A Tree-Prone Community: Residential and Street Tree Planting and Care in the Neotropical City of Xalapa, Mexico

Site Description

We carried out this study in Xalapa, a small-to-mediumsized city in central Veracruz, Mexico (Figure 1). The urban area of Xalapa covers approximately 64 km² and harbors approximately 550,000 inhabitants (INEGI 2021). Within an elevation range of 1120 to 1720 m above sea level (INEGI 2009), the climate of the city is humid semi-warm in the southeast and humid temperate in the northwest (Soto-Esparza and Gómez-Columna 1993). The geographical, natural, and social conditions gave rise to an important system of public and private green spaces (García-Campos 1993; Lemoine-Rodríguez et al. 2019). Xalapa is currently considered a ‘green city’, as its urban greenery covers more than one-third of its area (Falfán et al. 2018; Von Thaden et al. 2021). While the city is settled on the once-original vegetation of cloud forest and tropical dry forest and is surrounded by cloud forest fragments and agroecosystems (Castillo-Campos 1991; INEGI 2009), the current vegetation of Xalapa is composed of native and exotic species (García-Campos 1993; Falfán and MacGregor-Fors 2016). As in many other cities worldwide (Avolio et al. 2018), tree planting is a common practice in Xalapa, performed mainly by residents in private spaces (e.g., home gardens, front yards, backyards), and by local authorities in public spaces (e.g., parks, streets, and median strips), according to reforestation plans and their attributions within the legal framework of the city (Castillo-Campos 1991; Garizurieta 2018; DMA 2022). The plants to be sown can be obtained from municipal and private nurseries and by way of personal propagation of cuttings and scions from specimens located in the city’s green spaces. In Xalapa, urban tree care is the responsibility of both municipal authorities and citizens, according to local ordinances. This responsibility falls on citizens when trees are on private property or the front sidewalk of private property (GEV 2018), subject to certain regulations. For example, pruning of old or big trees requires permission from the competent authority, but pruning of shrubs or small trees for ornamental or aesthetic purposes does not require a permit. For urban tree removal, including those on private property, a signed permit must be obtained from the competent authority (AXV 2019).

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Figure 1.

Location of Xalapa depicting the sampling scheme layout. Satellite imagery from Google Earth taken in 2023 February: at 2023 Maxar Technologies (Westminster, Colorado, USA), 2023 CNES/Airbus (Blagnac, France), and Landsat/Copernicus.

Data Collection

We developed a questionnaire of 15 items divided into 4 sections: (1) information about the respondents, (2) information about the dwellings, (3) trees inside residential lots, and (4) trees on the sidewalks in front of dwellings (Appendix 1). To check and improve our questionnaire’s clarity, readability, feasibility, and suitability, we conducted a pilot test with 2 small samples of respondents similar to the target population. We obtained feedback from them on the difficulty, length, and format of our instrument and adjusted the wording, layout, and instructions, accordingly (Yusoff et al. 2021). We conducted interviews in dwellings throughout Xalapa, following a citywide sampling scheme (MacGregor-Fors 2019), which consisted of placing a 750 × 750 m point grid on a polygon of the city continuum, outlined following the criteria of building aggregation of and presence of communication paths according to MacGregor-Fors (2010) and Lemoine-Rodríguez et al. (2019). Points within the city polygon were relocated to the nearest accessible street if they fell into inaccessible locations. We considered only those points on streets of residential land use as final sampling sites, resulting in a total of 92 sampling sites (Figure 1). We collected information from 2 dwellings within a 100 m radius of each sampling site where residents agreed to answer the questionnaire, after first explaining the objectives of the survey. In 7 sampling sites (7.6 %), the residents of only 1 dwelling consented to participate. We surveyed a total of 177 dwellings. Since the respondents were the persons present in the dwelling at the time of the survey, over 16 years of age, who agreed to answer the questionnaire (i.e., only 1 respondent per dwelling, n = 177), no dwellings or respondents were selected a priori. We conducted all questionnaires face-to-face (i.e., a data collection method in which the interviewer asks questions through a questionnaire and the respondent answers these questions)(Loosveldt 2008), from August to October 2013. All respondents’ participation was voluntary and confidential.

