Urban development often results in diminished forest cover and severely fragmented landscapes, but most research on effects of urban development has been focused on densely forested regions and has not distinguished remnant from recently established forest cover. Urban development may have different effects in heterogeneous landscapes with high pre-urban fragmentation. Our study investigated spatial and temporal distribution of remnant forest ecosystems across a large urban landscape to assess effects of landscape structure and development patterns on forest conversion. Forest ecosystem distribution within the greater Chicago region (18,822 km 2) was mapped in three time periods using Public Land Survey records (1830's) and aerial imagery (1939 and 2010). Loss of original forest between sampling periods (conversion) was related to landscape features, land use, and sociodemographic factors. In 2010 ~17% of pre-urban forest area remained, which represented ~40% reduction relative to 1939. Conversion did not differ greatly with urbanization, but fragmentation was greater in areas with high population density and rapid population growth. Conversion was lower in areas close to waterways, where there was less impervious surface, and also differed among land uses (highest in agricultural and industrial). Remnant forests had higher canopy cover, basal area, and native species dominance than recently established forests. Urbanization may have lower relative effects on total forest cover in naturally fragmented landscapes, but may result in extreme fragmentation. Remnant forests had characteristics consistent with high functional value, but creating connectivity among ecosystems in highly urbanized areas will require promotion of canopy cover in urban land uses.

Waterbodies (natural lakes and reservoirs) are a critical part of a watershed’s ecological and hydrological balance, and in many cases dictate the downstream river flows either through natural attenuation or through managed controls. Investigating waterbody dynamics relies primarily on understanding their morphology and geophysical characteristics that are primarily defined by bathymetry. Bathymetric conditions define stage-storage relationships and circulation/transport processes in waterbodies. Yet many studies oversimplify these mechanisms due to unavailability of the bathymetric data. We developed a novel GLObal Bathymetric (GLOBathy) dataset of 1.4+ million waterbodies to align with the well-established global dataset, HydroLAKES. GLOBathy uses a GIS-based framework to generate bathymetric maps based on the waterbody maximum depth estimates and HydroLAKES geometric/geophysical attributes of the waterbodies. The maximum depth estimates are validated at 1,503 waterbodies, making use of several observed data sources. We also provide estimations for head-Area-Volume (h-A-V) relationships of the HydroLAKES waterbodies, driven from the bathymetric maps of the GLOBathy dataset. The h-A-V relationships provide essential information for water balance and hydrological studies of global waterbody systems.

No abstract