Study: House Sizes Increase at the Expense of Tree Canopies

Researchers with the USC Spatial Sciences Institute, led by Su Jin Lee, Professor Travis Longcore, Catherin Rich, and John P. Wilson have published a study finding that green cover for single-family home lots declined anywhere from 14 to 55 percent the Los Angeles area, with almost no single area spared from decline.

The study was published in the journal Urban Forestry & Urban Greening and announced in a press release on EurekaAlert.

As noted in the study, much of the "de-greening" of Los Angeles occurred as the city implemented a "Million Trees" campaign. The researchers began by taking an inventory of single-family parcels in the largest 20 largest cities in the Los Angeles basin, starting with the parcels that had added square footage to the home since 2007.

Baldwin Park led all areas in reduction, seeing a 55 percent loss of green cover on single-family residential lots in the mere span of nine years.

Other areas in the study that had at least 20 percent loss in cover included Pomona, Downey, Sylmar, Compton, and San Pedro/Port of Los Angeles.

The study noted one prominent exception: Pasadena, which maintained its verdant condition.

"[Study author] Longcore believes changing social views on the preferred size of single-family homes is the largest driver of tree cover loss, along with the increase in paved surfaces like walkways, driveways and swimming pools that come with home expansion," according to the press release.