Bi-stability in North American ecosystems: analyzing woody plant cover for temporal stable-state dynamics

Woody encroachment is occurring worldwide (Archer 1995), with negative
effects on biodiversity in North America (Ratajczak et al. in press) and
uncertain effects on ecosystem functioning (Barger et al. 2011). The
spatial properties of tree and grass dominance are well-studied and
strongly suggest that woody encroachment of grasslands represents a
shift to an alternative stable state (Archer et al. 1995, Shaver et al.
2001, Briggs et al. 2005, Young et al. 2007, Bond 2008, Sankaren et al.
2005, Browning et al. 2008, D’Odorico et al. 2011, Staver et al. 2011).

Forecasting Rates of Riverine Leaf Litter Decomposition in Response to Inland Climate Change

Recent work has suggested that freshwater ecosystems may play a significant role in the global carbon cycle, potentially emitting 1.2 Pg C y-1 to the atmosphere [1, 2]. The majority of the CO2 that is degassed from streams and rivers comes from the decomposition of allochthonous leaf litter inputs [3, 4]. The process of decomposition fuels aquatic food webs, helps to regulate surface water acidity, and links biogeochemical cycles [5, 6].

A Data Synthesis Working Group: Disappearing Snow in the Western US: Ecosystem Implications for the Rain-Snow Transition Zone

Introduction and Goals:

In the Western US mountain regions, winter temperature increases will lead to the reduction and even loss of winter snowpacks.

A shift from snow to rain-dominated systems will alter seasonal patterns of streamflow, soil moisture, soil temperature, etc. affecting a myriad of ecosystem processes.

This proposed work will develop a working group and fund a student to aggregate and synthesize data relevant to the ecosystem implications of disappearing snow in the rain-snow transition of the Western US.

Understanding Interactions within the LTER Network for Improved Collaboration

This proposed effort will “stimulate cross-site and Network-level synthesis” by addressing issues of collaboration within the LTER network. Scientific synthesis should be promoted as we better understand the nature of that collaboration.

The concept that the LTER program works as a network of interacting sites and scientists is grounded in the earliest documents of the US LTER (Callahan 1984) through the most recent decadal plan (US LTER 2007).

The initiatives proposed in recent documents (US LTER 2007) cannot be achieved without this interaction.

The Influence of Precipitation Variability on Diversity and Composition of North American Grasslands

Overview:

We propose to organize a working group that will analyze and synthesize long-term data on the relationship between precipitation variability and the structure of North American (NA) grassland plant communities.

This project will build on prior LTER-related synthetic efforts that have evaluated the response of aboveground net primary productivity (ANPP) to precipitation variability [1-2] and the relationships among ANPP, plant community composition and resource availability [3-7] in NA grasslands.