Soil respiration is a major pathway of flux in the terrestrial ecosystem carbon cycle and has received a great deal of attention recently. This is largely because even a small change in soil respiration can exacerbate the annual input of CO2 into the atmosphere. Soil respiration represents the combined respiration of roots and soil micro- and macro-organisms, and a number of studies on soil respiration have been undertaken in a variety of ecosystems.

Dynamic biogeochemical watershed models are the only practical approach that can predict concurrent exposure to multiple environmental factors and consider interactive effects between climate change, atmospheric deposition and CO2 fertilization effect. Therefore, they could be powerful tools to help to understand the long-term effects of climate change on ecosystems.

The MIRADA project was launched in the fall of 2007 to establish a Microbial Biodiversity Survey and Inventory across all 13 of the major aquatic (marine and freshwater) Long Term Ecological Research (LTER) sites in the NSF US LTER Program. The long-term objective of our study is to document and describe baseline diversity and relative abundance data for both common and rare members of microbial communities and to relate this diversity to the underlying physical and chemical environment.

Imprecise, inaccurate, and inconsistent soil sampling techniques are a major source of uncertainty in the calculation of nutrient budgets. Traditional methods of soil sampling include soil coring and excavation of quantitative soil pits. The major problem encountered with soil coring is that rocky soils limit the location and depth of sampling, and therefore the soil volume is not accurately measured. Quantitative soil pits resolve the rock volume bias, but they are notoriously laborious and destructive, making repeated measurements difficult in spatially variable sites.

Iron (Fe) is abundant among trace elements in forest ecosystems and important in the development and function of soils. We constructed a biogeochemical budget for Fe to better understand the behavior of Fe and its role in the development of Spodosols (podsolization). Fluxes of reduced (ferrous, Fe(II)) and oxidized (ferric, Fe(III)) iron draining through the soil profile were calculated.

The EcoTrends Project began in 2004 as a joint collaboration among the LTER Program, USDA Agricultral Research Service, and the USDA Forest Service with two goals: (1) to create a book illustrating trends in long -term data and showing the value of long-term data across a network of sites in addressing continental-scale questions, and (2) to make long-term biotic and abiotic data easily accessible through a common web interface with a focus on derived or aggregated data to allow cross-site analyses to be made.

With recent shifts in public attitudes across the United States concerning the problem of global climate change, momentum is building for aggressive action to mitigate greenhouse gas emissions. At the same time, the ongoing economic recession presents challenges for financing an aggressive climate change abatement campaign; hence, it is imperative that cost-effective strategies for reducing greenhouse gas emissions be identified and pursued. To accomplish this, policy instruments will need to be tailored to a complex range of local and regional conditions.

Although temperate forests have long been thought to be primarily nitrogen limited, resource optimization theory suggests that ecosystem productivity should be co-limited by multiple nutrients. In northeastern North America, air pollution and forest harvesting disturbance elevate N availability and contribute to the likelihood of P limitation.

Long-term data from the Hubbard Brook Experimental Forest show that air temperature has increased by 1-1.5 °C over the last half century. While more variable, annual precipitation has also increased by 19-26% during the same period. These changes in climate influence streamflow, which provides an integrated climate signal that incorporates physical (snowpack, evaporation) and biological (evapotranspiration) responses. Unlike the western United States, water is generally abundant in the Northeast.

Analysis of twenty-five years of forest floor sampling on Watershed 6 (W6) at the Hubbard Brook Experimental Forest (Woodstock, NH, USA) shows no significant evidence of N accumulation in the forest floor (O horizon). The uncertainty in this estimate is high (2 ± 19 kg N ha^-1 y^-1) due to large spatial variation in forest floor mass, as well as interannual effects that can bias sampling depth. However, the C:N ratio of the forest floor has increased slightly (p = 0.05), which is unexpected under the “N saturation” hypothesis.