Conformation of Bosque de Chapultepec

Bosque de Chapultepec was limited for many centuries to what is currently known as the 1^st Section. This is the place where historical sites are located, such as the Chapultepec Castle, museums (the Anthropology and History Museum for example), monuments, fountains, lakes, the Alfonso Herrera Zoo and the Lake House of the Universidad Nacional Autónoma de México (National Autonomous University of Mexico) (UNAM). Chapultepec also has an extensive surface of green spaces and tree cover that generate several ecosystem services that improve the environment of the city and consequently, the quality of life and well-being of the inhabitants of Mexico City and its metropolitan area.

In the 60’s of the last century and derived from the urban development of the city, a peripheral freeway named Boulevard Adolfo López Mateos was constructed (^{Díaz, 2018}), and caused the separation of the western part of the original Bosque de Chapultepec and a reduction of its surface. As a result, the old and historic forested area began to be called Old Chapultepec and later 1^st Section, while the space that was separated began to be called New Chapultepec and later 2^nd Section. In the last one, recreational, cultural and artistic elements were built, among which the Natural History Museum and the old and famous Roller Coaster, now gone, stand out.

Later, a 3^rd Section was added further to the west, at the Barranca de Dolores area, inaugurated on September 13^th, 1974 (^{GDF, 2006}). This area was somewhat distant from the historic place, and recreational and cultural infrastructure were built also (Figure 1).

Source: Prepared by the author based on an image from https://www.google.com/intl/es-419/earth/.

Figure 1 Bosque de Chapultepec with its three original sections and surroundings in Mexico City. 

The three sections of Bosque de Chapultepec have an area of just over 686.01 ha (^{PUEC-UNAM, 2002}; ^{GDF, 2003}), which makes the place as the largest UGA in Mexico City, its metropolitan area and the country. The place as a whole has an extensive recreational and cultural infrastructure, which makes it the most visited urban park in Mexico and among the most frequented in the world (^{GDF, 2003}).

Recently and within the framework of the city government program called Chapultepec: Nature and Culture, the forest was expanded and a new 4^th Section was added. It is located to the southwest of the 3^rd, separated by Constituyentes avenue, within the facilities of the Military Base 1-F, near the old town of Santa Fe, at the Álvaro Obregón District. The expansion is in a consolidation process, and thus it is not commented on this paper.

1^st Section of Bosque de Chapultepec

It is located to the west of the city, in the transitional zone between the volcanic foothills of the Sierra de Las Cruces and the lake area of the Valley of Mexico. The extreme parallels of this section are 19°24'46" and 19°25'45" north latitude and the extreme meridians are 99°10'35" and 99°11'32" west longitude. The area of this section is 274.0864 ha and the altitude is very homogeneous (2 245 m), except for the Chapultepec hill, which reaches a height of 2 325 m (^{Dirección General de Bosques Urbanos y Educación Ambiental, 2006}).

The 1st Section is delimited to the northwest by Campos Elíseos avenue and Andrés Bello street, to the north by Rubén Darío avenue, to the northeast by General Mariano Escobedo avenue, to the southeast by part of the Bicentenario Circuit, to the south by the Chapultepec and Constituyentes avenues, to the southwest and west with the Los Pinos Cultural Complex (former presidential residence) and the Peripheral Freeway (Figure 2).

Source: Prepared by the author based on an image from https.google.com.mx/.

Figure 2 1^st Section of Bosque de Chapultepec. 

Even though the 1^st Section is located at the Miguel Hidalgo District, the UGA does not depend administratively of such administration, because it was cataloged since 2003 as an area of environmental value (AVA, for its acronym in Spanish), under the responsibility of the Secretary of the Environment of Mexico City (^{GDF, 2006}). It is currently administered by the office of the Executive Director of Bosque de Chapultepec, under the office of the General Director of the System of Protected Natural Areas and Areas of Environmental Value.

Historical aspects

The multiple historic events related to Bosque de Chapultepec are associated with the so-called 1^st Section. There are references about early human occupation by indigenous ethnic groups such as Teotihuacan, Tolteca and Tepaneca, until the final dominion of the Mexica group (^{Campos, 1919}; ^{Matos, 2003}; ^{Rivas, 2005}). The importance and significance of this place is largely explained by its springs, which even led to consider Chapultepec as a sacred site by these cultures (^{Campos, 1919}; ^{Matos, 2003}). The name of the place by which it is currently known has a Náhuatl origin, whose roots are chapolli (chapulín or cricket) and tepetl (hill or mountain), which means “hill of the chapulín” (^{León-Portilla, 1970}; ^{Matos, 2003}).

