The ice-covered lakes in the McMurdo Dry Valleys, a polar desert, rely on glacial melt for almost all their inputs. A recent study of Lake Fryxell suggests that in this environment even small changes in climate can impact biological productivity in the lake.
A recent experiment examined the impacts of increased nitrogen on salt marshes—and the all-important microbes within them.
Nitrogen enrichment can dramatically change the existing environment for plants and typically leads to increased productivity, decresed diversity, and shifts plant community composition. But what mechanisms are responsible for these changes? Researchers designed a multi-site experiment to find out, experimentally manipulating each of three possible drivers across mesocosms of three ecosystem types (tall grass prairie, alpine tundra, and desert grassland).
New analyses demonstrate that long-term nitrogen enrichment substantially changes the community composition of soil fungi in a temperate hardwood forest. The mix of fungal taxa that emerges appears to be better able to tolerate high nitrogen but less able to break down the lignin in organic matter, which contributes to an overall accumulation of soil carbon.
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).
In stratified lakes, a large portion of phytoplankton biomass is found—not at the surface, where sampling is easiest—but somewhere down the water column, in what is known as a subsurface chlorophyll maximum (SSCM). Researchers in Global Lake Ecological Observatory Network (GLEON) compared automated high-frequency chlorophyll fluorescence (ChlF) profiles with surface samples and discrete depth profiles. In 7 of the 11 lakes studied, automated sampling captured the presence of SSCM’s that would have been missed by conventional sampling.
How do you begin to approach wicked problems, those that span socioeconomic and ecological spheres, when solutions involve multiple and varied stakeholders? Researchers at the Kellog Biological Station LTER began to tackle one of U.S. agriculture’s greatest challenges, excess nitrogen pollution, by hosting “The N Roundtable,” to improve the flow of information through a farming landscape that has changed dramatically in the past few decades.
Fungi, often spotted in cold, damp locations, are responsible for decomposing the plant litter that falls to forest floors, enriching soils. Without fungi, dead plant material would inundate ecosystems and overwhelm other organisms. What would happen, then, if anthropogenic nitrogen altered the fungi’s ability to perform this vital ecosystem function? A recent study capitalized on a 28-year nitrogen enrichment experiment at the Harvard Forest LTER site in north-central Massachusetts to find out. As nitrogen inputs to a system increase, researchers found, fungal decomposition slowed.
Talk Description: Air pollution control efforts have succeeded in reducing sulfur dioxide and nitrogen oxide emissions, but decades of acid rain have leached calcium and magnesium from Northeastern forest soils. These changes have increased the mobility of dissolved organic matter, and possibly altered soil organic matter dynamics, altering the long-term trajectory for forest ecosystems. What… Read more »
Scientists studying salt marshes at the Plum Island Ecosystem (PIE) Long Term Ecological Research site have long wondered why the marshes were disintegrating and dying at a faster rate than normal. Writing in the journal Nature this week the scientists, led by Linda Deegan of PIE and the Marine Biological Laboratory (MBL) in Woods Hole,… Read more »
E Zambello/LTER Network Office CC BY 4.0" data-envira-gallery-id="site_images_45201" data-envira-index="2" data-envira-item-id="82129" data-envira-src="https://lternet.edu/wp-content/uploads/2019/11/k-66-scaled-e1574700614704-600x367.jpg" data-envira-srcset="https://lternet.edu/wp-content/uploads/2019/11/k-66-scaled-e1574700614704-600x367.jpg 400w, https://lternet.edu/wp-content/uploads/2019/11/k-66-scaled-e1574700614704-600x367.jpg 2x" data-title="Konza Prairie Biodiversity Plots" itemprop="thumbnailUrl" data-no-lazy="1" data-envirabox="site_images_45201" data-automatic-caption="Konza Prairie Biodiversity Plots - E Zambello/LTER Network Office CC BY 4.0" data-envira-height="183" data-envira-width="300" />
E Zambello/LTER-NCO CC BY 4.0" data-envira-gallery-id="site_images_45201" data-envira-index="5" data-envira-item-id="80731" data-envira-src="https://lternet.edu/wp-content/uploads/2019/01/CAP1-e1548191193111-600x400.png" data-envira-srcset="https://lternet.edu/wp-content/uploads/2019/01/CAP1-e1548191193111-600x400.png 400w, https://lternet.edu/wp-content/uploads/2019/01/CAP1-e1548191193111-600x400.png 2x" data-title="CAP1" itemprop="thumbnailUrl" data-no-lazy="1" data-envirabox="site_images_45201" data-automatic-caption="CAP1 - The Tres Rios wetland of Phoenix, Arizona. E Zambello/LTER-NCO CC BY 4.0" data-envira-height="173" data-envira-width="300" />
