Developmental framework for a desktop hydrogeomorphic wetland functional assessment derived from field-based data.

With loss of wetlands and their associated ecosystem services within landscapes, it is imperative to be able to understand the change in ecological functions underlying these services. Field-based functional assessments can produce a range of specific scores among a robust set of functions but are time and cost prohibitive as the number of wetlands assessed increases. Remote-based functional assessments are an alternative for broad scale assessments, but trade-off cost for limitations in scoring and functional assemblage. To address these concerns, we created a framework for the development of the Hydrogeomorphic Remote Assessment of Wetland Function (HGM-RAWF). Rooted in the hydrogeomorphic approach of an existing field-based functional assessment and its underlying models, this remote functional assessment substitutes field-based assessment methods with remotely assessed proxies. As potential remote proxies were determined through literature review and statistically screened for use in the remote assessment, a field-based reference wetland database of 222 freshwater wetlands in the Mid-Atlantic Region provided a baseline by which remote data could be compared and calibrated. The resulting HGM-RAWF protocol remotely assesses seven hydrology and biogeochemistry functions in the Mid-Atlantic with assessment scores similar to its field-based counterparts. With noted limitations, the HGM-RAWF framework provides the means to create desktop functional assessments across broad geographic scales with the diversity and specificity of field-based assessments at the reduced costs associated with remote assessments. Its basis in the HGM approach and use of public spatial datasets allows the framework to be adopted regionally and can be used as a model for national wetland functional assessment.

Fine-scale spatial homogenization of microbial habitats: a multivariate index of headwater wetland complex condition.

With growing public awareness that wetlands are important to society, there are intensifying efforts to understand the ecological condition of those wetlands that remain, and to develop indicators of wetland condition. Indicators based on soils are not well developed and are absent in some current assessment protocols; these could be advantageous, particularly for soils, which are complex habitats for plants, invertebrates, and microbial communities. In this study, we examine whether multivariate soil indicators, correlated with microbial biomass and community composition, can be used to distinguish reference standard (i.e., high condition) headwater wetland complexes from impacted headwater wetland complexes in central Pennsylvania, USA. Our reference standard sites existed in forested landscapes, while our impacted sites were situated in multi-use landscapes and were affected by a range of land-use legacies in the 1900s. We found that current assessment protocols are likely underrepresenting sampling needs to accurately represent site mean soil properties. On average, more samples were required to represent soil property means in reference standard sites compared to impacted sites. Reference standard and impacted sites also had noticeably different types of microbial habitats for the two multivariate soil indices assessed, and impacted sites were more homogenized in terms of the fine-scale (i.e., 1 and 5 m) spatial variability of these indices. Our study shows promise for the use of multivariate soil indices as indicators of wetland condition and provides insights into the sample sizes and scales at which soil sampling should occur during assessments. Future work is needed to test the generalizability of these findings across wetland types and ecoregions and establish definitive links between structural changes in microbial habitats and changes in wetland soil functioning.

Assessing wetland condition on a watershed basis in the Mid-Atlantic region using synoptic land-cover maps.

We developed a series of tools to address three integrated tasks needed to effectively manage wetlands on a watershed basis: inventory, assessment, and restoration. Depending on the objectives of an assessment, availability of resources, and degree of confidence required in the results, there are three levels of effort available to address these three tasks. This paper describes the development and use of synoptic land-cover maps (Level 1) to assess wetland condition for a watershed. The other two levels are a rapid assessment using ground reconnaissance (Level 2) and intensive field assessment (Level 3). To illustrate the application of this method, seven watersheds in Pennsylvania were investigated representing a range of areas (89-777 km2), land uses, and ecoregions found in the Mid-Atlantic Region. Level 1 disturbance scores were based on land cover in 1-km radius circles centered on randomly-selected wetlands in each watershed. On a standardized, 100-point, human-disturbance scale, with 100 being severely degraded and 1 being the most ecologically intact, the range of scores for the seven watersheds was a relatively pristine score of 4 to a moderately degraded score of 66. This entire process can be conducted in a geographic information system (GIS)-capable office with readily available data and without engaging in extensive field investigations. We recommend that agencies and organizations begin the process of assessing wetlands by adopting this approach as a first step toward determining the condition of wetlands on a watershed basis.