During the last decade, several research studies related to trees and urban planning have been done in the capital, gathering a large amount of information about the tree species found in this area. Upon analysis, surprisingly only a minimal proportion of native-species trees were identified. In today’s column we will question why most of the trees that surround us each day and about which we probably have greater knowledge are those that come from other latitudes.
The great majority of city dwellers surely know or intuit the vast benefits generated by maintaining and planting trees in urban sectors. In fact, organizations like the FAO (The Food and Agriculture Organization) emphasize that trees within city sectors are excellent filters for pollutants with the capacity to sequester atmospheric carbon and generate a refuge for wildlife, among other benefits (1). They can even help reduce the so-called “urban heat islands” (2) that develop during the summer. In this sense, programs implemented at the national level by CONAF such as “+ Trees for Chile” (3), or internationally such as the initiative “Million Trees NYC” (4) or “Melbourne Urban Forest” (5) show the growing interest and planning around this topic as a decisive factor for city planning.
(1) Food and Agriculture Organization of the United Nations (2016), “Benefits of urban trees” <http://www.fao.org/resources/infographics/infographics-details/en/c/411348/ >.
(2) United States Environmental Protection Agency (2017), “Using Trees and Vegetation to Reduce Heat Islands” < https://www.epa.gov/heat-islands/using-trees-and-vegetation-reduce-heat-islands >.
(3) Corporación Nacional Forestal (2017), “Programa de Arborización + Árboles para Chile” < http://www.conaf.cl/nuestros-bosques/arborizacion/>.
(4) New York City Department of Parks & Recreation (sf), “Million trees NYC” < https://www.nycgovparks.org/trees/milliontreesnyc>.
(5) City of Melbourne (2016), “Explore Melbourne’s Urban Forest” < http://melbourneurbanforestvisual.com.au/>.
With just a short walk, the cultural and physical reality regarding the arborization in the city of Santiago can be observed. I stop in front of a woman watering her garden. Her name I would soon know is Doña Clara, and I ask, “Do you know what that tree you are watering is called?” to which she responds, “This is an aromo, a Chilean aromo.” I indicate that the tree is indeed an aromo (Acacia dealbata), but that it is not Chilean, but an exotic species and ask if there are any native trees in her garden. She replies, “No, then! Those are up in the hills, there in the mountains. Here it is difficult to grow them. As I continue on my way, I observe and distinguish the trees around me: Plum trees, Oriental plane trees, Jacaranda trees, Locusts and Poplars, all of them exotic species.
The ignorance regarding species native to Chile, reflected in that simple conversation, could originate from the first attempts at forestation, such as on San Cristóbal Hill (1921) or the Quinta Normal (1852), which were entrusted to foreigners who brought species from all over the globe and who lacked a history with our native species. Furthermore, the construction of the city was done primarily with European references. These adapted and acclimated foreign species are those that have continued to be among us until today. To these foreign species “accustomed” to our city, we can add the fact that when native species have been used in urban landscape projects, an incorrect selection has frequently been made without attention to the specific conditions of the site. For example, species that do best in the shade have been placed in full sun, species that develop naturally in rural environments have been watered excessively, while other species have been needlessly over-fertilized with chemical products, among other similar negative practices.
Various censuses of vegetation in the city in which I have participated, specifically registries of what is called Urban Tree-Covering have allowed me to observe the small percentage of native trees within the city. For example, in the framework of the road project Américo Vespucio Oriente (AVO) – between Principe de Gales and El Salto streets – it was found that of a total of 3,732 individual trees on the median strip and on the sidewalks, 268 were native species, i.e. only 7% (6). The majority of the trees corresponded to exotic species of the genus Platanus, Liquidambar, Acer, and Fraxinus, typical species present in a classic city postcard.
(6) Sociedad Concesionaria Vespucio Oriente S.A. Estudio de Impacto Ambiental (2015), (Enironmental Impact Study) “Capítulo 3.(Chapter 3) Línea de base” (baseline <http://seia.sea.gob.cl/archivos/2015/11/03/Cap_3_Linea_de_Base.pdf>.
In another case, the registry carried out for the New Alameda Providencia Project (7) from Pajaritos to Tobalaba Avenue identified that from a total of 7,349 trees only 353 corresponded to native species, i.e. 5% of the total, of which again the species of genera Platanus, Liquidambar, Robinia and Acer were the most frequent. Both urban areas mentioned cover extensive stretches where thousands of people pass each day. These areas constitute a common and identity-laden landscape formed by species that are not native to this place. Finally, another area that covers a considerable area in the neighborhood of Macul is the San Joaquin campus of the Pontifical Catholic University, which maintains about 1,750 trees, where only 14% correspond to native species. Efforts such as the one the UC Sustainability Office is developing, within the framework of the San Francisco de Asís project, seek to increase the presence of native species there.
(7) Nueva Alameda Providencia (2016), “El proyecto” < http://www.nuevaalamedaprovidencia.cl/el-proyecto/>.
Due to the current configuration and distribution of the species that make up the urban trees, it is understandable that people have greater knowledge and closeness to exotic species, even believing that they are native species, which is most likely a product of being around them every day. This situation is repeated for the case of our native fauna according to a study published by the Institute of Ecology and Biodiversity (IEB) (8).
(8) La Tercera (2016), “El 70% de la biodiversidad publicada en los textos escolares en Chile no es nativa” (In Chile, 70% of biodiversity species published in school textbooks are not native) < http://www.latercera.com/noticia/70-la-biodiversidad-publicada-los-textos-escolares-chile-no-nativa/>.
In this context, I consider it fundamental to integrate a greater variety of native species, at least in the public space, modifying their proportion in the mix and therefore increasing their visibility in the city. It is important to understand that cities and urban environments can − and should, in my opinion − integrate native species without confining them to the hills, mountains or national parks, as mentioned by Doña Clara. In this way, the integration of a greater number of quillayes, peumos, maitenes, and bushes such as corcolenes, romerillos, colliguayes or mayús, not only would contribute to the conservation of these species, but also to environmental education, among other benefits related to urban ecology.
Probably this column is read mainly by people interested in the subject and with some level of knowledge of these issues; however, it is essential that we make known the virtues of native species, commenting about this issue and spreading their importance and contribution to the development of our cities. In this way, I invite you not to wait for action at the State level through the development of associated plans and programs, but also to act by helping people like Doña Clara to become familiar with our native species, gradually incorporating them into our culture and local identity.
Joaquín Acosta Köhler. Forestry Engineer and Agronomist of the Pontifical Catholic University of Chile, who has participated in diverse registries and censuses of urban trees in Santiago and the Regions. He is currently working on issues of biodiversity and environmental management.