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The Resources Planning Act (RPA) Assessment uses a combination of land use and land cover data to evaluate trends in the United States land base and project future changes. This publication describes how the RPA Assessment uses the National Resources Inventory, National Land Cover Database, and Forest Inventory and Analysis to support analyses of forest trends. The authors compare and contrast differences in definitions and approaches of these three major data sources and document the recent status and trends of land use and land cover area according to these sources. While the general definitions of land uses and land covers are superficially similar among these sources, understanding the conceptual and technical differences between them is necessary to evaluate and compare trends in the U.S. land base. Some differences can be rationalized based on the sensitivity of the different databases to the underlying drivers of landscape change over time. However, the major difference is the perception of the land base in terms of its intended human use versus its current biophysical cover. The RPA Assessment will continue to use both land use and land cover data separately and in combination because each source offers both unique and complementary perspectives on land base trends.

Increases in anthropogenic emissions of sulfur (S) and nitrogen (N) have resulted in increases in the associated atmospheric deposition of acidic compounds. In sensitive watersheds, this deposition has initiated a cascade of negative environmental effects on aquatic ecosystems, resulting in a degradation or loss of valuable ecosystem goods and services. Here, we report the activities of an expert workgroup to synthesize information on acidic deposition-induced aquatic acidification from the published literature and to link critical load exceedances with ecosystem services and beneficiaries, using the Stressor–Ecological Production function–Final Ecosystem Services (STEPS) Framework and the Final Ecosystem Goods and Services Classification System (FEGS-CS). Experts identified and documented the sensitive aquatic ecosystem ecological endpoints valued by humans, and the environmental pathways through which these endpoints may experience degradation in response to acidification. Beneficiary groups were then identified for each sensitive ecological endpoint to clarify relationships between humans and the effects of aquatic acidification, and to lay the foundation for future research and analysis to value these FEGS.

Coastal plain ponds support many plant species that have been designated as threatened due to human alteration of the hydrology and nutrient availability. Understanding how these species respond to environmental gradients at multiple spatial scales can support conservation efforts. I examined the relationship between plant species composition and environmental variables that operate at two spatial scales: within (local-scale) and among (broad-scale) 18 coastal plain ponds on the island of Martha's Vineyard, Massachusetts. Patterns in species composition occurred at both local and broad scales. Elevation along the water-depth gradient was the only local factor strongly correlated with species composition. Significant broad-scale environmental factors included surficial geology, hydrology, and specific conductance of pond water. Overall patterns in vegetation species composition and abundance were more closely related to broad-scale environmental variables than to local environmental variables, sug...

Buried seeds that germinate during periods of low water or water level drawdown can play important roles in shaping plant community composition, community dynamics and species richness in ecosystems with fluctuating water levels. Northeastern US coastal plain ponds have fluctuating water levels and contain a characteristic shoreline flora that contains many rare plants. The objectives of this study were to: (1) test whether geographically distant ponds in Cape Cod and Martha’s Vineyard had distinct seed banks, (2) determine if hydrologic status as permanent and ephemeral ponds led to differences in seed banks, and (3) examine seed diversity and seed abundance across gradients of shoreline elevations and sediment characteristics. Viable seeds of 45 plant species were identified from nine ponds. Native species dominated pond-shore seed banks and made up 89–100% of all species. There was high overlap in seed bank composition across hydrological classes and geographic regions. One hydrological class captured 73–76% of total species and one geographical region captured 69–78% of the total species recovered from the entire suite of seed bank samples. Seeds were relatively evenly distributed along the shorelines of ephemeral ponds but seed diversity and abundance were lower at low elevations in permanent ponds. Results suggest that strategies to protect pond shorelines to capture maximum diversity of coastal plain pond plants contained in pond sediment seed banks should be implemented across pond hydrologic classes and across a wide geographic area. Shoreline seed distributions indicate that ground-water withdrawals or climate changes that lower pond water levels in permanent ponds will reduce the diversity and abundance of plants recovered from seed banks by shifting water levels to a shoreline zone of high sediment organic matter where seed densities are lower. This effect will be much less in ephemeral ponds where seed diversity and abundance on pond bottoms was high.