Restoration of a degraded oak forest in Mexico City by introducing tree native species

Abstract

Background: Uncontrollable urban expansion and population growth converted Mexico City into one of the largest cities of the world. Ravines remain important oak forest relicts that should be conserved and restored to recover the biodiversity and the ecological services they provide. Question: Is an open area equally appropriate for ecological restoration as is the forest edge? Does plant performance of introduced species vary between the open area and the forest edge? Study species: Prunus serotina, Quercus rugosa, and Crataegus mexicana. Study site: Oak forest in Barranca de Tarango, Mexico City; July 2010 to July 2012. Methods: Plants of these species were planted in the forest edge and in an open area adjacent to it, where soil properties and light conditions were measured. Results: Soil properties and leaf area index were better and significantly larger, respectively, in the forest edge than in the open area. Stem height, basal area and number of sprouts of these plants did not differ between sites or years. Plants of C. mexicana produced the largest number of sprouts, followed by Q. rugosa. Survival of plants was similar in the open area and the forest edge; however, P. serotina had the lowest survival, and C. mexicana the highest. Conclusions: Q. rugosa and C. mexicana with higher survival are more likely to perform better in both sites than P. serotina, on account of their ability to produce more sprouts. The forest edge is better than the open area for introducing native species in Barranca de Tarango. Low performance of these species was mainly due to the construction of a highway that crosses the study area.