Phosphorus export from a restored wetland ecosystem in response to natural and experimental hydrologic fluctuations

Wetland restoration is a commonly used approach to reduce nutrient loading to freshwater and coastal ecosystems, with many wetland restoration efforts occurring in former agricultural fields. Restored wetlands are expected to be effective at retaining or removing both nitrogen and phosphorus (P), yet restoring wetland hydrology to former agricultural fields can lead to the release of legacy fertilizer P. Here, we examined P cycling and export following rewetting of the Timberlake Restoration Project, a 440 ha restored riverine wetland complex in the coastal plain of North Carolina. We also compared P cycling within the restored wetland to two minimally disturbed nearby wetlands and an adjacent active agricultural field. In the restored wetland we observed increased soluble reactive phosphorus (SRP) concentrations following initial flooding, consistent with our expectations that P bound to iron would be released under reducing conditions. SRP concentrations in spring were 2.5 times higher leaving the restored wetland than a forested wetland and an agricultural field. During two large-scale drawdown and rewetting experiments we decreased the water depth by 1 m in ∼10 ha of inundated wetland for 2 weeks, followed by reflooding. Rewetting following experimental drainage had no effect on SRP concentrations in winter, but SRP concentrations did increase when the experiment was repeated during summer. Our best estimates suggest that this restored wetland could release legacy fertilizer P for up to a decade following hydrologic restoration. The time lag between restoration and biogeochemical recovery should be incorporated into management strategies of restored wetlands. Copyright 2010 by the American Geophysical Union.

On the multiple ecological roles of water in river networks

The distribution and movement of water can influence the state and dynamics of terrestrial and aquatic ecosystems through a diversity of mechanisms. These mechanisms can be organized into three general categories wherein water acts as (1) a resource or habitat for biota, (2) a vector for connectivity and exchange of energy, materials, and organisms, and (3) as an agent of geomorphic change and disturbance. These latter two roles are highlighted in current models, which emphasize hydrologic connectivity and geomorphic change as determinants of the spatial and temporal distributions of species and processes in river systems. Water availability, on the other hand, has received less attention as a driver of ecological pattern, despite the prevalence of intermittent streams, and strong potential for environmental change to alter the spatial extent of drying in many regions. Here we summarize long-term research from a Sonoran Desert watershed to illustrate how spatial patterns of ecosystem structure and functioning reflect shifts in the relative importance of different 'roles of water' across scales of drainage size. These roles are distributed and interact hierarchically in the landscape, and for the bulk of the drainage network it is the duration of water availability that represents the primary determinant of ecological processes. Only for the largest catchments, with the most permanent flow regimes, do flood-associated disturbances and hydrologic exchange emerge as important drivers of local dynamics. While desert basins represent an extreme case, the diversity of mechanisms by which the availability and flow of water influence ecosystem structure and functioning are general. Predicting how river ecosystems may respond to future environmental pressures will require clear understanding of how changes in the spatial extent and relative overlap of these different roles of water shape ecological patterns. © 2013 Sponseller et al.

Community Vulnerability and Adaptation to Climate Change in East Palo Alto

Climate change and sea level rise continue to devastate communities around the globe. The impacts have a disproportionate effect on those of lower socio-economic levels, and the consequences are frequently not borne equally amongst impacted individuals (UNDP, 2013). Community-based adaptation has been widely used to assess vulnerabilities and impacts at the community level, with an inclusive process that addresses root causes of risk. The process provides the opportunity for local government to empower and engaged impacted communities in identifying and prioritizing their urgent adaptation needs. This study aims to understand East Palo Alto community vulnerabilities by assessing local knowledge and perception of risk to climate change. East Palo Alto, an urban city in California with socio-economic challenges, is vulnerable to flooding and coastal inundation. The limited financial and institutional capacity of the local government and community increases vulnerability and risk. Recommendations and steps are presented to guide actions and programs that are crucial in addressing community priorities and concerns.

Community Vulnerability and Adaptation to Climate Change in East Palo Alto

Climate change and sea level rise continue to devastate communities around the globe. The impacts have a disproportionate effect on those of lower socio-economic levels, and the consequences are frequently not borne equally amongst impacted individuals (UNDP, 2013). Community-based adaptation has been widely used to assess vulnerabilities and impacts at the community level, with an inclusive process that addresses root causes of risk. The process provides the opportunity for local government to empower and engaged impacted communities in identifying and prioritising their urgent adaptation needs. This study aims to understand East Palo Alto community vulnerabilities by assessing local knowledge and perception of risk to climate change. East Palo Alto, an urban city in California with socio- economic challenges, is vulnerable to flooding and coastal inundation. The limited financial and institutional capacity of the local government and community increases vulnerability and risk. Recommendations and steps are presented to guide actions and programs that are crucial in addressing community priorities and concerns