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This chapter discusses how particular global change phenomena impact on soil biota and their activities, and how these effects feedback to nutrient dynamics and the productivity and structure of above-ground communities. Earth's ecosystems are subject to multiple and simultaneous assaults of global change phenomena. The chapter focuses on selected global change phenomena — climate change, nitrogen deposition, invasive species, and land use change — to explore how single components of global change impact on soil and ecosystem processes.

The story of air pollution research, policy development, and management in national parks is a fascinating blend of cultural change, vision, interdisciplinary and interagency collaboration, and science-policy-management-stakeholder collaborations. Unable to ignore the loss of iconic vistas from regional haze and loss of fish from acid rain in the 1980s, the US National Park Service (NPS) embraced an obligation to protect resources from threats originating outside park boundaries. Upholding the Organic Act requirement for parks to remain “unimpaired” for the enjoyment of future generations, and using the Clean Air Act statement that the NPS has an “affirmative responsibility” to protect park resources, the NPS has supported, and effectively used, research as a means to protect lands, waters, and vistas from a mostly unseen threat. Using visibility and atmospheric nitrogen deposition as examples, we illustrate some success stories where the NPS led the way to benefit not only parks, but the nation.

Nitrogen inputs into terrestrial ecosystems have more than doubled since pre-industrial times, causing significant disruption of aboveground and belowground communities, and the ecosystem services they regulate. This chapter reviews the causes and consequences of nitrogen enrichment, with a focus on effects upon plants and the soil biota, including saprotrophic fungi and bacteria and mycorrhizal fungi. It explores the implications of these changes for several key ecosystem services: greenhouse gas emissions, carbon sequestration, food production, clean water supply, and human health and biodiversity conservation, highlighting the trade-offs between these services that nitrogen enrichment generates. The chapter finishes with recommendations for future research in this field, in particular the requirement for a holistic but mechanistic knowledge of how nitrogen alters higher-level ecosystem services.

The micro-environmental conditions of different soil habitats are influenced by prevailing vegetation, aspect, soil texture, soil colour and other variables that influence the incoming and outgoing solar energy. The variability is especially pronounced in sand dunes because of shifting substrate, burial by sand, bare areas among plants, porous nature of sand and little or no organic matter, especially during the early stages of dune development. Even within a dune system there is disparity in radiative heating of different habitats that is manifested as variation in micro-environmental factors such as relative humidity, temperature, light, moisture content and wind turbulence. The major factor affecting these changes is the establishment of vegetation that stabilizes the surface, adds humus, develops shade, aids in the development of soil structure and reduces the severity of drought on the soil surface. The system changes from an open desert-like sandy substrate on the beach to a mature, well-developed soil system with luxuriant plant communities. The principal topics discussed in this chapter include accounts of micro-environmental factors of coastal sand dunes that influence the growth and reproduction of colonizing species. The water content of the substratum in sandy soils is one of the most important limiting factors in plant growth. Sandy soils have high porosity and after a rain most of the water is drained away from the habitat because of the large interstitial spaces between soil particles and the low capacity of sand to retain water. Evaporation in open dune systems also removes substantial quantities of water. Lichter (1998) showed that evaporation was greater on non-forested dune ridges than on forested areas and the rate of soil drying was influenced by soil depth and dune location. After 3 days of a heavy rainfall there was a drastic decrease in the percentage of moisture (67–80%) at 0–5 cm levels in open habitats compared to only 30–36% in the forested dune ridges. The same measurements at 10–15 cm depths showed much lower reduction in the percentage of moisture. In the swale (slack) even though the evaporative demand was the same, there was actually an increase in moisture because of seepage from the dune ridges.

Seasonally snow-covered areas of Earth’s mountain ranges are important components of the global hydrologic cycle. Although their area is limited, the snowpacks of these areas are a major source of the water supply for runoff and ground water recharge over wide areas of the mid-latitudes. They are also sensitive indicators of climatic change. The release of ions from the snowpack is an important component in the biogeochemistry of alpine areas and may also function as a sensitive indicator of changes in atmospheric chemistry. The demand for water in the semiarid areas of the western United States is reflected in extensive systems of reservoirs, canals, and flow diversions that have been constructed over the past century. Most of the water resources tapped by these systems derives from the mountain environments of the Rocky Mountains, where contributions of the alpine have long been recognized (Martinelli 1975). In Colorado, 9000 km2 of alpine terrain, less than 4% of the state’s area, provide more than 20% of the state’s streamflow and is especially important in maintaining late-summer flows (Martinelli 1975). Lakes in the Rocky Mountains are relatively uncontaminated compared with many other high-elevation lakes in the world, with the median value of NO-3 concentrations less than 1 μeq L-1 (Psenner 1989). However, in comparison with downstream ecosystems, these high-elevation ecosystems are relatively sensitive to changes in the flux of energy, chemicals, and water because of extensive areas of exposed and unreactive bedrock, rapid hydrologic flushing rates during snowmelt, limited extent of vegetation and soils, and short growing seasons (Williams 1993). Hence, even small changes in atmospheric deposition have the potential to result in large changes in ecosystem dynamics and water quality (Williams et al. 1996a). Furthermore, these ecosystem changes may occur in alpine areas before they occur in downstream ecosystems (Williams et al. 1996b). Apart from its use in municipal supply, agriculture, recreation, and power generation, this water also mediates transfers of geomorphic and biological materials. For this reason, the drainage basin, or catchment, has long been recognized as a basic geomorphic unit in environmental research (e.g., Chorley 1967; Bormann and Likens 1969).

This chapter explores snow as a biological medium. Snow coloured red and pink has been described since ancient times, and is caused by so called ‘snow algae’, which have been researched since the 1960s. Snow algae are exposed to high levels of damaging ultraviolet radiation and have evolved mechanisms to counteract is effects. Aspects of their physiology (growth and photosynthesis) are outlined. Recent work has shown that bacteria are functionally active in snow, and molecular analysis is shedding light on the nature of these bacterial communities. Snow has a major impact on the ground that it covers seasonally. Contrary to what one might suppose, considerable biological activity occurs beneath the insulating snow layer in winter. In some parts of the Arctic there is significant aerial deposition of nitrogen on the winter snow pack that provides a pulse of nitrogen to fertilise the tundra on summer melt. These aspects of snow cover impact are examined in detail.

This chapter describes the physical environment surrounding Wytham Woods by providing illustrations of the area. It analyses information gathered from the Environmental Change Network (ECN), and examines the location's topography, climate, geology and soils, and hydrology. It also briefly tackles the issue of pollution in the Woods due to acidification and the fertilizing effects of nitrogen deposition.

This chapter studies the patterns and behaviours of flowers thriving in the woodlands. It describes the flora distribution and vegetation patterns in the woodlands, and looks into recent changes in the flora as a result of the changing environment and other external factors. It presents information gathered from various studies of the common flower types, and discusses some of the changes such as the overall decline in species richness and the effects of increased nitrogen deposition. It also highlights the vital role of shade in species richness and the relationship of deer grazing and species richness.