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December 2016
LTER in the News
News from the National Science Foundation Other Media
Recent LTER Publications
Demystifying Governance for Ecologists |  Ecosphere
vegetable truck

There are certain events, such as severe storms or a crash in financial markets, that catalyze transitions in social-ecological systems, in a process that is akin to the way a hurricane or insect outbreak might catalyze an ecological transition. To understand the patterns that emerge in social-ecological systems, ecologists must understand governance, a process rooted in the key social science concepts of power and networks. 

Using illustrations from cities in which long-term social-ecological governance research is underway, this group of urban ecologists and social scientists identifies and synthesizes important governance dimensions of urban sustainability transitions. When ecologists develop pathways for sustainable urban transitions, the authors say, they need to consider not only the ecological conditions, but also people’s values, visions and social relations. They argue that understanding the dynamics affecting governance networks and linking these with environmental stewardship practices is essential to nurturing transformative and sustainable changes in urban ecosystems. --Erin O'Reilly

Coastal Everglades in the Cold: Mapping Ecological Sensitivity |  Wetlands

How sensitive are coastal ecosystems to sharp changes in temperature? Using a detailed spatial analysis in the Florida Everglades, researchers found that cold snaps reduced ecosystem productivity most dramatically in areas with low water levels that were located away from the coast. With more extreme weather events predicted in the future, knowing the likely effects of low temperature events on subtropical wetlands systems can inform management of these important ecosystems. 

Over a four year period (2009-2012), researchers sampled three sites across the Florida Everglades National Park, accounting for variations in water inundation heights and duration across freshwater marshes as well as coastal mangrove forests. Results demonstrated that a site’s sensitivity to low temperature events (<5°C) varied by water level and geographic proximity to the coast, both of which influence the frequency and intensity of these cold weather events. At sites where low temperature events were less frequent, photosynthetic capacity declined more sharply in response. The differences in CO2 assimilation rates in response to temperature highlights the changes that could occur to species and ecosystem functioning in response to climate change. --Madison Harris

Growing Grass: A Story of Nitrogen, Phosphorus, and Leaf Size | Oecologia
bison grazing

Ecologists know that nitrogen, phosphorus and leaf area play key roles in the productivity of plant communities. But how tightly are they tied together? And are those relationships sustained over different types of landscapes? A recent study of tallgrass prairie communities, building on a previous study of arctic tundra, found leaf area index (LAI) to be strongly correlated to both total foliar nitrogen and total foliar phosphorus in several plant functional types (grass, forb, woody, and sedge) and grazing treatments (cattle, bison, and ungrazed). 

These findings suggest that in many kinds of systems, optimal growth requires a consistent ratio of N and P per unit leaf area. Co-limitation, in which higher levels of N may not lead to an increase in primary productivity if not coupled with a similar increase in P, may be more common than ecologists have thought. Furthermore, since researchers can use LAI to infer changes in primary productivity regardless of vegetation type and grazing treatment, they may now also be able to predict plant N and P on an areal basis, using remote sensing. This would make it easier to assess the spatial distribution of these limiting nutrients resulting in more informed predictions about ecosystem productivity and other ecological functions. --Alina Werth

Winter Conditions Vital to Year-Round Lake Dynamics  |  Ecology Letters

ice fishingThis month’s Ecology Letters features the first global quantitative synthesis of under-ice lake ecology. In their analysis of 36 abiotic and biotic variables across 101 lakes, the authors issue a call to arms for more winter lake research—currently the focus of only 2% of freshwater publications. As the climate warms, they warn, temperate ecosystems are losing ice, and limnologists remain unsure what ecological processes are at stake. Though winter has long been understood as an inactive period, some data suggests that winter foodwebs and physical processes remain vigorous and that winter ecology can drive subsequent summer conditions. 

The synthesis results confirm these observations: while primary producers and consumers are less abundant under ice, they maintain substantial populations, which along with relatively high chlorophyll a values, suggests high productivity in winter waters. In addition, the scientists found frequent correlations between values from winter and the previous/subsequent summer. For both plankton and chlorophyll, a summer peak often preceded a winter low, and vice-versa. The authors urge the limnological field to explore the drivers of these relationships, in order to better understand how changes in winter weather will alter year-round lake dynamics. --Terra Alpaugh

Announcing 2017 LTER Synthesis Working Groups!
Synthesizing Population and Community Synchrony to Understand Drivers of Ecological Stability across LTER Sites
Populations of plants, animals, and microbes fluctuate all the time. Whether populations rise and fall in tandem, independently or alternately can affect ecological stability. Offset fluctuations between species can enhance ecosystem stability. Or alternate fluctuations of the same species in different regions can support species stability. Building on many sources of long-term data, the LTER Synchrony working group aims to understand the drivers and timescales of synchrony and its effect on ecological stability.

Scaling-Up Productivity Responses to Changes in Biodiversity
It seems like a simple question. Are diverse ecosystems more—or less—productive? Most experiments to test the question are done on small plots. Scaling up to natural ecosystems introduces complications that could tip the balance toward a stronger—or a weaker—connection. Drawing on data from biodiversity experiments at multiple LTERs and global experimental networks, the Biodiversity and Productivity working group asks what role time scales, spatial scales, type of experiment, and ecosystem type have on the strength of this key relationship.
In the 1990s, scientists at McMurdo LTER, NSF representatives, and international partners held three collaborative workshops to develop protocols for working in the Dry Valleys while protecting the ecological integrity of this vulnerable region. In May 2016, 53 attendees from six nations again convened to examine the efficacy of present management and make recommendations for future strategies. Their conclusions and recommendations are now published online
Open Positions
Photo Credits (top to bottom): Baltimore Ecosystem Study LTER; Florida Coastal Everglades LTER; Konza Prairie LTER; John Magnuson (NTL); Jacob Miller (CDR).
Copyright © 2016 LTER Network Office, All rights reserved.

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