How much importance is given to native plants in cities’ treescape?

Posted by Greenhousedecor Team on

 

Even though Brazil is a mega-diverse country, many Brazilian cities prioritize exotic plants in their treescapes. Aiming to evaluate how much the treescape in Fortaleza (the fifth largest city in Brazil) is aligned with the policy of valorization of native biodiversity, we sampled street and backyard trees surrounding one of the few vegetation fragments of the city, which is an area considered a priority for conservation. We used the vegetation fragment’s flora as reference to compare the potential number of local native species with the actual number of native species in the treescape of the site. To account how much of the native flora was present in the surrounding treescape, we made an inventory of the
trees in streets, squares and backyards around the vegetation and compared with the native flora of the vegetation fragment. We then compared the ratio of native to exotic species and checked how many native species of the fragment were also in the surrounding treescape. Exotics were prevalent in both number of species and number of individuals,plant stand, comprising 70% of the species and 86% of the individuals of public spaces, and 79% of the species and 78% of the individuals of private spaces. Only 14% of the native species of the vegetation were also represented in the treescape, and, in general, they comprehended only a few individuals. We argue that the city’s treescape should be re-evaluated in order to value native plants more. Native plants in the treescape could be used as an environmental education tool to publicize native biodiversity to citizens.

 

Introduction
The importance of street and garden trees to cities is much beyond esthetic benefits. Besides improving climate and psychological wellbeing for humans (Lombardo, 1985; Kweon et al., 1998), cultivated plants also integrate the ecology of cities (Gaston et al., 2005; Smith et al., 2006), timber plant stand being an important element of urban biodiversity. But landscaping and gardening can also bring
negative effects when cultivated exotic plants escape cultivation and become invasive (Zipperer, 2002; Harrington et al., 2003; Christianini, 2006; Mondin, 2006; Mengardo et al., 2012). Most of the introduced exotic species do not cause any ecological problem (Richardson et al., 2000a,b), but the ones that manage to turn into invasive can cause considerable hazard to ecosystems and have a
high cost to control (Zipperer, 2002; Guézou et al., 2010; Gardener
et al., 2012; Mengardo et al., 2012).
Another aspect to be considered when planning the implementation
of urban treescaping is that citizens of heavily urbanized ∗ Corresponding author.
E-mail addresses: bio moro@yahoo.com.br (M.F. Moro),
westerkamp@cariri.ufc.br (C. Westerkamp), plant pot stand tchesca@ufc.br (F.S. de Araújo).
countries will have more chance to know and appreciate trees that
are cultivated in the urban environment. If those are native plants,
treescaping could be used as a tool to present native plants to people
and increase public’s support for conservation (McKinney, 2002,
2006; Dearborn and Kark, 2010; Herzog, 2013). The use of characteristic,
native species from local ecosystems would be beneficial
also to provide a sense of place, connecting people with the particularities
and species of their own region (Dearborn and Kark, 2010;
Abendroth et al., 2012; Herzog, 2013). Although Brazil is deemed
a mega-diverse country, with more than thirty thousand native
plants (Forzza et al., 2010), many Brazilian cities give priority to
exotics in their treescape (Rocha et al., 2004; Santos et al., 2008,
2009; Barros et al., 2010; Moro and Westerkamp, 2011), reducing
the contact of people with native biodiversity. Moreover, some
of the plants now behaving as invasive in Brazil were originally
introduced as ornamentals (Mondin, 2006; Mengardo et al., 2012;
Moroet al., 2013), reinforcing the necessity to re-evaluate the urban
forestry model adopted in the country.
Thus, to quantify how much native plants are been ignored in
Brazilian treescapes we performed a quantitative survey in Fortaleza,
the fifth largest city in the country.Weaimed at answering the
following questions: (1) which are the most common species in the
treescape of the city; and are the most common species native or exotic? (2) Which is the share between native and exotic plants in
public (streets and squares) and private (gardens and backyards)
spaces? (3) How much is the native flora included as ornamental
plants in the treescape? (4) Are exotic species from the treescape
acting as invasive plants?


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