Data Analysis

To assess differences between the proportions of tree presence, planting, and care, we did 1- and 2-sample tests for equality of proportions with continuity correction, reporting χ² values. When the χ² assumptions were not met (mainly when one or more of the expected frequencies was less than 5)(Crawley 2013), we performed Fisher’s exact test (which reports odds ratios [OR] and 95% confidence intervals [CI]). To test the relationships between the presence of residential and street trees and between tree planting and care practices, we performed a Pearson’s chi-squared test with Yates’ continuity correction. We assessed the relationship between the presence, planting, and care of residential and street trees (dependent variables) and dwellings’ characteristics (independent variables) by using GLMs (generalized linear models) with a binomial error distribution considering an inverse logistic link function (i.e., “logit”)(Hosmer and Lemeshow 2000; Crawley 2013). Dwellings’ characteristics were (1) dwelling inhabited by homeowners (no, yes), (2) time of inhabitance in years, (3) location of dwelling in neighborhood or subdivision (in a neighborhood people buy a land lot and build their houses according to their preferences and financial possibilities; in a subdivision, builders divide the land into lots of similar size and build the houses according to the same design for eventual sale)(HAV 2018), and (4) socioeconomic level of the household (i.e., low, medium, high; using a categorical qualitative wealth scale based on house construction materials, facade condition, condition of surrounding urban infrastructure, and house size, following MacGregor-Fors and Schondube 2011). We ran the models for residential and street trees separately. We report χ² and p-values for the fitted models, as well as McFadden’s pseudo-R² , where LL_mod is the log-likelihood value for the fitted model and LL₀ is the log-likelihood for the null model)(Hardin and Hilbe 2007; Gordon 2012). For the tree planting and care analysis, we assigned dwellings where respondents reported that some of the existent trees had been planted but some had not, proportionally to the observed frequencies; missing values were not considered. We performed all statistical procedures in R (Figure 2)(R Core Team 2019).

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Figure 2.

Methodological process for survey data collection and analysis.

Respondents’ and Dwellings’ Characteristics

All respondents (n = 177; one per dwelling) were Mexican, from 17 to 86 years of age (average 47.1 ± 17.2 SD), and predominantly female (57.6%); males accounted for 36.7%, and 5.7% were missing data. The schooling degree of 67.8% of respondents was high school and lower; 22.5% had a bachelor’s degree, 2.3% had a postgraduate degree, and only 5.1% had no schooling (2.3% of the data was missing). Half of the respondents (50.8%) were born in Xalapa, 33.4% in other urban and non-urban settlements of Veracruz State, and the remaining 15.8 % in other settlements in Mexico. The time that respondents had lived in Xalapa ranged from a few months to 80 years (average 30.9 ± 18.7 SD), with one-third having lived in Xalapa their entire lives. Of the surveyed dwellings, 78.5% were inhabited by their homeowners, with only one missing data (0.6%). Most of the dwellings (83.6%) were in neighborhoods, and a few (16.4%) were in subdivisions. At the time of the survey, the dwellings had been inhabited by their current residents for 0.02 to 69 years, with an average time of inhabitance of 18.7 ± 15.1 years.

Residential Tree Presence, Planting, and Care

Of the 177 dwellings surveyed, 52% were reported with the presence of trees, and 48% without trees, with no difference between these proportions (χ² = 0.203, df = 1, p = 0.652). Of the dwellings where respondents reported having trees (n = 92), in 70.7% of them, residents planted the trees, while in 34.8% of dwellings did not (percentages equal > 100% due to respondents who indicated they planted some of the trees, but not all of them). In the latter case, previous residents planted the trees or were established naturally. Data showed a significant difference in proportions in favor of residential tree planting (χ² = 14.880, df = 1, p < 0.001). Tree care occurred in most dwellings, whether residents planted the trees (86.2%) or not (78.1%), with no significant relationship between residents’ tree planting and tree care (χ²= 0.505, df = 1, p = 0.477). All these frequencies and percentages of the presence, planting, and care of residential trees across Xalapa are shown in Figure 3A. Tree care practices reported in 76 dwellings included pruning (n = 49; 64.5%), watering (n = 41; 53.9%), adding fertilizers or compost (n = 25; 32.9%), phytosanitary measures (e.g., insecticides, fumigation; n = 11; 14.5%), and cleaning and weeding (n = 8; 10.5%). Only one respondent (1.3%) reported that they “care” for their trees without further explanation (Figure 4).

