Strategies to enhance biodiversity at SECIL. Outão Plant, a unique case study

By Alexandra Silva, Corporate Technical Centre, SECIL


Extraction activities have a profound impact on the landscape and on biodiversity. As the natural regeneration of these areas and the restoration process of ecosystems may take hundreds of years, it is important to minimize these impacts and accelerate the process of natural colonization, especially in areas of high conservation value. This can be achieved by developing programmes to recover the structure and functioning of plant and animal communities, and the original ecosystems, that are not aimed solely at restoring the aesthetic qualities of the landscape.

SECIL-Outão plant is located within a Natural Park and a Natura 2000 site, south-west Portugal. The exploitation area covers about 99 ha, which includes two active quarries, one for limestone and one for marl. Both quarries and the cement plant are surrounded by natural areas, which cover about 425 ha.


Landscape Rehabilitation Plan and Biodiversity Action Plan

Resource exploitation started from top to bottom in both quarries, leaving a set of benches available for restoration after exploitation. The process of progressive revegetation began in 1983 aimed at recreating the natural habitats surrounding the quarries, dominated by Mediterranean sclerophyllous vegetation, using various techniques:

  • Reintroduction of substrate to facilitate plant development.

  • Introduction of herbaceous and shrub vegetation by hydroseeding.

  • Encouraging the development of native species (through planting) produced in the plant´s own nursery.

During the 36 years of this revegetation programme, habitats have been established with different plant communities, ages and cover in a restored area of 44 ha.

SECIL Quarries

SECIL Quarries

SECIL has adopted an ecological approach using native species in the revegetation of the quarries, which helps to accelerate the colonization of these areas, thus improving the self-sustainability of the ecosystem and its resilience as well as promoting spontaneous colonization by plant and animal species.

The native species used in revegetation are produced in the plant’s own nursery. Since 1983 the company has invested in creating its own nursery, where 17 native species are currently grown. All the seeds used in germination processes are collected in the natural areas surrounding the quarries, which secures the genetic resources, as well as the local biodiversity, especially in areas of high biodiversity value.


  • Adapted to the Mediterranean climate and soils.

  • Drought resistance strategies (leaves, roots, water use), mainly evergreen sclerophyllous species.

  • Resistance and resilience to disturbance (fire, grazing).

scientific partnerships

Scientific knowledge and applied research are important pillars in the process of restoration in SECIL's quarries. Carrying out scientific studies and communication within multidisciplinary teams is essential for the identification of innovative solutions and the development of new techniques.

Since 1998 an extensive team of researchers from the Faculty of Sciences of the University of Lisbon (FCUL) has been scientifically monitoring the restored areas. The team’s studies focus not only on vegetation, but also on soil quality.

Based on continuous evaluation, research and implementation, within a framework of several projects, FCUL´s team has carried out a scientific follow up of the revegetation of Outão´s quarries.

Main objectives of these projects:

  • Optimize the cost-benefit ratio;

  • Optimize ongoing revegetation techniques;

  • Asses the success of ecological restoration in line with the ecological attributes produced by the Society for Ecological Restoration (SER);

  • Obtain biological and ecological information on Mediterranean species with the potential to colonize degraded areas;

  • Contribute to accelerating the succession processes, thus promoting the development of the structure and functioning of the ecosystems;

  • Evaluate the services provided by the new ecosystems and define reliable indexes of success, biodiversity and sustainability.

In 2007 SECIL introduced a fauna component into its Landscape Rehabilitation Plan with the aid of a team of researchers from the University of Évora who are assessing the occupation rates of fauna in the restored areas. The first phase of the study aimed to characterize and evaluate the occupation level of fauna in the restored areas, after 25 years of revegetation, and compare with natural surrounding areas.

The criteria for selecting the fauna communities were the ability to act as bio-indicators of habitat quality, relevance in the early stages of ecological succession (e.g. seed dispersers) and threatened species. Fauna plays an important role in the restoration of quarries, acting as a seed disperser for several species, promoting spontaneous regeneration of vegetation, or in controlling pests.

After the 1st phase, the baseline referential data was used to define an Action Plan for fauna recovery connected with the existing Landscape Rehabilitation Plan. The objective of the Action Plan is to create conditions, in the medium and long-term, to promote the process of natural (re)colonization through actions that focus on the restoration of the structure and functioning of the original ecosystems. Furthermore, a monitoring program was designed to evaluate the effectiveness of the implemented actions and to assess fauna populations’ status.

secil nursery plant - the process:

1.  seed collection

All the seeds used in germination processes are collected, in the appropriate seasons, in the natural areas surrounding the quarries.

For the germination process, some seeds should be separated from the fruits using different treatments (pre-germination treatments).

Some examples of the seeds/fruits of the species produced in the plant nursery

Some examples of the seeds/fruits of the species produced in the plant nursery

2.  Germination

Seeds are sown in the greenhouse in specific structures, such as seed trays, cellular seed trays or containers (bags), depending on their characteristics and respective periods of germination. For example, oak seeds are directly germinated in bags. 


Once the seeds are germinated, they need space to establish a strong root system. Therefore, when young plants are ready (those germinated in seed trays and cellular seed tray), they are transplanted individually (pricking out) into appropriate bags, where they remain in the nursery before being transplanted to the quarry.


3.  Planting in the quarry

During the planting season (October to February/March), the young plants are transported from the nursery to the quarries, where they are transplanted to the final location - the restored areas.


4.  Maintenance and vigilance

In addition to the germination process and to have healthy plants, having a nursery plant requires continuous maintenance and vigilance. It’s necessary to protect the young plants from damaging insects and diseases, and to carry out irrigation and other necessary procedures. To assure all procedures, SECIL has a dedicated team that is responsible for this entire work.

Learning and experience are also two of the most important factors for this success, particularly because of the team that works in the nursery plant. Through past years, this team has acquired experience and information related to all the process (e.g. how and when to collect, select the best seeds and individuals). Also, the Faculty of Sciences of the University of Lisbon has been conducting several scientific studies to optimize the process of producing native plant species in SECIL´s nursery.

With the contribution of: António Mira, Carmo Silva, Pedro Salgueiro, Sofia Eufrázio, Vanesa Rivera, Vânia Salgueiro, Otília Correia, Adelaide Clemente, Alice Nunes, Andreia Anjos, Cristina Branquinho, Graça Oliveira, Patrícia Correia, Teresa Mexia, José Oliveira, Filipa Costa, Eulália Freitas and many other contributors...

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