compiling information

In January 2018 we started efforts to compile information about the existence of large trees in Lousada.

The early citizen science campaign

With the initial objective of implementing a citizen science campaign that would allow the discovery of large trees that were recognized by citizens, simple forms in digital and printed formats were created and disseminated. The first, made available through this website and the second in flyer format, as a page of the municipal magazine and also in a letter attached to the water bill, thus trying to reach all citizens of the municipality. Despite this effort, we did not obtain more than 100 records in the entire municipality and therefore we had to change the strategy.

The walk

We started by looking for the large trees in the municipality. For this project, any tree with a trunk with at least 1.5 meters in circumference measured at chest height was defined as large. Something like the limit that an adult person can hug a tree.

We then went outside and after going through all the streets in the municipality of Lousada and with the help of satellite images, at least 7400 large trees were identified.

and the value of each tree?

We needed to know more information about each one of these large trees in order to actually be able to preserve them. Detailed information was compiled for three purposes:

  1. to understand which trees are most important for biodiversity;

  2. to calculate the ecosystem services provided by each tree

  3. to have precise data that allow the definition of priorities for actions focused on the conservation of these trees.

Thus began a process of characterization of each specimen, where several types of information were compiled:

  1. About the characteristics of each tree:

    1. Species

    2. Health status (dead or alive)

    3. Chest height perimeter

    4. Overall height

    5. Richness of microhabitats

  2. About the applied management to the tree

    1. Tree owner (public, private)

    2. Isolation status (grouped, aligned, isolated)

    3. Pruning frequency (periodic, arbitrary, without pruning)

    4. Pruning quality

    5. Surrounding land use

results achieved

By the end of 2020 it was possible to characterize 3700 large trees, which is an ongoing process of the project.

On the defined objectives, there are the following results:

  1. Master's dissertation by João Gonçalo Soutinho, available here,
    and with a summary of the results here .

  2. Calculation report for each tree, developed by Marisa Graça. For example, in average values, each green giant has 1500kg of CO2 stored and sequester 50kg of CO2 annually, thus being true atmospheric carbon sequestrators.

  3. Publication of the Municipal Regulation for the Management of Trees and Natural Spaces, where the data compiled in point 1 were incorporated into the created regulatory measures.

Unfortunately it was also possible to notice that at least 400 large trees disappeared in Lousada in this period of time, resulting from 5 main factors:

  • Urbanization / Soil Waterproofing - 27%

  • Agricultural intensification - 23%

  • Unknown - 17%

  • Security issues- 17%

  • Personal use - 10%

  • Natural death - 6%

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