Monitoring must be a continuous process interspersed with evaluation events defined during the design phase and applied from before construction and throughout the operation to enable adaptive management of the infrastructure and the mitigation measures. Some specific monitoring activities provide information for determining the effectiveness, or ineffectiveness, of mitigation actions. Other monitoring activities need to be maintained for the long-term because of changes in traffic, infrastructure and landscape conditions. Such variations increase due to climate and land use change and must be assessed to undertake corrective actions or adaptation of the infrastructure to increase its resilience and mitigate any new impacts in biodiversity.
The content of this chapter focuses on two specific goals:
- Identifying the real impact of transport infrastructure on target species, habitats and ecosystems is therefore one of the main goals of monitoring and evaluation. This means that all negative impacts such as habitat loss and fragmentation, wildlife mortality, disturbance, pollution or the spreading of invasive alien species could be subject to monitoring and evaluation on long term period (even more than 10 years), as long as these impacts remain significant according to recurrent evaluation.
- Identifying whether mitigation measures fulfil their expected objectives. This may require a specific monitoring design focused on results achieved by a specific measure, or by a set of them.
In practice, the main goals for evaluation are usually:
- To identify and measure what effects are caused by the infrastructure on biodiversity by comparing the measured effects with reference and/or expected effects.
- To evaluate whether the mitigation actions applied provide long term mitigation or compensation for the species and habitats concerned.
- To detect failures in mitigation measures installation, construction or maintenance which reduce its effectiveness (see Chapter 7 – Maintenance). If failures are detected corrective measures must be applied and also evaluated to identify if they are being effective.
Appropriate monitoring and evaluation along the infrastructure life cycle is therefore crucial to achieve the following benefits:
- Ensuring long term viability of wildlife populations and the preservation of healthy ecosystems and the services they provide.
- Improving future design and maintenance of transport infrastructure, identifying actions with an optimal cost-effectiveness ratio and avoiding the repetition of mistakes and use of ineffective measures.
- Ensuring a more efficient use of funds invested to mitigation measures.
Evaluating the impact of transport infrastructure on biodiversity
Evaluating the impact of transport infrastructure on nature using monitoring means defining clear goals and methods to be applied and collecting data on habitats and on the presence, abundance and diversity of species and populations before construction, during construction and, at least, in the first phases of operation (e.g., in some EU countries monitoring is mandatory over a period of 3 years but long term monitoring could be needed in some conditions).
Monitoring continues the biological survey process carried out during the planning phase (EIA, documentation for planning and building proceedings) and provides the results for further evaluation after a longer period of operation (3, 5, 10 years or longer). The description of changes in ecosystems, habitats and distribution and density of species during the design, construction, and operation provides information about the effects of transport infrastructure on wildlife. Ideally, it is necessary to consider all relevant groups of species as well as habitats when proposing a monitoring plan. However, this is usually not possible for several reasons, such as lack of time, budget, etc. In these cases, the monitoring can be focused on the more representative or threatened groups as ‘proxy’, such as endangered target species or habitats of community interest. In any case, monitoring should include as many groups as possible to be accurate and representative.
Evaluating the impact of transport infrastructure on nature is a complex task which often requires using metrics on biodiversity state, but also other considerations such as meteorological data or information about the socio-economic transport infrastructure surrounding which may affect biodiversity independently or in interaction with other transport infrastructures (cumulative effects). If relevant, the way to collect existing data from external monitoring programmes such as meteorological surveys must also be considered or complemented if it is not sufficient or missing during the monitoring program duration (see Chapter 4 – Integration of infrastructure into the landscape for some examples).
Evaluating the effectiveness of mitigation measures
Measures to ensure the permeability of transport infrastructure for fauna and to reduce wildlife mortality (such as wildlife passages combined with fencing) are considered by many countries in recent decades as standard for most transport infrastructure projects. However, verification of whether the measures fulfil their purpose is often missing, poorly undertaken, or carried out with inadequate methods which lead to non conclusive results. These gaps in information are caused mostly by not clearly setting goals for mitigation, which results in no possibilities to undertake appropriate assessment of mitigation success. Authorities responsible for infrastructure design and construction usually perceive the implementation of mitigation measures as a formal obligation and do not prioritise monitoring their effectiveness. Consequently, failures in measures implemented go undetected and measures which are not fulfilling their purpose are often applied elsewhere. Defining outcome-based specifications for mitigation measures, namely establishing the results to be achieved by applying those measures instead of defining the measure to be applied (i.e., maintaining ecological connectivity versus building a wildlife passage), can contribute to prevent this issue. In any case, it is necessary to establish KPIs allowing an effective evaluation. A key objective of evaluating effectiveness is to provide feedback to avoid errors and malfunctions.