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Figure 3.

Diagram of presence, planting, and care percentages for (A) residential trees and (B) street trees in Xalapa. *Percentages sum up > 100% due to respondents who indicated they planted some of the trees in their homes, but not all of them. ** Percentages do not equal 100% due to four missing data.

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Figure 4.

Reported care practices for residential and street trees in Xalapa. Percentages equal > 100% due to respondents that reported providing 2 and 3 types of care to trees.

Street Tree Presence, Planting, and Care

The presence of street trees on the sidewalks in front of the 177 surveyed dwellings was low; only 26.6% (n = 47) of the dwellings were reported to have tree presence, while 73.4% (n = 130) did not, representing significant differences between them (χ² = 37.989, df = 1, p < 0.001). Of the 47 dwellings with street trees, residents reported that they planted the existing trees in 72.3% of them. In 19.1% of the dwellings with street trees, residents did not plant the trees, showing significant differences (χ² = 8.511, df = 1, p = 0.004). We had missing data for 8.6% of the dwellings. Of the 34 cases where residents planted street trees, 91.2% reported caring for them, and 8.8% did not. Of the 9 dwellings where residents did not plant street trees, 66.7% cared for these trees, and 33.3% did not. Residents’ care for street trees was higher when they planted them than when they do not, however, this difference was not significant according to Fisher’s exact test (p = 0.095; CI 95%: 0.530, 46.535) for an odds ratio of 4.9. The frequencies and percentages for the presence, planting, and care of street trees on the sidewalks in front of surveyed dwellings across Xalapa are in Figure 3B.

Of the 47 dwellings with street trees, most respondents (87.2 %; n = 41) reported providing care to the trees. The most frequent care practices reported for street trees were pruning and watering (> 50%), followed by adding fertilizer or compost, and cleaning and weeding (17.0% and 10.6 %, respectively). Phytosanitary care, provision of mechanical support, and surveillance were reported in only one dwelling each (Figure 4).

Residential and Street Tree Presence, Planting, and Care

We found a higher presence of residential trees than of street trees, with significant differences in the proportions (χ² = 22.933, df = 1,p < 0.001). We recorded a few dwellings with the presence of both residential and street trees (n = 23; 13.0 %), with no relationship between their presence (χ² = 0.100, df = 1, p = 0.752). Nonetheless, once given the presence of trees inside or in front of dwellings, the probability that those trees were planted was high and similar in both cases (χ² < 0.000, df = 1, p = 0.992). The proportion of dwellings where people cared for residential trees and the proportion of dwellings where they cared for street trees were similar (χ² = 0.213, df = 1, p = 0.645). Such a tree care affinity was maintained when considering the proportions of dwellings with planted residential and planted street trees only (OR = 0.605, p = 0.537, CI 95%: 0.098, 2.663). While the presence of trees was related to tree planting, tree care was not statistically related to tree planting (χ²= 2.937, df = 1, p = 0.087). However, the frequencies of the reported care practices varied depending on whether the trees were street or residential, with street trees receiving comparatively more care and attention from residents than residential trees (Figure 4).

