Hotspots indicate areas in Houston we project could be fragrant in the future due to changes in ecology. Base data acquired from Harris County's vacant parcel information.

Hotspots indicate areas in Houston we project could be fragrant in the future due to changes in ecology. Base data acquired from Harris County's vacant parcel information.

 

HOUSTON COULD BE FRAGRANT

 

CITY OF SUBURBS
Houston is a city defined by sprawl. It is comprised of 627 square miles — double the size of Singapore with only 50 percent of the population. Manicured suburban subdivisions are the norm with single-family detached homes comprising over 60 percent of all housing stock in the county.   

HOUSTON IS GETTING HOTTER AND WETTER
Houston is experiencing increased temperatures and precipitation. According to Climate Central, the average summer temperature in Houston is currently 13 degrees higher in the city than in nearby rural areas, a differential that is expected to grow. At the same time, since warm air contains more water vapor than cool air, the city has been hit with an increase in heavy rain events. Over the past seven decades, Houston has seen a 167 percent increase in heavy downpours, one of the fastest rates in the United States. 

A SWEET SMELLING CITY?
Recently, ecologists have discovered that non-native, invasive plants — often  subtropical and tropical species — are better able to respond to these climatic changes than those that are endemic to the region. Many of these spontaneous urban plants are shifting their flowering schedule to align with the longer growing season, blooming earlier than the natives. This has, in turn, allowed them to shade out their competition, giving them access to more water, nutrients, and pollinators. Elizabeth Wolkovich, Director of the Biodiversity Research Center at the University of British Columbia, states “It’s shocking to see how quickly the playing field is being shifted in favor of species that can be super-adaptable. The species that win are going to be those that can take advantage of new opportunities very quickly. And I don’t think natives will often be among those species.”

In an effort to detect and report the spread of these species in Texas, a number of state agencies, conservation organizations, and academic partners have collaborated to form a successful citizen science program called “The Invaders of Texas.” The program trains volunteers to appropriately identify spontaneous species in their neighborhoods and add them to an online mapping database. In exploring this publicly-available map, it is clear that a number of the newly recorded plant species are highly fragrant, many with a sweet and pleasant odor profile. 

 Houston spontaneous plant fieldwork, observing  Uncaria tomentosa . 

Houston spontaneous plant fieldwork, observing Uncaria tomentosa

 
 

HINTS OF AN OLFACTORY SHIFT
Though anecdotal, there is evidence that Houstonians are beginning to perceive an olfactory shift in their city, especially with the most fragrant of the spontaneous species. Japanese honeysuckle, originally from eastern Asia, is one of these. Around Houston, honeysuckle can be found almost everywhere – in ditches, behind garbage cans, and at the peripheries of landscaped yards – drawing people in with its overpowering sugary and lemony perfume and sweet nectar. The Persian silk tree, from southwestern and eastern Asia, is beginning to take root on the outskirts of town. It produces a delicate flowerhead with similar compounds to citrus and coffee plant flowers and emits a green and dry scent profile. Kudzu, an aggressive woody vine from eastern Asia, is also starting to make its way into the city. Many believe that the flowers of this plant smell identical to artificial grapes.

URBAN JUNGLE ON THE HORIZON
Houston has no formal zoning code. While there are codes to address appropriate right-of-ways, building lines, parking, setbacks, and access, none address land use.  As a result, the city is a random mosaic of residences, warehouses and industrial areas,  with vacant lots dispersed throughout. In the future, many of these abandoned parcels could become overgrown with spontaneous and opportunistic vegetation, providing the city with a sweet smelling perfume.

OR THE FUTURE OF HOUSTON COULD BE LESS FRAGRANT
Houston is currently implementing a pilot program to tackle the issue of  overgrown lots by collaborating with neighborhood groups to mow and maintain spontaneous vegetation. Called “Neighborhood Mow Down,” the program is managed by the Department of Neighborhoods’ Inspections and Public Service Division, and seeks to increase neighborhood advocacy and engagement. This initiative might keep the invasive species, and their fragrances, at bay. 

 

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