When the capital of the Mexica empire (Mexico-Tenochtitlan) was founded on an islet in the brackish Lake of Texcoco in 1325, the springs of Chapultepec became a strategic site because it supplied the potable water needed by the city. It was carried in the beginning by containers on canoes, and later, transported by an aqueduct constructed in the reign of Chimalpopoca (1418). The aqueduct cross over part of the lake, and later was improved during the reign of Moctezuma I (1466), with the technical advice of Nezahualcóyotl, king of Texcoco (^{Campos, 1919}; ^{Armijo, 2005}; ^{Moreno, 2005}; ^{Rivas, 2005}).

During the Mexica empire the forest was considered as a sacred place and purification space for the tlatoani or Mexica emperors, and a site for rest and recreation. A temple (teocalli), which served as an astronomical observatory was constructed on the top of the hill, and were built for the royalty and nobility water pools, country residences, a botanical garden and it was used also as a hunting preserve (^{Campos, 1919}; ^{León-Portilla, 1970}; ^{Solís, 2002}; ^{Matos, 2003}; ^{Moreno, 2005}; ^{Rivas, 2005}). According to ^{Moreno (2005)}, the enclosure as a whole was protected by a fence and was called the “Garden of the Tlatoani”, a term that evidenced the recreational and resting vocation that Chapultepec had since pre-Hispanic times, although in this case, it was exclusive to the Mexica nobility.

After the Spanish Conquest (1521), Bosque de Chapultepec became a property of Hernán Cortés for few years after the Spanish Crown granted the place to him. Notwithstanding this situation and because the springs of Chapultepec continued to supply drinking water to Mexico City (even until the 19^th century), the members of the City Council asked to the king Charles I of Spain (and V of Germany), that the forest would be removed from Cortés's possessions and would belong to the city. The king agreed to this request and on June 25^th, 1530, he decreed that such place, with an approximate area of what would now be 330 ha, be excluded from any private property and be delivered in perpetuity to Mexico City (^{Campos, 1919}; ^{Armijo, 2005}; ^{Zapata, 2007}). It should be noted that this decree marked a worldwide milestone in urban forestry. In accordance to the current concept of a peri-urban forest (forest sites located on the periphery of a city, that provide one or more environmental services to the city and could be property of the city), Chapultepec could be one of the first peri-urban forests in the world (Mexico City was still located about 7 km away), if not the first.

In 1550 another transcendental event was recorded at Bosque de Chapultepec and in the history of the urban forestry and urban arboriculture of Mexico (and probably in the world again), when viceroy Luis de Velasco y Ruiz de Alarcón allowed the access of the city's inhabitants to the place for recreational purposes (^{Campos, 1919}; ^{Armijo, 2005}; ^{Moreno, 2005}). The only place that was restricted to the visitors was the area of the springs that supplied water to the city, but visitors could enjoy in the proximity of a “wider than deeper reservoir called “pool of the swimmers”, privately owned but open to the public” (^{Campos, 1919}; ^{Arciniega, 2005}).

It is important to highlight that Bosque de Chapultepec, with this second provision, strengthens its position as a peri-urban forest, providing drinking water to Mexico City and facilitating recreational activities.

Pre-Hispanic and viceroyalty era

The beautiful gardens and the recreational constructions that the Mexica tlatoanis had at the site (Garden of the Tlatoani), were referred by conquerors, chroniclers, friars, viceroys and visitors during the first years of the viceroyalty (^{Alcocer, 1886}; ^{Campos, 1919}; ^{Nuttall, 1923}; ^{Morales, 2004}; ^{Moreno, 2005}; ^{Rivas, 2005}; ^{Lascurain, 2010}). The chronicles always emphasized the greatness of the Taxodium mucronatum Ten. trees (ahuehuete or sabino), the importance and beauty of the place and the springs, which must have been magnificent without a doubt.

The stories from that time probably gave rise to the myth that king Nezahualcóyotl had created the forest with specimens of T. mucronatum, an idea that several centuries later ^{Campos (1919)} and ^{Martínez (2002)} continued to repeat. Not intending to diminish the great contributions that the king of Texcoco made in the Valley of Mexico basin, widely documented and there is evidence of them, the creation of a forest of ahuehuetes in Chapultepec is surely exaggerated. These kind of trees were established naturally thousands or millions of years before, when the conditions of the site (presence of springs and a lake area) were favorable for them. This species is native to the Valley, very common in other parts of the basin and even in the country (^{Calderón de Rzedowski and Rzedowski, 2001)}.

What it is very likely that king Nezahualcóyotl carried out in Chapultepec (because he was an expert of the characteristics of the basin), was the planting of trees of this species in strategic or specific places to protect the banks of the springs, define paths, as well as the improvement of the forest. It is important to remark that king Nezahualcóyotl lived in Chapultepec and was conscious of the mythical importance that both the tree species and the place had for the Náhuatl nobility and the recreational importance of the place for the tlatoanis (^{Campos, 1919}).

