From Lisbon Tropical Garden to the Geomonuments

The objective of this training course was to get to know Lisbon's Tropical Botanical Garden (JBT), to carry out didactic tours on geodiversity and urban biodiversity, making teachers aware of the use of these urban spaces as a place to study and to build didactic resources.

Waiting for us at the entrance of the Tropical Garden was César Garcia, garden coordinator at the Lisbon Museum of Natural History and Science, who was going to guide us through another activity that highlights the importance of the approach to urban biodiversity and direct observation as a teaching and learning strategy.

Dr. César Garcia, coordinator of the Gardens of the Museum of Natural History and Science, presenting the Tropical Botanical Garden to the participants.

And so we set off to discover this oasis of strong educational vocation that is over a century old. Located in the monumental area of Belém, which was once an area of estates and recreational homes of the Portuguese nobility in the 16th and 17th centuries, the Tropical Garden was created in 1906 by Royal Decree. With some 600 species, most of them tropical and subtropical (most of them originating from the former colonies) it is a living documentation center with many species of ornamental and agricultural value.

Throughout the visit César Garcia explained to us some peculiarities of the various species of flora, some of which stood out for their size, such as the Araucarias or the Cycas - dioecious plants (each individual has only male or female organs) with leaves similar to the palm trees that border the lake, known since the Triassic and which have the most primitive female flowers. Walking along the path that led us to the paths of the tropics, surrounded by palm trees (Washigtonia robusta and filifera), we visited species from all continents, including the autochthonous European ones, such as the broom palm (Chamaerops humilis) or the leaf palm (Viburnum tinuas) and observed specific problems, such as the problem of invasive species. The Asian wasp plague (Vespa velutina) with some nests installed in the treetops or the palm beetle that endangers several susceptible plants, particularly the species Phoenix canariensis (Canary Palm) but also other palm species are situations that have been addressed in the Tropical Garden.

And we were transported to habitats and environments very different from the city to observe the Pine of S. Tomé - (Afrocarpus mannii (Hook. f.) C. N. Page, endemic coniferous tree, very high conservation status (only exists in S. Tomé between 1200m and 2024m altitude). N. Page, an endemic coniferous tree, of great conservation status (it only exists in São Tomé de Príncipe between 1200m and 2024m altitude with leaves completely different from the usual pine needles) or seeing live ecology through the competition between an imposing fast growing tree, the Fig tree - Ficus macrophylla and the Sycamore, a tree with several references in the Bible.

From left to right: Australian Fig (Ficus macrophylla); Sycamore (Ficus sycomorus).

"More than a garden it is a plant research laboratory," sums up César Garcia as he showed us the fruit of the Orelha de macaco (Enterobium contortisiliquum, a tree native to Brazil with a recurved shape reminiscent of an ear.

Monkey ear fruit – Enterobium contortisiliquum

After the visit to this live classroom space, where we could contact with the most varied tropical species, after lunch we started the walk with the orientation of Jorge Sequeira, LNEG's technician to decode the geodiversity in Lisbon's streets and geomonuments.

The natural heritage conservation includes the geomonuments and although the urban environment sometimes hides the geological outcrops, there are several inventoried geomonuments in Lisbon, among which the Geomonuments of Rio Seco and Aliança Operária, connecting the geosciences with the city's history, with its urban, artistic, social and economical dimension.

After the explanation of Lisbon's Geology, heading to the Geomonument of Rio Seco, we observed the ornamental rocks that constitute the monuments and streets of Lisbon - the Upper Cretaceous limestones, with fossils of rudists (group of extinct bivalves), existing, for example, in the Memory Church and in the façades of buildings. From the rocks, their fossils translated the paleoenvironments, transporting us to the time of the dinosaurs, showing a reef environment, of warm, tropical, shallow marine waters.

A brief historical description was given by Jorge Fernandes, a teacher at LPN, in which the connection of the history and architecture of the place to Geology was inevitable. After visiting the Church of Memory built by King José I, grateful for having saved himself from an assassination attempt two years earlier in 1758 and where the Marquis of Pombal is buried, we passed by the Ajuda National Palace, which replaced the Royal Tent, so called because it was made of wood and where King José I settled after the 1755 earthquake.

With Jorge Sequeira's guidance, the city of Lisbon was shown with "another look", the "eyes of knowledge" that allow us to feel more involved by this fascinating city, of great historical and cultural wealth and in particular in its western area.

Rio Seco Geomonument - Limestones of the Bica Formation - Upper Cenomanian.

In the Rio Seco Geomonument, an old quarry, it is possible to interpret the phenomena of the advance of the sea level (transgression), observing old lime ovens and flint nodules used as raw material for the manufacture of weapons, utensils and flint.

Rio Seco Geomonument - Cenomanian - Upper Cretaceous. Flint nodule.

Continuing our tour through the streets of Lisbon, we suddenly witnessed episodes of volcanism in Lisbon, observing prismatic disjunction in the basalts through the Aliança Operária Geomonument.

Through the dynamic natural and cultural repository of the parishes of Ajuda and Alcântara we walked until we reached our final destination, the Santo Amaro Chapel, classified as a national monument and surrounded by four olive trees, trees of Public Interest, classified in 2008, some of the oldest trees in the city that share the history of the chapel founded in 1542 and which contains in its interior magnificent tiles dating from the late sixteenth century. 

Located next to the Santo Amaro Chapel, the Santo Amaro viewpoint offers a privileged panoramic view of the Tagus River and the 25th of April Bridge. It couldn't be a better context for Jorge Sequeira to characterize Lisbon's Geology.
The past and the present walked side by side in living spaces of recognition for the need we have to preserve our testimonies and natural and cultural values.

Shaped by geodiversity and biodiversity, Lisbon's history and culture, natural and cultural values can only be preserved by those who know and get involved. Education is fundamental and this is one of LPN's missions - to know in order to protect and value.