Shrub encroachment into grass-dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a fourfold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (41000 g m À2 ) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the relationship between MAP and ANPP shifted from being nonlinear in grasslands to linear in shrublands. Thus, relatively abrupt (o50 years) shifts in growth form dominance, without changes in resource quantity, can fundamentally alter continental-scale pattern of C inputs and their control by MAP in ways that exceed the direct effects of climate change alone.

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Coastlines have traditionally been engineered to maintain structural stability and to protect property from storm‐related damage, but their ability to endure will be challenged over the next century. The use of vegetation to reduce erosion on ocean‐facing mainland and barrier island shorelines – including the sand dunes and beaches on these islands – could be part of a more flexible strategy. Although there is growing enthusiasm for using vegetation for this purpose, empirical data supporting this approach are lacking. Here, we identify the potential roles of vegetation in coastal protection, including the capture of sediment, ecological succession, and the building of islands, dunes, and beaches; the development of wave‐resistant soils by increasing effective grain size and sedimentary cohesion; the ability of aboveground architecture to attenuate waves and impede through‐flow; the capability of roots to bind sediments subjected to wave action; and the alteration of coastline resiliency by plant structures and genetic traits. We conclude that ecological and engineering practices must be combined in order to develop a sustainable, realistic, and integrated coastal protection strategy.

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Abstract. In contrast to stable inland systems, coastal landscape positions are dynamic, changing as shorelines migrate and storms alter topography. We define landscape position by distance to ocean shoreline and elevation above sea level, two metrics that integrate a suite of environmental and biotic factors. As shoreline and elevation change, suitability of a geo-referenced position for a given plant species may also change. The objectives of our study were to use two methods for measuring landscape position (GPS and hyperspectral/light detection and ranging or LIDAR) to develop habitat polygons, compare habitat polygons for five species representing several adaptive strategies, and illustrate change in landscape position due to migrating shoreline for a Virginia, USA barrier island. Habitat polygons for each species were distinct, represented several growth forms or functional groups, and were indicative of tolerances to biotic and abiotic stresses. The habitat polygon for Cakile edentula (annual forb) was relatively small, indicating narrow habitat requirements for the strand environment. Cirsium horridulum (biennial forb), with succulent shoots and roots, occurred on dunes where water is most limiting. For the dunebuilding grass, Ammophila breviligulata, as distance from shoreline increased, minimum elevation also increased. Two woody species occurred across the entire island; however, Morella cerifera (N-fixing shrub), was limited to mesic swales whereas Juniperus virginiana (evergreen tree), with the largest habitat polygon, occurred on both dunes and swales. For a geo-referenced point on the north end of Hog Island, distance to shoreline increased from the shoreline to 1100 m inland over 139 years. In contrast, the geo-referenced point on the eroding portion of the island decreased from 1700 m to 120 m from the ocean shoreline over the same time period. Where sea level rise and storms are expected to alter shorelines and island topography, generation of habitat polygons from hyperspectral and LIDAR imagery provide rapid assessment of potential effects on species distribution patterns at local and regional scales. Habitat polygons have broad applicability beyond coastal systems and may contribute to a rapid assessment or identification of vulnerability for species as climate patterns shift through time.

In addition to the well-known positive space charge, electron irradiation of MOS capacitors with 25-keV electrons is shown to introduce additional uncharged electron traps into the oxide layer. These traps persist after most of the positively charged defects have been removed by the usual low-temperature (~ 0c) anneals. Their presence after this anneal is determined by injecting hot electrons into the oxide where they are captured by existing defects. The effective trap densities increase with increasing electron fluence and are reduced by forming-gas anneals at temperatures in excess of 500°C. Observed electron-capture cross sections are between 10-15 and 10-18 cm 2 • The residual radiation damage in oxides exposed to 10-4 Ccm-2 of 25-keV electrons and subsequently annealed at 4OQ°C results in an additional neutral density of 5 X 1011 trapscm-2 with cross sections distributed over the above range. Electron-trapping cross sections and effective trap densities associated with this damage are found to be identical at 77 and 295 K. The traps are possibly associated with dipolar defects formed when valence electrons localize around an ion after the bonds are broken.

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