It should be noted that in addition to the previous species, there were probably also specimens of other hydrophilic native species on the banks of the springs and surroundings, such as Salix bonplandiana Kunth (ahuejote), Salix mexicana Seemen (Mexican willow), Fraxinus uhdei (Wenz.) Lingelsh. (ash) and Alnus spp. (aile), in addition to the marshes composed mainly of Typha latifolia L. (cattail), characteristic of this type of sites (^{Calderón de Rzedowski y Rzedowski, 2001}).

After the conquest, the magnificence of the Garden of the Tlatoani induced the first viceroy of New Spain, Antonio de Mendoza Pacheco, to consider that it was an ideal site to establish a resting place. According to a document consulted by ^{Moreno (2006)} at the Historical Archive of Mexico City, the viceroy mentioned to king Charles I of Spain in 1537, that "near this (Mexico City), there is a small forest called Chapultepec", in which "the construction of a wooden fence was carried out to protect the historical and recreational garden, made up of springs, flora and fauna of a great variety of species and a rock formation (the Chapulín hill) and (the construction) of the royal houses”.

There is evidence that viceroys occupied the Royal Houses during the 16^th and 17^th centuries and it is possible to consult official documents at the Archivo General de Indias dated in Chapultepec, such as a letter from viceroy Gaspar de Zúñiga on May 20^th, 1601, addressed to the king of Spain (^{Archivo General de Indias, 1601}).

After the report of the place by viceroy Antonio de Mendoza, it was not possible to find information regarding the trees and Bosque de Chapultepec conditions. The events that allow certain continuity to what happened in the forest are the constructions that were carried out, such as the establishment of a gunpowder factory and a cannon foundry by viceroy Gaspar de Zúñiga (^{Archivo General de Indias, 1599}), factory that later exploded (^{Campos, 1919}), a proposal in 1787 for the renovation of what had been the palace of the viceroys at the foot of the hill (^{Archivo General de Indias, 1787a}), and the construction of a royal palace in the fortress (at the top of the hill) (^{Archivo General de Indias, 1787b}).

From the arboricultural standpoint, an important issue was the establishment of the Royal Botanical Garden in a vast surface of Chapultepec (Figure 3), that was active from 1793 to 1820 according to the information that appears in the notes of the architectural drawing (^{Archivo General de Indias, 1792}).

Source: ^{Archivo General de Indias (1792)} (http://pares.mcu.es/ParesBusquedas20/catalogo/description/21357). This plan was drawn up in 1792 for the establishment of a botanical garden and in which the springs that supplied drinking water to Mexico City (yellow), as well as those intended for the recreation of visitors to private property (red) are located.

Figure 3 Image of the architectural drawing of the Royal Site of Chapultepec. 

In such drawing are shown three pools (springs), which implies that three centuries after its designation as provider of environmental services to Mexico City, the forest continued to fulfill its function as a peri-urban forest, providing drinking water and recreation places for its inhabitants (Figure 3). In addition, a very large wooded space is observed on the left side (west) of the drawing, as well as fragmented square and rectangular spaces. The Real Alcázar or royal palace already built on the top of the hill is possible to observe, and some constructions in the lower part of it, among which the old square-shaped gunpowder factory stands out on the lower left side (Figure 3).

Towards the end of the viceroyalty, the forest continued to be called the “Garden of the Royal Palace of Chapultepec” (^{Moreno, 2006}). During such time, one of the few specialized contributions about the trees was reported by Alexander von Humboldt, in his essay on New Spain published in 1822, that was derived from his famous trip in 1803 (^{von Humboldt, 2014}). The naturalist said that Chapultepec “… is covered with the most lush vegetation …” and observed that “… the trunks of the ahuehuetes, more than 15 or 16 m in circumference, raise their crowns above the Schinus (undoubtedly referring to Schinus molle L. (pirúl), which he previously knew in Peru during that same trip), which in their appearance or look (refers to the ahuehuetes) resembles the weeping willows of the east …" (most likely Salix babylonica L.).

No pictorial works or drawings of Bosque de Chapultepec were found that showed the tree appearance during the viceroyalty era, however, an example close in time was elaborated by the German painter J. M. Rugendas in 1833, in which the magnificent ahuehuetes and a group of people on horseback visiting the place can be seen (Figure 4).

Source: https://mnh.inah.gob.mx/historia.

Figure 4 Bosque de Chapultepec by J. M. Rugendas (1833). 

