Impacts of Climate and Land Use Change on Terrestrial and Marine Systems

Turkey Creek serves as a feeder stream to the Sampit River, which joins
with waters from the Waccamaw, Black, and Peedee rivers in Winyah Bay,
Georgetown, South Carolina. Historically, these tidal freshwater forested
wetlands experienced diurnal tides, driven by freshwater backing up
along the upper intertidal zone and swashing back and forth with tidal
ebb and flow. While these systems may have historically received aperiodic
pulses of salinity (e.g., hurricane surge), the incidence of salinization
has increased considerably over the past several decades owing to
sea-level rise, persistent river channel dredging, and fresh water extraction
up-stream. Years with low rainfall now concentrate soil salinity to levels
beyond what freshwater forests can tolerate, facilitating a state change
from forested wetlands to marsh along many coastal rivers in the
southeastern US.

Climate change effects on ecosystems often involve very long time scales (centuries), yet the trajectory of change in a specific region can be punctuated by shifts in land use over short time frames, i.e., days in some cases. Paleoclimatic records are critical for understanding what types of long-term shifts have occurred among ecosystems during past, abrupt climate change periods (e.g., Little Ice Age, AD 1500-1900), and have provided a sentinel record for biologists and land managers. The primary goals of contemporary biological research projects are to understand the specific climate-related processes responsible for mediating major shifts in ecosystem structure and persistence, to understand how major changes discovered in the geological record may have physically occurred, and to allow prediction for how faunal and botanical communities may adjust. Many studies take a systems approach, and include ecological modeling, advanced statistical protocols (e.g., structural equation modeling), and direct collaborations with paleoclimatologists. Biological projects attempt to understand how ecosystems are affected by specific environmental drivers, how biological systems affect those environmental drivers themselves, and how land management and/or land cover change affect biological integrity on local, regional, and landscape scales.

Interdisciplinary research among R&D scientists have focused on the role of sea-level rise and drought on coastal marshes, freshwater forested wetlands, and mangroves in the eastern US and greater Caribbean region; persistent drought and fire effects on the migration and mortality of montane forests in the western US; alterations in avian migrations among wetlands in semi-arid regions of the Great Basin experiencing variable rainfall patterns; the role of overgrazing on bird movements and habitat use among different forested ecosystems; and understanding the pervasive effects that drought severity can have on water quality, eolian transport, and food security for Native American communities with strong cultural linkages to the land. Projects focus strongly on energy and nutrient flow through multiple ecosystem types, and allow scientists to understand how even minor shifts in land use or environmental variability may influence ecosystems in a contemporary sense, and how processes critical to the health of the Nation – such as carbon sequestration, water table recharge, and nutrient filtration – are affected by rapidly changing climates within the current geological period (Anthropocene). Contemporary biological studies during this on-going, abrupt climate shift offers strong insight into processes of the past, and how land managers may even be able to influence change in some cases.