supported in Federal Court rulings. Having clearly defined project goals allows application of the success criteria in a predictable, consistent, reasonable, and fair manner.