Roundup: Plant Succession, Glacier Surges and Organic Pollutants

Phosphorus, Not Nitrogen, Limits Primary Succession

From Science Advances: “Current models of ecosystem development hold that low nitrogen availability limits the earliest stages of primary succession, but these models were developed from studies conducted in areas with temperate or wet climates. We combine field and microcosm studies of both plant and microbial primary producers and show that phosphorus, not nitrogen, is the nutrient most limiting to the earliest stages of primary succession along glacial chronosequences in the Central Andes and central Alaska. We also show that phosphorus addition greatly accelerates the rate of succession for plants and for microbial phototrophs, even at the most extreme deglaciating site at over 5000 meters above sea level in the Andes of arid southern Peru.”

Read more about the factors affecting plant succession in cold-arid regions here.

Plant succession occurring after the retreat of the Exit Glacier, Alaska (Source: National Park Service).

 

Tidewater Glacier Surges Initiated at the Terminus

From Journal of Geophysical Research: “There have been numerous reports that surges of tidewater glaciers in Svalbard were initiated at the terminus and propagated up‐glacier, in contrast with downglacier‐propagating surges of land‐terminating glaciers. We present detailed data on the recent surges of two tidewater glaciers, Aavatsmarkbreen and Wahlenbergbreen, in Svalbard. High‐resolution time series of glacier velocities and evolution of crevasse patterns show that both surges propagated up‐glacier in abrupt steps. Geometric changes near the terminus of these glaciers appear to have led to greater strain heating, water production, and storage at the glacier bed. Water routing via crevasses also likely plays an important role in the evolution of surges.“

Find out more about this proposed mechanism of glacier surges here.

Profile of a glacier during normal conditions (left) and during a surge event (right) (Source: Jean-Louis Etienne).

 

Hexachlorobenzene Accumulation in Svalbard Fjords

From Springer: “In the present study, we investigated the spatial and historical trends of hexachlorobenzene (HCB) contamination in dated sediments of three Svalbard fjords (Kongsfjorden, Hornsund, Adventfjorden) differing in environmental conditions and human impact. HCB concentrations ranging from below limit of quantification (6.86 pg/g d.w.) to 143.99 pg/g d.w. were measured… In case of several sediment cores, the HCB enrichment in surface (recent) sediments was noticed. This can indicate importance of secondary sources of HCB, e.g., the influx of HCB accumulated over decades on the surface of glaciers. Detected levels of HCB were generally low and did not exceed background concentration levels; thus, a negative effect on benthic organisms is not expected.”

Discover more about organic pollutions in Norway here.

The Arctic fox and other living organisms in Svalbard could be affected by hexachlorobenzene contamination (Source: Natalie Tapson/Flickr).