Relationship Between Presence, Planting, and Care of Trees and Dwelling Characteristics

Our results showed that the presence of residential trees, the planting of street trees, and the care of residential and street trees were largely independent of the evaluated dwellings’ characteristics (socioeconomic level, time of inhabitance, home ownership, dwelling in neighborhood or subdivision). The presence of street trees was positively associated with the time of inhabitance and the dwellings’ socioeconomic level. For each year increment in time of inhabitance, the probability of the presence of street trees increased only 1.03 times, while by 1 increase in socioeconomic level, the probability of street tree presence would be 1.89 times higher. Residential tree planting was positively related to dwellings inhabited by their homeowners and would be 5.11 times higher in dwellings occupied by homeowners than in the case where they were not (Table 1).

Residential and Street Tree Presence and Planting

The presence of residential trees was higher than the presence of street trees as has been shown for other cities in Australia, Canada, and the United States (Summit and McPherson 1998; Kirkpatrick et al. 2011; Sousa-Silva et al. 2023), highlighting the important role of residents as active agents of residential greenery. Contrary to the expected, the presence of street trees did not indicate much about the presence of trees in dwellings since the proportion of dwellings having both residential and street trees was low, with no relationship between the presence of both types of trees. Nevertheless, this absence of association could indicate different underlying processes in the presence of trees related to the private or public nature of the spaces, and to the stewardship type and stakeholders acting on each type of space (Kirkpatrick et al. 2011).

Residential and Street Tree Care

The performance of tree management practices indicates the people’s interest in maintaining healthy, aesthetic, and safe trees (Summit and McPherson 1998). The diverse tree care practices performed by residents in Xalapa suggest their active involvement in the survival and aesthetic value of trees. Pruning was the most reported care practice for residential and street trees (Summit and McPherson 1998; Speak and Salbitano 2023), which is important to maintain their proper structure, help in their growth and aesthetics, and prevent branch fall (Badrulhisham and Othman 2016). Watering, the second most common reported care practice in the city, ensures access to water for both residential and street trees (Nowak et al. 1990). However, watering practice varies across climatic regions, being more frequent in hotter and drier regions (Locke et al. 2019). In Xalapa, although it rains year-round, there is a heatwave in the summer (Soto-Esparza and Gómez-Columna 1993), when watering is vital. Other less frequent care practices included adding fertilizer or compost, phytosanitary care, and cleaning and weeding, which had been also infrequent in other studies (Summit and McPherson 1998; Locke et al. 2019).

Tree Presence, Planting, and Care Related to Dwelling Characteristics

The results showed that the planting and care practices of residential and street trees were related to some dwellings’ characteristics, although relationships varied according to the practice and the type of tree. In the case of residential trees in Xalapa, homeowners were active promoters of residential greening of the city, deciding what, why, when, and where to plant, which is consistent with what has been described in other cities (Summit and McPherson 1998; Acar et al. 2007; Marco et al. 2010; Dilley and Wolf 2013; Conway 2016; Guo et al. 2019; Danquah et al. 2023), with an impact on the tree species composition, diversity, and coverage (Kirkpatrick et al. 2012; Conway and Vander Vecht 2015; Avolio et al. 2018; Roman et al. 2018). Street tree presence was associated with dwellings’ socioeconomic level, showing that Xalapa follows the trend already reported for other cities of generally more street trees in wealthier zones (Landry and Chakraborty 2009; Kirkpatrick et al. 2011; Li et al. 2015; Lockwood and Berland 2019). Since the socioeconomic level of dwellings was associated with street tree presence but not with street tree planting, it is plausible that their presence was more related to the planting efforts of municipal authorities rather than people (Kendal et al. 2012; Kirkpatrick et al. 2012). Furthermore, the low proportion of street trees on the sidewalks in front of the dwellings could indicate that efforts from local authorities have been oriented towards planting in public spaces such as parks and large avenues, rather than in neighborhood streets, as also shown in the calls for tree planting campaigns in the city (Garizurieta 2018; DMA 2022). This seems to be a generalized situation in cities (Pincetl et al. 2013), although some efforts have also been oriented toward private spaces (Perkins et al. 2004; Conway et al. 2022). The significant positive relationship of time of inhabitance only with street tree presence, linked to the lack of evidence of their association with street tree planting, as in Summit and McPherson (1998) for residential trees, could indicate a positive relationship between street tree presence and the age of the neighborhoods, as older neighborhoods are often reported to be greener (Grove et al. 2006; Lowry Jr. et al. 2012).

