Climate models predict that precipitation patterns will change in the coming decades, and in the U.S. Great Plains, the frequency and duration of summer droughts is predicted to increase. Because water is the most frequently limiting resource in arid and semi-arid systems, changes in water and nitrogen availability may cause linked carbon (C) and nitrogen (N) processes to become asynchronous, changing retention and loss patterns that control ecosystem function.

 Seventy-four catchments, with a total area of 790 km2 (ranging from 1 to 50 km2), drain from the Santa Ynez Mountains along the northern coast of Santa Barbara Channel. The topography of these coastal catchments is characterized as mountainous headwaters and sloping coastal plains separated by transitional foothills. From west to east, there are both elevational and land use gradients. Headwater elevations increase from approximately 300 to 1400 m, and land uses on the coastal plain and foothills change from mostly rangeland to a combination of urban and agricultural lands.

Elevational Controls on Organic and Inorganic Nutrients in Stream Waters, Boulder Creek Watershed, Colorado Front Range

Jordan N. Parman and Mark W. Williams

Department of Geography and Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA

Woody encroachment and its effects on terrestrial ecosystems have been well-studied. However, the effect on riparian and aquatic ecosystems, specifically denitrification, has been lacking. Riparian areas of headwater prairie streams were historically dominated by grasses, but have become increasingly covered by woody vegetation. To determine potential consequences of woody plant invasion on denitrification, three adjacent reaches were delineated from two branches of King’s Creek, which drains Konza Prairie Biological Station.

  Litter decomposition is an important process for nutrient and organic matter dynamics in forest ecosystem, and influenced by various biotic and abiotic factors. Ltter quality such as nitrogen and lignin contents is one of the important indicators to understand the difference of pattern and rate in the litter decomposition among different vegetation in forest ecosystem of northern Hokkaido, Japan. However, the pattern and rate in Sasa litter decomposition, their difference with the tree litter and their relations to the litter chemical property has not been clarified yet.

Nitrate deposition in terrestrial and aquatic ecosystems is increasing worldwide as a result of human activities. Between 1984 and 1996, deposition of inorganic nitrogen in Colorado’s Niwot Ridge Long Term Ecological research site doubled. Previous research suggests that small streams are the most effective sites for nitrate processing and retention; however, the role of alpine lakes has not been adequately examined.

 The primary research focus of the Santa Barbara Coastal (SBC) LTER is on the relative importance of bottom-up processes and allochthonous inputs to giant kelp forests, a highly diverse and productive marine ecosystem that occurs on shallow rocky reefs at the interface of the land-ocean margin. Giant kelp forests are found along the temperate coasts of western North and South America, southern Africa, Australia and most sub Antarctic islands, including Tasmania and New Zealand.

Diverse plant litter mixtures frequently decompose substantially differently than expected, compared to the average of the individual component species. These strong “non-additive” effects constitute an important way in which biodiversity influences key components of below-ground ecosystem function like soil C and N cycling, and it remains unclear which plant traits drive diversity effects on soil C and N cycling.

The groundwater-derived nutrient flux to estuaries and the coastal ocean can rival that of surface water inputs due to high groundwater nutrient concentrations. Groundwater inputs thus have an important impact on coastal water quality. Understanding patterns of variability in groundwater nutrient fluxes and the mechanisms generating this variability will help to inform coastal water resource management decisions. A suite of groundwater geochemical constituents has been monitored over the course of at least one year at two sites in coastal Georgia.