Numerous physical, chemical, and biological processes operate in positive feedback loops during the invasion of C3 shrubs into C4 grasslands. These processes occur at multiple spatial and temporal scales, ranging from a few mm2 over a period of weeks to hundreds of km2 over a period of millennia.

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.

Stabilization of organic matter on mineral surfaces strongly affects rates of soil organic matter (SOM) accumulation and turnover. Controls over SOM are of particular interest in arid and semi-arid systems where the abundance of woody plants has increased globally over the past century. This proliferation of woody plants may lead to significant soil organic carbon (SOC) accumulation, although a large degree of uncertainty exists in the direction and magnitude of SOC pool responses to woody encroachment.

In arid ecosystems, current year precipitation explains a low proportion of the annual aboveground net primary production (ANPP). There is evidence that precipitation that occurred in previous years is responsible for the observed difference between actual and expected ANPP, a concept called legacy. Here, we study the mechanisms that generate these legacies, thus we will able to better understand the controls of the global carbon cycle, and to forecast changes in ANPP with a changing climate.

Primary production in arid and semiarid systems is predominantly limited by water availability. Precipitation is a strong predictor of primary production at broad scales in these systems. However, due to local variability in soil-water availability associated with landscape position, soil characteristics, and species composition, precipitation can be a pore predictor of production at finer scales. Thus, measured soil moisture content should provide a better predictor of primary production at fine scales.

The EcoTrends project is an LTER network-level synthesis program geared toward making long-term ecological data highly explorable, accessible and comparable for cross-site synthesis research. Five years of working with 50 sites (LTER, USDA ARS, USFS, and other agencies) have offered many lessons that can be utilized as we strive to improve and upgrade EcoTrends services. Here, we describe the project’s goals and products, discuss lessons learned, and lay out plans for a future system that will better serve the ecological research and information management community.

The Chihuahuan Desert, similar to many arid and semiarid ecosystems, has experienced dramatic changes in vegetation structure and ecosystem processes over the past 150 years. This “desertification” is manifested by the broad-scale expansion of unpalatable woody plants into perennial grasslands with associated loss of grasses and increase in soil degradation that compromise the ecosystem services provided to human populations.

Regime shifts from grasslands to shrublands in arid and semiarid ecosystems are thought to be irreversible, similar to state changes in other systems. We analyze long-term data from the Jornada Basin LTER site to determine if a directional change in climate provides an opportunity to reverse this conversion in the Chihuahuan Desert. We compare historical dynamics based on 140 years of landscape change (1858-1998) with 18 years (1990-2007) of detailed ecosystem responses under a variable climate to predict future responses under either a directional increase or decrease in rainfall.