Assessing riparian structure and composition in Quebrada Chiclana, Puerto Rico, a restored tropical creek.
Harold Manrique-Hernández, Jorge R. Ortiz-Zayas, Tamara Heartsill-Scalley and Maritza Barreto
We aimed to assess the ecological success of a river restoration project conducted in Quebrada Chiclana, a first-order creek located at the headwaters of the Río Piedras in San Juan, Puerto Rico. The study was mainly focused in the reforestation element of the restoration plan. In order to evaluate success, we selected forest structural variables such as basal area, species diversity, and land cover as success indicators. The assessment was divided into two objectives: one focused on forest succession, and a second focused on restoration success. The first objective focused on the current land cover composition of the Quebrada Chiclana and the second objective focused on evaluating if the reforestation plan was ecologically successful.
Land cover analysis showed a loss in the watershed natural landscape of 11% between the period of 1998-2010. Today, the watershed of the impacted area is comprised by 57% of forest cover. For the impacted and later restored area, we concluded that eight years after the restoration, the area is dominated mostly by range lands (71%). We encountered a riparian vegetation community composed of 119 species, 35 tree species and 84 non-tree species. Albizia procera and Spathodea campanulata are the most abundant tree species within the study area. The study was conducted at a parcel, plot and subplot scale comprising both restored and non-impacted areas (reference sites). The plot scale is the ideal to assess differences between reference plots and non-impacted plots. We concluded that the reforestation plan has yet to meet its two objectives. Even though we have shown evidence that the river restoration project has not met its reforestation objectives, our results showed a favorable recovery of the vegetation community in the impacted area.