What (and when) is the point-of-no-return?

How-and when-do ecosystems change character? Are those shifts reversible? And what signs might precede them? Such questions are hard enough to answer in a single place. One might think that incorporating different kinds of ecosystems would only complicate the problem. But a group of scientists in the Long-Term Ecological Research Network is finding a remarkably consistent pattern by combining models and data across several long-term ecological experiments.

Climate variability predicted to affect outcome of exotic grass invasion

Novel ecosystems can emerge through many kinds of changes, including changes in mean climate, species invasions, and increased or decreased variability. Researchers at Jordana Basin LTER have highlighted the role of interannual climate variability in changing the outcome when an exotic grass species invades dry shrubland. Using a process-based model, they predicted three outcomes, depending on the degree of variability and timing relative to invasion.

Genetic Differences May Help Corals Adapt to Changing Conditions

Individuals—even individuals of the same species—don’t always respond to a stimulus in the same way. Studying calcification in a key coral species, Acropora pulchra, researchers at the Moorea Coral Reef LTER found greater variety in the corals’ response to temperature than to high levels of CO2 in seawater. Since individual variation is the raw material of evolution, the contrast suggests it may be easier for this coral species to adapt to rising temperatures than to increased ocean acidification.

The Spruce and the Hare: Backing Up Leopold’s Intuition

snowshoe hare

Snowshoe hares prefer many other plants to white spruce seedlings, but when the population of hares skyrockets—as it does about once a decade—they can decimate even a bumper crop of spruce seedlings. Researchers with the Bonanza Creek LTER reconstructed over 40 years of browsing history by analyzing the age and browse scars of thousands of seedlings and saplings at 18 locations on the floodplain of Alaska’s Tanana River.

The grazing effect: How bison impact plant water use

When one envisions a grassland community, imagery of tall grasses and bison often come to mind. Bison are an iconic species on the landscape, and they also impact the structure and function of the grassland ecosystem in important ways.  Using natural variations in the abundance of oxygen isotopes, researchers at the Konza Prairie LTER found that  grazing influenced plant water use through changes in diversity.

Harvard Forest researchers say whitebark pine tree’s future may be at risk

New research by Harvard Forest (HFR) LTER scientists suggest that widespread death of the whiteback pine tree from beetle infestations and tree disease outbreaks may be affecting seed production and hence the future of the tree–a mountain tree important to wildlife and water resources in the western United States and Canada. In a paper published… Read more »

Harvard Forest carbon research featured on NSF “Science Nation”

The National Science Foundation’s online video magazine, “Science Nation,” has released a short video featuring long term research by scientists at the Harvard Forest (HFR) Long Term Ecological Research (LTER) program to determine how the forest responds to carbon dioxide in the atmosphere. The short video and the accompanying short article can be viewed at… Read more »

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