The impact of land use and land cover changes and human dynamics in Jobos Bay National Estuarine Research Reserve in Puerto Rico.

Abstract

The Jobos Bay National Estuarine Research Reserve has been facing land changes in its watershed since the 1970s, particularly in agriculture activities and urban growth. The Jobos Bay Watershed (JBW) is historically considered an agricultural watershed, even when urban development began in the last four decades. Thus, population and housing estimates were needed to analyze the people residing within the reserve thru the Intelligent Dasymetric Mapping method as part of the urban growth analysis and agricultural land conversion. This study assessed the potential impacts of land changes in the estuarine ecosystem on soil erosion by using Transition Matrix Analysis, the Revised Universal Soil Loss Equation (RUSLE), and Hot Spot Analysis from 1970 to 2010. <br /> <br />Therefore, this work aims to develop a study to link changes in human population and housing units' distribution, and land changes to soil erosion rates to give insights into how these terrestrial processes at a local watershed scale may affect the estuarine waters quality of JBNERR. The results suggest that urbanization and sprawl occur mostly from pasture and were continually increasing for the study period and in areas closer to the coastal line. Reforestation trends have a high potential to continue because forest recovery occurred at 44.7% between 1991 and 2000 and 42.4% between 2000 and 2010, especially in the upper east area of JBW. The spatiotemporal distribution of soil erosion exposure showed from 1977 to 2010, more than 40% of the watershed had slight soil loss, around 10% was slight to moderate, more than 13% was moderate, and around 5% was moderate and around 11% was very highly exposed. The potential soil erosion risk and severity increase from the mid-upper Northeast to the lowlands reaches of the JBW. <br /> <br />This study revealed that the assessment of population and housing distribution linked to land changes provides an insight into the soil erosion process due to economic shift and cultivated land conversion in JBNERR. This finding gives a great base for further research integrating local knowledge from the communities in JBW to track soil erosion related to agriculture activities and come up with recommendations related to soil conservation policy.