Contrary to our expectations, tree care was not associated with dwellings’ characteristics as reported in the literature (Grove et al. 2006; Roman et al. 2014; Locke et al. 2019). The lack of such associations shows that in Xalapa, residents are engaged in tree care in both public and private spaces regardless of ownership situation, socioeconomic level, time of inhabitance, and location of the dwelling in neighborhoods or subdivisions. According to the local ordinance, the care of trees is the responsibility of residents when they are on the sidewalk in front of private property (GEV 2018). However, based on our results, it seems that in Xalapa, residents care for trees because they want to, rather than out of obligation.

In terms of socioeconomic level, tree planting and care by people involve time and money investment, whether they do it themselves or hire people to do it for them (Summit and McPherson 1998; Dean 2005; Locke et al. 2019). This suggests a high level of commitment by Xalapa residents to their trees, including street trees for which residents often consider that their care is the responsibility of the government authorities (Moskell and Allred 2013). Limitations to tree planting and care of residential and street trees due to a lack of financial possibilities, support, or incentives (Pincetl et al. 2013) did not appear to be the case in Xalapa.

Limitations of the Survey

While residential and street tree planting and care practices appeared to be related to some of the dwellings’ characteristics evaluated, it would be useful to evaluate the role of other dwelling, neighborhood, or individual attributes that we did not consider in this study, such as education, population density, age, or gender (Greene et al. 2011; Donovan and Mills 2014; Conway 2016; Watkins et al. 2017; Guo et al. 2019; Cattivelli 2022; Ibrahim et al. 2022; Danquah et al. 2023). At the individual level, we did not assess possible relationships between respondents’ characteristics and residential and street tree planting and care in Xalapa, as has been done in other studies (Marco et al. 2010), because our respondents were not necessarily those who made the decisions regarding tree planting and care in the surveyed dwellings, the reason why we here focused only on dwelling characteristics.

Because we aimed to keep the questionnaire as short and simple as possible, we missed information from a more in-depth approach on residents’ knowledge, possibilities, preferences, willingness, and motivations regarding residential and street tree care and planting. We did not record information on the number, species, or structure of the reported trees, which would have provided a richer context for tree planting and care in Xalapa. Finally, while our data were recorded ten years ago, to our knowledge, there is no previously published information on the presence, planting, and care of residential and street trees in Xalapa. Although the numbers may have changed, we provide valid and useful information to compare with current or future information on this topic for the city.

Implications for Urban Greening in Xalapa

It is important to develop local strategies to integrate the residents’ willingness to plant and care for urban trees into greening programs and campaigns that motivate them also to continue planting and retaining their trees (Summit and McPherson 1998; Summit and Sommer 1998; Marco et al. 2010; Carmichael and McDonough 2018; Danquah et al. 2023). People’s participation is an integral part of the overall strategy to use urban greenery and green space systems against climate change and to achieve sustainability and resilience in cities (Gill et al. 2007; Pitman et al. 2015). This strategy needs to be implemented at different scales within the city and with the collaboration of several stakeholders intervening at several levels of stewardship (Andersson et al. 2014; Breger et al. 2019). To implement these strategies, additional information is needed on motives, knowledge, and decisions behind people’s tree preferences (Camacho-Cervantes et al. 2014; Speak et al. 2022), other tree planting and care practices (Cattivelli 2022; Ibrahim et al. 2022; Lange et al. 2022), as well as on aspects such as tree species composition, survival and mortality rates (Roman et al. 2014; Breger et al. 2019; Salisbury et al. 2022), frequency of care practices, and assessment of other household and individual characteristics (Marco et al. 2010; Ibrahim et al. 2022). This study is a first step toward a comprehensive understanding of how people’s actions on private and public lands can impact the city’s greenery for the benefit of the people themselves and the wildlife groups in Xalapa.