XIX century

As the centuries passed, an environmental deterioration was registered in the upper part of the basin and in the Valley of Mexico. This process was observed and reported also by von Humboldt during his visit to Mexico City. He noted that “… since the 16^th century, trees have been cut down recklessly, both on the plain on which the capital is located and in the mountains that surround it” (^{von Humboldt, 2014}). These actions undoubtedly caused a severe impact on the hydrological regime of the basin, and during the 19^th century the flow of the Chapultepec springs started to reduce and at the end of the same century, they dried (^{Cabrera et al., 2005}). Associated to this situation was the decrease of the water table level, which marked the beginning of the decay that has been damaging the T. mucronatum trees for a long time.

The lack of dendrological information prevails in the years that followed von Humboldt's visit and the forest was surely deteriorated after the battles of Molino del Rey and Chapultepec during the war of intervention by the army of the United States of America in September 1847, which, however, could not be verified in any document.

^{Blasio (1903)} mentions that after the U.S. Invasion, the Castle of Chapultepec was used as a presidential house and in the brief empire of Maximilian (1864-1867), the emperor chose it as his residence (Miravalle). An important rehabilitation work took place on both, the palace and its gardens, which gave rise to information on the tree cover.

According to documents from such time consulted by ^{Gómez (2012)}, the original surface of the forest was increased, as Maximiliano ordered the purchase of surrounding land from La Hormiga ranch (towards the west) and others areas close to this place, paying more than one hundred thousand pesos. Another tracks were bought to build the Paseo del Emperador (now Paseo de la Reforma), in order to connect the palace and forest with the city in a more direct way (^{Blasio, 1903}).

The emperor was accompanied from Europe by his gardener Wilhem Knechtel (who should be considered rather as a professional horticulturist and a proto-landscape architect of the time), and because of the publication of his memoirs at the end of the 19^th century, published few years ago in Mexico (^{Knechtel, 2012}), it is possible to know a specialized description of Chapultepec. He described the site as a beautiful park and highlighted the garden construction activities that he carried out at the palace. He also mentioned the magnificence of the T. mucronatum trees, which he referred as T. distichum (T. distichum (L.) Rich. var. mexicanum (Carrière) Gordon), which he commented that they were “… testimony of the sanctity of a place consecrated to the gods in the times of the indigenous empire …” and pointed out that “… a tree was so large that it took nine men with their arms outstretched to surround its trunk”. However, he did not provide information about other tree species or their condition, which suggests the greatness that the ahuehuete cover must have had for him (^{Knechtel, 2012}).

The significance of the ahuehuete cover at that time was also discussed by other visitors, as was the case of the plenipotentiary minister of the king of Portugal on a visit to emperor Maximilian and who, according to the document that ^{Gómez (2012)} consulted, the minister reported that “… Chapultepec stood out with its tall and black-green ahuehuetes, its ash trees and weeping willows and gardens …”, a reference that, together with that of von Humboldt, provides data on other species in the forest.

The springs of Chapultepec during this period were also referenced. ^{Blasio (1903)} commented that in the privately owned pool called “Alberca de Chapultepec" “…was used by emperor Maximilian after paying his fee", "… swimming fifteen to twenty minutes", and was “… so abundant that overflowing on both sides, it fed a pond for unexperienced swimmers and on the other a series of small ponds for ladies”.

After the Second Mexican Empire, there is no information regarding the trees at Bosque de Chapultepec, although the castle (which looked more like a palace) continued to be used as a presidential residence since 1872 by President Sebastián Lerdo de Tejada (^{Moreno, 2005}; ^{Moreno 2006}).

Towards the end of the 19^th century (1895), during the government of General Porfirio Díaz, works were carried out to restore and improve the forest. A commission formed by Eduardo González Gutiérrez, Eduardo Cañas and José Yves Limantour were designated, with the aim to enlarge and improve the park's infrastructure for the recreation of the population (^{Tovar and Alcántara, 2002}). These authors referred that a large part of the current design of the 1^st Section is derived from the 1895 renovation project, adapted and modernized by Engineer Miguel Ángel de Quevedo y Zubieta between 1903 and 1906, based on a governing plan similar to that one used in the Forest of Boulogne of Paris. The renovated 1^st section was inaugurated in 1907 (^{Tovar and Alcántara, 2002}), information that will be addressed in the second part of this work.

Final comments

The magnificence and beauty of Bosque de Chapultepec since Mexica times transcended and endured throughout the centuries. Stories and chronicles always referred the ahuehuetes or sabinos, however, there are few comments about the rest of the species in the literature from such time. It is feasible to deduce from the environmental conditions of the place, the kind of species that coexisted in Chapultepec, except for those exotic introduced during the viceroyalty era, such as S. molle that von Humboldt mentioned in his essay.

Unfortunately, this naturist also commented on the deterioration that was already noticeable in the basin, and consequently, the reduction of the springs and the initial depletion of the water table that followed in the last part of the XIX century. This situation affected the development, survival, beauty and size in the long term of the ahuehuetes and other tree species, subjects that will be commented on in the 2^nd part of this work.