Examples of goals for monitoring the effectiveness of implemented measures could be to evaluate:
- differences in wildlife crossing rates before and after road construction;
- effects of wildlife passages on population size (which requires additional information on population size);
- reduction of number of wildlife vehicle collisions after the installation of fences or after using wildlife deterrents;
- reduction of bird mortality from the application of measures to prevent collisions with powerlines.
Monitoring and evaluating the effectiveness of mitigation measures must be based on the identification of an initial state or biodiversity baseline which provides sufficiently precise information and is adapted to the context that will exist after the installation of the measure being evaluated. Measuring the effectiveness of fauna passages, for example, is often only focused on providing list of the species that use the passage along with daily or monthly figures. In this case, there will be little data to assess whether the number of individuals using the structure can guarantee a long-term conservation of a target species’ population. If the effectiveness of a wildlife passage at population level is to be measured in terms of gene flow, then the genetics of the populations on either side of the crossing must be assessed before the fauna passage is built, and after its construction for a period of time appropriate to the longevity of the species concerned.
Monitoring changes induced by transport infrastructure on the landscape
Monitoring the integration of transport infrastructure on the landscape should be done by monitoring the different compartments underpinning the landscape dynamics. This chapter is dedicated to biodiversity monitoring in the context of transport infrastructure mitigation measure efficiency evaluation. As a complement, this section focuses on landscape scale monitoring systems, including not only biodiversity but also other components of landscapes, such as their social, cultural and economic dimensions (for more details, see Chapter 4 – Integration of infrastructure into the landscape).
Monitoring the landscape structure
A suitable method to monitor landscape dynamics during the transport infrastructure life cycle are pictures and aerial photos. Repeated pictures of an area or construction in regular intervals provide information of large-scale landscape dynamics, e.g., urban development, forest growth and expansion, amongst other. Complementarily, time series of tangential photogaphs on chosen sitehighlights the local-scale dynamics contributing to understand the causal relationships between landscape dynamics and its underpinning processes.
Monitoring ecological connectivity
Previous sections are dealing with monitoring systems devoted to assessing the efficiency of mitigation measures. However, it is also possible to estimate changes in population functioning of target species at landscape level. Several monitoring process can be undertaken depending on the expected conservation targets. Some examples are:
- Mapping species distribution along time which contributes to estimate if transport infrastructure influences species presence or absence but provides little information about the actual connectivity.
- Capture Mark Recapture (CMR) surveys which allow to determine animal movements between core habitats of an ecological network and to assess the role of TI on the demographic structure of the surveyed species.
- Genetic surveys can measure and map genetic connectivity at large scale. Similarly to CMR surveys, these surveys can be implemented to assess the effect of transport infrastructure on the surveyed species’ genetic structure.
Monitoring socio-cultural dynamics and economic impacts
Transport infrastructures are often presented as a driver to improve citizen quality of life and to support local economy. Local observatories monitoring both life quality and economic changes related to transport infrastructure could be developed. Besides their respective specific indicators, these observatories should include how Habitat-related to Transport Infrastructure (HTI) benefit both landscape dimensions, i.e., providing environmental services that contribute to benefit life quality or local economy, such as improving landscape aesthetic or enhancing pollinator´s activity.
Similarly, observatories of life quality can be developed to follow the socio-cultural changes induced by the infrastructure exploitation in a territory. Such observatory would also include under the umbrella of the transport infrastructure its environmental asset and how they are integrated into the day-to-day life.
Integrated landscape monitoring
An ideal solution would be to combine these monitoring approaches under a common umbrella and implementing an integrated landscape monitoring framework considering environmental, socio-cultural and economic aspects. This multistakeholder approach contributes to conduct a comprehensive assessment of the impacts and opportunities that transport infrastructure can bring upon a territory.